Two Water heaters and Watts Recir System

[EV01]

1. How do I hook up a Watts recirculating pump on two water heaters hooked up in sequence like picture shown? Tank # 1 on right. Tank # 2 on left.
2. Shouldn't that Expansion Tank on the # 2 tank be on the cold side of tank # 1 or is that OK?

 

[Reach4]

1. I would think that connecting the return between the the WHs would be best. Connecting at the cold input of the first unit should be acceptable. My thinking is that just cycling one WH may be better.

2. Maximum working temperature rating is 200F. So I think putting the tank on the the hot side is acceptable, but examples always show the cold side. Directions don't specify the cold side.

I am concerned with what appears to be galvanized steel piping. That rusts.

Next is something I consider odd. https://www.flexconind.com/literature/warranty/flex 2 pro thermal expansion 7-2-14.pdf says

Adequate thread sealant (pipe dope) must be added to ensure a leak free
installation. DO NOT USE TEFLON TAPE.​

I wonder why that is.

I am not a pro.

 

[Sponsor]

 

[Fitter30]

When heaters are piped in series the first tank removers most of the lime in the water and works the hardest. Piped in parallel with first in last out total hot water would be both tanks capacity. Fitting should be brass but galvanized worked. Expansion tank should be on the cold water. Dope instead of tape has to do with the type of fittings. There are pipe thread which are tapered and some relie on a o ring with fitting has straight threads. Pieces of tape can if not properly wrapped can end up in a aerator.

 

[EV01]

When heaters are piped in series the first tank removers most of the lime in the water and works the hardest. Piped in parallel with first in last out total hot water would be both tanks capacity. Fitting should be brass but galvanized worked. Expansion tank should be on the cold water. Dope instead of tape has to do with the type of fittings. There are pipe thread which are tapered and some relie on a o ring with fitting has straight threads. Pieces of tape can if not properly wrapped can end up in a aerator.

Where should Watts Recirculating pump be located? Tank 1 Cold water or hot, or Tank 2 Cold water or hot?

 

[Phog]

You need to have the pump "downstream" of the point where the recirculation return line is connected to the system. The pump can also be put into the recirculation return line itself. Every pump is different and some are made to only be used in a certain way, typically you have to read the installation instructions for a specific pump before you buy it, to make sure it can be mounted & used in a way you are happy with. You can usually find such instructions for any pump online. One common way is for pump to be mounted at hot outlet of the water heater (tank #2 in your case), another common way is to have pump under a sink cabinet in furthest lavatory (which is not compatible with home-run style systems). Other configurations are possible too, there is no one right way.

 

[Fitter30]

Whats the model of the watts recirculation kit.