Hot Topics: No Hot Water

A close up on a shower head.

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Original post: No hot water in sink and shower but hot water heater good

Boogreg Member

Help! So my unit has two bathrooms. The upstairs bathroom stopped having hot water in both the sink and the shower two weeks ago. No repairs or work had been done on the house in the past 6 months. It was working fine before. Both shower handle cartridges have been checked by a plumber and are good. Here is where it gets weird. When the hot water is shut off at the water heater, the kitchen and downstairs bathroom have no hot water, but the upstairs bathroom has cold water coming out of the hot side with good pressure. The water temperature is cold but does seem to be a different temperature than the water coming out of the cold side.

It is a very old two-story house built in 1910. Where should I look next? The plumber is stumped and so am I.

PJmax Group Moderator

Welcome to the forums.

upstairs bathroom has cold water coming out of the hot side with good pressure.

Yes, that's normal as the faucet shares a common spout.

We have to assume it was working correctly in the past so what is the exact problem?

1) You aren't getting any water out of the hot water side or

2) The water never gets hot out of the hot water side

Are the other sinks in the house working correctly?

If shutting the water off at the hot water heater stops water flow to the hot water taps, it sounds like the water needs to run a little longer to get hot.

Boogreg Member

Your answer is Number 2. Water never gets hot even after running for minutes and minutes. It worked just fine up until two weeks ago. The house is only 1,100 square feet. The hot water heater is on the main floor in the middle of the house, so not a great distance to travel. Same renters in the house. The rest of the house has hot water. Once again, when the shut-off valve from the hot water heater is turned off, both other sinks and shower have no water (as it should), but the upstairs bathroom still has water in both the sink and the shower. The cartridge has been replaced twice — it made no difference. So where else could there be something located in a wall? Walls are plaster and I have no access to view pipes.

Zoesdad Member

Are you shutting off the cold water supply to the water heater?

Pilot Dane Group Moderator

If you do the test mentioned by turning off the water supply to the water heater and turn on the hot water at the problem fixtures, you should get no water.

Turn the water back on to the water heater. Then go to the problem fixtures. You should notice a slight increase in flow as you go from all cold to warm because the faucet is letting hot and cold water through the fixture.

A few times I have seen debris clog hot water lines. It's usually hot water, I assume, because of mineral deposits breaking loose inside the heater. They usually get stuck and clog at valves and fittings. In the hot water lines, with the hot water faucets open and calling for hot water, I move the valves from full open to full closed several times. Sometimes you can feel that the valve is jammed by debris and sometimes the opening and closing chews up the debris and lets it pass (which means you need to clean the aerators/screens at the faucet and shower head).

Zoesdad Member

There might be another hot water heater tucked away somewhere for the secondfloor bathroom (maybe some kind of on-demand heater that has failed). Otherwise, the story doesn’t make much sense.

Zorfdt Forum Topic Moderator

One other question. When the hot water is shut off and the downstairs bath has no hot water, do both the shower and the sink run cold water out the hot side?

I can definitely see a cartridge going bad, or maybe something in the housing that is causing two cartridges to not work correctly. But if the sink is doing the same thing, that means there's definitely a piping issue.

Your shower is a single faucet/mixer, what about the upstairs sink faucet?

Boogreg Member

The sink in the upstairs bathroom is two handled. The shower faucet is a single/mixer. And yes, both have water coming out the hot side even when water is shut off to the hot water heater. No, there is no second water heater. This house is very small and there is no place to put one. If it is a pipe issue, I'm not sure what that means since no one has changed any pipes in decades in this house. I have owned it for three years. This is an old house (1910) in Ohio and all the walls are stucco. There is no attic space over the shower so I am going to have to cut into walls. My first thought is obviously the wall behind the upstairs shower which is the same wall for the sink. To me, there still has to be something in the mixer, joints.

The first plumber said that when he replaced the initial cartridge in the upstairs bathroom, the old one came apart in his hands. Couldn't a small piece have gotten caught somewhere and is now keeping even new cartridges from working properly? It just seems like there aren't that many places to be looking, but the now three plumbers that have been to my house all act like they have no idea where to look next. I am sure they are not wild about having me cut into a wall to find out there is nothing back there.

The shower is a one-piece fiberglass insert, but at a glance it looks very old, very yellowed with age. It obviously is not as old as the rest of the 1910 house, but it clearly has been either added on or updated in the last 30 to 50 years. It appears they took a two bedroom, one bath house and added a second bathroom to what would have been a storage space since there is a very strange step down step to even get into the bathroom and the ceiling is clearly the exact same as the roof line, and lower than the rest of the upstairs bedrooms. There is no attic above and no extra space.

The downstairs bathroom is two-handled but the kitchen sink is a single handle. The downstair's tub handle is also single and has been given a new cartridge also. Now the kitchen single handle has not been given a cartridge but it is furthest from the hot water heater and furthest from the upstairs bathroom. I guess I can pay to change that too. I agree, it doesn't make sense. There can't be that many places in an old house that hot and cold get the option of mixing. I saw online something about an anti-sweat valve in regards to toilets. Is that something that might be going on here and if so, where would a valve like that be since none are in the open?

Boogreg Member

l cut off hot water coming directly from the hot water tank. I can go back and shut off cold water going into the tank, but I don't see what the would do.

Once again when hot water directly from the tank is shut off, all downstairs plumbing has no hot water but the upstairs still does. Also when water is cut off to the entire house all water stops coming out from any location in the house.

Pilot Dane Group Moderator

If you closed the valve at the water heater and some fixtures no longer get hot water but some do, it indicates that there is another hot water source. You probably have two water heaters.

Zoesdad Member

Guys could there be a tempering valve hidden in the wall somewhere supplying both the upstairs sink and shower? If there were such a valve installed, and it did fail, could that explain things? Seems like it would fit. But it sure seems like the plumbers would have found that valve.

@Boogreg –

I would check for an access panel that might be hiding a tempering valve for the upstairs bathroom. The valve would have a hot pipe and cold pipe coming in, and then an output pipe that then branches and goes to the hot side of the sink and the hot side of the shower. If the valve fails you could possibly get only cold water out of that valve. Turning off the hot water at the hot water heater would not stop water flow to the hot side of the sink and shower upstairs. The water out of the valve would be cold but would still feed both the hot side of the shower and the hot side of the sink.

I think that’s correct. If not, I’m sure the other guys will correct that idea.

Zorfdt Forum Topic Moderator

Guys could there be a tempering valve hidden in the wall somewhere

I think that may be the only answer. Single-handle faucets can sometimes function as tempering valves when not working correctly. Maybe there's another single-handle cartridge that is causing all these problems.

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