I’d like to try heating a bath floor with in-floor poly tubing in the tile mud bed, drawing hot water off the conventional water heater. The house primary heating is with a furnace, thus, no boiler or other radiant water heat.
Anyone know of a valve/pump setup that could accomplish this? Might also need some mixing valve to add cold water to moderate the temperature. What’s a typical radiant floor water temp.?
Thanks, Jim B.
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Replies
What you want is available and is called a "mixing valve" or "tempering valve". Three ports, hot, cold (inlets) and mix (outlet). "Cold" should tee to both the returning water from the radiant floor and to the HWH "cold" inlet. The pump will circulate a mixture of return water from the radiant floor and hotter water from the HWH. The excess goes back on the return side to the HWH "cold" inlet.
Watts makes a sweat version in 1/2" or 3/4" that can be had at Home Depot for about $45. But its range is 120F-160F (a bit high) and while I get inside of them modify them sometimes, not everyone knows how.
Much better is Taco Model 5000 tempering valve. About $75 at the plumbing supply. Goes down to about 80F and has unions on all three ports.
Typical outgoing RFH temps are 80F-100F. Lower in tile than under carpet or wood. A bit higher in the winter when it need to put out more heat. The Taco is marked 1 to 6 and you learn that, for instance, you want 1.5 in mild weather and 3 when it is -20F outside. Or just leave it at 2 all the time, but adjusting does give slightly better control and comfort.
David:
Thanks for the direction. The tee of the return water to the cold side of valve & the water heater is a key tip.
But further, I'm not expecting that a pump is built in to the mixing valves. And my first notion is that the pump will be placed after the valve "mix" outlet, to in effect, suck the hot & cool water into the valve. Yes?
Any tips on a pump? Seems like pretty small volume required and the typical Grundvos boiler system pump might be overkill.
And to control the pump, just an electrical switch leg in the bathroom with a timer or thermostat would do the trick.
Jim B. Salt Lake
Correct-o-mundo. The pump goes between the mix port and the radiant floor. The pump can be the smallest one out there. Like a 1/40 hp Taco for $90 give or take. A 1/12 hp Gundfos or anything larger is way overkill. Wire an SJ cord (chop up an extension cord) to the pump. Plug the boy end into the receptacle. Run romex to a receptacle through a timer or a line voltage thermostat. I'd suggest an electronic, line-voltage thermostat. So you can have it come to temperature just before you get up each morning. And set it later on the weekends.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
N--I--C--E
Thanks for gettin me over my hump of never done it before.
An electric floor heat mat would just be too simple, though they work good.
Jim Burdette Sunup Building Co. building my live-in lab