RealLivePlumber

Went to a new customers house today. Referral. She recently remodeled her Master bath. Complaint was that the stall shower faucet temperature wildly fluctuates, scalding hot to cold. It was a Peerless. There is a tee in the shower riser, to a showerhead(above the faucet), and to a handheld(on the opposite wall). Both are on all the time. The handheld volume can be turned down to a trickle at the head.

I figured it's a POS, so I install a Moen Positemp. I turn it on to set the high limit, and the same problem occurs. Water temp will not stay consistent. I set the limit all the way to hot, and the water temp is around 110 degrees. Back it off a tad, and it gets cold. Fast. Turn the handle to around the 11:00 position (limit a stop at around 2:00), and its lukewarm at best. (Traditionally, this handle position is plenty hot)

I called Moen, they asked if there was a tankless water heater. I look, and there is. A Navien condensing 98. They say pressure balanced faucets don't work well with tankless water heaters. Install a temperature balanced faucet. WTF MF'ers.

I called Navien, they had me push a bunch of buttons, and give them the numbers off of the LCD. They said the flow rate is consistent, and the outlet temp of the WH is at 120 degrees. Thermistors are ok. (They said that, honest) Must be the faucet. I tell them this is the second one, from a different manufacturer, and it'd only 20 minutes old. They said UUUHHHHHHH, the unit is working fine, and within it's design paramaters.

I called Moen again. This time, they say I need to adjust the temp of the water heater down. It's at 120 degrees now. We need that for the dishwasher and clothes washing machine, so we can't. The second guy wasn't sure what to say.

They have other bathrooms in the house. This is the only one with a problem.

Any ideas?

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RealLivePlumber
You can make it happen, you can watch it happen, or you can wonder wtf happened.
Phil Harris 2009

Master Mark

too bad you did not see that tankless heater before
you got mixed up in that god awful mess...

I think it might have been
nice of them to mention that to you in the first place....

I suggest you have the guy that installed that tankless
heater in that home to come back and fight with it...
but my guess is they have probably **** canned him over this whole issue already and have gotten you into it knee deep now

I would like to hear the history behind the Navien tankless
heater and why plumber #1 aint around anymore........
.


the double heads in the pressure balanced shower are probably screwing up
the tankless heater somehow,,,,....
you already know that and I my guess is that they probably knew it too before you ever stepped foot in the home.........




how about trying a 75 gallon tank type heater, I bet
that will solve the problem??

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holman23

i wonder if a circulating pump would be affecting you if any installed somewhere that u din't see

TheMaster

Remove the showerhead and cap or plug that oultet off.....assuming its the closest outlet to the shower valve......and then run the handheld and see if the temp stabilizes......if it does you need to add a positive cut off in the piping to the handheld. Or you could install a thermometer in the hot line near the navien and see if it fluctuates when you run the shower.

Protech

Put your hand on the tankless outlet pipe. If it stays hot but you are getting temp fluctuations at the shower valve then there is a cross connection in the hot water side somewhere. The number of shower heads does not matter as far as temperature goes, only flow-pressure drop.

Addition: I have installed proly 15-20 moen posi-temp valves on various tankless hot water systems and nver had that problem unless there was a cross connection between the hot and cold systems.

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TheMaster

Easiest way to check for a cross connection beteen hot and cold is to turn the cold water off to the tankless and see it you sill get flow at a hot faucet thats not pressure balanced

aero1

what protech said is the key, just had that experience with a single handle price pfister changed the cartridge and charged the customer parts, labor and head knowledge[thats my favorite charge].

Protech

good advice

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RealLivePlumber

The original plumber was a no show twice. Customer was a referral, and seems pretty reasonable.

They remodeled the house, and she wanted copious amounts of hot water. I would have installed a Bradford M2, or better yet, a GX.

I was laying awake last night, and was thinking cross connection. (The washer is directly below this shower). I guess I'll go back in the next day or two, and have a look around. (There is no recirc)

Pro, The guy at Navien told me that the numbers on the LCD represent 1)hot water temp leaving the unit, which was 119-120, and 2) flow rate, I don't recall the number. (There was also a couple more values for other ratings). He told me that they have a built in thermistor in the outlet pipe, and that the temp and flow numbers were all good. I hope he ain't bs'ing me.

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RealLivePlumber
You can make it happen, you can watch it happen, or you can wonder wtf happened.
Phil Harris 2009

RealLivePlumber

I though about that, but if they wanted to use the handheld and the showerhead together, were back to square one.

Although, it might help to identify the root cause of the problem

Thanks for all the advice, guy's

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RealLivePlumber
You can make it happen, you can watch it happen, or you can wonder wtf happened.
Phil Harris 2009