burnham's heat loss calculator

mitch moore

In thier heat loss calc they are looking for a 3",6",or 9" overhang for the multiplier for floors.What are they refering to when they ask for the overhang?

Travis G.

Have you tried calling burnham?

paul lessard_2

This comes to mind mitch

When doing second floor additions the second floor sticks out a foot or two past the floor below it. at least on the front and back of the house.
And this place is always a concern for me when heat pipes are involved .If the carpenters helper's helper insulates it chances are the people living there won't be very comfortable. and if it's really drafty you will have frozen pipes
but maybe they're refering to something else .

bottomheater_2

overhung floor

its when your second floor is cantilevered out over the first floor; the overhang section is not over a heated space, so your floor heat loss for that area is dependent on the insulation factor. Note that the values are close to the same insulation levels for wall and cieling.

Unknown

Mitch

The factors or Heat Multipliers for Floors considered to be an overhang implies floors that are over an unconditioned or cold space. An axample of this would be a typical Raised Ranch where the upstairs rooms actually overhang the lower floor by about 2 feet to the outside. Another example would be a real nasty crawl space. I hope this clears things up a bit. I might add that the Perimeter Heat Loss method detailed in the heating helper and on our web site is intended for hot water boiler replacement purposes primarily. None the less, it's a very good and fairly accurate tool.

Glenn Stanton

Burnham Hydronics

mitch moore

no

no I havn't

mitch moore

ruled out

It only gives you 4 options 1)insulted or non-insulated floor 2)3" overhang 3)6" oh 4)or 9" oh I could see your point but it would seem it would give you options in feet

Unknown

That option is yours Mitch

All you need to enter is the square feet of overhang that you have for that living space. You have to remember that the perimeter heat loss method is only taking into effect the house or building as a whole or as one big entity. All you need to tell it is the Gross Wall Area, Window and Door Area, Ceiling Area, Exposed Floor Area and Total Floor Area x Height for Infiltration. I will admit that the Overhang Business can be a bit confusing, but if you consider that you only need to enter the square footage of overhang or floor area to an unconditioned space, it works. Hope this helps.

Glenn

mitch moore

what about eg. 10'

yes it's for hot water heat. So if I overhang over an unconditioned space or to the out side I would take the 6" over hang multiplier and double it x the amout of feet for the over hang eg. 10' overhang (.04 h.m. for 6" x 2 = .08 h.m. per foot of overhang- 10' x .08=.8) .8 per sq ft of overhang? This is a single level with no overhang although it has aprox. 200' of 1 1/2" pipe in basement. HO says it stays comfortable in basement (I treat this as a conditioned basement-correct?)

mitch moore

Gross wall area

Do I factor the outside wall area at the top of the home which encloses the unused,unconditioned attic portion of the home? Seems like this would throw the #,s off.

mitch moore

inches of insulation

I think I,ve got it. Inches of insulation in the floor of the overhang. Thank you

Unknown

Not sure where

you are coming up with the .04 HM factor Mitch. If, for example , you have 10 lineal feet of wall that overhangs the lower floor by 2 lineal feet, then this will give you 10' x 2' or 20 square feet of floor overhang. Enter this in the chart under Floor Area and select the relative value of the insulation you have in the overhang. If that is 6" of insulation, then you will use a Heat Multiplier (HM) of 3 for the Floor Overhang. Simply multiply 20 square feet x 3 (HM) to get a Floor Loss of 60 btuh for that overhang. If the basement is conditioned or comfortable due to standby losses of existing piping, then no floor loss is needed and you can leave that row blank.

If the basement was a walkout type basement that was relatively cool and uncondtioned, then you would use the entire floor area exposed to that basement and select a Heat Multiplier for the type of insulation you have in the floor. If there is no insulation, you would use a HM of 4. Hope this helps.

Glenn

mitch moore

what H.M. will I use for

lathe plaster walls no insulation and floors over a 4" insulated floor over a unconditioned crawl space (no overhang)

Robert O'Connor_4

Is this program

available on the web?


Regards,

Robert

Unknown

Only the conditioned space Mitch.

You are only going to consider the spaces you are going to heat. If, for example, the house is a full two stories and each floor is 20 feet x 30 feet and ceiling heights are 8 feet, you figure it this way.

20' + 20' + 30' + 30' = 100' x 8' = 800 square feet of Gross Wall Area per floor. 800 square feet x 2 = 1600 square feet Gross Wall Area Total.

Glenn

mitch moore

# outof the air

just used H.M. because I didn't have actual #'s on hand.I understand now.It doesn't give H.M.'s for unconditoned basements just overhangs should I treat them as one in the same.

Unknown

Use

a Heat Multiplier of 15 for the walls and 5 for the floors.

Glenn

mitch moore

yes

Burnham's website go to the tool box for heatloss calculations for hydronic heating

mitch moore

got it

the basement standby losses will be factored in the DOE rating of the boiler therefore no heatloss calcs should be factored for the basement? even though it will be conditioned due to stand by losses.As for the floor- no H.M. for floor area will be factored

mitch moore

Thanks Glenn

I treat unconditioned spaces below the same as overhangs?Seems a big temp difference from an outdoor second floor OH and a unconditioned basement.