Can Anyone Suggest A Link For House Heat Loss Study?

[velvetfoot]

As everyone says I should, I'd like to do a heat loss analysis on my house. Can anyone suggest a link to an online way of doing this? Is there one that's best.

Thanks.

 

[muncybob]

http://www.pvsullivan.com/Downloads.html

I cannot download on this computer but I think this is the Slant Fin one that I used.

 

[velvetfoot]

Thanks!

 

[arbutus]

Gary's build it solar website has an estimator and a good discussion about what goes into a heat loss calculation.

If you have excel or a pad of paper and a basic understanding of what goes into a calculation you can do your own pretty easily.

I posted a year or so ago asking about heat loss calculations here:
https://www.hearth.com/talk/threads...staple-up-and-sandwich-radiant-floors.108631/

Bob Rohr replied in that thread with a link to www.pprbd.org that has an excel spreadsheet based calculator.

 

[jeffesonm]

You can use an online calculator like this or estimate using the average annual heating degree days in your area and the amount of oil/propane/electricity/wood you used.

 

[mrjohneel]

You can use an online calculator like this or estimate using the average annual heating degree days in your area and the amount of oil/propane/electricity/wood you used.

Yes, I used the one jeffesonm posted from Build it Solar but I have to tell you the thing that threw me off and that I'm currently trying to understand is how you add the heating needs of an indirect water heater into the final figure I arrived at for just heating my house. That is, I got a final heat loss number for my house that indicated I needed a pretty small boiler; then when I wanted to add an indirect tank, it skewed the whole calculation. (I'm currently trying to convert from oil to gas in Mass. and take advantage of some rebates/0% interest loans to do it.) I had some contractors in this week to do a calculation and give me bids -- which I don't have in hand yet. Who knew HVAC could be so complicated!

 

[velvetfoot]

Not to derail my own thread, but I have noticed that my indirect causes my boiler to run a pretty long time compared to usual heat calls (subjective). I do have priority set which shuts down all loads except for the indirects. Also I took the reset out of the equation so the indirect sees 180. Not sure if that was necessary.

 

[velvetfoot]

Hey, there're apps for that:
(broken link removed to http://www.slantfin.com/professionals-page/heatloss.html)


I deleted the second one I originally put there...Seems to be equipment, not heat loss.

 

[velvetfoot]

Gary's build it solar website has an estimator and a good discussion about what goes into a heat loss calculation.

If you have excel or a pad of paper and a basic understanding of what goes into a calculation you can do your own pretty easily.

I posted a year or so ago asking about heat loss calculations here:
https://www.hearth.com/talk/threads...staple-up-and-sandwich-radiant-floors.108631/

Bob Rohr replied in that thread with a link to www.pprbd.org that has an excel spreadsheet based calculator.

I couldn't find that spreadsheet.

 

[arbutus]

http://www.pprbd.org/plancheck/Heatcalcpublic-v2.xls

If you have excel you can build your own pretty easily. Follow the steps in the Uponor Complete Design Assistance Manual or the Zurn Radiant Design Manual.

I tried to upload the very simple calculator I made, but I don't think this website will let me attach an excel file. Send me a message with your email if you want it.

 

[velvetfoot]

Thanks much.

 

[Floydian]

Any of the online heat loss calculators are only as good as the numbers you plug in, otherwise garbage in, garbage out. Plus these calculators are really only doing the final step of the calc which is some pretty simple math. A room by room calc is important to know how much heat you want where. The real work of the calc is measuring up your areas of heat loss-pretty straight forward but count it all. The trickiest part of the calc, and important, is assigning the correct R values (or U factors) to these areas.
For example:
A 2x6 wall, 16" oc with R19 fiberglass does not get entered as R19 as that is the clear wall Rvalue. You want the whole wall Rvalue which acounts for thermal bridging of all framing that goes from conditioned space to the outside. When you account or this you get a whole wall Rvalue of about R14 (R13.65 according to this thermal bridging calculator (broken link removed to http://web.ornl.gov/sci/roofs+walls/AWT/InteractiveCalculators/NS/Calc.htm)

Once you know your areas and your R values you can simply do the math yourself using this formula:

A÷Rx T =heat loss in Btu/hour

where
A=area in sq ft
R=Rvalue
T=temperature differential for inside to outside in

Basements can be tricky and you will have to guess on air infiltration unless you have had a blower door test.

Just pointing out that you have to be meticulous if you want an accurate number but it can be done.
Gotta get to bed.....

Noah