Btu calculator

sobriquet

Hey all, I'm trying to do an evaluation of my one pipe system. I'd like to calculate to btu required to heat my home, room to room. So I've gathered all the dimensions of the rooms in my house. I used this calculator http://www.bestheating.com/btu-calculator . Does anyone know if this calculator is accurate or reliable? If so, I determine btu requirements on each room, add them together to find what my boiler should be rated at, right? I read a few posts here mentioning the "heat loss calculator" here on the site but all the links are not working. Just looking for an accurate way to determine if my boiler is properly sized and if my radiators are properly sized. Using that Id like to use the vent capacity chart to dial in my rad venting. Thanks

JimmyNJ

Hello - I have used the Slant/Fin calculator in the past and it seems pretty good. You can download it on your Android or iPhone device directly from the App store. Unfortunately it appears that their PC version is no longer supported.

bmwpowere36m3

I used the SlantFin tool, but it is VERY conservative. You also have to understand the variables within the program. The biggest contributor to heat loss will likely be air-infiltration and that really is a "best" guess, unless you have it measured.

I participated in a energy-saving audit (from utility), it cost $100 and it included a "blower-door" test. Typically just the blower-test is a few hundred $$ and as part of the audit you get a few LED bulbs (big deal ) and they do some air sealing.

Anyway, that'll give you a more realistic number and make your heat loss calculation more accurate.

bmwpowere36m3

If you have a gas boiler currently running... then you could clock the gas meter and figure out the BTUs needed to heat the house too.

nicholas bonham-carter

For a one pipe system, the boiler should be sized to fill the radiators, and not the heat loss of the house. The radiators would have been originally sized to the room heat loss at a minimum.
Look at a table of the radiator EDR, (measured in square feet of steam), and calculate your total of all your radiators. All boilers have an EDR (square feet of steam), rating on their specifications, which should be matched up.--NBC

Jamie Hall

As @nicholas bonham-carter says, for steam systems you don't have to calculate the building heat loss, unless you are adding or subtracting radiators from the system.

In fact, if you size your boiler based on building heat loss, the chances are excellent that it will be the wrong size. Sufficiently wrong as to be worthless.

Add up your radiators' EDRs, and size the boiler based on that.

ChicagoCooperator

But shouldn't the radiation be sized to the heat loss? If the house has been significantly modified or radiators swapped it would be useful to be able to confirm that and then base any changes in EDR on that.

delta T

As others have said, you need the EDR of the radiators. If you post some pictures we may be able to help with that. The heat loss of the structure is unimportant in steam systems when considering boiler sizing.

Jason_13

Both of them are off by more than 50% according to my calc from a manual J