In Floor heating

[hillegom]

+1 on the pressure test.
You have to ask yourself, the previous owner went to the expense of laying the pipe, why did he install a different type of heating?

[russp]

I built a 1400 sq ft house with attached garage, for the main heat I installed a forced air furnace but I also ran in floor heat in the basement & garage. I used a standard 33 gal gas hot water heater & it works fantastic. It is a closed system and I run a max pressure of 10lbs hot. If you hire a plumber to install it they will tell you that it is not allowed but if you do it yourself it is a great way to go. I could easily maintain a 20dg temp all winter & the square footage of the heated area was about 1000 ft in the house & 500 in the garage. The main items you will need are a water heater , circ pump & expansion tank. but as previously mentioned the first step is to pressure test the pipe layout.

[intarsiabox]

A friend of mine just did in floor heating in his new garage. He was going to use a hot water tank but found that it is a code violation. He found a hell of a deal at Bartle & Gibson on a boiler, pump, manifold, plumbing, etc for only a couple hundred bucks more than a high effeciency hot water tank alone. The catch is he rebuilds classic cars and so did the salesman so he ended up with a better deal than most would, but even before this B&G was way cheaper than anywhere else.

[Slick Fork]

Some great responses so far guys thanks,

I'll definately pressure test, any suggestions on equipment needed for that that's easily rentable? I think the previous owners installed the reznor units first and then decided to look into in-floor as the new slab with the pipe is quite a bit higher than the side that doesn't have it.

Mike: How do you feel about the return on your investment with the electric in-floor heat? I've considered it for places like bathrooms, kitchens, etc. as retrofitting the house for hot-water heat is way too big a project for us right now. Same goes with Geo-Thermal although I would absolutely love to do something like that.

Carpentersreef: Thanks for the link and info, I'd love to add solar but am doing this project on the cheap.

Russ: What are you using for a circulation pump and Temperature controller?

[mike31154]

ROI on the electric infloor heating? It's going to take a while to figure that out since I've only installed the small 183 watt loop recently by the bay window, approx 20 sq ft. My living room faces north, I think the bay was an add on by a previous owner and that area of the room has always been a little cool in the dead of winter. So the ROI was not a prime consideration when installing this, I'm just glad that this area is now a little warmer without having to rely on the forced air furnace. Heck, I use 3 times that amount of power to light up my fish tank! Not sure what the cost of the system was anymore since I purchased it a while back. As I mentioned, the electronic, digital thermostat with built in GFI (a requirement apparently) cost quite a bit. I think almost $280, that almost made me flip out and reconsider. I think they may have a less costly mechanical thermostat available, not sure. I just set up the heating cycles last week. Similar to most modern digital thermostats with different programming options etc. The features are way overkill for what I'm using it for at the moment. An On Off switch would probably do the trick just as well. The heating loop itself was less than $200 I think. It's made by True Comfort Systems and I got it at the local HD.

You need dedicated circuits from your breaker panel for any electric heating and the larger runs for more power/square footage are wired for 240 volt, same idea as your electric dryer or range. Even though I only have a 183 watt run at the moment, I've used 12 guage wire so it won't be a problem to tap into that run when I get around to doing the kitchen & bathroom floors. Should be able to do all of them on one 15 amp circuit, my house is not large by today's standards.

[mike31154]

At the risk of hijacking your thread, here are a couple of photos of the electric infloor heating install before I laid the tile over top.



You should be able to see the soft copper tubing I used to house the thermostat sensor in the second photo. This is so I can remove or replace it should it become faulty. It's an option and the system manufacturer's normal instructions call for simply embedding the sensor in the mortar. And yes, the sensor is a bit too close to the one wire, it should be centered between any two of the wires.

[mark]

Originally Posted by intarsiabox

A friend of mine just did in floor heating in his new garage. He was going to use a hot water tank but found that it is a code violation.

Well not totally true. You can't mix your domestic hot water supply with a radiant heating system, but they do make hot water tanks that can be used in radiant floor applications. Can be cheaper than the cost of a boiler based system.


CMHC radiant link

[BMW Rider]

I have radiant infloor heat in my garage and set it up using a hot water tank. It has been working quite well for the past ten years. I do want to upgrade to a proper boiler at some point since it is a more energy efficient method. I have a plan to add a bit more shop space on in a few years and will look at that upgrade then.

The hot water tank is cheaper to buy, but holds a lot more volume. If you choose to run antifreeze rather than plain water, that adds some cost back in. I don't recall the size of pump off hand, but its not overly large. I have three loops of piping in the floor fed off a manifold from a single pump. The thermostat cycles the pump on and off to modulate the temperature. i keep the tank set at a medium temperature setting. I also have a small expansion tank and an air bleed valve on the system, so it is a fully closed system.

One thing to look at with the piping that was laid in the floor is what type did they use. The proper stuff has an oxygen barrier to prevent corrosion in the system due to O2 transfer through the piping. I used OxyPEX, which is like regular PEX with the addition of the O2 barrier on the outside. it is red in colour.

The second question is, how long is the run(s) of tubing they laid. It is important to not use too long of runs as there will be excessive flow reduction due to friction loss and thus excessive heat loss in the run. Usually 200 -250 feet is the maximum length. This is why I have three loops and the manifold setup.

[Slick Fork]

Ok, so it looks like what they put in the floor is just regular 1/2" pex tubing. There look to be 3 loops of unknown length.

[MitchM]

I know you're trying to set this up on the cheap, but because the building is separate, I would still run a glycol mix through the system.
Even though you have a separate heat source, if the electricity goes out in below freezing temps....
The unknown is what effect the glycol will have on PEX made for domestic water supply.
Also, I wasn't promoting solar in my previous post , the link was for you to enter the values of the building and come up with a BTU loss number.
There are other calculators if you google for "heat loss calculator" or "BTU loss calculator".

Also, the crimping tools (rent or purchase) and hardware for a pressure test are all available at HD.

Mitch