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Tankless Water Heater and Recirc Pump Plumbing

655 Views 4 Replies 3 Participants Last post by  xclaim
Can someone share a drawing of a installation using the following components :

1. Tankless GAS water heater. I have a RHEEM - (No Re-circ included)

2. Re-circulation pump. (Grundfos)

3. Return Line, Cold Line and Hot water line.
4. Check valve (back-flow preventer)

Please advise best way to plumb this in.

Recirculating pump i have is below :

Also, when the recircurc pump is running does the Heater come on ?
1 - 5 of 5 Posts
Demand water heaters for recirculating systems have a small tank in them. Without a reservoir, the heater will probably run whenever the pump runs and might short cycle.
Tnx. Mine short cycles I think. Do you have a drawing of how to plumb it?
Does the installation instructions that came with your rheem say how to do this? They do make units with recirculation pumps built in.
want to revive this thread !

Any ideas on how to plumb Thankless and Recirc pump with return line ?
I'm looking for specific instructions (drawing) like how many check valves etc etc and where they go.
Rheem's instructions are super confusing.

I also found out that the flow-rate of the Recirc pump might not trigger the thankless from switching on so that might be an issue as well.

Thanks in advance.
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