In my first chainsaw post I discussed saw sizes and components. No component is more important than the chain that does the work. And no aspect of a chainsaw is as controversial and creates more arguments among users than the type of chain you should use.

Chainsaw Chain Basics

A chainsaw chain consists of drive links, cutters, tie straps, guard links, and the rivets that hold them all together. Oregon has a great picture showing these parts at http://www.theoregonshop.com/userimages/ChainParts.jpg.

By Horst74 (Own work) (Public domain)

All the parts are also shown in the photo at left. The parts don’t matter to most users since most people don’t assemble their own chain. But understanding them helps when it comes to understanding chain sizes.

Chain Sizes

Saw chain size is defined by three parameters:

1. Gauge, or the length of the links.
2. Pitch, or the thickness of the drive links.
3. Length, or the number of drive links.

There’s a picture of this on the page at http://www.stihllibrary.com/pdfs/SawChainSelection.pdf from Stihl. Remember that chains are sized according to the bar they run on, not necessarily by the size of the powerhead, although larger powerheads tend to run larger bars, so there is some relation. In general, smaller saws with bars under 16″ run chain as small as 1/4″ pitch. Medium size saws with bars between 16″ and 20″ run .325″ or 3/8″ pitch chains. Larger saws with bars longer than 20″ may run .404″ pitch chain.

Chain information stamped on my guidebar.

For example, my 18″ Rollomatic E bar on my Stihl MS 290 runs .325″ pitch chain, .063″ gauge, with 74 drive links. here is the information plate from the bar. I also have an older Rollomatic E bar that is the same 18″ length which I used to run on my old 032AV, which is actually a 3/8″ pitch, .050″ gauge, and takes a chain with 66 drive links.

Although it’s important to buy the correct size chain for your bar, most people don’t pay much attention to other parameters. Some people like to argue the merits of .325″ pitch chain vs. 3/8″ pitch, but most people don’t care. What people do care and argue about is the type of cutters on the chain.

Chain Cutter Types

The number one argument among chainsaw people is whether full-chisel or semi-chisel chain is better. What’s the difference? It has to do with how much of the cutter is sharpened and the geometry of the cutter on the chain itself. A simple explanation is that if you look at a full chisel chain end-on, the cutter looks like the number seven “7″. A semi-chisel chain looks like a question mark, “?”. There is also a difference in how much of a point is filed into the front profile of the cutter, with full chisel chain having a sharp point, while semi chisel is flatter.

Wikipedia says this:

Full chisel chain has a square cornered tooth, splitting wood fibers easily in the cut for fast, efficient cutting in clean softwood. Semi-chisel chain has a rounded working corner formed by a radius between the top and side plates. While slower than full chisel in softwood, it retains an acceptable cutting sharpness longer, making it the preferred choice for dirtier wood, hard or dry wood, frozen wood or stump work, all of which would rapidly degrade full chisel chain.

Chain Types (from Bailey's)

Bailey’s, an excellent source for chainsaw parts and chain for all brands posts this picture describing chain types. (Note that what I call full chisel they call round chisel – same stuff.) For homeowners and non-professionals the choice is really between full or semi chisel. The other stuff, especially square chisel, is used only by pros and really dedicated amateurs.

The Argument

One of the best sites for chainsaw information on the Internet is Arboristsite.com. And they relish the debate over full or semi-chisel chain.

For example, see this thread from 2007. Or this thread from 2004. Or this thread from 2006. Or this thread from 2004. Or this recent thread from 2011. Get the picture?

Reading through all those threads the consensus opinion is that full-chisel chain cuts faster when sharp, but loses its edge quickly, especially in “dirty” wood. Semi-chisel chain cuts a little slower, but holds its edge much better. So which is better? For homeowners and occasional users it really doesn’t matter. You see, most of the argument happens between guys that cut wood for a living. Or at least serious amateurs who spend hours in the field on any given day. So to them, the speed that a chain cuts makes a difference in how much money they make. For me it doesn’t. I simply don’t cut that much wood.

And the definition of “dirty” certainly isn’t standard. Is dirty wood a log that has been skidded on the ground through a swamp and is caked in mud? Some people in those threads argue that trees which grow on the side of dirt roads count as dirty because of the microscopic sand embedded in the bark. The point is – the posters are technically right. In my experience full-chisel chain dulls quicker than semi-chisel. But since I don’t cut ten trees a day it doesn’t matter to me if it dulls and slows down much. I’ll spend a few more minutes with the file between tanks of gas if I have to – it gives my back a rest! So read the posts and make up your own mind. But realize that for occasional use, it probably won’t make much of a difference.

What do I Run?

Keep your chain out of the dirt. Here I am using a timberjack to lift a large trunk off the ground to prevent running my saw into the dirt.

Mostly full-chisel chain. Currently I have four loops of Stihl RSC (Rapid Super Comfort) full-chisel hanging in my tool shed. I also have two loops of Stihl RMC (Rapid Micro Comfort) semi-chisel hanging there. Most of the time I run the RSC full-chisel. Even in hardwood (I cut mostly oak and maple here in Massachusetts, with some white pine thrown in) and even in cold weather when the wood may be frozen. But I am very careful, and after years of experience am quite adept, at keeping the bar out of the dirt. Because it doesn’t matter whether you’re cutting hardwood or softwood and whether the wood is dirty. Nothing will kill your chain faster, whether full or semi-chisel, then running your bar into the dirt and rocks under a log!

Note that I mentioned using a file. Yes – you must sharpen your saw chain. No, taking it back to the hardware store doesn’t count. Sure, all chains need to be reground periodically, but a single chain is only going to last a couple of hours, even in clean wood, before it needs to be touched up. In this area the forum consensus is also right: semi-chisel chain will go longer between filings. If you have no intention of learning how to file a chain, you need to assume that you will go through three to six chains in a full day of work and plan on buying that many. So if you only want to to take them back to the store for sharpening, buy six or eight or ten loops to get you through a full weekend’s work.

So my recommendation comes down to this:

• If you are careful with your cutting and keep your bar out of the dirt, full-chisel will work for most applications, if you’re willing to occasionally file and maintain the chain.
• If you are new to using a saw and don’t want to file your own chains, run semi-chisel.

Regular or Reduced Kickback Chain

In my previous post about guidebars I mentioned that manufacturers make both regular and reduced kickback bars. I said that there wasn’t a tremendous difference between them and I saw no reason not to run the reduced kickback versions. The same is definitely not true for chain, where there is a tremendous difference between regular and reduced kickback versions.

This is an argument that the guys on ArboristSite REALLY like to engage in. Look no farther than this 8 page thread from 2009. There is another good one from 2010 also. In their world, reduced kickback chain is called “safety chain” and all safety chain is shit. My experience tells me that the real world isn’t so cut and dried. I started cutting long before the ANSI B 175.1 chainsaw safety standard was introduced in 1985. So reduced kickback chain wasn’t readily available until I had already been cutting for close to ten years. And current reduced kickback chain has improved tremendously over the stuff that was originally available.

That said, it is generally accepted that modern reduced kickback chain cuts a little slower and less aggressively than regular chain. This varies considerably between manufacturers and even within a manufacturer’s line between chain types. Because I am familiar with Stihl, that’s what I’ll use for my comparison.

When I bought my MS290, it came from the dealer with a loop of Stihl RSC3 full-chisel reduced kickback chain (identified by a green master link). When I first started the saw and cut with it I thought it worked pretty well, though it didn’t “pull” into the cut in the way I was used to with my old saw. But it cut well enough. After a while I switched over to a loop of RSC full-chisel regular chain. And the saw instantly felt more like I was used to. It really grabbed and pulled into the cut. But this same aggressiveness is what can make the saw kick back if the operator isn’t careful.

So I’m not going to get deep into this argument. From my personal experience, modern reduced kickback chain works well. I had no real problems with the RSC3 chain that came on my saw, and I certainly have the loop sharpened and ready to go. If I ever loaned my saw to someone, this is the chain I would give them until I really trusted them. But I admit that I do use the yellow link regular RSC chain most of the time. With all the years I have behind the saw I feel I’m prepared for the increased kickback potential. Your situation may be different. On your first saw I would always recommend a modern reduced kickback chain. Read the threads I referenced above if you want to learn more.

Good luck and safe cutting.

R.I.P. - 1982 to 2011

A couple weeks ago, Mr. Murphy paid me a visit and I had to replace my beloved 29 year old Stihl 032AV chainsaw. Soon after I wrote about how awesome and reliable it was, a valve in the chain oil system cracked and the part wasn’t available for a saw that old. So I had to buy a new one.

What I realized during my research is that there is a lot of confusion about the basic components of a chainsaw and few places where someone can find comprehensive answers. There are some great sites with very comprehensive answers and where professionals share their experience with homeowners, but it would still help to have an grasp of the basics before wading into these arenas.

What gives me the right to talk about this? I consider myself an advanced amateur. I grew up in a time and a place where there were far fewer nanny state rules. I was given my first real gas powered chainsaw at 10 years old and, after watching my dad for a while was given the intensive safety training of, “Don’t kill yourself,” and turned loose on brush piles with a Homelite saw with a 12″ bar. Bu the time I was 13 I was given a new Stihl 032AV (pictured above) and turned loose on 75 acres of fields and woods to cut whatever the hell I wanted. As long as there were a few cords of firewood for winter, no one cared. I used to practice felling trees by driving sticks into the ground in a field where I wanted the tree to fall and trying to drive them into the ground by dropping the trunk on top of them. Since then I’ve felled hundreds of trees, cut many cords of firewood, and cleaned up after dozens of storms. For a summer I worked for the US Forest Service in the early 90′s and that’s where I actually learned about safety and technique. I didn’t get to run the saw, but I was on work crews with guys who really knew what they were doing. And I soaked in everything I could.

What I wear now.

Gone are the days of being an invincible kid with no safety gear at all. You will never catch me cutting now without my full compliment of chaps and forestry helmet (hard hat with built in face shield and ear protection).

So, based on that experience, here’s what you need to know.

Types of Chainsaws

Manufacturers usually divide their chainsaw lines into three categories. Known by various names, I will call them: Homeowner or Occasional Use saws; Medium Duty saws; and Professional or Heavy Duty saws. In general, as you move up from Homeowner to Professional saws you get larger sizes (both bar length and engine displacement), more power, and more advanced features (like high efficiency engines and anti-vibration features).

I am partial to Stihl chainsaws, for no reason other than I have always lived near quality Stihl dealers. So I’ll use their line as an example.

A middle of the pack Occasional Use saw might be the MS 211. Offering a 2.2 in³ engine that produces 2.3 horsepower, Stihl recommends guide bars in 12″, 14″, or 16″ length. Other than some new engine technology Stihl is introducing, there are no special features to this saw, though some Homeowner saws have “convenience” features like easy start systems. Saws in this class would typically be used for cutting small trees (up to maybe 16″ in diameter), large branches and pruning ornamental plants, and light cutting of firewood.

Out with the old and in with the new. My new MS290 and my old 032AV

A Medium Use saw is the MS 290 (my most recent saw). The 290 has a 3.45 in³ engine making 3.8 horsepower (65% more than the MS211). Stihl recommends guidebars in 16″, 18″, and 20″ lengths. In addition to the basic features, medium range saws offer adjustable chain oil rates, anti-vibration systems (which help reduce fatigue when using the saw for hours at a time), and easy access maintenance features. Medium use saws might be used for felling trees up to 36″ in diameter, limbing large trees, and bucking (cutting into smaller lengths) trees for firewood.

A Professional saw is the Stihl MS460. With a 4.6 in³ engine making 6.0 horsepower (58% more than the MS290). For this saw, Stihl recommends guidebars in 18″, 20″, 22″, or 28″ lengths. Saws in this range get the latest features to make them light and powerful. This saw might be used for felling trees to 48″ in diameter and bucking large trees. The largest Professional saw in Stihl’s line, the MS880 Magnum can take a guidebar up to 59″, for felling trees 6, 7, 8, or even 10 feet in diameter.

What Size Saw Do You Need?

Because chainsaws tend to be tools for men, there is a perception that bigger is always better. That perception is commonly held by people who have watched too many episodes of Ax Men on TV and have never spent a day bent over cutting firewood with a 20 lb. chainsaw.

Chainsaws can be dangerous, and a bigger saw can let you get into dangerous situations faster than you might expect. So it is important to match the saw to the job you will actually be doing. For example – even when I fell a 30″ diameter tree, that whole process might take 120 seconds of actual cutting. But the next two hours will be spent limbing and bucking that tree into firewood. So as nice as an MS880 Magnum would be during the felling process, my back is much happier limbing with my MS290 for the next two hours because it weighs ten pounds less.

You need to realistically assess the size jobs you will really do. Will you really be felling three or four foot diameter trees? That can be difficult and dangerous work and it’s way too easy to drop a tree on your home or car if you don’t know what you’re doing. Want proof? See this video:

Or this one:

Or this one:

Remember – each of these guys thought they were smart enough to handle the job. Although lack of safety equipment, no felling wedges, or no notch and back cuts is usually a dead giveaway that someone doesn’t have a clue.

Here’s your first pro tip – the saw binding in your felling cut is nature’s way of telling you something is screwed up and the tree isn’t going the way you expect. This is why they invented the felling wedge.

Here’s your second pro tip – if you don’t know what a felling wedge is, stick with an Occasional Use or smaller Medium Duty saw.

If you want to know and see how they are used properly, this guy on YouTube gives a great lesson in cutting a tree that’s leaning in the wrong direction and safely directing it where he wants it using wedges. When you can do cuts like this, you’re ready for a large saw and larger trees.

Chainsaw Parts

To many people, this whole system is a “chainsaw.”

In fact, a chainsaw is made up of several components, and it is common to mix components from a variety of manufacturers. The basic anatomy of a chainsaw is:

• The engine or powerhead. This consists of the engine and related controls, the oiling system, and related components.
• The guidebar. This is the bar on the front of the powerhead around which the chain runs.
• The cutting chain. Exactly what the name says. This is the chain that does the cutting.

Information about the proper chain to use is on the guidebar, not the powerhead. Here's the block on my Stihl MS290.

On all but the cheapest Occasional Use saws, you can buy chain and guidebar systems from a different manufacturer than made the powerhead. For example, many Stihl chainsaw owners use guidebars and chain made by the Oregon company.
Here’s the important thing to know: the chain on a chainsaw must be matched to the guidebar, not to the powerhead model. And the drive sprocket must be matched to the chain as well. So there really is no answer to the question, “What chain do I run on a Stihl MS290?” The answer is, it depends on what bar you have. The picture on the right shows the information from my MS290. It tells me I should run a .325″ pitch chain, .063″ gauge, with 74 drive links on this 18″ bar.

Guidebar Types

In America, there are really only two guidebar manufacturers. Stihl and Oregon. Any brand of chainsaw other than Stihl uses Oregon manufactured bars, even if their own brand name is on it. And regardless of which manufacturer you use, there are two broad categories of guidebars, regular and reduced kickback.

Kickback is the rapid and unexpected movement of a chainsaw towards the operator caused when the chain on the top of the guidebar sticks in a cut or contacts something in a dangerous and unexpected way. If this happens at the tip of the bar, the movement of the saw and running chain is both back toward the operator and up towards the operator’s head. This is perhaps the most dangerous type of chainsaw accident and a very common occurrence. A good demonstration by a chainsaw instructor is in this video:

A common way for kickback to occur is during plunge cutting (when the tip of the guidebar is pushed straight into a cut, rather than a slicing cut made with the top or bottom of the guidebar). To lessen this, reduced kickback guidebars tend to be fatter in the middle and tapered towards their ends. Compare the Stihl Rollomatic E reduced kickback bar against the Duromatic E standard bar on this page for an example. Note that in the picture, the Rollomatic bars have a green dot at the end and the Duramatic bars have a yellow dot. Stihl uses this color coding system to designate bars and chain as reduced kickback (green dot) or regular (yellow dot). Oregon uses blue dots for reduced kickback and yellow for regular.

I have run reduced kickback bars on my saws for years and never missed my old straight bars once. In my mind, there really isn’t a decision to be made here. If you’re reading this you should be running a reduced kickback bar.

Chain

The next discussion is about chain types. But this discussion among chainsaw people is like asking someone what beer is the best or which football team to root for. There is a lot of fighting and arguing that takes place, so I intend to cover this in a second post. Keep an eye out.

A while ago I wrote about my Black and Decker home energy monitor. I mentioned that I had problems with the sending unit leaking and then failing soon after I received it. So Black and Decker replaced the sending unit under warranty. Well guess what … the second one died about six months later. This time it didn’t leak, it just stopped transmitting. Yes I’ve changed the batteries and re-sync’d it. I’ve removed and reinstalled it. It simply doesn’t transmit a radio signal any more.

So even though I was originally pretty happy with this thing, I now recommend that you stay away from this and do not buy a Black and Decker Power Monitor. Unlike many of the negative reviews on Amazon, mine has nothing to do with setup or whether it will work on your meter. Rather, the quality of the sending unit seems poor. As always, your mileage may vary, but my experience with this unit has been bad. I think I’ll buy a TED monitor system instead.

HF Blaster Gun

It was time for a big tent sale at Harbor Freight tools and I made a trip today. Picked up a few things, including a really good (and cheap) sand blasting gun. I used it to prep the surface of my New Braunfels smoker for painting. I liked it enough to give it its own page.

Give my Harbor Freight page, and especially the review table, a good read if you’re interested in tools.

I finally finished cataloging and writing mini reviews of all my Harbor Freight tools on my updated Harbor Freight page. If you buy from them it’s worth a read. Also check out the new data table using the WP-Table Reloaded plugin.

Life with a Kohler 12RES (12 KW) whole house backup generator.

1. Background
2. Decision to Buy
3. Installation
4. Review

(7/9/2009) When I originally wrote this I had no idea it would become the most popular post on this blog. Please — I’d like to improve it and make it more useful. Post comments if there are areas you’d like me to add or fix.

I spent a large part of my life growing up in rural Pennsylvania. I actually split my time between suburban New Jersey where I went to school and an 80 acre farm approximately 40 miles from Scranton, PA at the northern end of the Pocono mountains. For most of the time that my family owned it, the farm had a single house originally built in the mid 1800s. It sat up a 1/2 mile long driveway off of a dead-end dirt road. The power lines ran cross country to the house, and needless to say, with few customers in this area PP&L (Pennsylvania Power & Light) wasn’t interested in responding to calls at a moment’s notice. Which meant that we spent a lot of time without electricity. And I don’t mean one hour interruptions either — I mean that the place was without electricity for a full week at least once if not two or three times a year.

When I was young, this was a workable arrangement for my family, but once I left for college (I’m an only child) and my parents started aging, they couldn’t go for days on end carrying buckets of water from a surface well to the toilets to flush them (or head to the outhouse in the back yard in winter) or devote the time to splitting, stacking, and carrying enough firewood to keep the stove burning for 7 days straight in the winter. So they eventually built a second, modern ranch-style house and had a generator installed. This setup consisted of a 7.5 KW gasoline-powered generator located on a concrete pad outside the back door and a manual transfer switch in the basement connected to a panel which ran a few lights, the water pump, the furnace, one light or outlet in each room (including one for the refrigerator in the kitchen), and an extra outlet in the living room for the TV. Since they cooked with a gas stove, they were also able to cook.

This was a dramatic improvement, but still not an optimal solution. By today’s standards it was a terribly inconvenient installation, primarily because it meant that my parents had to constantly pour gasoline into the thing to keep it running (about every 8 hours at a moderate load), even though they cooked and heated with propane and had a giant bulk tank right in the driveway. Plus, a manual transfer switch isn’t fun for young people, never mind my almost elderly parents tromping down to the basement by flashlight in order to throw this thing on and off.

So, when I bought my latest house in Massachusetts and my parents sold the farm in Pennsylvania, we used some of the proceeds to investigate a new generator.

Right about the time that I started research, whole-house generators were gaining popularity. The largest manufacturer, Generac/Guardian, started to put commercials on major TV networks showing people making margaritas with a blender during a major thunderstorm that knocks out power to their neighborhood. Sounded good to me.

I researched brands, sizes and types and learned a few things along the way. I quickly established that I was interested in a whole-house unit with an automatic transfer switch. I had no desire to tote large tanks of gasoline around and constantly fill up a small portable unit. Nor did I want to worry that my pipes were freezing while I was on vacation because even with a generator there would be no one around to plug it in and run it. So a propane fueled whole-house system was what I focused on. Here are a few things I discovered along the way:

1. The market for residential systems is dominated by Generac/Guardian and Kohler.
2. Other than the manufacturers, there is almost NO information on the web about installing or living with a residential generator.
3. There are very few installers who deal with residential generators and the special concerns that accompany a residential (as opposed to a commercial) installation. Like siting the generator so it doesn’t piss off your neighbors, and taking the aesthetics and usability of your yard into consideration.
4. Most propane/gas companies are useless when inquiring about these units, even when they sell them. Only a good propane supplier will take the time to work with you for little return. After all, if the generator is all you run with propane, you will be a very tiny customer for them.
5. Many small town inspectors outside of traditional hurricane country have never seen these units and could be a significant impediment to the installation, unless they’re willing to learn and adapt like mine was.

If you are interested in a generator like this, unless you find one of the top installers in the country (like I believe I did), you had better prepare yourself for some serious learning. I believe that to truly do an installation yourself and get a satisfactory product, you will need to become familiar with:

1. Propane measurements and usage requirements. This includes understanding bulk propane delivery units, tank sizes, headspace, vaporization rates at various temperatures, pressures, volumes, and what BTUs represent. You’ll need to make sure that your tanks can deliver the propane required to run the generator at the lowest temperature you’d expect it to run.
2. Propane company delivery plans including renting vs. owning the bulk tanks, auto-delivery, minimum usage, etc.
3. Flammable gas piping requirements including materials required (black iron, galvanized, other), minimum distances from ignition sources, easy access for delivery, flow rates, pipe sizes, burial requirements, etc.
4. Generator siting requirements including gravel vs. poured concrete pads, minimum code required distance from openings (windows, doors), sound requirements, etc.
5. Electrical codes including load requirements for what you want to power, circuit panel capacity, wire gauges vs. distances, pass through requirements, transfer switch requirements, electric company rules, etc.

For someone with no background or no desire to dive into the details, this is no small feat. And there are a few horror stories about bad installations leading to non-working systems (see this for example).

So, I went about researching and used the dealer locators to find dealers in my area that sold both Guardian and Kohler generators. In spite of being listed on the manufacturer’s website, I really had difficulty getting people to call me back (note this was 2005 during the building boom — I bet people are more responsive now). I found a dealer local to me in Massachusetts and called them. They were responsive and knowledgeable (part of a respected large electrical contractor). They came out and did an initial home survey, took pictures and measurements, and asked a lot of good questions. Then they went away and a couple of weeks later gave me a quote for over $11,000!

I had seen a company online that had a good website, but they were located almost 100 miles away in New Hampshire and I figured they would never come as far down as my area. But only because I used to live in New Hampshire and I knew where the business was I took a chance. This proved to be the single best decision of the entire process. Powers Generator Systems proved to be the kind of expert resource I needed. They were prompt, courteous, knowledgeable, flexible, professional, and … wonderful. Without question they were the single best contractor I have ever worked with. And they did the complete job for under $9000 (including gas tank costs)!

In consultation with Powers and with a little figuring about loads, I settled on a Kohler generator for a variety of reasons, but primarily because I felt that their transfer switches were more advanced and faster acting (and safer for my computer equipment), and there was (an admittedly unsubstantiated) feeling that the Kohler unit and housing were slightly higher quality than Guardian. Thus began the installation.

The following is not intended to be a step-by-step guide to installation walking you through all the possible calculations and permutations, but rather a basic outline of the steps I took to get the job completed. In order:

1. Calculate power requirements
2. Decide on generator size
3. Calculate gas flow requirements and determine tank size
4. Determine installation location
5. Order generator and gas service and apply for permits
6. Install gas piping and gas pipe inspection
7. Generator site prep, installation, wiring, and run test
8. Final propane installation & tank fill
9. Final inspections (Fire Department & electrical)

Your actual steps may vary depending on local requirements.

Calculate Power Requirements

This is the first area where one can go astray. The main strategy a prospective generator owner needs to employ is to keep the manufacturer and dealer from over-sizing the generator you buy. Unless you have some kind of dramatic load (like central air conditioning which cycles on and off with a large current draw at startup), all the online calculators and manufacturer recommendations are designed to do two things — maximize their profit margin and limit their liability.

The method promoted by most manufacturers and installers all but guarantees an oversized installation and higher profits for both manufacturer and dealer. The typical method simply adds together the maximum capacities (amperage) of the circuits you want to power and specs a generator with enough capacity to cover them all. This maximizes profits in two ways. First, within any given manufacturer’s line of generators, different capacity generators are often built on the same basic chassis. The only substantial difference is the size of the stator winding. The incremental cost for larger stators is insignificant, yet the price difference that the manufacturer can charge is substantial. Thus, within generator families, larger generators are more profitable to sell. Second, coming to your house to conduct the power survey costs the installer money. Time spent with you is time not spent on other projects. So anything the installer can do to minimize the time spent gathering specs increases his or her profit. So what you typically get is a cursory survey that results in a larger generator than actually needed. And, by over-specing the generator they all but guarantee that there won’t be problems later when you add appliances.

A more appropriate survey adds up the actual loads which are on the circuits that will be protected and makes a realistic estimate of how often they will truly be simultaneously run. A really good survey will use an actual power monitor (like the one I have) to actually record the draw of various appliances. As an example, I have an 1800 square foot house with an electric range, electric well pump, electric dryer, and three room air conditioners in summer. By any online calculator I need a minimum 16KW generator. Yet I have had a 12KW for years without a problem. And in fact, as an experiment, I once fired up all three air conditioners (a 15,000 BTU and two 6,000 BTU units), the clothes dryer in maximum, the oven at 350 degrees, the large stove burner on high, and then made my well pump engage by running the water. The peak draw on the meter? 10.9 KW. So instead of following the manufacturers recommendation, all I need to do is not turn on absolutely EVERYTHING in the house at once and I should be fine on my 12KW unit.

Decide on Generator Size

Kohler 12RES 12 KW Generator

I want to point our here that my original installer went with the 16KW recommendation, but it was Powers that pointed out that a 12KW would do fine. That was my first clue that they were a good company.

So I decided on a 12KW unit. If you have some additional loads, like central air or an electric water heater, then your requirements will need to account for those loads.

Calculate Gas Flow Requirements

The first step here is to find the right gas company. In the world of residential propane, generators are an extremely low volume business and therefore not very lucrative for gas companies. In most higher-volume installations, you lease the propane tanks from the gas company and pay a monthly fee just to have them. The gas company will tell you that this is for your own protection (they will change/replace cylinders when they are old and unsafe) but this is just marketing bullshit. They do it because it’s a predictable revenue stream that more than pays the cost of the tank over their lifetime and so that they can recycle tanks among customers increasing their profit even more. Most residential propane hardly notice the small rental charges on their invoices because their use of propane dwarfs the modest charge. But for a generator user who might not use more then 50 gallons in a year the cost is significant.

There are a few propane dealers around who understand this and will outright sell you the propane tanks which, although a larger upfront cost, will minimize their cost over their lifetime. Eastern Propane here in Massachusetts is just such a company, and they were the second great find during my search for help. [Disclaimer: I worked with someone for 9 years whose wife is a Customer Support manager at Eastern, so I tried them early in my search and wasn't disappointed. But I didn't research propane dealers nearly as much as I did generator installers.] After consulting with the Eastern representative, we agreed that for generator installs, owning the tanks is probably a better deal.

Now the arithmetic begins. Each manufacturer will provide a gas requirement as part of their installation instructions (203,000 BTU/hour for the 12RES). The key to this part of the installation is in working with your gas company to ensure that enough propane is delivered to your generator to let it start and run when needed. This is a more complicated task than it might initially seem, particularly if you live in a cold climate.

[September 2011 - I've written a more detailed article on gas usage and generator runtime calculations.]

Propane is stored as a liquid, but it must transfer to the vapor phase in order to run the generator. The rate that this happens is directly proportional to the heat available to make it happen which is in turn a function of both temperature and surface area exposed to the heat. This means that in a cold climate, the size of your propane bottles may be more of a function of ensuring an adequate gas flow during the minimum expected temperatures than it is of how long you might want the fuel to last. A good discussion of this is at Propane 101 and is shown in the chart below which I borrowed from http://www.flameengineering.com/Propane_Info.html.

VAPORIZATION RATE – 100 lb. Propane Cylinder (Approx)

My Dual 125 Gallon Tanks

As you can see, the energy available to your generator at 0 degrees is dramatically different than at 70 degrees. My installation is done with dual 125 gallon (450 pound) tanks which can be seen at http://www.eastern.com/pdf/PropaneTankOptions_062606.pdf.

Determine Installation Location

Once you’ve figured out the tank size, the next step is location. You will need to figure out the placement of the generator at the same time so that piping can be calculated. The distance between the tanks and the generator will determine the type of piping run needed. For example, codes define a maximum length of unsecured pipe, so much of your piping will need to be attached to a structure or run underground. The availability of structure to which you can secure the pipes can be a major issue (I needed to bury mine). In addition, the propane installers will worry about specific codes governing cylinder placement including minimum distances from potential ignition sources, which can include lots of stuff you probably didn’t think of like outside lighting, Bar-B-Que grills, electrical outlets, etc. And, they’re going to want the cylinders in a location that they can reach with their delivery hoses too. After your installer explains local requirements to you, you will have narrowed down the available locations for the cylinders and generator significantly. Astute readers will also have picked up on a central paradox governing this calculation. The generator itself is an ignition source! So yes, the cylinders must be both a minimum distance from the generator to prevent ignition, and a maximum distance governed by the piping required. See, this isn’t as flexible as you thought!

While siting the cylinders, you’ll need to keep in mind some things about the generator as well. The most universal requirement is that it be close to the electric service entrance to minimize the cabling required and that it must be a minimum distance from any openings to inhabited areas (to prevent the exhaust from pumping carbon monoxide into the house if you leave a window open).

Locating the generator away from the electrical service is possible, but remember that the size (diameter) of the cable run between the generator and the transfer switch will need to be increased with distance to overcome resistive losses. So there is a practical limit based on the maximum cable size that can be run. Your installer will be dealing with large bundled cables here, not typical 14, 12, or 10 gauge copper house wire.

My Generator Location (see text at right for an explanation)

If you balance the propane requirements with the generator requirements, you will have few choices of where to site the units. I am lucky that my house has a detached garage connected by an open breezeway (meaning it’s not inhabited so the distance from a window in the garage doesn’t matter) and this is close to both the driveway (for propane delivery) and the electrical service. Plus it’s separated from the main house to keep the noise at a minimum.

My Installation

In the picture at left, you can see then entire installation of my generator. The path of the cable is shown as the red line. The propane tanks are located directly behind the generator, out of view of the camera. The garage is about 15′ wide, and the breezeway is 10′ wide. Where the cable runs in front of the breezeway, it’s run under some wooden stairs and comes back up to enter the basement near the meter.

Once these decisions are made, the propane installer will develop a piping plan which balances flow requirements with local codes governing pipe material and allowable distances. In many areas, codes can vary from town to town. For example, in Grafton, MA where I live only black iron pipe is allowed. But just one town over, black iron pipe is not allowed and copper must be used. Only a local expert can navigate this mess.

Apply for Permits

Once you, your generator installer, and your propane installer have all agreed on the locations for things, it’s time to place the order and pull the permits. A good installation contractor will do this for you, but it’s always a good idea to double-check and ask to see the paperwork.

Piping Install

The next step was the installation of the piping. The gas installer should have specified all the pipe sizes to be used and you will likely need a licensed plumber to do this install, or else the inspector won’t pass it. Don’t get me started on this gross restriction of freedom and total scam by states bowing to the plumbing and union lobby. But anyway, the gas company may have a certified pipe fitter on staff who will do the job. In my case, the run between the tanks needed to be buried, so the gas company gave me the dimensions for the tank placement and the generator company gave me the dimensions for the generator placement and I connected the points and dug a trench between them. The trench needed to be 40 inches deep with 6 inches of sand in the bottom. When complete, I notified the gas company and they sent the fitter to install the risers and the run between them. When done, the fitter capped both ends and pressurized the pipe with compressed air. Then he notified the town who sent the plumbing inspector to sign off on the install. As long as the line held pressure everything would be good.

Once the inspector signed off, I was free to fill in the trench (another 6 inches of sand on top and then the dirt). Then I notified the generator company that the rough piping was complete.

Generator Prep & Wiring

This was the easiest part for me because Powers generator handled everything so professionally. On the day of the scheduled install, two guys showed up on a truck with the generator. A few minutes later an electrician from Powers also arrived. I had discussed the install location with the original Powers rep, but the location wasn’t optimal and I was sure that the information about the work hadn’t reached the team.

Essentially, my installation was done on the left side of my garage. The wiring penetrates the garage, goes up and across the door header, and then down and out the other wall. From there it needed to go under some wooden steps and underground, and finally through the wall and into the basement near the main service. I was certain that no one had told this poor crew that the were going to need to remove wooden steps and trench across my breezeway plus penetrate three walls. When I met them in the driveway and explained it to them, all they said was, “Yup. OK.” And that was it. Unbelievable.

While the guys outside began leveling the pad area and dumping the gravel they brought for a base, the electrician headed for the basement. I live in a house built in 1978 that originally had electric heat. So it always had 200 amp service. But when the electric heat was removed by the previous owners, no one really cleaned up the wiring, so the 220 circuit breakers are still in the box and the old wires are hanging all around. To further complicate things, another previous owner has installed a sub-panel to power a basement workshop they had set up. This didn’t even phase the electrician who went right to work preparing for the transfer switch and the rest of the install.

Transfer Switch & Panels

At this point, I just let them work, occasionally reminding them to help themselves to the refrigerator with soda and water that was in the basement. Several hours later I heard the generator fire up (they were testing it with a portable propane tank). I went outside and was stunned at the complete job they did. The wires were run perfectly, the trench had been dug and conduit installed, everything had been sealed, caulked, and glued, and the steps had been replaced like nothing had happened. I went to the basement where a brand new transfer switch was mounted and where the circuit panel was neater because the electrician had not only done the installation, but consolidated important circuits from the subpanel to the main panel and fixed a couple of unbonded neutrals and a missing ground! They even swept the sawdust off the floor, some of which I had left there. I was utterly stunned, never having had such a professional experience.

After a few minute rundown of how things worked and how they set it up, they left me the paperwork and it was complete.

My Generator (forgive the mess)

Final Propane Hookup

After the install was done I contacted the gas company one final time. In a few days a truck arrived with the two 125 gallon tanks and the concrete pads they would sit on. The driver muscled them into place and let me know that the final connection would be done in a few days after the scheduled fill-up. A couple of more days passed until I returned home from work to find that the tanks were suddenly full. The day after that I returned home to find that the piping was finally all connected. Success!

I simply had to try because I didn’t believe that it would actually work. So I went to the basement and pressed the button as the instructions said and the generator fired in less than 10 seconds and ran great. And it hasn’t missed a beat yet in three years!

Final Inspections

This last part was the easiest, though somewhat nerve racking. I let the town know that everything was complete and they told me that the inspector would arrive in a couple of days. True to his word he arrived as scheduled and admitted he had never seen a generator like this before. His number one concern was that there was a transfer switch to keep the generator from back-feeding the grid. He asked me about this while he was staring right at the transfer switch. Rather than be a royal pain though, he looked at the the documents that came with the transfer switch and was satisfied that it was good enough. He left without really looking at anything else. Sometime in the next few days, the final required town inspection by the fire department happened and they left a nice letter to be displayed in the window nearest the generator.

And it was all finally over!

Summary

I’d say this whole process took about 10 days of research, a week of calling companies and scheduling visits, and then about 4 weeks of work from the start of the installation to the end. It required a lot of coordination and quite a bit of research and learning.

We’ve had the generator installed for 3 years and it’s performed flawlessly. The first year was remarkably free of power failures, but by last winter the generator really paid for itself. In December we had an ice storm in Massachusetts, and while we were less affected in my town than in some areas, we were without power for 14 hours. I work in Boston and though I didn’t travel that day, while my neighbors were hunkering down figuring out how to keep the pipes from freezing, I was able to keep working online like nothing was wrong.

Update, 7/2011: It’s been closer to 5 years now that my generator has been working and I’m still satisfied. This spring there was a minor car accident on my road and someone hit a power pole with a transformer on it. As expected, my generator came on and ran for 12.5 hours. It wasn’t particularly cold out, but it was nice to be able to continue watching TV and to have a nice hot shower in the morning which many of my neighbors had to skip. And then, the most important test of my generator’s life: June 1, 2011 was game one of the Stanley Cup finals when my beloved Boston Bruins took on the Vancouver Canucks. It was also a night of tornadoes and terrible thunderstorms here in Massachusetts. And, although a tornado didn’t approach my house (the closest was about 12 miles away) the thunderstorms did cut power just before the puck dropped. Tens of thousands of Bruins fans were left unable to watch the game … but not me. Again my generator ran for about 10 hours, and I was the only house in my neighborhood with power. Miraculously, even though electricity was down, my Verizon FiOS cable feed stayed up, so I didn’t miss the game (even though the Bruins lost). Thank you Kohler!

Update, 8/2011: Hurricane Irene blew through Massachusetts and I was without power for about 10 hours. Again, my FiOS cable and Internet connection stayed working the whole day, so we weathered the storm in total comfort.

Can you see it in there ... yup, that's my car.

Update, 10/2011: 2011 isn’t going to go quietly. Just a few weeks after hurricane Irene, we had Snowtober. A freak early-season Nor’easter dropped 6+ inches of heavy wet snow on my town and because the trees still had leaves, brought down millions of branches (including an oak tree on my car … see the pic at left). Hundreds of thousands of people were without power. This time we weren’t spared … but the generator again proved itself. We were without electricity for 65+ hours with outside temperatures in the 40s. The generator ran the whole time. At one point we had some people over and the generator was holding its own with the electric oven on, two big burners on our stove on high, the well pump cycling while the shower was running, and all sorts of miscellaneous lights and TVs running. What a comfort having  this generator.

Through several short duration outages and now one that lasted several days, the generator starts in seconds and keeps the appliances running with no issues. I would do it all over again in a moment.