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[ssr]

I AM A  NEW MEMBER TO THE SITE.BUT NOT  NEW TO FABRICATION.I'VE BUILT A OWB THAT IS A LITTLE OVER 300 GAL. WITH A 32''X42''
FIRE BOX IN IT. IT IS ALL INSULATED REAL GOOD.PROBLEM IS I GOT 2800' FT. OF 1/2'' PEX IN MY CONCRETE FLOOR AND CANT SEEM TO GET IT WARM NO MATTER WHAT I DO.IF THE BOILER IS NOT CIRCULATING I CAN GET IT HOT AS I WANT IT.BUT WHEN I START CIRCULATING IT THROUGH THE FLOOR IT JUST WONT RECOVER.MY PUMP IS 40GPM AND 30 FT HEAD. I KNOW YOU DON'T WANT THE WATER HOTTER THAN 120 DEG. IN THE CONCRETE BUT WHEN ITS CIRCULATING I CANT EVEN GET THAT CLOSE.ANYONE GOT ANY OTHER IDEAS.I GOT A MIXING VALVE ON ORDER SO I CAN GET THE BOILER AROUND 170 THEN SEND 120 DEG WATER TO THE FLOOR.IE TRIED ALL I CAN THINK OF.THE BOILER I BUILT IS OFF A SHAFER DESIGN. IM RUNNING OUT OF IDEAS  HELP.........

[ssr]

here is a pic

[Scott7m]

2800 ft all on one loop?? 

Normally radiant heating is done in zones and 300-400ft with zones valves and pumps coming off of a header system.  The shaver design is not nearly as efficient as some IMO but it should do what your asking.

[ssr]

no sorry the longest run is 300 foot . i got 10 loops running to one manifold.1'' pex running to the feed manifold. and 1'' running from the return manifold to the boiler

[Bull]

It is going to take a while to get things heated up, why only 120 to the concrete?

[Bull]

Oh and Welcome to the site

[ssr]

ive had it going for 2 weeks.i heard you dont want it above 120 degree or it will start busting the concrete.its just not coming around.the concrete is 6'' thick with 2'' foam under it it and the pex is 2'' from the top.

[ssr]

thanks for the welcome this site is great for all the people like me

[yoderheating]

Yea, don't get it over 120. Actually about 100 should heat it. What is the problem? The furnace can not keep up or you are not getting hot water through the system? If its the furnace not recovering then I would ask if your pump runs all the time? If it doesn't I would bet you don't have as much storage as you may think. The water on top of the water jacket may be hot but without the pump running it will not mix and the water below the firebox will not be as hot. The ideal way to do a infloor system is to have the pump on the furnace run 24/7 and the pump for the floor to stop and start. This way you can slowly adjust the mixing valve to a position that will allow the furnace to maintain its temperature while pulling some heat into the floor. 

[ssr]

I ONLY HAVE ONE PUMP FOR THE SYSTEM,IT IS INSIDE THE SHOP  IT IS 50' AWAY FROM THE BOILER.IM SURE THE TANK IS 350 GAL.THE HOT FEED IS TOWARD THE TOP OF THE TANK.AND THE RETURN IS AT THE BOTTOM,ON THE RETURN INLET ON THE TANK I MADE IT RETURN UP BY THE FRONT OF THE BOILER SO IT WOULD HAVE A LONGER TIME TO MIX.I MUST BE MISSING SOMETHING.I THINK THIS SYSTEM SHOULD BE PLENTY TO HEAT A 40X 60 SHOP FLLOOR.BUT I COULD BE WRONG. ANY HELP IS ALWAYS GREAT

[mcarter]

Unless it is redirected inside, my HeatMaster has the return going in at the top and the supply feed is on the bottom with circulating pump.  Im not knowledgeable about which should go where or whether it makes a difference or not but that appears to be how mine is connected.

I just looked at the Shaver design, I am perplexed as to why they designed their system to heat the hot water at the OWB.  Additionally, it appears you would need more pex tubing.  Is this more efficient or have some advantage?  I cant make sense of it.

Anyways, good luck!

Michael

[Scott7m]

Mcarter. That's just kinda the old way of doing it so to speak

I know that most stoves I've fooled with have the pump pulling out of the bottom and returning to the top, better mixing that way I suppose

[yoderheating]

The reason to have the supply on the bottom is because it helps mix the water in the furnace. Hot water rises, cool water sinks. When you pump the cooler water into the top it will naturally falls which mixes the water nicely in the furnace. If you only have one pump on the whole system you have to be starting and stopping it. I would guess the majority of water in your furnace that isn't all that hot and so when the pump kicks on you use the hot water on top rather quickly. Also the water coming back from the zones is going to be cold from being in the concrete so you are pumping cold water into lukewarm water. Add to it the fact that shavers design isn't as efficient as many models and I would say all of that together is your problem.
 Scott, what do you think? Am I missing anything?

[willieG]

first thing i would do is check at your OWB how many GPM are being returned to your boiler (i think your system would require at least 10)

you say you have 2800 feet of pipe in your floor-----how many square feet is your floor?

as some one has allready suggested, your OWB should have a line that allows water to circulate to and from the OWB 24/7 and your floor loops should be controlled with a pump (such as a pump hooked with a zone valve controlled by a thermostat)

when you say thiings just wont recover, do you mean your OWB will not recover to yoru set temp?

you should be using a mixing valve and have your floor temp about 100 to 110 (i think that is average..i have run mine as high as 120)

what you shold be lookinig for is a delivery temp from your OWB to the return temp of the OWB to be no more than 20 degrees )say 160 in and 140 out) this should allow your OWB do recover if it is large enough for the amount of btu you are drawing off it.

if this is the only draw you have i am "guessing" you are (or need to be) drawing about 80 to 100 thousand btu per hour and this would mean your pump needs to be delivering at least 10 gpm to the floor header.

[Scott7m]

The reason to have the supply on the bottom is because it helps mix the water in the furnace. Hot water rises, cool water sinks. When you pump the cooler water into the top it will naturally falls which mixes the water nicely in the furnace. If you only have one pump on the whole system you have to be starting and stopping it. I would guess the majority of water in your furnace that isn't all that hot and so when the pump kicks on you use the hot water on top rather quickly. Also the water coming back from the zones is going to be cold from being in the concrete so you are pumping cold water into lukewarm water. Add to it the fact that shavers design isn't as efficient as many models and I would say all of that together is your problem.
 Scott, what do you think? Am I missing anything?

Nope, I think what your saying is right on track.  Im not sure yet that it's all of his problems but it's sure a good place to start.  He needs that stove cranked up and a zone valve/mixing valve.   

But, like your saying, I don't think the water inside his stove ever has a chance to mix properly. 

Hey ssr, how thick is your firebox???