Can I use electric radiant heating as primary heating?

Question

Our home was build in 2001 and currently has a oil furnace that is at the end of its life. We are looking for a more efficient heating option and stumbled across an electric radiant heating product called STEP HEAT that can be installed between the floor joists (we have access) so we wouldn't need to remove the existing floors. Would it be possible to heat the entire home with a product like this or would it be considered secondary/supplemental heating?

Answer 1

You can. But don't.

Resistance electric heating, no matter what the fancy name, is really a giant toaster. Toasters are wonderful things - for making toast. But you use a toaster for a few minutes a day and that's it. So it doesn't use much power. In fact, because a toaster concentrates most of the energy onto bread/waffles/etc. instead of heating up a large oven, it is actually very efficient.

But using a toaster to heat your house is not very efficient. Generally speaking, due to conversion efficiencies, peak demand issues and other factors, resistance heat is generally the least efficient way to heat an entire house. It works well as supplemental heat - little 1500W space heaters under desks and in corners of cold rooms, etc. though even that can have some problems.

In most places, the better solutions are:

• Oil or (even better) natural gas heat. This uses fossil fuels, but so does a large portion of utility electricity generation (especially peak demand). But since it is at point-of-use, the conversion loss from fuel to heat is typically a lot lower, especially with modern furnaces, than fuel to heat to steam to electricity to heat which you use with electric resistance heat.

• Heat pumps. A heat pump works as an air conditioner in the summer and a heater (using the same mechanism in reverse) in the winter. Within certain constraints, a heat pump can produce a lot more useful heat than the same electricity would produce via resistance heating.

If you already have air conditioning then you have ductwork in place and a heat pump is worth considering. If you don't have (and don't need) air conditioning, then I would recommend a replacement oil furnace unless you have utility natural gas available, in which case a natural gas furnace would be a bit of an improvement (generally cleaner burning, no need for oil deliveries).

Answer 2

I had our oil-fired hot water baseboard (HWBB) heat removed when we had our major renovation done, went with all-electric (heat pump), and regret not leaving the hot water BB in. The heat pump works fine down to about 30 deg F. But the resistance auxiliary heating that starts to kicks in below that temperature is costly.

Prior to the change over, I had standard AC for summertime cooling (no heat pump) and the oil fired HWBB provided all the heat, in addition to heating the hot water. Since the changeover, my total energy cost (now just electricity) is lower than my combined oil + electric cost was prior to the change over by roughly $1,000/year. Even though I am ahead of the game cost-wise, I think I could have saved more overall had I used the HWBB as the aux heat (or even for 100% heating) on those days when the temperatures never rose above freezing.

I am in the mid-Atlantic region.

Answer 3

My retired parents had electric base board heat and liked it. A small ( 1000 sq.ft) new , well insulated house in a mild climate; northern Arkansas. Each room could be set at a different temperature. They did not complain about the cost but I do not know what it was. One drawback, adding central AC required installation of ductwork.

Answer 4

Stepping away from oil is awesome for national security, as current events certainly show. (using less oil allows us to support our allies so they are not dependent on fascist governments, which seem to take over every nation whose economy depends on raw resources.)

Resistive electric heating? Are you sure?

However, this is "100% efficient" electric resistive heating. Which sounds great, except it's only 100%. The deciding factor in such an installation is the electric tariff or rate plan available to you.

The worst case scenario for any power system is 4 PM on a hot summer with everyone's automatic thermostat kicking their A/C on full to cool the house for people coming home, meanwhile factories are still going full-tilt and retail is open. This defines how many surge generators or "peakers" they have. However, a number of jurisdictions (Ontario; North Carolina) have a glut of nuclear or run-of-river hydro, which are expensive-to-build, cheap-to-run "use it or waste it" sources. They have the same crunch time as everyone else... but the rest of the time, they have too much base load. As such they have very favorable rates most of the time, and certainly anytime you'd want heat.

In such a plan, resistive electric heating makes sense - it'll just go over the spillway otherwise, or the nuclear plant will have to throttle down (changes increase maintenance; that's why Fukushima was trying to slow the cooling of unit 1, which was the first domino).

Heat pumps are the better plan

Without question in moderate climates. And, as a bonus, heat pumps provide air conditioning inherently. In fact the only difference between a heat pump and A/C is deleting the reversing valve so it can only go 1 direction.

Because heat pumps are merely moving heat, and not creating heat, they are highly efficient - vastly over 100%. That is, a unit with a COP of 3 can "pump in" 3 watts of heat for every watt of energy it uses. I.E. it is 300% efficient.

COP is a standard unit designed for comparison, but actual performance will vary with temperature.

When it comes to air conditioning, units are rated differently - in SEER, which is BTUs per watt. But 1 watt is 3.41 BTUs, so you can divide SEER by 3.41 to get "air conditioning efficiency". 13 SEER is the bare minimum legal to sell in the US (so 381% efficient), and I've heard of SEER as high as 39, or 1140% efficient -- wow!

Even in very cold climates, there are two solutions.

• The latest heat pumps are really good at going low-temperature. Just the same, you keep (relatively cheap) electric toaster heating as a backup.
• The heat pump can interchange heat with a ground source. Reasonably underground, temperatures are a fairly constant 50-60 degres F (10-15C), which is an absolutely ideal temperature for heat pumps. This "ground source" is obtained either by burying long loops of coolant pipe, or by simply pumping water from an aquifer, interchanging heat with the water, and letting it fall back into the aquifer.