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looking at a 3000 watt electric heater vs. a 1500 watt heater
3000 watt heater rated @ 12.5A, 240V
at 125% load (15.6A), would require a double (tied) 20A breaker w/ 12GA wiring.
3000 watt = 10,242 btu/hr (1 ton)
should be enough capacity for a 500 sqft area with ceiling @ 8′
1500 watt = 5,121 btu/hr (1/2 ton) – 250 sqft w/ ceiling @ 8′ (16 sqft) (with no special circumstances like large/many single-glazed windows, poor insulation,…)
am i correct? other considerations?
thanx ladies and gents,
brian
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How many places are you going to post this question? Anyway, here's my thoughts, again:
You are correct, subject to the following assumptions:
Average new construction R-19 in the walls, R-30 in the ceiling, something in the floor. The easy things were done to reduce air infiltration (closed cell foam under the bottom plates, sealing around exterior windows) but no heroic efforts were made. Design temperature of 0F.
If your house is below average or it gets below zero (I get -40F here) then you need 50% more or so wattage. If your house is tighter and better insulated than average; or locate in Miami, then you could use use less wattage. -David
*thanks david. yeah, i realized that there was a separate heating discussion heading a little later...what's your background? not miami... sunny san diego, ca. people here freak at +40 degrees.
*I worked as a plumber, rocker (sheet, not & roll), programmer, and computer repairer between my two stints at Berkeley in chemical engineering. Last 14 years I have been cleaning up toxic waste sites as an environmental engineer. I hold the minority view that an engineer should be able to build, install, and operate anything he/she designs and practice that. My professional engineering regristration is in Civil. Finally got to build an entire house (my own) instead of just bits and pieces of others' houses when we moved to Alaska and bought 13 acres.In San Diego, you could cut those wattages in half. (e.g. 1500 watts for 500 square feet). Heck, skip the heaters all together. 45F is T-shirt weather. 35F does require a sweater, but how often to you get that "cold"? :-)
*San Diego... Eat toast for breakfast...more on cold days.near the stream,aj
*gotta love ya, david. i personally worked for an engineer for 5 years. the inexperienced ones definitely fit the category of "a little bit of kn owledge is dangerous". , disregarded practical input based on hands-on experience, opinionated, arrogant, fought every suggestion... never again. i've gotten to the point where i can walk into a home and spot if an engineer has been around (dead giveaway - casing mouldings used for baseboard. why??? i don't know, but reliable indicator).aj. you'd be surprised how people here react to 39 degrees. but it's not my heater, people have children and babies, and i have the responsibility of selecting the appropriate package based on sound principles. how many pieces of toast for a 500 sqft area ;)brian