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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
Replies
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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