Ran the oven through its 3 hour self-cleaning cycle today. The heat it gave off kept the house warm and the furnace from kicking on for like 6 hours. My gas bill appreciates that.
How many kWh does an oven draw during cleaning mode?
All of them lol. Somewhere between 2,000 and 5,000 watts and it’s basically running full-on the whole 3-hour cycle.
Which works out to 6-15 kWh. That’s less than $1 (30 cents at the low end) worth of electricity off-peak (no need to run self clean during peak hours!) where I live.
The real issue with self clean is the thermal stress it puts on the oven’s electronic control board. My oven can no longer regulate its temperature since it put up an error message after the last self-clean I did. Now if I try to preheat it even to a low temperature it just runs full out until it overheats and shuts down.
Unfortunately, heat joules are heat joules regardless of source; the total cost to your electric bill was probably about 3x what it would have cost to run the gas furnace, as resistive heating electric kWh are almost exclusively more expensive than heat via gas.
Since you’re going to do that, this is the time of year to do it (in the Northern hemisphere at least).
That’s 100% true even with the multiple rate hikes on the gas over the last 2 years. But I needed to run the cleaning cycle anyway, so it’s basically waste / free heat.
Oh yes, when you get to use “free” heat it’s great. It’s how I justify running computers that contribute compute power to science projects via BOINC at the house I moved into- the house uses exclusively electric resistance heat (shitty rental), so if I’m burning the same amount of kWh running a computer instead of a heater, it’s a net benefit.
We really need Windows installable heat pumps. Just ac units with reversible valves and better fan motors.
Why isn’t that a thing yet?
They do exist! Units like this have started to become more prevalent in the market, although they are still too expensive for most people to consider for energy savings alone. Heat pumps are magic.
Alternatively, you could take your existing windows ac and flip it around… that won’t work very well though haha
A proof of concept has been done on YouTube at least:
Yeah, I seriously considered trying to heat my garage/shop with an old AC this way after watching this originally. Gotta insulate it better before that though.
Their proposed AC units would go in Windows, not windows, unfortunately
My iPhone autocorrected that too of all things.
That depends entirely on how much each costs. If you have a solar panel and battery, the whole thing might not hit your wallet at all.
Note that I didn’t say it was free, since for example installing such infrastructure is not without cost.
What’s more interesting is that gas and electricity are charged in such a way that you cannot actually properly compare them, ostensibly because gas burns differently depending on what comes out of the ground - interesting, since that same gas is used to generate electricity at the power station.
What’s more interesting is that gas and electricity are charged in such a way that you cannot actually properly compare them
You can, though, with a little bit of engineering math. The goal is to get to an amount of end user energy per $, counting your appliance efficiency. (I’m about to mix ISO and Imperial units here, please nobody murder me)
Nat.gas is a variable mixture for sure, but it is required to fall within a “reasonable range” of producible heat energy per cubic foot of gas at atmospheric pressure and 60F. In the US this typically ranges from 1,000 to 1,100 BTU per cubic foot, and the accepted industry average is 1,038 BTU/cu.f (1095.15 kJ /cu.f)
US bulk gas deliveries are priced in $ per thousand cubic feet, using the standard cubic foot described above. In December 2023 this was $12.94/kcu.f, but has varied between $8 and $24/kcu.f in the last few years. And your furnace is typically between 80 and 90% efficient at getting the heat out of the gas and into your home; the rest is lost up the flue. Plugging these values into a unit conversion equation:
If we do the same for electricity using resistance heating its much easier, as resistance heaters are 100% efficient; all wattage put in comes right out as heat. (Heat pumps actually improve efficiency to above 100% but i’m not worrying about those, as those are not practical for an oven.)
The average cost of a kWh of electricity was 12.38 cents in the US for 2023.. counting for delivery charges this was likely closer to 16c/kwh based off my own bill, so I’ll use that.
Where a kWh is 1000 watts for 1 hour, a watt is 1 joule per second, and there are 3600 seconds in an hour, you get:
Even counting for furnace efficiency, it’s still more than 3x the cost to get the same heat from electricity than from gas. YMMV with different input costs of course.
Im sure u could calculate a comparison using the rated heat output and efficiency curves of ur variouse gas devices. Im pretty sure the variation in energy density per kg of gas is limited by some standard. I would do the maths but that sounds a little too exciting for this sub.
