radiant floor heat

Slofr8 · December 05, 2003, 05:28:02 PM

Hi all,
I'm getting the sense that more than a few people here have radiant floor heat and or an outdoor wood furnace. We would like to build a home next year and I like the idea of radiant floor but not at the price the dealers are quoting so I am considering doing most of the installation myself to cut costs. After that I'll look at the feasibility of an outdoor wood furnace as I have all the wood I could ever use on my own land.
My question to you is
~do I go with an open or closed system for the in floor?
~What are the pros and cons of both?
~Are you happy with your outdoor wood boiler?
Thanks. Dan.

RavioliKid · December 05, 2003, 06:24:46 PM

I'm glad you posted this question.

I don't know anything about it, but I keep thinking that it would be a good idea to do in my garage/workshop. I look forward to informed responses. (Or, anything else you guys have to say. ;))

Frank_Pender · December 05, 2003, 07:21:58 PM

I am estatic about the system I have installed. I have tow Taylor hotwater furnaces; one for the house and one for the kiln. For the house I have a radian system in the cement floor for the new addition 24' x 24'. There was a room placed above this same floor. In the older portion of the house I installed a heat exchanger in the atic and have the asir blown into the center of this 70 long section of the house.

pasbuild · December 05, 2003, 09:39:50 PM

  When I rebuilt my shop/garage I put infloor heat in it, I went with an open system it is very simple and a lot less $$. I did all of the work myself at a cost of apx. $4,600 this included the outdoor boiler, 200' of 3"id X 7"od insulated pipe, 500' of 1" pex tubing, 800' of 1/2" pex tubing, one 5 zone manifold, one 80,000 btu heat exchanger, three circulating pumps, three old cast iron radiators and all of the valves and fittings.
  I'm heating a 1600 sq. ft. shop my 1480 sq. ft. house and the kids 1300 sq. ft. basement next door, The kids basement is heated with the old radiators my house with the heat exchanger and the shop with the infloor heat which is by far the most profitcient.
  My vote, open system. Pros- simple, cost efficient Cons- you have to manually add water ( 1 or 2 times per year )
  closed system - pros self contained system cons - line voltage thermistat to low voltage valve, mixing valve, anti-siphon check valve, demestic water line.
  I'm very happy with my outdoor wood boiler, half of my yearly fire wood needs comes from my waste ( just about anything that burns ) thats free heat.
  feel free to e-mail me if I can help in any way.
Bob

Mark M · December 05, 2003, 09:44:41 PM

May I suggest Hydronic Radiant Heating - A Practical Guide for the Nonengineer Installer by Dan Holohan. I just recieved my copy today and it is packed full of good information. This website also has a heck of a lot of good information.

I'm in the process of installing a boiler now. It will go into the garage and hook to the existing gas boiler. I have several rooms that I will probably install radiant in the floor. Here is another site that has some information: Radiant Floor Company

Ron Wenrich · December 06, 2003, 04:30:24 AM

When I converted my summer house into my bedroom, I put in radiant heat. Since my floors already existed, I had to go with a system that fit between the finish floor and the subfloor. I used the Stadler system (a German company), and tied it into my hot water furnace.

Even though I did a lot of my own installation, it was still pretty pricey. I had qualified plumbers tie into the furnace. If you are going with poured floors, I would think the cost would be somewhat lower.

We love the radiant heat in the house. No more cold floors. Windy days in the winter can be a challenge. They use an outside sensor to regulate the water temperature in the floor. The only problem is it doesn't take into effect the wind chill factor.

Tobacco Plug · December 06, 2003, 06:42:18 AM

:-/ Those of you with radient floor heat; how does the temperature affect wood floors? Is there a chance of damage?

Ron Wenrich · December 06, 2003, 06:49:57 AM

According to manufacturer, as long as you keep your temperature below 135 you shouldn't have any problems. Most of the time I'm in the 90-110 range. I can adjust it. The water circulates most of the time, but at lower temps than the iron radiators in the old part of the house.

Tom · December 06, 2003, 07:15:28 AM

I just wanted to take this opportunity to say that I don't have much to say about floor heat. When we have floor heat down hear, especially wood fired, then it's time to get out of the house because the walls are next. :-/ :D

Jeff · December 06, 2003, 07:35:57 AM

I just came in from outside. I miss the temperature thingy on the left side of the page. If it would have still been on there I woulda never went out. :D

D._Frederick · December 06, 2003, 08:08:32 AM

I have designed and installed a number of hydronic heating systems using hot water boilers in a closed loop system. The closed system have some advantages over the open system. If you live in the mountains, the elevation does not effect the water temperature. The hydronic boilers run at a pressure of 5 to 15 psi. and run at temperatures up to 220F. It is easier to purge the line of air with the closed system, you put a vent at highest point and bleed air until water comes. The circulation pump is moving water in the closed system instead of pumping head in an open system if the boiler is lower than the heat exchangers. The closed system allow more BTU to be moved and smaller heat exchangers to be used.
I have not seen any outdoor boiler that can be run at a pressure, so open loop systems are required and the plumbing will have to be designed so that water will flow to all points and not just run down hill.

Mark M · December 06, 2003, 04:52:32 PM

We had an Aqua-Therm wood boiler that was pressurized. Corrosion of iron parts can be an issue with non-pressurized systems since oxygen continually enters the system. Additives will likely be needed more frequently. Pressurized systems with iron parts (pipe, boiler, etc.) need to use tubing (PEX) with an oxygen barrier whereas non-pressurized systems do not. It is possible to combine both types by using a heat exchanger. In my case I am considering using a heat exchanger so I can put glycol in the new boiler in the garage and keep it isolated from the existing system in the house. I am concerned about finding "new" leaks I didn't have and decreased heat transfer efficiency.

OneWithWood · December 08, 2003, 06:40:52 AM

We heat our house, domestic hot water and my wifes greenhouse with our Central Boiler furnace. The greenhouse is in slab heating. We did most of the installation ourselves. The biggest problem we have encountered is keeping the insulation surounding the 180' run of water lines ( feed and return for a total of 360' ) dry. If it gets water logged you will lose a great deal of heat. Our soil is clay and hardpan so when we reinsulated the pipes this summer we put a tile drain directly underneath the lines. Seems to be working fine and we have had some torrential downpours in the last few months. We do use a lot of wood. I expect to burn about 40 rick this season. The greenhouse is not insulated and sucks a lot of heat.

Slofr8 · December 09, 2003, 05:11:57 PM

Been away for a few days. Thanks for the replies! Got some good advice and great leads to follow up on. Thanks again and happy holidays!
Dan.

Oregon_Sawyer · December 09, 2003, 11:29:14 PM

I am installing infloor radiant heat in the new house that i am building. It is an open loop system. Both floors will have pex tube in concrete slab.

My plumber died (really) before he got it installed so we have to figure out how he was going to do it. The lay-out was done by a company that sells you the tubing, so that will be easy to get done. What I don't know is how many pumps and thermostats he was going to use.

Do any of you Canadians know about a hot water tank that is stainless steel with tubing running around the outside of the tank? My plumber was going to use one but I don't know the manufacturer. It's not a hot water heater but a storage tank.

I will have oak hardwood floors in one room and fir in our bedroom. I will have to put some nailer's down in the concrete.

Loren

D._Frederick · December 10, 2003, 08:39:16 AM

Loren,
Decide what temperatures you want in diffferents area of your house, like bedrooms, bathes , rec- rooms, family room, and etc. These rooms/areas can be controlled with zone valves and circulator pumps, it is easy to do and will make your house more comfortable.

Mark M · December 10, 2003, 10:42:59 AM

Loren

Here is a manual on Radiant design and install from Burnham: PDF FILE .

The water tank you discribed might be an indirect water heater. Burnham has one called the Alliance and you can see it HERE. Click on the link for the Installation Manual, on the cover is a picture that shows a cutaway.

DouginUtah · December 10, 2003, 12:17:17 PM

I suppose this will offend some here who have designed their own hydronic systems, but don't feel too bad. Even the big boys get it wrong--as in Mark's previous post link.

You don't put the pumps on the hot side. You put them on the cold side. Think about it--which makes more sense?

-Doug

D._Frederick · December 10, 2003, 04:33:46 PM

Doug,
You forgot the zone valves which should also be on the cold side. If you make a control manifold of zone valves, you can get by with only one pump.

Mark M · December 10, 2003, 08:03:11 PM

I've seen some pretty good arguments for putting the circulators on the hot side. I don't have the book handy but if I remember correctly it has to do with air removal, increased flow, and being quieter. I'll be glad to look it up if anyone is interested. Our previous wood system and current gas boiler the pump is on the return. In my new system I am going to have one on the return (going to the wood boiler) and one on the hot side (coming from the wood boiler). The manufacturer recommended this because it will move more water with less expensive pumps. I hope he is right.

pasbuild · December 10, 2003, 08:24:57 PM

Pumps are designed and work best pushing water rather then pulling water this will dictate were the pump should go.

DouginUtah · December 11, 2003, 10:20:51 AM

Hmmm, seems to me that in a pressurized system the pump is pushing water no matter where it is in the loop.

-Doug

Oregon_Sawyer · December 13, 2003, 08:46:04 PM

Mark: thanks for the links. I am collecting a bunch to read.

Don: I may have to get with you for another reason than your edger. My system does have a control manifolds with valves for each zone. I think the plumber was going to put in two pumps. One for each floor. The stove is higher than the basement and is about level with the main floor.

Loren