Tankless Water Heater and Recirc Pump Plumbing

655 Views 4 Replies 3 Participants Last post by xclaim, Sep 13, 2020

xclaim

Discussion Starter · Jun 25, 2020

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 :

https://ordering.fwwebb.com/woitem/...HhIwtcTfu7k-ltBBOE4C50V6xcgj-j8hoC0bwQAvD_BwE

Also, when the recircurc pump is running does the Heater come on ?

Save

1 - 5 of 5 Posts

Old Thomas

· #2 · Jun 25, 2020

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.

Save

xclaim

Discussion Starter · #3 · Jun 28, 2020

Tnx. Mine short cycles I think. Do you have a drawing of how to plumb it?

Save

Ghostmaker

· #4 · Jun 28, 2020

Does the installation instructions that came with your rheem say how to do this? They do make units with recirculation pumps built in.

Save

xclaim

Discussion Starter · #5 · Sep 13, 2020

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.

Save

1 - 5 of 5 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month