Type: Posts; User: unclebingo
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Can anyone verify the formula to calculate the Equivalent Full Load Hours for either heating or cooling as being:
EFLH = 24 x CDD / Delta of indoor design and outdoor 1% Dry Bulb.
No, it's a simple 2 bedroom single story home with fireplace used for all locations. It's infiltration rate is average.
I made sure to use the same envelope each time. The only change was the...
Using the supplied ManJEd8 spreadsheet, I have performed a number of test calculations in different locations using a default set of controls, and construction envelope.
The defaults are:
Anyone run into this little gem?
I'm pleased my Garbage In has a Carnak Out filter!
I'm referencing the ASHRAE 2005 Fundamentals > Climate Data > IP Stations > 725450.PDF
Monthly Design Dry Bulb and Mean Coincident Wet Bulb Temperatures
1% Dry Bulb for each...
I managed to find the ASHRAE 2005 Fundamentals at my local library but the climate data doesn't include HDD / CDD. So I was hoping I could calculate it by subtracting the 1% Dry Bulb data for each...
Carnak, you were right re Degree Days. Cedar Rapids has 6924.
Month 1% dbF Days HDD
Jan | 45.7 | 31 | 598.3
Feb | 54.6 | 28 | 291.2
Mar | 70.6 | 31 | -173.6
Apr | 80 | 30 | -450
May | 85.2...
Thanks for laying it all out Carnak, much appreciated!
Pity the correction factor can't be calculated... It sounds like it has something to do with octane and elevation?
Cedar Rapids, Iowa
But understanding the formula is more important to me than just getting you guys to tell me the answer.... I wanna learn!
So the correction factor is only needed if I adopt a standard 97.5% design temp difference?
I know that the Manual J spreadsheet I have automatically calc's the HTD for me when I enter the...
If I'm using monthly 1% DB data then outdoor design temp varies from month to month. Does this suggest I need to calc each month?
What is the correction factor?
I've yet to collect the HDD figures, and for the purpose of building the formula I was using default figures from www.hvacopcost.com for both HDD and BTUH loss.
When I can gain access to the house...
Please check my math...
If my home losses 80000 BTUh, and I live in a region with 3784 Heating Degree Days, then I use 7,265,280,000 BTU per year.
(BTUh x 3784 x 24)
Which is 72652.8 Therms...
Would you expect the standby, startup and shutdown losses to = 48% of a AFUE 90 furnace?
However, after comparing the results from my calc with those of hvacopcost.com a pattern emerges. As efficiency changes, so does the percentage difference between results.
How can I resolve the thermal efficiency (defined as percentage of fuel converted to heat) from the AFUE rating?
I understood the AFUE # was the percentage of fuel converted to heat, but the...
Many thanks. I believe I have included all factors you mention into my calculations. I would appreciate a fresh per of eye's from someone who has completed the process.
May I send you a...
Any Excel guru's with knowledge of how to calculate the cost to operate out there?
I'm building an Op cost xls, but my results so far are way off those of http://www.hvacopcost.com/
I'm performing a detailed Manual J (Block load only) on a house in Valencia, Spain.
This home is of a monolithic construction, i.e. it's floors are concrete slabs (poured into forms) and supported...
I would describe a partition wall to separate a conditioned utility room or den in the basement with a garage that sits within the house envelope. In that case there might also be a...
So, to clarify. You used HVACCalc to perform a block load of the house envelope only, rather than performing a room by room load and have HVACCalc total up for a block load?
Presumably the room by...
I'm using the Manual J "MJ8ae v1.08" spreadsheet to calculate the block load of a house.
Is it possible to perform a block load without entering all room loads, i.e. just enter data about the...
Garbage In Garbage Out, right.
I've noticed there are disparities between ACCA and ASHRAE data when calculating design grains difference between inside / outside grains.
Birmingham AL - ACCA