Hydronic reversing valve

AMservices · February 11

I've only ever heard of this from @DanHolohan talking about his trip to Germany. You all know the story, talking with the German engineer about his square baseboard.

The last question Dan asked was how they were able to keep a balanced temperature across such a long loop with so many radiators?

That's when the German engineer brought them to the boiler room and showed them a four-way valve that would reverse the flow every 30 minutes so that both ends of the loop would receive the design water temperature.

Does anybody know of a four-way valve and actuator that can do this?

hot_rod · February 11

Belimo offers a variety of mounting kits for their actuators. Basically a bracket and coupling for the shaft.

I've built a couple mounts, like this one, for reversers on 1000' radiant loops.

A piece of flat metal, some spacers and modify a 1/4 pipe coupling to go over the valve shaft. Th U bolt comes with the actuator. It pinches the split coupling against the flat on the valve shaft.

I used a simple lamp timer to flip the valve every 15 minutes. This 90 in/lb model Belimo can accept AC or DC from 24- 240V

Flow reversal with two circulators. I tried this with two ECM inline, but the one that was powered off would flash weird displays when un-powered and rotated backwards :)

jumper · February 11

I seem to remember that Tuthill or somebody offered a reversible pump.

AMservices · February 11

Thank you @hot_rod

I'm really surprised that TACO, Tekmar or Caleffi hasn't put something like that on the table.

Other than giving technicians a good solution to fixing a poorly designed baseboard system, I would think it would help efficiency, If you are evenly distributing the heat through the home. Possibly reduce heating cycle time, less temperature migration during off-cycle.

Maybe it makes more sense to use room sensors at the beginning and end of the loop to communicate which direction the water should flow in? For those homes that the sun moves across.

Is there a valve like a refrigerant reversing valve made for hot water?

Is there any reason other than temperature limits or pressures drop ratings that a reversing valve would be a bad idea?

I think I would need the circulator to turn off a few seconds before and after the reversing valve shifts, maybe?

hot_rod · February 11

There was a general contractor in my area putting 1000' coils in basements of his spec homes and billing them as "radiant ready" As people bought these homes I got called to connect the radiant. So I built a few of these and they worked well.

There is no problem with the valve moving positions while the pump continues to run. There is never a position in the valve where the pump deadheads.

There are other applications, comfort enhancer, like you mentioned and also loading a buffer tank, then reversing flow to pull heat off the top, stratified portion.

Oh, I've had plenty of off the wall product ideas over the years. It usually gets as far as the sales and marketing team asking how many could we sell a year!!

But putting a parts list of off the shelf components is easy to share. There is very low pressure drop in a typical spool, or ball type 4 way valve, no issue adding one in a hydronic circuit.

Hydronic reversing valve

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