DIY RADIANT MANIFOLD—WILL THIS WORK?

REKBDR

I'm adding supplemental heat to my kitchen, using Warmboard. I want to locate the controls down below in the basement but horizontally up between the joists. Pre fabricated manifolds offer various challenges, so I hope to just set up my own system, using copper bullhead tees to split 3/4” piping into two 1/2” loops.
I can find flow meters (Uponor A4332050 and appropriate connectors) and snap on thermometers that will work, but I’m wondering about what to use as the balancing valves. Will a common ball valve or waste (globe) valve work, or would those be too tricky to adjust in the narrow range I’m facing (.25 to 2.0 gpm)?

Any suggestions for an inline balancing valve? Caleffi used to make an in-line balancing flow meter that would have been perfect, but they stopped making it several years ago.

hot_rod

If the loops are within 10% of each other in length you probably do not need to balance. Unless you just want to read the flow rate?
You are probably looking at .5 gpm or less.

Caleffi still offers this low flow rate inline meter # 669150 1/4- 1 gpm, it is designed for connection to the manifold thread so you would need some adapters.

REKBDR

Thanks, but I ruled out that flow meter because it (like nearly all other manifold designed units, it seems) supposedly will not work reliably if mounted horizontally. The Uponor meter says vertical or horizontal.

I also want to avoid a meter that might restrict the flow to the top reading on its scale (Uponor goes up to 2 gpm). I'm a bit concerned about air collecting in the tubing, and I want to be able to “flush” out the loops from time to time if need be.

If I go with a flow that is too low, of course, I bump up against the problem of the mixing valve not working reliably.

In any event, any thoughts about what would work as balancing valves? I'm right at the 10% difference in loop lengths.

Zman

I would not bother with the flow valves of the snap on t-stats. The system will be very close to balanced with 10%. If you size your circ correctly the flow will in the right range. Be sure to use a mixing valve designed for radiant and you flow rate.

REKBDR

Dahl makes a 1/2” combo inline shutoff and balancing valve that goes from copper to Pex. That would be perfect except that I need to go to Pex-al-Pex and Dahl has confirmed that its built in fitting will not work for that. Anyone know of a Pex to pap adapter?

hot_rod

This valve? You can buy sweat by sweat and build it with your own sweat/ PAP adapter.

I'm pretty sure they once offered a PAP, like this G101. But it may have been an OEM valve. I may have a few that you are welcomed to.

The difference is the o rings and brass compression ferrule on PAP compression fittings compared to pex , usually.

There is no indicator on this valve, how will you balance? By temperature?

REKBDR

That is the Dahl valve I was wondering about but I did not realize it was made with sweat fittings at both ends. I found only the pex/sweat version. Thanks!

Current plan is to come off the PAP through the Uponor flow meter (PAP to R20 connector and R20 to 1/2” sweat at the ends) and then try using an ordinary 1/2” ball valves to regulate the flow between .25-.50 gpm in each of the two loops. If those valves are too tricky to use, I’ll have the option to swap them out for the Dahl valves.

Much appreciated!