# baseboard heat

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#### pmoney44

##### Member
im wiring a finished basement..they want electric baseboard...how do i calculate how much is needed..meaning how many 8fters 6fters 4fters and so on.

#### Rewire

##### Senior Member
you will need the sqft of each room.

#### westelectric

##### Senior Member
1 watt per cubic foot is a good place to start, but many factors to consider.

#### hardworkingstiff

##### Senior Member
I believe back in the '70's in Tidewater, VA, we used 10 watts per square foot. Looking at the calculator Bob posted, it says we were low.

#### jaylectricity

##### Senior Member
I believe back in the '70's in Tidewater, VA, we used 10 watts per square foot. Looking at the calculator Bob posted, it says we were low.
1 watt per cubic foot is a good place to start, but many factors to consider.
And looking at that same calculator it appears that 2 watts per cubic foot would be closer.

#### gndrod

##### Senior Member
Btu-sq ft

Btu-sq ft

Baseboard 240Vac heaters consume approximately 250w per lineal ft. The State Climate Zone rating for the location of your project is the first qualifying data required for local energy code baseline using resistant heating. For a quick answer using a prescriptive method, the following example will give an idea...

Climate Zone 1 (sea level) WA State......By Design= 8 BTU/sf....By Prescript=20 BTU/sf
Climate Zone 2 (High Elevation) 500'+.....By Design=12 BTU/sf....Prescription= 25 BTU/sf

Example 18' x 10' Room= 180 sf..........(1 w= 3.412 BTU)

Location at Climate Zone 1 by Prescription= 20 BTU x 180 sf / 3.412 = 1055w (4' heater)

A basic design would be to install a 20% higher output heater with wall thermostat. The larger heater warms the room quicker to the stat setting shutoff level. For a more energy saving choice, IR radiant heater would heat quicker and save up to 15% energy. rbj

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#### hardworkingstiff

##### Senior Member
Baseboard 240Vac heaters consume approximately 250w per lineal ft. The State Climate Zone rating for the location of your project is the first qualifying data required for local energy code baseline using resistant heating. For a quick answer using a prescriptive method, the following example will give an idea...

Climate Zone 1 (sea level) WA State......By Design= 8 BTU/sf....By Prescript=20 BTU/sf
Climate Zone 2 (High Elevation) 500'+.....By Design=12 BTU/sf....Prescription= 25 BTU/sf

Example 18' x 10' Room= 180 sf..........(1 w= 3.412 BTU)

Location at Climate Zone 1 by Prescription= 20 BTU x 180 sf / 3.412 = 1055w (4' heater)

A basic design would be to install a 20% higher output heater with wall thermostat. The larger heater warms the room quicker to the stat setting shutoff level. For a more energy saving choice, IR radiant heater would heat quicker and save up to 15% energy. rbj

180 square foot room gets a 1,000-watt heater? Seems small, even if you add 20%.

180 x 10 (watts per square foot) = 1,800-watt heater, we would have installed an 8-foot heater (2K-watt).

#### gndrod

##### Senior Member

180 square foot room gets a 1,000-watt heater? Seems small, even if you add 20%.

180 x 10 (watts per square foot) = 1,800-watt heater, we would have installed an 8-foot heater (2K-watt).
Hi Hardworking,
Does seem small and I agree remod might not incorporate high energy efficient construction but I wonder what the local Climate conditions are in MA...or was that AZ?.

I posted the WAC51 energy requirements for Seattle area which is 40 Lat. and rainy....and where a 1000w baseboard in a 12 x 16 Bedroom does great with an R38 insulated ceiling. rbj

#### mtfallsmikey

##### Senior Member
Have any of you done a heat loss calc. on a building, then sized the baseboard from that?

#### Cold Fusion

##### Senior Member
Have any of you done a heat loss calc. on a building, then sized the baseboard from that?
That's the method I've used in the past.

Delta T, wall area and insulation, ceiling area and insultation, floor area and insulation, window area and insulation, wind speed, and air changes, are most of what you will need.

Try some of the electric heat mfg websites. I suspect they will have some calculators.

cf

#### Dennis Alwon

##### Moderator
Staff member
In Mass. and in a basement I can't imagine you would need more than the sq. foot times 7. Seven works here in NC without the basement. The basement is bermed in and thus less heat loss so I bet 7 times the sq. footage would work.

#### jim dungar

##### Moderator
Staff member
In Wisconsin, we often end up with 10 watts/ft? as a conservative number for a house heated by baseboard only. But the heat loss formulas are not really that complicated to use for a 'house'.

#### gndrod

##### Senior Member
Have any of you done a heat loss calc. on a building, then sized the baseboard from that?
Yes....on a room by room basis stat zone controlled. It is very difficult to determine heat loading by single volume extrapolation in residential design unless the structure was one room with same ceiling height without windows.
In the beginning days of CA Title 24, heat loss calculations included using the crack method for leakage loss and insolation rates required for heat gain through glass to floor mass where there were no fenestration ratios considered.

There were no Climate Zone environmental knowns established in the early 60's either. Now the architectural guidelines are based on the Federal mapping along with State adopted energy conservation Climate Zone regulation with options for calculation by design mostly.

The days of using square footage to volume for residential energy calculation in new construction is disappearing for heating and cooling. I can predict more complex rules will be coming to your neighborhood eventually if the Feds have their way. rbj

#### Cold Fusion

##### Senior Member
...there were no fenestration ratios considered. ...
I'm likely the only one here that doesn't know. What's a "fenestration ratio".

cf

#### donselectric

##### Senior Member
i'm in so nh and have always used 10w per sq ft and never had a complaint

#### gndrod

##### Senior Member
I'm likely the only one here that doesn't know. What's a "fenestration ratio".

cf
The area R value of glazing to floor square footage.

#### gndrod

##### Senior Member
i'm in so nh and have always used 10w per sq ft and never had a complaint
Hi Don,
I think you are safe for some time to come in nh. (Less bureaucratic control for the tax \$.)
(8j

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