Help...temps for infloor radiant system

[OUBrew]

I bought a stove from a local guy that owns a steel shop. He makes them on the side and had a design very close to what I was looking at spending 5,000 more on...so I bought it. I am having trouble with the water temp. I have the aqua stat set to 210 deg to obtain around 140 deg water temp. I thought the aqua stat was bad but he came out and said it was fine. Seems weird to me but he says the water temp is higher at the higher points in the tank (it is a round design). The aqau stat is about 8 inches higher than the thermostat. Is this true? Also, he says that I should only be running my boiler at 120 deg because I have all infloor heat. Is it true that water temps should only be 90-100 running through the floor? I have been running 120 the past 5 years with no problems. I would like to run the boiler water temp at 150-160 and my temp going into the floor at 120-130. I think part of my problem may be ash/creosote build up in the firebox. The unit is designed to drop ash through the steel slats in the round burn barrel but I think the coal bed is getting so deep that the ash is getting blocked and is actually working against me as insulation. How much will this affect the heat transfer to the water?? 20-30 deg worth? Thanks

 

[AOD]

You really should run a primary/secondary system with a mixing valve for in floor radiant. That stuff is designed for 120-130 degree water, hot hot water will shorten it's life. With a primary/secondary look you can run your boiler wherever it likes to run and adjust your radiant loop accordingly.

 

[trimmmed]

My boiler heats the water to 180* I have the return also tied to the feed with a mixing valve. The valve lets out 140* water to the floor. The tubing is underside between joists, if it was in concrete I would let it go out straight at 180*.

 

[AOD]

if it was in concrete I would let it go out straight at 180*.

I wouldn't do that, you must raise the temp. of a slab of concrete very slowly to prevent cracking. If you hit a cold slab with 180* water you're really really asking for big trouble.

 

[showrguy]

I wouldn't do that, you must raise the temp. of a slab of concrete very slowly to prevent cracking. If you hit a cold slab with 180* water you're really really asking for big trouble.

i think your misunderinformed,
i run 195 in my OWB to a 125 gal. nurse tank inside (set at 140), then 140 to all zones, all radient, consisting of carpet, tile, hardwood, vinyl and concrete garage and basement..
a couple of years ago i kept hearing all this talk about mixing valves for concrete floors so i asked my brother in law to ask one of the engineers at work "why the water temp in concrete has to be no more than 120" ??
the answer i got was "because of liability, anything over 120 could burn someone, other than that it don't matter"..... this is a commercial HVAC contractor mind you..
as for personal experience, it takes a real long time to bring concrete up in temperature, it can only absorb so much heat in so much time, but once it gets to where you want it it does'nt take much to keep it there !!! thus, it raises temperature slowly by nature !!
by the way, if you ever got a concrete floor to 120 you would'nt wanna be in the room anyway, it'd be way too hot.........unless it's wide open/no insulation whatsoever.. my layout, yours could be different alltogether.

 

[ericjeeper]

in slab radiant

I try to run no more than 120 to my slab. If you run straight 180 to the concrete, it will over heat the room big time after the stat is satisfied.

 

[cleanburn]

My boiler is set to heat the water to 185-165, then mixing valve so my water to my lines under my concrete are 140ish...comes back around 110. My boiler lines are not in my slab, it goes like this: insulation, sand, boiler line, sand, concrete....I didn't want my lines right in my concrete...

 

[ericjeeper]

My boiler is set to heat the water to 185-165, then mixing valve so my water to my lines under my concrete are 140ish...comes back around 110. My boiler lines are not in my slab, it goes like this: insulation, sand, boiler line, sand, concrete....I didn't want my lines right in my concrete...

Who engineered that design using the sand? I am not under the impression that sand makes a very good heat sink.. Think of standing on the scorching hot sand on a beach then simply wiggle your feet down a few inches to cool sand.. But if it works well for you good luck.

 

[cleanburn]

Who engineered that design using the sand? I am not under the impression that sand makes a very good heat sink.. Think of standing on the scorching hot sand on a beach then simply wiggle your feet down a few inches to cool sand.. But if it works well for you good luck.

It's really all the same heat, I just didn't like the thought of cracking lines or cracked concrete for possible future issues.

http://www.rosebudelectric.com/products/radiant_floor_heat/index.html

 

[streeter]

It's really all the same heat, I just didn't like the thought of cracking lines or cracked concrete for possible future issues.
QUOTE]

From what I have been told it really depends on the concrete mixture for the temp. BUT, like some one already said, why run high heat into a floor? it will be over powering. Water temp comming out of the boiler can be 200 but, personaly, I would use no more then 120-130 for a comfortable even heat.
I think radiant heat should be a even comfortable heat

 

[maytagman]

I have been experimenting with my setup. I took some bad advice, I think, from a relative that had been installing some radiant heat setups 9 years ago when I built my house. He didn't think it was necessary to put down insulation under the concrete. He was telling me that heat will rise and although it may take a while longer to heat up the slab and fines under it, it will hold the heat after it warms up. I still don't know about this, I am sure it is less efficient, but I didn't notice a big increase in propane the first year I hooked up in floor heat. Now that I have the owb hooked up I was running the water in at 120 till it got heated up and the last few days I have turned the mixing valve all the way down and it goes in at about 95. I have been running the pump constantly and my basement seems to stay about 76-77. I may turn down the owb and see if that will lower my lowest output temp on the mixing valve. My thinking is if I can find a running temp that will maintain a desirable room temp, I can just run the pump 24 hours a day and my slab will keep a more uniform temp. I have forced air vents also that I can try to fine tune the room temp with if needed when we get a blast of sub zero weather. Let me know if this is a really stupid idea and if anyone else has infloor without insulation under it.

 

[showrguy]

hi maytagman, yes, i do,
my garage and basement slabs have no insulation under them, they work fine, i'm sure it would be better if they were insulated but at the time i did'nt have the time to do the garage, and the basement has only been run during construstion, that was the staining/polyurethane finishing area.. if i had to do it all over again i would have pushed the concrete guys back a few days and done the insulation gig......... guess i could saw cut the perimiter, jackhammer it out, and and re-do it.........NOT.. it works real good, just could probably work real, real good if i would have had/spent the time/money to insulate..
oh, my garage seems to be 20 deg. different from concrete temp to room temp, 10 ft. ceiling, 2x6 exterior walls with R-19, good windows, 2-18 ft. insulated garage doors (not the most expensive) with thermopane glass windows...
hope that helps.?

 

[mtfallsmikey]

Lots of losses without slab insulation for sure...I wouldn't have radiant in a slab without the mixing valve, any other pro will tell you the same...