What is the heat source for the water into the radiant system, just straight hot water electric (resistance)? Is this a separate dedicated heat source just for the garage? Is the house also heated with electric?

To do simple math, assume this is 2000-2300 'extra' kwh just for the new radiant floor. That's about 3kw load (i.e. continuous) for the entire month.

My gut reaction is that this is plausible - perhaps on the high side; depends on how big the garage is, how well insulated (probably not well), stand-alone building, how cold your climate is (and was in December), etc. Are you heating the garage to room temperature (do you need to)? Is it controlled by a thermostat in the garage? Depends how you use your garage - mine is heated but only maintain it at perhaps 10-12C (very cold climate). (Unfortunately can't help with other comparisons, mine is off the house's boiler and it's gas).

Turning down the target temperature could make a very big difference. Garage doors typically have minimal insulation. If you want to diagnose how much energy it's using, there are various ways to do so, either at the hot water source, or for the whole house and experiment with turning it on and off.

This may not be much comfort but hopefully you'll only have to heat the garage a few months a year.

Separate electric hot water tank for the floor. Well water. It's a two car garage, attached, (split level home). I'm in PA so it can get pretty cold here. Probably 20's in December. There is a separate thermostat for the garage, set to I think 63 (constant). We installed new garage doors also. Not cheap but I'm sure you're right about the insulation. I know the ceiling in the garage is well insulated but block walls of course.

My non-estimated electric bills are typically anywhere from 80-165 USD so you can imagine my shock at a $420 bill. Our whole house is electric. If that doesn't sound astronomical to you, I guess we're going to have to turn it way down. We obviously had no idea it was going to cost this much to run. My brother-in-law has it as well but he has gas heat so I guess that's the difference....Like I said, we'd read that it was very economical to run, part of the reason we installed it...

Thanks so much for the input.

" Another point is whether your concrete pad in garage is insulated below. " Yes. there should have been say 4" of foam under the slab when it was poured. Else, you're heating the planet.

And 63F seems awfully warm for a garage floor, unless you're trying to live in your garage. Usually all you should care about is keeping ice from forming, so 45F would be fine.

Ice melts at 33F, so if the bill is still too high... you know what's next. Electrical resistance heat is not cheap, even when it comes to hydronic heating systems.

What is your electric rate per KWH in PA?

I'm not sure about the foam, I'd have to ask about that...Hubby came home and I said "I turned the heat down in the garage." and he said "I turned it down even farther."

I believe our rate is around 10.75. I don't get a detailed paper bill since I'm on auto pay. I never chedked because my bills were always so low.

A stupid question, but what exactly is using all the electricity? I know it doesn't cost much to run a hot water tank....

If you ran your hot water continuously, it would use up quite a lot of energy.

Or another way to look at it: doesn't cost much to run a toaster - but then you only run it for a few minutes a day. Now, get three of them, rig them to run continuously, and use them to heat your garage. (Actually don't do that, it would be unsafe).

The toaster works on the same principle, resistance heat generated by electricity, as an electric hot water tank, it's just heating up water instead of air. Sitting in your insulated hot water tank - when all the taps are closed, which is most of the time for household water - the water doesn't lose much heat. Hook that hot water up to a pump, through tubes in cement in an uninsulated garage and back to the tank cold, the heating element may need to run full time.

Ok, that makes sense. Honestly though, my husband and I have both been in the garage extended periods of time and the hot water tank doesn't really run that much.

I don't know...the toasters may be cheaper.... :

Thank you all for being so helpful by the way....

Your water heater might be more like eight toasters and so not running all the time, you could look at the panel. Do you hear it running? ImI'm still curious how your house is heated, odd it is cheaper.

An electric hot water heater typically will not make sound when it runs. I would think this system you have is a closed loop, meaning you fill the tank and loop the incoming water is shut off and the water is moved thru the loop in the floor via a in line water pump, controlled via temp sensor(s). I am only guessing here...

Note: just because the circulation pump is off doesn't mean the resistance heating strips within the water heater are off. (The pump you should hear, the strips you will not)

Your electricity rate is pretty average, but being on balanced billing it can be upwards of 11 months of usage on your end until you realize the increase. Unless your balanced billing works differently? I had a customer of mine in which it took 11 months of the balanced billing to drop after I installed a new more efficient air conditioner.

So if you use a lot of energy in any one month on balanced billing the energy company may rack this up and charge you for it pronto < I can only assume it would be this way because the energy company wants to get paid and possibly alert you to a problem.

With all of that said, was this water heater sized properly for the 'heating' load you are putting it under?

The colder it is, the heavier the load. At some point, the load 'could' be so great in which the elements that heat the water do not shut off.

The only true way to know the heating elements are off in an electric water heat is to hook amp probe around electric lead and see what the amp draw is. If it reads 0 they are off.

Because you are in an all electric house, there could be issues with your other systems. While rare this does happen >>> an electric resistance heater the strip breaks and shorts to ground. This causes the strip to remain on indefinitely, only turning off due to heat limiting controls of the appliance in question.

The other outcome, even more rare than above besides this is an electrical fire. We all know these occur as well.

I am so sorry, We use heating oil. I neglected to specify that. I'm just used to saying all electric just because everything else is.

If you're referring to the budget billing, where your cost is spread out over the year, we don't do that. We just pay whatever the usage or estimate of usage is every month.

Yes, the water runs in a loop.

The first thought we actually had was the power surge that fried our furnace circuit board and tv but the power company says that wouldn't affect the meter...Although in my mind, I could envision the power surge and the meter spinning like crazy...lol. Wishful thinking on my part.

Don't actually hear the tank running, but you can hear when it clicks on. I'm assuming the correct size was used. My brother-in-law has the same setup, as does my nephew so they had an idea of what size was needed.

My brother-in-law and nephew both have gas hot water tanks though so it's hard to compare costs....

so was it a high electric bill or high heating oil bill?

If the water heater runs on heating oil, I think you'd be able to hear it run to some degree.

Power surge does not effect your light bill, it can effect your wallet in damage though.

Raising the garage temperature from "the 20s to 63" with resistance heating and an uninsulated floor/walls will produce an insanely high electric bill. Turn the thermostat down into the 40s, or only use it when you need it.

Sounds like you were sold a bill of goods by someone!

@lorraine, ah, now it all makes sense. Note my simple calcs saying 3kw was on average, for an electric hot water tank it may be that 'on' is five or ten kw and it's only on some of the time.

The cheapest and easiest solution as others noted here is to turn down the target heat. Assuming it's primarily for cars - or more correctly, your comfort when getting into the car - above freezing temp should be enough (40s-low 50s). Cars usually warm up pretty quick when driving. (Frankly the car itself will be perfectly fine in freezing temps too).

And depending where you are, you may only really be using it 2-3 months a year. Just turned off the main heat in our garage and it's just above freezing outside (although system set up to keep it above freezing as there's water lines in there).

>If the water heater runs on heating oil, I think you'd be able to hear it run to some degree.

>Power surge does not effect your light bill, it can effect your wallet in damage though.

The hot water tank is electric. The only thing the oil is for is the furnace. Yes, it did, to the tune of $1500. That was actually the first thing we thought of when we got that bill was that the power surge messed the meter up but the power company says that's not possible.

>Sounds like you were sold a bill of goods by someone!

Yeah, my husband!

Yes, we've turned it down to 50. I think that's as low as the wall thermostat in there goes. We're in Pennsylvania so it's crap weather here half the year. The main reason we put it in was so he could wash the vehicles in there and I could use it for working on projects that I don't want to do elsewhere in the house (spray painting, cutting wood, etc.). While 40 may be warm enough to keep things from freezing, it's not conducive to wanting to do much else in there. I'd be ok if I knew that this was just going to be an astronomical bill once a year to initially get it warm but I'm not paying that every month to maintain the temperature. I just got my bill (estimated) and it's 265. Last year my estimated march bill was $116 and my actual bill in april was $74 so...

I don't know how your estimated billing works, but you can check your meter yourself how much you're using. Now that weather should be warm enough that you can leave it off with not much risk of freezing, try 24 hours with it off, 24 hours with it on at higher target temperature, and the same with the low target temperature. Allowing for different outdoor temperatures and starting conditions, you'll get a sense of how much it uses and can adjust for what you're willing to pay for.

Keep in mind: the amount of heat loss (and hence how much heat you're asking your boiler to generate) rises depending on the temperature difference, and it rises quite dramatically when insulation is poor and temperature difference high. Put simply, keeping the garage temperature at 50F when it's low 40s outside may not use that much electricity, but 55F inside when it's 20F may use quite a lot. Experiment and measure a bit and you can figure out how much you want to heat it.

Note that a concrete pad heated this way will take a fairly long time to add heat (and cool down). So as crazy as this might sound, if you occasionally want to plan to work in there for a few hours, for example, and want to take some of the chill off, you may be better served by plugging in a relatively cheap space heater in your work area than cranking up the thermostat. (Others might have input on what types, infrared or other).

You could also consider getting a programmable thermostat. Normally may not be worth it with a slow-heating pad like this, but then again, if you can turn it off entirely when you're away for a few days, might save you enough to pay for it (that is, if having the programmable thermostat makes it easier for you to do it). Or if you have electricity tariffs that are higher at peak, turn it off except when rates are lowest.

But biggest savings will mainly come from keeping the target temperature low and turning it off entirely when not needed (i.e. warmer weather).