Hi,
I have a problem and I'm hoping I can get some expert advice.
I am trying to heat my 2 x600 sq. ft. strawbale house with infloor radiant heat affordably but I'm having difficulty achieving this goal.  Unfortunately my only fuel choice for this winter is electricity.

I'm using a 40 gallon 3000 watt electric water heater as the heat source.  I'm currently running two 200 ft. loops at the bottom of a 3" slab.  Below that I have 4" of blue foam board.  I have 2 more loops stapled up under my main floor which I am not running.

At max. the water temp. in the pipes reaches 110 F. which in turn heats my walk-out basement to 68 F. the temp. outside a few degrees below freezing but promising colder.  I was hoping I could heat the slab enough to heat my upstairs also but that is just not going to happen.  If I run more loops the temp. drops down 5 degrees with each additional loop.  There is no cycling so this thing runs constantly and that equals 72 kw burned every day.  

Is there something wrong with this hot water heater or is it in my design?

Thanks

if you're dropping temp for more than a day, you are exceeding the ability of the water heater to generate heat.

at 3000 watts, that's not hard to do. that's only about 10kBTUs/hr. Even with strawbale it can be hard to do that for a peak load. Dunno how cold it is now, though.

you should put on all the loops and let it run for a couple of days and see where it stabilizes. it may be just that you are playing "catch up" in cold weather (which can take a long time with an underpowered heat source) or you may just not have enough output at all.

3000 Watts? That is the equivalent of two small electric space heaters. Heating a house with electric resistance heat is simple but rarely the low cost option unless your electric rates are really low.

How many square feet are you trying to heat? What does "2 x600 sq ft" mean? 2 floors @ 600 sq ft each for a total of 1200 sq ft total or the "x" is just a typo and you meant 2600 sq ft?

Also, where are you located?

Thanks for the replies.
To answer your questions. I am trying to heat a total of 1200 sq. ft.
Electricity, wood or propane are the only options for my area, last winter (Nov.-March) my electrical consumption cost me roughly $1500. Outside temp. is now 10-15 F.

I've now turned off the water heater completely
I have 2 1500 watt baseboard heaters on the main floor and that is keeping it above 65 F. With no heat in the basement the temp. falls to 50F. which gives us a cold floor on the main level.

I guess a specialized electric boiler is just going to produce more heat by consuming more electricity and there will be no savings on my electric bill. Is that correct?

I can't give you expert advice but some experience. I've got the same size house, but not strawbale: 2 levels, roughly 650sqft each. R27ish walls, R45 attic, R24basement but R5 slab insulation in only 60% of the slab. Pretty tight air seal (spray foam insulation), decent windows, etc.

This morning the temp here is -8F or -22C. I'm heating with 110F water in the ceiling upstairs and slab in the basement and it is just keeping up. I'm doing the opposite from you though and keeping the basement at 60F and the upstairs -our primary living space- at 70F, minus the bedroom. The basement zone hardly ever comes on. Upstairs I'm experimenting with setbacks at night (to 60F), and even though the ceiling heat is very responsive, after about 6-7 hours at 110F it hasn't quite recovered to 70F yet. Noteably, I've got the HRV running a lot right now to defrost some windows. It's bringing in lots of fresh air which probably isn't all that efficient in this cold weather.

I've got an 8kW electric wall mounted boiler which is probably running well below its capacity. I don't have actual kW/hr consumption data, but the temp is turned way down and it is not running all the time. I'm sure it exceeds 3kW/hr once in a while though - like when recovering from the setback. Forecast is for -17F (-27C) tonight! I'll probably have to reduce the set back, or turn up the boiler. When the temp is near freezing I'm thinking I could get away with 100-105F water, although I'm not sure if that is an advantage.

Lots of hot water tanks have a simple wiring option to boost the element up to around 4500 watts. Have you checked that?

PS I've got one small room upstairs with staple up under 1.5" of wood (full coverage with plates and R22 below) and it just can't deliver the btu in cold weather compared to the ceiling heat, which only needs to go through 5/8" drywall. I'd have to crank the whole system temperature way up just to fully heat up that room. I've got left over tubing and plates so I'm going to fir out one wall and extend the loop into it to get enough btus into the room.

gordieb, an electric boiler will not likely reduce your electrical usage over electric baseboard. maybe a little bit as you'll see some reduced stratification, but not much.