Adding floor zone

[nwomatt]

I have a vigas 60 in my shop 180' from house with storage and am heating house with water to air heat exchanger in plenum of lp furnace also am heating dhw with side arm. Just added a new porch 10x12 and plan to put radiant in the floor either pour 1-1/2" concrete over pex or use that plywood stuff with the channels grooved into it. At any rate my question is do I put the water into the floor at 180' or should I mix it. I'm sure there's more than one way to do it. Kind of stuck. Just looking for best affordable way. There will be ceramic ontop of whatever I do. Thanks

 

[ewdudley]

Probably should mix it. Then again, you might get away with diverting some of the lower temperature return flow from the plenum WAHX over through the slab loop if the water leaving the plenum WAHX is consistently down below something like 140 degF.

One way to divert the return flow would be to put a zone valve in the return line, with a tee over to the slab loop before the zone valve and a tee returning from the slab loop after the zone valve. Then you'd need a bypass around the zone valve so not all the return water is forced through the slab. The zone valve bypass would need a flow limiting device to balance the flow between the bypass and the slab loop when the zone valve is closed.

Alternatively you'd need two tees, a check valve, mixing valve, and a slab loop pump.

 

[Bob Rohr]

I have a vigas 60 in my shop 180' from house with storage and am heating house with water to air heat exchanger in plenum of lp furnace also am heating dhw with side arm. Just added a new porch 10x12 and plan to put radiant in the floor either pour 1-1/2" concrete over pex or use that plywood stuff with the channels grooved into it. At any rate my question is do I put the water into the floor at 180' or should I mix it. I'm sure there's more than one way to do it. Kind of stuck. Just looking for best affordable way. There will be ceramic ontop of whatever I do. Thanks

Better mix down somehow. Probably not more than 100° or so to a tile floor. Do you want to run that zone separate from the air HX, if so a bit more piping involved.

 

[ewdudley]

Better mix down somehow. Probably not more than 100° or so to a tile floor. Do you want to run that zone separate from the air HX, if so a bit more piping involved.

I run 140 degF through 300 ft PEX loops underneath 1.5" faux slate pavers and the surface heats evenly and only gets up to less than 80 degF before the in-floor thermostat gets up to setpoint. I agree that the floor itself would be uncomfortable at 100 degF, but the water can be considerably hotter than that without overheating the floor surface.

I don't have any experience with trying to heat concrete with 180 degF water, hence the less-than-140-degF disclaimer above. If the return from the WAHX is down below 140 degF I don't see why it couldn't be diverted directly without mixing.

 

[Bob Rohr]

I run 140 degF through 300 ft PEX loops underneath 1.5" faux slate pavers and the surface heats evenly and only gets up to less than 80 degF before the in-floor thermostat gets up to setpoint. I agree that the floor itself would be uncomfortable at 100 degF, but the water can be considerably hotter than that without overheating the floor surface.

I don't have any experience with trying to heat concrete with 180 degF water, hence the less-than-140-degF disclaimer above. If the return from the WAHX is down below 140 degF I don't see why it couldn't be diverted directly without mixing.

Yeah the required or acceptable supply to any radiant surface is tied directly to the heat load of the space. That's the beauty of ODR controls, they constantly adjust that supply to match the ever-changing load and temperature requirements.

Over the years the RPA has worked with various floor covering groups to make sure they were onboard with radiant. Early on some floor covering manufacturers were voiding warranty due to overheating of their products. Or flat out telling consumers not to use their product over radiant floor systems!

Pretty much all of them gave us input for operating temperatures they were comfortable with. We worked with the Tile Council, Oak Flooring Association, Carpet and Pad groups, Marble Institute, Plywood and underlayment groups, Sheetrock manufacturers, even various redi-mix concrete trade groups.

It led us to develop and publish the Radiant Flooring Guides, available at www.radiantprofessionalsalliance.org

Plenty of useful info for consumers and radiant shoppers in those guides.

 

[nwomatt]

I have allowed for two more zones as you can see in the picture (if it shows up) I was thinking of adding another pump controlled by thermostat run through a three way mixing valve. The return from my wahx is still too hot to pull off of i think.