Inefficient electric duct central heating

[John Vickers]

I have always thought that my system is inefficient and no matter how I set the thermostat, I always do not feel warm enough.

This is a 950 sqft apartment. The heat is gereated by two elements but I don't know the wattage.

The temperature at any register (all ceiling mounted) is 84f and at the return register is 74f which is a split of 10f. I have read that the ideal split is 19f-25f.

With the t/stat set at 70f, and having been off for 20 minutes or so, when it kicks in there is an initial draft of cold air which can last up to 40/50 seconds before feeling any warm air. I have nothing to back this up but I think that one of the elements may not be working.

Yes, the system is old but I cannot read any useful information off the plate over the furnace. Apart from replacing it is there anything that can be done to make the place feel comfortable?

 

[Dana]

Ceiling-mounted return registers are always a problem for heating systems, since it's taking in the warmest stratifcation layer in the room rather than the coldest, near the floor.

That's what you would want during the cooling season though- are the same ducts used for cooling? Is this a heat-pump, with electric heat strips, or just an electric furnace?

Are the ducts in an attic, above the insulation?

To make the place feel comfortable as a tenant, low temperature electric radiant panels space heaters or oil filled finned radiator type space heaters work, and would be more efficient than an electric furnace & ducts located in an unconditioned attic, since it wouldn't have the duct losses. The direct radiation off the panel or finned radiation onto humans increases comfort at at any air temperature, and it also heats up nearby objects, which is also a subtle comfort booster. Space heaters with fans are noisy, and rely solely upon air temperture for comfort, and space heaters with visible heating elements are more prone to starting fires, since (unlike panel or finned radiators) they can radiate enough heat onto nearby objects to raise them to kindling temperature.

Don't go overboard on wattage. A 250-500 watt panel heater can heat a decent sized bedroom or office, but for larger or more open spaces you might go for a 1500 watt finned radiator type (or even two, plugged into different circuits for a 500-600 square foot open livingroom + dining + kitchen type of arrangement. Most 950' apartments wouldn't need more than 3000 watts total.

For bedrooms, an electric blanket can be pretty comfortable at any room temperature above 45F (though if it's that cold in the room you may not want to get out of bed.

 

[Sponsor]

 

[WorthFlorida]

You’re in NC and heating is probably number 2 of concern and air conditioning is #1. You have an air handler for A/C with a electric heater added inside the air handler designed for cooling, not heating. Now that we’re having extreme cold, even in Florida, its short comings is obvious.

If you do not know if you have a heat pump, google your model number of the compressor unit. Another way is look at the thermostat wiring.

If you have a heat pump it can handle only so much before the “auxiliary” electric heat is turned on. This is controlled and determined by the thermostat.

If you do not have a heat pump it means the electric element size is too small and it is probably no more than 5 kilowatts. Maybe smaller. If your renting I doubt the owner will pay to up your heating element to a 10 KW but the wire size and breaker feeding the air handler must be large enough to handle the load.

My first home in Florida had two air handlers with 5 kw each (non-heat pumps) and on the few cold nights the heat would run all the time. I upped the first floor air handler with a 10 KW and it worked satisfactory afterward. Now in my second home in the Orlando area, I have one 3.5 ton heat pump plus a 10 KW electric element. It’s a two story 2400 square foot home and I can make the home quite toastie when it is in the low forties. Only this past week did it get colder.