High Efficiency Fireplaces for High Efficiency Homes? Is This Real?

by grillrepair on December 19, 2012

I just read this article about heaters in homes that was lamenting the lack of low capacity gas fireplaces.  We’ve sold 10,000 and 20,000 BTU gas logs for years so I know there is no shortage of low-capacity gas fireplaces or gas heaters.  That’s not what shocked me; I’ve worked with enough designers and contractors to know they sometimes get tunnel-vision and cannot see an obvious solution to a problem.    Nobody usually wants low capacity fireplaces unless they are installing in a bedroom or bathroom which is very rare.  The writer, David Butler is working with Energy Star Rated high efficiency homes and although i’ve seen the logo the description of what Mr. Butler calls bad design seems — in my experience — to be the standard.

For instance, mr butler explains the problem of standard homes, the thermostat is often purposely designed away from an exterior wall (and as i think of it i’m remembering all the homes we’ve had and the thermostats have been in a hallway or set to an inner wall). When the heat  cycles off cold seeps into the home from the outer circumference: walls, doors, windows and conducts through wall materials.  Because the air handler has cycled off this cool air is staying in perimeter areas until pushed further into the home.  By the time the cold reaches the thermostat the home has become uncomfortable, has dropped many degrees radiating away from the thermostat and the heater will now need to burn a lot of gas to return the home to its temperature settings by heating this cold air.

Isn’t this normal?  I am certainly not saying i like it but the air and heat are always cycling off and on and the house iscomfortable  on averge as the temperature becomes uncomfortable in one direction and then the other.   Every air and heating system i’ve used has been like this so i assumed that’s just how they work.

Apparently this is not normal in highly efficient homes?

I never thought there was another option!

Because we need the heat to battle our oscillating temperatures we usually need hotter fireplaces.  We also generally install   fireplaces on outer walls in these perimeter areas where temperatures  are more drastic and moving in to the center of the house.  Before reading the article i never thought of the area as a perimeter area but assume fireplaces are more frequently on outer walls because this makes them easier to build and less expensive.  A hotter fire place then usually would serve the same function as the overworked gas heater if the fireplace control valve is using a thermostatic transmitter that is not also installed in a perimeter area.

A typical vented gas fireplace valve will sen between 75,000 and 125,000 BTU.  A typical barbecue set to its highest setting will spread 60,000 BTU among three or four burners.  A gas fireplace will often burn twice as much gas and route through one main burner to maximize flame height and color.  The 2 appliances are engineered to heat and vent differently so the fireplace is more likely to direct the effect so air currents deliver warm air throughout the house.  This article is — quite correctly maybe — lamenting the waste of gas because a more effective architecture, a better designed house could use a much less powerful gas log set to deliver much more heat.

Homeowners who use a vent-free gas fireplace in a small room know this is true.  The unvented gas fire heat rooms quickly even if they lose effectiveness as more and more varied air currents travel through the home.

I really like this idea.  I like the idea that the home is not hot and then cold as the a/c and heat cycle off and on.  I am sure we would enjoy that — for at least a day or two before we took it for granted and no longer noticed.

as an aside most homeowners i have discussed fireplaces with tell me the fireplace is a decoration, not a heater.  The fact is most homes do have multitudinous currents of air dissipating heat so ventless gas fireplaces are rarely primary sources of heat.  Even vented gas fires that may burn much hotter indoors will have very effective chimney flues that remove most of the heat with the fumes generated by burning gas.  I have a wood burning fireplace that we love to burn for the light, soothing sound and ambience of a crackling hot harth.  However, we discovered one year after the heater stopped working that the fireplace is not a heater.  I can crank down the damper to push heat into the room but this is a lot of work because the flue must constantly be adjusted open and closed or the house will fill with smoke.

 

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