Radiant floor heat for the garage need help with mechanicals

well you guys know that i have built a garage and i was able to get 180 feet of pex 1/2" tubing to put into the floor for supplemental heating purposes to warm up the floor when i am crawling around working on the car. i have ample other electric heating (14,000 btu) so this is really just a supplemental heat source.

i am planning to use an electric hot water heater as the heat source for the radiant floor heating but i need help in figuring out and sourcing the tubing connnectors and the mechanical aspects of the system like the type of the mechanial pump and whether i need an expansion tank or not. i don't have any first hand knowledge of this type of system so if any one can help me figure out and source the actual parts i need to hook up the two pieces of pex 1/2" tubing to an electric water heater i would appreciate it. thks bob

That is an interesting idea,i know that same system has been added to drive ways to melt the snow and ice off of them,so it should be doable

I had a friend in Kensington Md, just up the road a notch, and he used a GAS WH for his garage install....course the house was all gas, so just a line and done....

I can't imagine a electric WH having the balls to keep up, especially on that size structure.....

I used one or two mattress pads under me....with gas heat into the garage itself and it seemed fine...

other than a recirc pump and standard fittings, there is nothing to it on the rest....really....

:goodevil:

i know it will work and i know the theory is sound i am just running out of money and i don't want to misspend on the wrong fittings and pumps, I am really looking for the least expensive way to accomplish this, the pex fittings require a crimping tool and i hate to buy the tool for two fittings, i also am sure that there is some basic rules of plumbing concerning circulating pumps, and expansion tanks that i am simply oblivious to concerning volume and speed and waht ever the water equivalent is to CFM...i wanted to do this on the low side of $$$$$$$$ spectrum

Lowes Depot has some plumbing advice that you dont need crimping tools for PEX it involves a O ring type of compression fitting.....pretty sure of that, PEX and I split ways long time ago when the initial problems came up, now I see it all over the place....as for the recirc pump, I can't help you...sorry....I forget what Carl had there....too long ago...

maybe do a web search, bet you find a maker with some site advice online....

Years ago there was a place in G'burg Md.....Standard Supply, near the RR tracks up there.....they maybe still around...and VERY helpful to me over the years....

:bounce:

the problem is all the internet sources are really expensive

Here is an all brass pump I've used for years to heat a hot tub. You need a low flow for heat and this draws about 1/10 amp.

Will work under a pressurized closed loop system.

http://shop.solardirect.com/product_info.php?products_id=100

Make sure your water heater relief valve is plumbed to the outside of building.

it might be easier and cheaper to just bury some type of heat trace in the floor. Home depot has heating wire that can be used on the roof to prevent ice dams.

http://www.pexsupply.com/CategoryPre.asp?cID=595&brandid=

Sorry Bob I have not been following this thread except sporadically, but if you are supplying this water heater from your house domestic supply, just hook it up like your regular water heater, no expansion tank needed, but you will want an air relief valve from off the top of the heater.
If you have a check valve or backflow preventer in the feed line (recommended), then you have a closed loop system & will need an expansion tank. An airbladder type would be be best.
If you do not have a feed from the house, them hmmm... I've never dealt with that kind of set-up, and while I have an idea or two, due to my profession I better stop here!
I can't really help about a pump because I've never dealt with a system this small, but that Taco above looks pretty good.
And remember, this is not atmospherically convected heat like a baseboard in the house---this your floor itself! You do not want 160* water coursing through your floor!

There's a truck dealer here (KC) that has a boiler and pipes in the floor as you're thinking. Keeps that shop very comfortable. But that's running low pressure steam too.

I just thought of something that messed me up but good here, I had replaced the WH with a new GE electric unit from HD....and so they come with water flow restrictors in the output nipple, I did not know that, it drove me crazy with the slo fill on the whirlpoole, I had no clue they doing that crap now....
just unscrew the nipple and knock the thing out with a 3/8 extension and a hammer.....

not sure of the flow rate you will need to even that puppy out...:bonkers:

Here is a neat place for the info.

http://www.radiantcompany.com/prices/prices.shtml

To date I have installed 27 major systems, and yes I am not a plumber.

Michael.

mdbelanger said:

Here is a neat place for the info.

http://www.radiantcompany.com/prices/prices.shtml

To date I have installed 27 major systems, and yes I am not a plumber.

Michael.

Click to expand...

Hey Mikey, question 4 U, curious what can be expected in operating costs for say a 40 gallon electric WH, running through your type setup, and heating a slab in the Wash DC area.....I am asking about MY old garage, which was 16' wide and 27' deep for the prime end spot work bay....the section I heated....

I did not have a insulated door, but no windows, and VERY well insulated...

8' ceiling 8' overhead door....two side doors one to the outside, another to the adjacent garage section....

speaking for a typical one month bill.....in winter....:bonkers::hi:

ok thanks that pump looks good, it will be a closed loop system dedicated just for the garage floor. i dont think the thermostat is turned up very high on the water tank and since its always circulating when the heater element is on i dont think it ever gets really hot. i am planning to use an expansion tank with a bladder in it but i am not sure of the size it needs to be, the 2-3 gallon tanks are pretty affordable, does this tank need to be mounted up at the highest point or since it has a bladder can it be mounted any where? and does the pump go on the hot side of the water heater or the cold side?

Michael thks for the web site i will look at that and see if they have a low buck option for the 1/2" pex, why would i need a manifold for a 1 loop system? i see they have lots of 3/4 and larger systems but no 1/2" stuff listed i wonder if i just connect the 3/4" to the 1/2 stuff, here is the picture of what i need to create but for $650 it seems alot for a $120 pump and a $50 expansion tank. again this is suppose to be a low buck system if i can create one.


and any ideas are always welcome PM me if you are concerned about a public forum, thks bob

Thats what you want. And you can build it yourself. There is alot of items in the pic that you dont need.

You need:

The pump. If running water I sugest the stainless steel. With antifreeze the cast iron one should be about $65. Keep in mind you will be running antifreeze throu the hotwater heater. No washy the hands.

A 1 or 2 gallon expansion tank will work.

For the air bleed-off, solder up a 3/4 T with a about 12 inches of pipe going up and install the a (pittler:banghead $14 dollar air bleed-off on top.

You only need two shut-offs. One from feed of top of hotwater heater, after this install a drain valve, next shut-off would be at the end of this mess prior to feeding the floor.

Last it the thermostat controller. This is no more that a relay in our cars, 12 volts switch on a 110 ac to the pump.

All this you can get at HomeDepot or Lowes, The stainless pump you'll have to go to a plumbing supply house.

Should knock close to $150.oo plus off.

As for my back ground in this: I am a Custom Home Contractor. I prefer to build energy efficient homes. Radiant is a must. For plumbing codes in NH and VT a home owner can do a low pressure system. As far as I am concerned when the home owner unloads my truck they installed it. While construction is going on, my crew pre drills floor joist and installs as they go. Shit we even predrill all studs while still banded for electrical, ain't that why they make 2 foot long drill bits. Plumbers average $65 an hour and arn't worth "piss in the snow", when it comes to high pressure and steam then they are worth there $$$.

Michael.

Pullen some ### on yours mrvette.

Michael this sounds good thks , i think i got it... however does the expansion tank go on the hot water tank side of the pump.....or does the pump feed into the expansion tank from the hot water tank?


thks bob,

Between hot water and pump, all it does is the bladder expands as the water heats up expands the opposite as it cools.

Do you hane a cold water supply to the shop?

M

mdbelanger said:

Between hot water and pump, all it does is the bladder expands as the water heats up expands the opposite as it cools.

Do you hane a cold water supply to the shop?

M

Click to expand...

ON a well pump they mount with the stem down, tank on top, like a kid's floor mounted punching bag....can they be used 'upside' down??

Tank on bottom is prefered so that it does not trap air in it. I have cut both set-ups open. Actually shot em.:rofl::rofl: The ones on the bottom had dirt in em, not enough to worry about. The top mounts had slim and what I would assume was mold that grew in the air pocket that made my skin crawl. Enjoy drinking that water.

I hope there isn't any air in the water side of the tank if tank on top.

Also most tanks have an air fill on em like your tire stems, don't mess with it. it sets the pressure on the other side of the bladder. Set at the factory.

Michael.

no water supply other then a garden hose stretched to it, it will be a closed loop system filled with a poly glycol/water antifreeze mixture , i think it is a food grade antifreeze what ever that means...ok thnaks let me draw a diagram and post it again thks i appreciate the help bob