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Help with heat loss and finishing existing design details_1
We've got a house with a heat loss calculation and tube plan done (old Wirsbo - 2002). The tubes are in the radiant panel floors.
There is a heating system and control design from a very experienced hydronic designer. The designer did the work out of interest, goodwill and kindness... did as much as there was time for, and did more than there was time for.
I know the designer had all the bits and pieces figured and understood. What I truly understood at the time, and now, years later, is a lot less than that.
I can't talk with the designer and there is no one around here that understands why the design is as it is. That is, the plumbers look at the design and say, "We wouldn't do it that way". I don't know a lot, but I do know they do not see how it works... why it works... why what they would do (and I asked) won't work as well as it could.
I think there are two parts to this:
1) Find out if the heat-loss calculation needs to be redone.
2) Based on above, validate boiler size, DHW indirect size, then fill in the blanks I have with the existing design.
So... one thing at a time...
I've gone over all the back and forth with the designer... e-mails and call notes. I've re-read years of collected links and papers pertaining. I've read a lot more pages in the Caleffi Idronics Technical Magazine issues now, and done searches on, and read "The Wall")... weeks of all the above.
I've come to wonder if the Wirsbo heat loss calculation is correct... or correct enough. I don't have any way of knowing.
* Total interior sq.ft. is 1.4% less than Wirsbo calculated on... 1750, not 1776
* Wall ht. not 9 ft.... 946 sq.ft. 1.4% less... 804 sq.ft. is 7.6% less than 9 ft. of Wirsbo calculation.
* All exterior wall is 8" lt.wt. concrete block with sand cement (6-bag) core fill... 3" XPS on outside,
with 3/4" stucco exterior and interior... very high amount of non-emitter mass.
* 91 feet of interior wall 8" lt.wt. block with filled cores... 36 feet interior frame wall with 7/8" stucco each side.
* South facing windows 6.5% of total floor area. In the books that is 0.5% below "solar tempering"... i.e., an amount of gain a 'normal' furnished stick house has enough mass to take up and hold.
* Floor 4" concrete... 1/2" sand... 2 1/4" extruded brick laid tight. 2" XPS under and at edge (with block stem wall and 3" XPS outside of that. PEX centered in concrete... (230 sq.ft. of total floor concrete or tiled concrete)... all piped slab meeting interior block wall with 2" XPS at edges.
* House is partially bermed... floor levels at 3" above grade to 2 1/2 feet below grade... most floor edge is below grade.
* Wirsbo used -15 Degree Day temp. We are 7 miles from KLND (LND) and the 99% heating is -6 to -7 (depending on report year... but I really don't know if I looked at the right thing, and I might not have understood what I looked at).
I can say, we are 500 ft. higher elevation than KLND (5587 ft.) at the base of the Rocky Mountains. Upshot of that is, we are above the valley's winter thermal inversions and KLND is not. Our normal is +5 F KLND in the winter... the cold slides down and away from us.
The house was built to be tight... all exterior penetrations foamed in... good U-value windows... sheet rock ceiling sealed at edges prior to mudding, with low perm. primer and paint... all ceiling and wall penetrations foamed shut... R-44 cellulose ceiling insulation laps over exterior walls and it's XPS/stucco. Not close to modern "Super Insulated/Supertight", but...
* Wirsbo used 0.35 for infiltration calculation.
That is WAY more yapping than I wanted....
The question is... does the above look like a decent fit with a calculated 37,460 Btu/hr design day loss?
If the answer is no... I'd like to find someone who (on a pay-for-the-work basis) has experience with this kind of house oddness and would like to mess with figuring it's heat loss out.
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