Seasoned garn jr. Owners

I never did any math for mine, but it did a good job of heating a 3500 sf house last winter. 2 a day firings keep the dhw at a point 140f or better. Would mine do a 2000 sf shop too? Not sure, the shop would have to be well insulated for sure.

> Pulls Yoda cloak from closet......"Square feet matter not, there is no number magic, only heat loss."

To illustrate, Here's a question I often ask customers.....and last winter would be a prime example. It is simply this. Have you ever heard your heating system running non stop? The only time it is producing it's actuall rated output would be when it runs 60 minutes out of every hour.

Fill us in on how your house is insulated.

heaterman said:

Have you ever heard your heating system running non stop? The only time it is producing it's actual rated output would be when it runs 60 minutes out of every hour.
.

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Yes.. yes I have. I also wired in a hour meter. When it was -10 or so outside.. I never caught up. Of course.. that year was running a bit of B100 home brew, not just dead dinosaurs. I think my boiler was sized pretty close. I kind of wish my plumber had been more into the alpha pumps and saving a bit more electrons. But I can't complain too much about his math skills. I wasn't 'in to' this stuff back during the build.

JP

Woodfarmer1 said:

Timber frame with 6" sip panels in the wall and 8" cathedral ceiling, I have spoken to you a couple times on the phone heaterman.

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Yes I know we have spoken previously. I just wanted to let the rest of the crew here know what you were dealing with.

My personal opinion based on experience with structures such as yours tells me that 32btu's per sq ft of floor space is very high. Even if you have a lot of windows.
Your basement is ICF construction which has a good R-value but more importantly, is virtually air tight. Same with the SIP walls in the main level.
That being said, the devil is always in the details such as how well all of those things were put together. Sloppy sealing around doors and windows can have a great effect but I would be very surprised if the overall heat load in your house was over 20btu's per sq ft. ....more along the 70,000 btu range at design temperatures.
Bear in mind that we spend a very small percentage of the winter at those temperatures also. Your ASHREA design temp is actually higher than mine here in Michigan.
-1*F vs -6*F.

If that's the case.. I think the 'measure twice cut once' should be the order of business. Get a real energy evaluation to include a blower door test. IR camera for air sealing, and make sure you have a REAL design load. A few hundred bucks now could mean a lot more later.

JP

JP...If I remember my conversation with him correctly he had a couple estimates done and they showed a lot of variation.

When in doubt.. go with science, not a salesman. Get your own energy audit. Just my .02

JP

JP11 and heaterman are both correct. Energy audit should give you good numbers to go on. If there is much variance in the two audits done someone was wrong......... Worst case you could go with the higher one, or somewhere in the middle. At -40 my heatloss is 14btu/ft2. With SIP construction you should be in the 15-20 range w/o question.

TS

Sounds reasonable. I'm around 90k btu/hr.. at -20.

That falls right in your range. I did the math just by watching my hour meter on the boiler. Math was a bit fuzzy for me as I knew my home brew biodiesel wasn't quite putting out the same BTUs. I don't use that fuel anymore.. it doesn't store long enough... I rarely use the oil now. I let it kick over once every 6 weeks or so just to keep everything moving.

JP