Tankless water heater and Circulator pump

[Mark_Franklin]

Pumps with timers can void your tankless warranty. Tankless water heaters are not designed to run full time. There are systems designed for tankless water heaters and dead-end lines. WaterQuick Tankless, ACT D'Mand and Chilipepper all work with tankless water heaters.

Please note that I work with Faster Hot Water who manufactures the WaterQuick Tankless circulation system.

 

[Diehard]

Well I had a couple of questions on these units and just got off the telephone with Rinnai Customer Support. And I have to say, the young lady that helped me was extremely knowledgeable and answered my question expertly.
First off, she confirmed what @RenewDave just said about throttling incoming water flow based on water temperature.
Also, in the effort to maintain the set delivery temperature, if the demand on the system was to exceed the output capabilities of the unit, it would again throttle the flow to maintain the set temperature.

I also asked about their recirculation system. More specifically how the pump was controlled. Although it sounded like there was more then one way to control it, the standard automatic control was that the pump would be turned on and off based a temperature sensor located on the return line.

Now this may or may not apply to older units or some other manufacturers units.

 

[Diehard]

Just saw @Mark_Franklin comments.
I'd like to add, although I didn't ask, I would think that within the logic, to control the recirculation systems using temperature sensors to control pumps, that a simple timer logic may very well be available for controlling those hours when recirc system is not required. (Similar to a setback thermostat on a heating system.)

 

[Jamesplumbing06]

im not sure how i go about isolating the pump. the pump and the water heater are directly beneath the master bathroom. any suggestions on how to move forward besides raising the temp are appreciated. we are going to try and raise the temp and see if that fixes the time it takes to heat up as well as the lack of higher temps of hot water. as is, the shower is run on full hot and its not hot enough.

Sharkbite 1/2x1/2 shut off valve. Turn hot water valves off. Drain pressure. Cut line. Install sharkbite. Turn water on. See what ya got.

 

[Jamesplumbing06]

We kinda got side tracked. Sounds like we assuming it never worked and jumping on installation. I got 5 rinnais been outside for 7 years and sensors haven’t been an issue. But a few indoor units have had the condensate drain never unplugged from shipping. The unit produced hot water but not hot enough. For 3 years before asking me. Took forever to find that plug. Circulation systems are notorious for a check staying open for as long as pump is on. This causes the water to attack and creep inside crevices. This causes the swing to stick. Especially when it’s installed flowing straight down. Like this one is. I bet that valve from above post fixes it. But second would be the condensate drain

 

[jparker371]

you would think the sharkbite valve fixes it? an update, plugging in the pump seems to fix the issue. however, im not seeing that as a long term fix as I dont desire to pay the gas bill, or void the warranty on my THWH. the condensation drain is not an ideal install either, it sags in the middle. upon lifting the pipe i can hear some runoff into the sump pump. im going to fix the sag so it runs straight down hill, but could this small amount of pooling in the middle of the drain run be really causing this? so my questions:

1. COuld the sagging in the condensation drain line be really causing the root issue?
2. Will isolating the pump per the valve instructions above fix the issue?
3. The pump has an auto feature which through my research is adapts to your needs. Will this still void my warranty and force my gas bill higher?

thanks for all the information and help, great community. SWMBO isnt complaining but im gertting close to being fed up chasing down different leads to the fix.....and calling in a pro

 

[Jamesplumbing06]

Yes if the condenser drain is ran without an air vent then any in a belly can cause a vacuum lock in that line and not allow unit to drain the build up. But I would use a sharkbite first on return line to eliminate it. You plugging in pump and it suddenly fixes everything kinda helps that. I think your check valve is hung open. Very common for me.

 

[jparker371]

thanks james. would i install the check valve in between the heater and the pump or on outflow out of the pump?

 

[Jamesplumbing06]

Between pump and heater. Shut new valve off and give things a try

 

[jparker371]

will do. how hard of an install will this be? im pretty handy but have no experience with pex work. where do i need to shut the water off to do this work?

 

[jparker371]

is this what i need?
https://www.homedepot.com/p/SharkBi...PIPHorizontal2_rr-_-205744773-_-202270642-_-N

 

[jparker371]

just an update, if i didnt say so already, we have the pump plugged in full time and all hot water locations in the house are functioning perfectly with very hot water.