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Alaska: stay true to heat load?

I live in Anchorage and have just received my heat load calculations from a State energy audit.

The resulting heat load required 71,280 btu/hr, and the rater added 20% for domestic hot water and a "cushion" for a total heat load of 85,486 btu/hr.

My house was built in 1952 and is 1650 sq ft. It's one story with finsihed basement. Our ancient boiler is running the show and I have a Triangle Tube SMART 60 hot water maker. There is 120 feet total of 1/2" baseboard fin tube total. I have a family of four.

I'm looking at a Burnham ES2-4 that has a DOE of 89,000 btu/hr and would like to pair the boiler with Burnham's IQ control that includes an outdoor set back.

Should I stick with the 89k btu boiler, or jump up to the next size Burnham which has a DOE of 119,000 btu/hour to give myself more of a cushion?

I've asked two "pros" here in Anchorage and one guy said stick with the raters recommendation, and the other said bump up to the next size boiler.

Anyone in colder climates like to chime in? I would hate for the rater to have made an error in the calculations, and I end up with a cool house and cool wife.

Is going with a bigger boiler a mistake? Anyone know anything about Burnahm's IQ control?


Re: Alaska: stay true to heat load?

There are calculations to determine the right size. For your size house I guess that 89K is sufficient.

Re: Alaska: stay true to heat load?


Your posting implies that you are going to attempt to install this boiler yourself, and it's a free country, outfits that sell boilers either via the internet or locally will gladly sell you the product, but I would strongly advise against such a course of action.

For a number of good reasons, most states prohibit the installation of a boiler to anyone not licensed, and has not gone thru a supervised apprenticeship on a number of technical & safety issues, and just the practical complex procedures like near-boiler piping, proper venting of the toxic gases, proper hookup of the gas lines, etc. that should only be done by licensed technicians; that's why local, state & national laws and the policy of the boiler mfgrs mandate against a diy installation.

The mfgr will not honor the warranties on diy work for failure of the cast iron combustion chamber, or any other of the numerous parts that comprise a boiler system, and what happens if the install is not planned properly, and things go wrong---it's highly likely that you will have to call someone in to correct a malfunctioning heating system, & end up paying twice what you would have had you hired a knowledgeable tech in the first place; decisions have to be made regarding the near-boiler piping arrangement, zoning, whether to install an aluminum chimney liner, etc.; these are all code issues that will jeopardize the health & safety of the house occupants if they are done incorrectly.

I think you'd be much better off getting 3 estimates from local installers and pick the most qualified tech at the most reasonable rate; that way the installer has the responsibility to use their expertise to get the installation right, on a completely safe basis, or they'll have to come back no matter how many times it takes until the new system is functioning at its most efficient and safest potential.

On paper, the Burnham ES2-4 sounds like a great boiler---but it may simply not be the the right boiler for your particular residence, and your house's heating needs---this is another issue where the experienced installer has the responsibility to suggest several other units that may be more appropriate for the heating needs of your particular home, and to safely remove the remnants of the old existing boiler, which may very well have hazardous material like asbestos that by law requires special handling to avoid health issues.

The comprehensive heat loss calculation program that licensed installers do as part of their install may well come up with quite different heat loss numbers that would be quite different (up or down) from what you have been given so far---this insures that the new boiler will be properly sized for the heating needs of your particular home, and will prevent you from buying the wrong size boiler on a diy install.

Re: Alaska: stay true to heat load?

Ideally, you want the smallest boiler that will work to reduce your cycling costs, but it needs to be large enough to do the job on the coldest days.

Chances are that your existing boiler is oversized, that was the practice back before the energy crisis. Do you know the size of the existing boiler? That would serve as a guide. Next would be if you can determine the worse case (lowest temp with high winds) cycle times. For example, if your current boiler is a 150k BTU unit and it operated 50% of the time on the coldest and windiest days, then you could get by with a 75k BTU boiler.

If you are using propane instead of natural gas, find out what the boilers output is with propane. Propane holds a lot more energy than natural gas. My heater is rated at 105 BTU/hr on natural gas and 150k BTU/hr on propane. I use propane. Also if you use propane, make sure you get the propane nozzles or you will waste a lot of the precious gas.

Heat load calculations are a good input for selecting the best size heater, but you should look at the size and performance of the existing system for clues as well. Also review the energy audit to see if the heat load calculation is based on current levels of insulation and infiltration or if it included recommended upgrades to this. Also, if you live in a log house, I would not trust the heat load calculations at all.

Re: Alaska: stay true to heat load?

Heat loads are prepared for a reason, i.e. you don't have to guess. We perform ACCA Manual 'J' heat loads for every house we install a boiler or furnace in.

Your current radiation will not get rid of more than a 80mbtuh when new so buying a boiler with greater output will only serve to burn more fuel.

No manufacturer of indirect-fired water heaters recommends up-sizing boiler output. We consider it bad practice.

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