Calculate my heating loss!

Gene Davis_2

Answers to your questions:

1. The basement underneath is heated.

2. Roof pitch is 12:12

3. The 29' width is the width of the large south-facing
wall with all the windows.

4. Lake Placid, NY, Essex County, winter design dry-bulb
temperature of -15 F., 8,255 heating degree days.

5. 9' sidewall heights

6. Windows east wall, (2) ea. @ 3/0 x 1/7, (1) @ 2/6 x
4/0, west wall, (2) ea. @ 3/0 x 4/0, (1) @ 2/6 x 3/0

Gene Davis_2

Please help me calculate my heating loss, so I can try to size some equipment. The large "great room" of this new house has me stumped.

On the main floor of a "vacation style" house with a 30' x 40' footprint, the inside-the-walls dimensions of this vaulted ceiling room are 29' w x 19' d, and the average ceiling height is 16 feet.

The entire south-facing wall is just about filled with windows, as can be seen in the Sketchup model view, attached here. The total of all the openings is 323 sf, and low-e squared argon-filled glass will be used. Insulation throughout is sprayed urethane foam, R50 roof, R23 walls.

If I do staple-up hydronic underfloor with plates, under the entire room, how much of the heating requirement can the floor handle, and how much is left for supplemental units (under-window radiators) to do?

S Ebels

OK

Is the basement heated space?

What's the pitch of the roof?

Which side of the room is the 29' side?

Where do you live so I know what to use for design temp?

How high are the side walls?

What size are the windows on the East and West walls?

S Ebels

Here goes.........

Sorry for the slow response time but I had to break for chicken and baked potatoes coming off the grill with fresh strawberry shortcake and home made whipped cream for desert. ( My wife wonders why I keep gaining weight)

HVAC-Calc came up with a total of 25,133 btu's at your negative 15* design temp. That figures out to about 45 btu's per sq ft. A bunch for any type of radiant floor. The window wall is the problem contributing a total of 15,484 btu's out of the total window loss of 17,814. Maybe some insulated drapes, closed at night would help your actual heat loss but you still have to design for what's there, which is a lot.

Personally, I don't like to count on anything more than 20-22 btu's per sq ft with staple up, even with plates. I'm not saying that you can't get more but to do so means higher water temps than I like to see. If you're going to have a hard surface floor in there like wood or tile, you could get more (25-30/sq ft) with an above the subfloor system like Climate Panel from Viega. The response time is much quicker than a below the sub system and you'll need quick response in that room. The reason is this, when the sun goes down or quits shining through all those windows, the room will lose heat at a startling rate. Especially if the zone serving that room has been off due to the fantastic heat gain you will have when the sun is beaming in. An above floor system will ramp up much faster than a below the subfloor system.

If you were my customer I would be steering you away from staple up of any kind. I'd have you looking at Climate Panel with a couple rads on that south wall capable of turning out 10-12,000 btu's. These would each have a TRV on them in order to respond quickly to those times when the sun is on one and off the other.This would leave the floor providing about 27-28 btu's per sq ft instead of 45.

Do it right the first time.


Hope this helps.

David Sutton_6

Nice,

Very , very Professional!!

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S Ebels

I humbly submit that,,,,,

Everyone, everyday, deserves our best effort.

Thanks David

DanHolohan

Nice.

S Ebels

Gene

In shock?


Did I offend you in some way?

Are you so frustrated that you're scrapping the whole project?


I'd like to hear your feedback.

Gene_2

Gene

Contact Hulbert's Tri-Lakes Supply in Lake Placid. I am quite sure they will direct you in the right direction. If not shoot me a email.


Darin