In floor heat?

[yotachad]

It looks like this has been talked to death but here it goes.

I have a 24 X 24 2 car garage I am getting the floor poured and looking to put 1.5 pink and pex-tube down . Well a friend of mine told me he saw this set up with a 30gal drum (wood stove) with copper tube wrapped around it with one end connected to the pex and the other to a pump then to the pex has anyone heard of anything like this?

 

[5wndwcpe]

Wood boiler perhaps ?

http://www.nirpc.org/oldnirpc/pdf/Woodburner.pdf

 

[yotachad]

nope. I guess its a 30gal drum turned on its side with a door to put wood in with copper tube wrapped around it with one end connected to pex and the other connected to a pump connected to the pex.

 

[5wndwcpe]

While it would work (sort of) it's a terrible idea. More so than even your basic storage water heater. Think of it this way: Most people go to work in the morning and they're out of the house for 9 to 10 hours. All that time the water heater is cycling on and off, trying to keep the water in the tank hot, even though there is no demand. With a wood boiler, it's producing heat constantly, that is, until it runs out of fuel, then it's producing nothing. By their nature, radiant floors are going to call for heat more often, but for shorter periods of time and at relatively low temperatures. In this instance, a storage type water heater can work, but you must pay attention to it's recovery time, especially if using an electric unit.

 

[yotachad]

so what your sayin is that he should have his lines full and have some kinda tank to ?

 

[69Cat]

I've been thinking about a similar set-up using a wood burning stove and some tubing to absorb heat from the stove and heat water to be pumped around the shop. Rather than the stove heating a local area via air circulation it would allow heat to be pulled off and routed elsewhere. Heating a slab would be best when you work out there for days in a row and then not at all since you can get the fire going and start putting heat into the slab so that it becomes a heat storage device if the fire goes out at night so you still have warmth in the morning. Could also run some of the heated water through a radiator to heat local areas. Its nothing to throw wood in a fire when already out there working. The exact details of how to do it with valving, expansion tank, pump, etc, I haven't worked out yet.

 

[yotachad]

I was not thinking of water in the lines thoe . I live close to a Menard's and they have some special mix of stuff to put into the lines and it don't freeze. I have been told to watch out for that it don't get to hot or the heat might crack the floor is this true? What would the valving be for ?

 

[69Cat]

You would definitely need antifreeze in the lines of any system installed where the temperatures go below freezing. The Wisbro PEX I have is rated for 180F so there is going to be a temperature limit on how hot the water can be. That could be dealt with by how close the tubing is placed to the heat source and manner of how the heat is extracted from the wood fired source. Or, you could rig up some sort of mixing valve arrangement if the fluid is too hot to go straight into your floor. Don't think too much heat would damage the concrete (within reason) but I would say the tubing would be the limiting factor.

I mentioned valving because my plan is to run and electric boiler of water heater as a main heat source and then, if I do follow through with a supplemental wood fired heat source, I would tee that source into the existing floor heat plumbing with some hand operated valving. Also, if running a radiator to extract heat from the wood fired source I would use valving to control the amount flow.

A system such as this would be a lot of trial and error and experimentation to get it right. It would be a hobby in itself. If you want something guaranteed to work then you would be buying a wood fired boiler as there are many different options.

 

[yotachad]

Well Iam one more step closer. I got my 4yr project pulled out and the garage is cleaned up. I feel guilty cause its just laying on its frame out side.

OK what is better shielded pex or non also is their a good, better and best circulation pump? How big of a tank do I need I only have a 24X24 garage?

 

[yotachad]

So I have been thinking with the set up I am doing I am going to need to plum in a Steam Pressure Relief Valve my question is How do I figure out what psi valve to get. I need to do this to protect my set up if liquid gets to hot and ends up going to steam so I assume that if I put it before the pump and for some reason it goes off then I can shut the valves and pump off so no steam can enter into the floor.

Before anyone says anything like "what if your not around and it goes off". Well I wont have a fire in the wood stove when I am not around.

 

[72Tunaboat]

A 30lb relief valve will be sufficient if it is a closed system. You need to keep in mind a few things.

• 
  With radiant heat, you can't just turn it off and on when you need heat. When you initially fire up the heat for the first time, it will take a couple of days for the slab to warm up. You don't want to turn the temp down more than about 4 or 5 degrees from what the occupied temp will be(when you are not there).
  The maximum water temp you will want to run in the slab is about 110 degrees(on the coldest day). Otherwise you risk cracking the slab.
  As far as circulator size goes, anything equivalent to a Grundfoss 15/58 will be more than enough.
  
  There is a lot more to it than just this. Do your research. Good luck on your project.

 

[yotachad]

well here is what me the guy At the hardware store and a plumber came up with . Well the cheapest expansion tank is 40-50 (used old hot water tank) Iam just going to use a 3core Chevy radiator and I can buy different psi caps for that then I have a taco pump to move the liquid Ill have a shut off valve before and after the radiator with a box fan behind the radiator ..

72Tunaboat
you say not to turn down below occupied temp when I am not in their why is this?
when I am not in their its about 10* above the out side temp.

why cant I make fire in wood stove then allow it to warm up then keep the fire going all day while I am out their and then when I am done just jet the fire die wont the slab retain heat over a couple of days once heated ?

 

[72Tunaboat]

Radiant heat does not recover qucikly like forced air. you cant expect the slab to retain its heat for that long and recover quickly. It sounds like you are doing this with whatever materials you have available. It is not how i would do it or how i would recommend doing it. Do some research on it before you dive into it. How are you going to control the water temp?

 

[69Cat]

You have to remember that wood stove will provide the necessary heat till the slab warms up. The wood stove as a primary heat source just like many people use it for, the slab is simply a heat storage device for when the stove is not lit. Sure, the floor will take a while to warm up but: 1) it will still be warmer than an un-heated floor the next morning that the stove is lit, and 2) the stove will warm up the area that much quicker if there is any heat left in the slab.

For controlling the water temp you could simply use another radiator. If the water gets to hot (thermostat to control a valve such as a therostat housing from a car), then the valve is operated and redirects the water flow to the second radiator to bleed the heat from the water. Just one idea, could be many others.

 

[yotachad]

As for controlling the floor heat I am going to plum in two sun pro temp gages in the farthest two corners of the garage and once they are up to temp I going to shut the pump off and shut the two valves off .

 

[yotachad]

O I ll be sure to take pic's as things progress.

I like to point out if things dont work the way I think they will, hey Ill have the pex and the insulation down when I do end up with a out door boiler!

 

[HoosierBuddy]

I'd just like to point out that a steam explosion from an exploding hot water storage tank is powerful enough to turn your garage into a pile of match sticks.

I'm all for experimenting....but this isn't like hooking up a couple of lemons and some copper wire and seeing if you can run a penlight off of it. If this thing goes (and by "goes" I mean "goes BOOOOOOMMMMMM!), your neighbors are going to be on CNN. "He was a nice feller. He loved to tinker. I'm gonna miss 'em".

Phil

 

[72Tunaboat]

I'd just like to point out that a steam explosion from an exploding hot water storage tank is powerful enough to turn your garage into a pile of match sticks.

I'm all for experimenting....but this isn't like hooking up a couple of lemons and some copper wire and seeing if you can run a penlight off of it. If this thing goes (and by "goes" I mean "goes BOOOOOOMMMMMM!), your neighbors are going to be on CNN. "He was a nice feller. He loved to tinker. I'm gonna miss 'em".

Phil

Co Signed

I commend these guys for thinking of economical ways to heat their floors, but IMHO it will not work as planned, and could lead to injury. If cost is the issue, just get the tubing in the slab for now. You can always get a heat source for it at a later date and use portable space heaters in the meantime.
I am not trying to knock your project, but I install hydronic heat for a living. THere is a right way and a wrong way. This falls into the latter catagory.

 

[yotachad]

As for controlling the floor heat I am going to plum in two sun pro temp gages in the farthest two corners of the garage and once they are up to temp I going to shut the pump off and shut the two valves off .

I wanted to ad with me using a rad I can put a box fan behind the rad and this will allow it to cool the liquid a little before it goes into the floor .


If Iam not mistaken pressure comes before steam so if you have pressure and you have a low psi relief valve then I don't see any problems right . ?

 

[yotachad]

Co Signed

I commend these guys for thinking of economical ways to heat their floors, but IMHO it will not work as planned, and could lead to injury. If cost is the issue, just get the tubing in the slab for now. You can always get a heat source for it at a later date and use portable space heaters in the meantime.
I am not trying to knock your project, but I install hydronic heat for a living. There is a right way and a wrong way. This falls into the latter catagory.

This is the kinda forecast I was expecting but sooner I kinda thought their would be some guy's on here that sell the product for in floor heat.

In no way do I say that any body go out and do as I am doing Iam a penny pincher and I don't have a hole lot of cash so I look for new and cheep ways to do things and so far its not cheep just the insulation and the pex came to $620.00 then the slab Ill be well over $4000.

 

[69Cat]

I have to agree with you Yotachad, the danger with this scheme is no more dangerous than having a hot water heater in your basement or a radiator in your car. You have a wood stove (boy, I could make a big list about that safety hazards there), a car radiator, a pump and some tubing. If worried about an exploding radiator then don't go anywhere near a liquid cooled engine. I have seen rads pop and they certainly don't explode because the weakest tube is the one to rupture and bleed off the pressure, and that is assuming the pressure relief device(s) don't operate.

I like the idea of a rad and fan to cool the water if it is too hot for the pipes - makes sense. Like I say, I haven't worked out the details, just got as far as the concept so you are way ahead of me.

For the stove to water heat exchange via the radiator, what have you planned out there? The auto radiator for this is a good idea, I was thinking you could use something like you see on the woodstoves made using two 45 gallon drums where the bottom drum is the fire box and the top extracts additional heat from the smoke. If you had a large chamber just above your stove where the smoke flows through and put your radiator in this chamber then that may work very well. Or skip the radiator and just pass tubing through this upper chamber that the water would circulate through.

Also, something to consider but perhaps not practical for your application:
When the slab is up to temperature and you have heat from the stove that you could continue extracting and storing, what you could do is direct the hot water to a large tank of water. You continue heating this tank (lets say a 500 gallon tank or such) and now this tank also becomes a heat storage device from which heat can be extracted from when the fire is out. Solar water heating systems use the same idea. You could keep the stove/slab fluid seperate from the water in the tank so you don't have to care about whether the bulk water tank freezes so as to save on adding antifreeze to that tank.

 

[yotachad]

For the stove to water heat exchange via the radiator, what have you planned out there?

I am going pex (1/2inch) to ball valve to soft copper(1/2inch) that I am going to wrap around my stove (its a old 45 gal oil drum so its round) to the radiator to the taco pump to the ball valve to the pex to brass T to put in the temp gauge back to pex to another temp gauge to pex . I was thinking of a steam valve in between the stove and radiator. Oce done I ll take a few pic's.

 

[69Cat]

Putting coils against the outside of the fire box was my first thought, just like what you plan. But the radiator idea got me thinking of other options. Another option using the radiator concept would be to put a box on top of the stove (if a flat top) and put the rad in there such that heat from the stove would heat the radiator and thus the water passing through the rad. Basically an car cooling system in reverse. I heard of other ideas where you build a tank on the outside of the fire box to heat the water like the good old days of our grand parents and then circulate that water directly to the floor.

Definitely not a new concept you are working on, simply a different package. I like what I hear so far.