baseboard heat and insulation


  #1  
Old 01-18-16, 02:53 PM
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baseboard heat and insulation

I have 2- 8 ft baseboard heaters(240 volt) in a room that is 19x36.(single thermostat in center of room)

with an outside temp of 28 F they both run 13 minutes and are off for 8 minutes to maintain an indoor temp of 63 F, would increasing the ceiling insulation to R60 be any help? it has R 11 in the ceiling now.

should i install a vapor barrier first?
 

Last edited by RonR399; 01-18-16 at 03:17 PM.
  #2  
Old 01-18-16, 04:35 PM
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Welcome to the best DIY forum on the Internet!

Help what? Your room is about 684 square feet and two "standard" eight foot electric baseboards are putting out about 6,826 BTUs each or a total of 13,652 BTUs total. That calculates to just under 20 BTUs per square foot which is a fairly good figure, the "normal" range being somewhere between 25 and 35 BTUs per square foot with "average" construction IF the heaters were running constantly. Since your heaters are running approximately 2/3 of the time your BTU/hour input is actually closer to 9,000 which would make the BTU/square foot number closer to 13, a very good number. Of course these numbers would change if you raised the temperature in the room to a more normal 68-72 degrees F.

That stated, increased insulation, in ceilings, walls and floors will usually drop the BTU requirements as will air sealing. The big question is...would the capital cost of increasing the insulation be less than the saving realized by lower electrical usage. In your case the answer would probably be no.
 
  #3  
Old 01-18-16, 05:35 PM
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Hi Ron,
I ran your ceiling through a basic calculator to see what the heat loss difference would be for the upgrade to r-60. Your r-11 is at best r-8 because it is in the cavity only and you have to average in the joists. Using 10 degrees as the design temp and 6000 heating degree days your design load for just the ceiling is currently 5,130 btus per hour. Would be higher at a lower design temp.

If you increase the attic to r-50, still losing some of that r-60 to bridging, the design load drops to 821 btus per hour, basically out of the picture compared to the rest of the heat loss.

If you added r-19 to what you have it would be about 1,500 btus per hour.

Not sure what your electricity costs are, but I can add that is to get your yearly savings.

Bud
 
  #4  
Old 01-19-16, 06:35 AM
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You don't mention the wall (or floor) construction ...
Added ceiling insulation would help of course, but it may not be money well spent if the losses through the walls are higher.
 
 

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