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Figuring heatloss on a super tight home
Running into a head scratcher on a newer home.
Customer has 2 air source heat pumps and is not a huge fan. Just does not keep him warm.
Wants a hydronic system.
Figuring on a wall hung mod con w/ panel rads.
The heatloss number do not compute. There seems to be no good way to make adjustments to the home being super tight. No diferentiation if the air infiltration is 10 changes per hour or 1 air change per hour.
House has a HERS rating of 52 and had a blower door test less than 1 change per hour.
R51 in ceiling,26 in walls. ICF foundation and slab
Is there a program that allows for this?
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You can download a trial version for free.
https://www.hydronicpros.com/downloads/
Albert Einstein
Yours, Larry
What do they have for bringing in outside air?
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
The Ductless mini split will still be there.
The Air Exchange will still be there.
Langans Plumbing & Heating LLC 732-751-1560
Serving most of New Jersey , Eastern Pa .
Consultation , Design & Installation
Rich McGrath 732-581-3833
Nat 0.03
Ach @ 50... 0.08
CFM @ 50... 465
I'd consider putting some of that required heat into coils in the intake duct from the exchanger, to eliminate cold draughts, and then the rest of it into the panel rads...
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
I burn pretty much the same amount of wood when it's 20 degrees outside as when it's 0 outside. R32 walls a d R60 ceilings. 1ACH were my calculation. 14btu/ft2 at -40F.
As @Jamie Hall said, the air exchanger may be the largest heat loss from the home.
What @Larry Weingarten said, only is use 100% electric heat for a month to calculate real world heatloss, mini splits can vary their output so much based on outdoor temp and outdoor humidity necessitating many defrost cycles. Hard to put a real world number on what their actual output is for a given period of time. Electric heat is easy, 100% efficiency all day long. Add some Kill-A-Watt meters and a portable heater for each area and you have some real numbers.
You would think it would be straightforward.
A lot of guys talk about " fluff " in the manual J calculations.
Getting high numbers in this place that is supposed to be energy star rated.
I tried the Hydronic Pros version and had a hard time figuring it out in the 15 min window they give you.
Ill keep plugging away.
Figure can't lie. If you really want to fine tune it, then calculate the R value of all wooden framing components, and calculate them separately from the stud bay cavities.Wood has an R value of roughly 1 per inch, so a 2 X 6 stud wold have an R value of 5.5 . You have to calculate the total square footage the studs displace, and don't forget to deduct that amount from the wall as a whole.
Infiltration is calculated as volume * .018 * DT * Air Changes per Hour (ACH). You know what that number is, so no guessing needed there.
ME