Mixing of cold and hot water

[DuaneT]

I have a NPE-240A installed with an independent return pipe to the west end of the house and it works great. I'd like to install a navicirc valve at the east end of the house as there is no access to install an independent return.

Only my hot water is softened.

1. Won't the navicirc valve cause hard water to enter the tankless heater?

2. Won't the navicirc allow soft water to enter the cold line at the east end of the house?

3. Won't I now have to wait for cold water to clear out the soft and heated water at the east end? Thus, I've exchanged waiting on hot to waiting on cold?

 

[Fitter30]

Navian circ 1-2-3 are all true. The problem is the pressure drop through the navian circ is probably higher than the existing recirc line so water flows through the least resistance so it might not work.

 

[Sponsor]

 

[Reach4]

Only my hot water is softened.

What you say makes sense. Maybe you could consider routing cold softened water to the bathrooms and laundry, and only run unsoftened cold to the kitchen and outdoors.

 

[Bannerman]

You will obtain a vastly different experience from Navicirc compared to your dedicated recirculation loop system.

While circulation through your dedicated loop can be continuous so as to obtain full temperature hot water at the furthest fixture where the hot supply is connected to the return line, Navicirc is a temperature controlled cross-over valve.

To prevent the cold water supply from becoming filled with hot water, the Navicirc will suspend cross-over flow into the cold water supply once it senses the incoming hot water temperature has risen to 95 degrees F. As such, the water temperature at the fixture where Navicirc is located, will be mostly 'warm' initially, but the temperature will further increase once additional hot water is further consumed.

Depending on your home's cold water plumbing layout, any warm water within the cold water piping after the Navicirc, will usually be mostly eliminated by flushing a nearby toilet, or opening a nearby bathtub/shower cold faucet.

Further to Fitter30's comment, for 2 recirculation loops utilizing a single pump, to balance flow between both loops will require partially closed 'balancing' valves in both, or at least within the loop with the lowest flow restriction such as your dedicated loop.

Why the concern about soft water in the cold water supply piping?

 

[DuaneT]

You will obtain a vastly different experience from Navicirc compared to your dedicated recirculation loop system.

While circulation through your dedicated loop can be continuous so as to obtain full temperature hot water at the furthest fixture where the hot supply is connected to the return line, Navicirc is a temperature controlled cross-over valve.

To prevent the cold water supply from becoming filled with hot water, the Navicirc will suspend cross-over flow into the cold water supply once it senses the incoming hot water temperature has risen to 95 degrees F. As such, the water temperature at the fixture where Navicirc is located, will be mostly 'warm' initially, but the temperature will further increase once additional hot water is further consumed.

Depending on your home's cold water plumbing layout, any warm water within the cold water piping after the Navicirc, will usually be mostly eliminated by flushing a nearby toilet, or opening a nearby bathtub/shower cold faucet.

Further to Fitter30's comment, for 2 recirculation loops utilizing a single pump, to balance flow between both loops will require partially closed 'balancing' valves in both, or at least within the loop with the lowest flow restriction such as your dedicated loop.

Why the concern about soft water in the cold water supply piping?

Thanks for all the info. Part of this application is a bathroom and we simply don't like the taste of drinking soft water and waiting for it to clear is not desired. I also don't like running hard water through the heater as I assume it would build up calcium faster.

I also assume the dedicated loop would become "contaminated" with hard/soft water which would be undesirable.

I had not thought about the unequal pressure between the two loops and that may be the more important issue.

 

[DuaneT]

What you say makes sense. Maybe you could consider routing cold softened water to the bathrooms and laundry, and only run unsoftened cold to the kitchen and outdoors.

Thanks.

If I had access to the plumbing, I would do exactly that. Actually the laundry is in the center of the house and I was able to provide cold soft water there but I didn't state that because it didn't contribute to my original question.

Your response was appreciated.