Purchased HVAC Calc program

[Freezeking2000]

if the basement is conditioned space you should add it into the calculation.

[turfgrass]

Another -HVAC Calc update- LOL

1) I deleted "duct" from the 1st floor of the program now that the basement in considered a "conditioned space".

2) I changed all of the first floor, floors to "over conditioned space".

Hope this is all correct. My total heat loss reduced from aprox. 62,000 to 47,500 btuh

[beenthere]

Sounds close/about right for a lot of 1600 to 1900 sq ft homes in this area.

[turfgrass]

Looking at the report for heat loss-


Heat Loss of 34,000 btuh for 1st and 2nd floors at 1,763 sq. ft.

total heat loss including basement is 47,925 btuh at 2,813 sq. ft.


How do these numbers compare? Which set of btuh's do you consider when selecting a furnace? Thanks.

[beenthere]

Since you have supplies in the basement. The total including the basement(47,925).

[turfgrass]

I have two areas to solve before the reports will be complete. One is the area over the stairwell. I added the area of the stairs (would be floor) to a zone called hallway. The hallway is at the top of the stairs. What I did not do is add addition area to the ceiling for the stairwell. Should that be added as well.

One the furnace has been selected based furnace BTUH output and heat loss load. How would I know the CFM rating? I need this rating to plug into the duct size and cfm per room.

The CFM must be known to the installer prior to hanging all the trunks and duct work. Right?

Thank you.

[pstu]

beenthere, the summer grains of moisture came up as 96. Should I delete that and add 32 at 50% RH?

I added the area (9x3) of the stairwell ceiling to the area of the upstairs hallway ceiling.

Not sure what to do with the basement? Your manual mentions adding 4 walls at different height, (above/below ground). But, when I click on basement in my tree there is no wall tab to click?

I am a homeowner who has licensed Hvac-Calc on two occasions, first for a whole house model and later for a room-by-room model. Please double check that humidity number, it definitely is my recollection that Hvac-Calc wants to see absolute humidity and not the difference between indoor and outdoor. If I am not mistaken you are now telling Hvac-Calc that you live in near desert conditions.

In all likelihood you will not change your equipment choices, I just like to see the model used as intended. Other Manual J programs may well work differently and I imagine Beenthere has deep experience with more expensive, more professional programs. A simple way to decide this question would be to call the program's author, who is very reachable and provided good technical support to me.

Best of luck -- Pstu

[beenthere]

Stair way ceiling won't add much to the load.

CFM is also based on allowable temp rise of equipment also.

On a 60,000 output, 1,000CFM wuld be around a 55° temp rise, which is good for most if not all brands.

Duct size is a funcion of both CFM, and duct length. The duct sizing module of HVAC Calc doesn't allow for duct length.