radiant slab heat setup help

[83trekker]

Hi all new to this site, awesome site by the way. Got some questions.

Who on here is running a electric water (no boiler) with in floor radiant heating. I am going to run a electric water heater as that’s the only choice I have. Just wondering what your setup is and how you like it, and what it costs for you to run it. Please post pics. Also I’m not to sure how to set mine up, just want a basic easy system. Hot water tank, pump, something to let the air out of the lines. Just not sure what to run for everything. This is what I have.

23 x 26 garage 10 walls, scissor trusses with 13 foot peak in the middle. R20 walls, R20 roof for the first 4 feet of the room, R40 after that. (the R40 was to thick to put in the roof near the walls as with the scissor trusses its really narrow there and want the roof to breath.) I have est but not 100% sure 800ft of ¾ pex running 12”s apart in the slab with 2 zones. What size pump and water heater do you think? Electricty here in Calgary Canada is .07cents khw.

Any help would be greatly appreciated.!!

 

[HoosierBuddy]

OK,

I'll try. It's cold in Canada, right?

Since a standard electric water heater pulls 4.5 KW, you can easily convert that to BTU's to get a "feel" for what you want to do is reasonable. 4.5KW is equal to just over 15,000 BTU/h.

You can do a heat loss study on your garage. Do a google search for it, and you'll find several...but my guess is your garage will lose more than 15,000 BTU/hour when the weather turns cold. That makes the second part of the equation easy, because the water heater element is going to come on and never go off.

4.5 KWH X $.07/KWH X 24 H X 30 Days = $226.80 per month in the winter.

The hard part is figuring how much warmer it will be inside compared to outside. You might be able to create a 30 degree differential (just guessing) so that no matter how cold it gets, you'll be able to hold the inside temp 30 degrees higher. Thus when it's 20 outside, it'll be 50 inside. Zero outside it will be 30 inside...whatever. My point is the heat loss will depend upon the temperature differential. I don't think an electric water heater will put enough heat into the building to ever catch up.

Ohhh...and it won't help to get a bigger water heater. The elements are the same regardless. A bigger tank just gives you more storage.

Good Luck!

Phil


I bet you could do all your pumping with a single Taco 007 pump.

 

[z28toz06]

Hi all new to this site, awesome site by the way. Got some questions.

Who on here is running a electric water (no boiler) with in floor radiant heating. I am going to run a electric water heater as that’s the only choice I have. Just wondering what your setup is and how you like it, and what it costs for you to run it. Please post pics. Also I’m not to sure how to set mine up, just want a basic easy system. Hot water tank, pump, something to let the air out of the lines. Just not sure what to run for everything. This is what I have.

23 x 26 garage 10 walls, scissor trusses with 13 foot peak in the middle. R20 walls, R20 roof for the first 4 feet of the room, R40 after that. (the R40 was to thick to put in the roof near the walls as with the scissor trusses its really narrow there and want the roof to breath.) I have est but not 100% sure 800ft of ¾ pex running 12”s apart in the slab with 2 zones. What size pump and water heater do you think? Electricty here in Calgary Canada is .07cents khw.

Any help would be greatly appreciated.!!

Can you use a propane unit?

 

[Throttlejockey]

I have a very basic setup in mine. I tried the electric hot water heater route and it didn't shut off.
I ended up going with a propane fired water heater and it works great but now that propane is $2.35 a gallon it's not cheap to run anymore.
I'm thinking about the electric on demand heater myself.
I e-mailed the company asking for info but never got a response yet.

 

[EvilEye]

I have a 28x36 Garage.9.5 h walls scissor truss with 13.5 center height.
r30 in ceiling well over r21 in walls. 5 loops of 1/2 in pex 1 circulator. a 40 gal electric water heater. Thermostat goes down to 40 degrees.

with the garage closed up during the day it stays fairly warm with no heat on.

when I want to use the garage I turn the thermostat up to about 60 In a few hours the floor is warm enough and the garage is comfortable. If I am going to use it all weekend I let the themostat at 60. after 12 hours or so it will start to cycle off.

I don't try to keep this garage at 70 degrees like you would a house.

I do really like the warm floor, it is the best to work on - warm feet and legs after a while I am working in just a sweatshirt.

enclosed is a picture of the whole system.

 

[83trekker]

well for propane i have never seen anybody use it around here, Id imagine theres some sort of code against here cause nobody has it.

The old guy at work built his retirment home in a small town out of calgary and he has this set up, 24x26 garage insulated, 30gal water tank 120v, pump 120 volt, not sure on size of the tubing, i think 3/4 not sure, and he keeps his garage at around 12-14 celceius thats around 56-57 f at all times. He said his electricty bill hasnt gone past 130 cnd at any time since hes been in his house, not sure how hes getting away with this, but he hasnt been to work in a while so i cant ask any questions latley. Any body else running a similar set up on here?

 

[83trekker]

I have a 28x36 Garage.9.5 h walls scissor truss with 13.5 center height.
r30 in ceiling well over r21 in walls. 5 loops of 1/2 in pex 1 circulator. a 40 gal electric water heater. Thermostat goes down to 40 degrees.

with the garage closed up during the day it stays fairly warm with no heat on.

when I want to use the garage I turn the thermostat up to about 60 In a few hours the floor is warm enough and the garage is comfortable. If I am going to use it all weekend I let the themostat at 60. after 12 hours or so it will start to cycle off.

I don't try to keep this garage at 70 degrees like you would a house.

I do really like the warm floor, it is the best to work on - warm feet and legs after a while I am working in just a sweatshirt.

enclosed is a picture of the whole system.

EvilEye what do you think its costing you run your system?

 

[EvilEye]

EvilEye what do you think its costing you run your system?

I don't know. I have an old meter and base that I plan to install and it will tell me the KWH on the heating circuit. I just haven't had time to put it in the circuit yet.

I don't believe it runs more than $25.00 US a month.

 

[83trekker]

I don't know. I have an old meter and base that I plan to install and it will tell me the KWH on the heating circuit. I just haven't had time to put it in the circuit yet.

I don't believe it runs more than $25.00 US a month.

ya well thats around 30 bucks cnd but i guess us / cnd doesnt matter its what the elctricty costs im at .07 cents, what are you paying.

I would have no problem paying 30-35 a month for heat i would only run it 6 months out of the year and if it cost me around 210 bucks its all worth it, if you ask me.

 

[ptschram]

I had intended to use this system for a planned build, until I priced out the tubing. I can put three gas logs in the shop for what the tubing costs.

I'm going propane and live with it.

PT

 

[Throttlejockey]

I had intended to use this system for a planned build, until I priced out the tubing. I can put three gas logs in the shop for what the tubing costs.

I'm going propane and live with it.

PT

It's definately not the cheap way out, but I wouldn't trade it for anything.
No cold spots and a warm floor are worth it.

How much tubing do you need? IIRC my cost was $600 for the tubing.