We're doing a bathroom reno. and just got the shower up and running a few days ago.

It has an new two handle valve, so there is no automatic temperature controlling device, just hot and cold water running past their own cartridges.

The water heater is also a tank type heater.

I had a strange occurrence during my last two showers. The shower water was running hot but then cooled down for a few seconds and then returned to hot. It felt as if the water heater had run out of hot water, but when I turned the cold faucet down, I felt it getting warm again, and I had to restore the cold faucet back to where I had it positioned as the water heated up again. I was home alone so it's nothing like someone else turning up the hot water somewhere else.

Would a defective hot water cartridge cause this?

Did the plumber install a mixing valve on top of the new water heater? Sounds like it could be a cause you describe.

If I had to guess, I would think you have a hot water recirculation system and it needs to be serviced.

I also agree with hj's guess. A photo helps us not to guess but he is correct in his assessment.

The hot water heater is not new, it's a few years old.

There is no recirculating, just the hot water pipe from the water heater tank to the kitchen faucet, the washer, shower and bathroom lav (which is capped off pending the vanity installation.

The only picture I can show you is the one of the valve after installation:


It's a California Faucets 2-VR. The top outlet is capped, the bottom pipe goes under the house and up a adjacent wall to the shower head.

that's what happens when you don't install a pressure balancing valve.

It would be nice to know the incoming water pressure -- gauges that screw on to a hose bib are available and not expensive -- and whether or not you you have a pressure-reducing valve. Also, the material and size of the water service (water piping into the house).


And just for the heck of it, make sure all valves are full open.

Jeff L, can you show a picture of the top of the water heater?

I have a pressure gauge. I also have a PRV outside which I replaced about a year ago. The previous one was full of crud causing the pressure to be too high and not adjustable.

Just a thought that I will have to take better notice of if it happens again. When the water temp dropped, I turned down the cold. I don't think I turned it down all the way, but if I got close to it being nearly turned off, and the problem was the hot water cartridge somehow closing off, I would have lost nearly all the water flow from the shower head, but I didn't. If that was the case, the problem would be more like the water heater stopped sending hot water for 10 seconds or so and them started working again. I don't see how that could happen with a tank heater but it's something to experiment with if it happens again. I've been in this house for 40 years and never had a momentary hot water loss before. As I said, I was home alone at the time, so no one else was running hot water from other faucets, washing machine, or dishwasher.

There is nothing in that valve that could cause the symptom you describe so it has to be in the piping system.

I tend to think when a problem pops up that it is due to the last thing that was changed. The only thing changed was the hot and cold supply lines rerouted to a different wall, and the valve changed from an old Price Pfister compression valve to a new California Faucets cartridge valve.

This morning after a few minutes in the shower, I felt it cooling off again. I immediately turned off the cold thinking that the hot had somehow stopped flowing. I was wrong, the water kept flowing, and in about 5 seconds it was full blast hot again. I'm not familuar with how cartridges work. Is it possible for more cold water to start coming in without me touching the cold handle? Is it possible for the cold to suddenly push back against the incoming hot water so that the mix cooled down? I've been doing DIY plumbing projects in my home for 40 years and I feel as if I've entered the realm of dark magic

Oh, and due to some outside work on a hot day I took another shower several hours later with no problem.

it is a 'pressure balancing' issue

as in : you installed a NON pressure balancing valve

was either the dishwasher or the clothes washer running when the issue occurred ?

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Nothing else was running, with the possible exception of the refrigertor's automatic ice maker (which would have been cold water).

I certainly don't know every thing, but I've never heard of an old style two handle valve with pressure balancing. I also didn't have the problem with the old Price Pfister 3 handle valve.

abracadabra



stumped

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The ONLY difference between your old faucets and the new on is HOW the water shuts off. There is nothing "magical" about a two handle faucet with "cartridges", therefore the problem is in your water piping somewhere.

Knock on wood, I haven't had the problem for a while now, and I have a theory as to what was behind it. I think it may have been a user error, the user being me.

The new shower was built in the space where the bathtub had been, it gives me a little wider space on the inside then I had before, but not much... it's enough room but still a fairly tight space.

I didn't want to have to get into the "stall" to turn on the water with handles under the shower head because I would have been immediately hit with cold water, so, I had the handles placed opposite the swing open shower door where I can just reach in, turn on the water, and wait for it to heat up.

The handles are lever type that are on an easy to turn 1/4 turn valve and protrude about 4" from the wall. It would be very easy for me to brush up against the cold water handle and nudge it up a little without noticing, then about 10 seconds later (due to the distance) the water temperature would drop. I've since titled the shower head down just a little so that I'm deeper into the stall away from the handles and I haven't had a problem since then. Guess there is no black magic at work here.

sis boom bah



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638