I'm looking for advice of how to best heat a converted garage space (w/ some insulation). I live in So. Cal and so the lowest winter temp at night is about 40 degrees. Normally I only need to heat the place up a maximum of 10-15 degrees and only at certain times of the day, not constantly.

I've pulled a gas line into the room. One contractor suggested a unit like the Modine Hot Dawg but worry that it may be too noisy (we use the space as an office / guest room). A local heating company suggested a dustless mini split unit which is electric. I've been reading about the benefits of radiant heating units. Would appreciate any tips and suggested sites to visit to learn more.

  • 1
    Careful with gas -- International Residential Code (IRC) G2406.2 (303.3) doesn't allow gas burning appliances in bedrooms unless it is direct-vent type or gets its combustion air from the outside and is separated by a weather-stripped door. – gregmac Jan 6 '15 at 3:24
  • I really hate cold floors - so make sure you put some insulation under the floor. I used solid Fiberglass pink sheets (2x8), taped them with the red sheathing tape, and just laid the wood flooring on top of that. – Mark Jan 6 '15 at 5:39

In that climate, the most energy efficient method is a heat pump. An added bonus is that it can air condition during hot times, something that is presumably a requirement for an office space or guest room in SoCal.

Heat pumps come in all kinds of flavors, but those designed for and often used in commercial and residential space should be plenty quiet. Perhaps a 3/4 ton (9,000 BTU/hr) ductless unit (at $500) like this would be more than adequate:

from www.acwholesalers.com/Mitsubishi-Air-Conditioners/MSZ-FE09NA-9000-BTU-Ductless-Heat-Pump-I-SEE-Sensor-Air-Handler/19513.ac?gclid=CK-ltM3m_cICFYVafgodvoYAVg

Beyond that, energy efficiency can be further increased with better insulation, decreased air infiltration, and more efficient windows.

Comfort probably can be further improved by adding thermal mass: heavy furnishings, dense partitions, heavy curtains and wall hangings, etc.

  • I would examine carefully the economics of heat pump vs gas given that electricity prices in Southern California are so absurdly high. For typical SoCal electrical usage, pricing tiers and heat pump COP, it is likely that the heat pump will be more expensive than gas. – bobfandango Jan 6 '15 at 0:29
  • @bobfandango: Good point. SCE rates are about $0.06 per kWh and that isn't so expensive that it upsets the relative efficiency. However, natural gas prices at the source have declined substantially: I don't know how, or if, that affects SoCal. – wallyk Jan 6 '15 at 3:09
  • Actually, the .06 cents is just for delivery. You also have to pay generation costs which are about 9 cents at the base tier. So, rates start at about .15 cents and go up pretty quickly. See the tier structure for SCE here: on.sce.com/1qZDasg For my house, with 2 adults and 2 children, we almost always end up in tier 3 which is .28 cents per kwh! We have LED lights, and have gas hot water and heat. We have done what we can to conserve, and still, we are in tier 3. Of course, we don't pay tier 3 rates for all our power. But, any added consumption would be at the .28 cent rate! – bobfandango Jan 6 '15 at 19:55
  • @bobfandango: Leave it to California. They are buying mostly our power (from the PNW) at like 2.3 cents per kWh, then they mark it up to 28 cents! Isn't that illegal? – wallyk Jan 6 '15 at 21:02

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