Wildly Fluctuating Water Temp

[Shel]

Hi ... this is my first post here ... very happy to have found this place. Hope you can help us, or at least provide some suggestions.

My companion has a rental property and the tenants have been complaining about the water temp in their showers. Here's their latest communication which should give you an idea of their plight:

Today's experience:

Anthony did dishes. I took a shower. Then he took a shower.

I washed my hair, normally a 10-12 minute experience, but figuring in all the times I had to deal with the water temperature and pressure changes, it was more like 20, and the worst shower I've taken in that shower to date. The water was hot right away, almost too hot, and a minute or two in, went scalding, then ice cold, back and forth. From that point on, I could never get a decent temperature. I tried to just take a hotter than normal shower, then suffer with cold for rinsing, but mostly tried to keep my body away from the water as much as possible.

I burned my face, not once, but twice. Both times, I had the shower cold for rinsing, already very unpleasant, and with my face right under the showerhead, first when rinsing my hair, and second when rinsing my face, it got scalding hot, no warning. My left cheek is burned. It stings. It will go away in a couple of days, I'm sure, but it's been an hour and I am still shaking. When I told you that showering here is traumatizing, I wasn't kidding. Pictures attached.

Anthony said yesterday he had to do all cold and a little hot to get a decent temperature. Today he had to do a lot of hot, and a little cold, and it took several minutes before he could get in. He kept it as cool as he could stand, since he was fearful of getting burned like I did. Then 1 minute in, two huge surges of hot. There were 2 other smaller surges of hot for the rest of his shower, about 5 minutes total.

This has been going on for months, and you've done everything you can to try to help. The plumbers were here 4 times in a week and it's still not fixed. Seems you have a more complex issue that cannot be easily solved.

After 2 days since the last plumber's visit, the problem is at the very least intermittent, and at the most, a daily issue, and either way, is unsafe and unacceptable.

We've installed a new water heater (the old one was 30 years old, we wanted to replace it before any leaks, etc.) The heater has a recirculating pump on it ... could that be the problem, maybe take it out of the loop?

My companion built a small apartment on to the "big house," rents the big place and lives in the apartment. This gives her some retirement income and a place to live that's, essentially, free. The two units share the plumbing system, and my companion has no water temp issues.

The tenants are concerned that the pipes in the big house are "old" and that might be why there's this temperature fluctuation.

I'd be happy to answer as many questions as possible, and certainly welcome all input. Thanks!

 

[Twowaxhack]

Does the apartment get its hot water from the same hot water source as the big house ? Are both on the same recirculating loop ?
mixing valves at the water Heater ?

Important questions,wrong answers throw everything out the window.

I’d start at the shower faucet that’s giving the problem. What type is it ? Pictures ? Could be it’s pressure balance spool or cartridge.


The big house should have more than one bathtub or shower.......any problem there ? How about the kitchen ? Can the water be adjusted and it keep that temp ?

Unplug the pump and turn off the cold water to the water heaters inlet. Go to a hot water faucet and open it. The pressure should drop either immediately or after a few seconds. If water continues to flow and the valve to the water heater is working then you have a cross connection.

It’s where the hot water snd cold water lines are mixing some place. This can cause water temp fluctuations.

If your pump circulation doesn’t run continuously 24/7 then it will require a check valve to prevent cold water from entering the hot system. This would be a cross connection and would cause your trouble.

 

[Twowaxhack]

Just a guess. If there’s a valve at the circulator pump.......turn off the power to the pump and close the valve. In that order.

See if your problem goes away.

But this could be as simple as the faucet is not pressure balanced snd when others are using water in the house the pressure is changing at the shower valve......when the pressure changes so does the ratio of hot to cold mix resulting in a change in outlet temperature.

The answer to that is a pressure balancing valve.

 

[Jeff Handy]

Yes, it sounds like a shower valve that is older style, not anti-scald or pressure balanced.
I have this same exact issue in my condo shower, 50 year old Moen shower valve.

Or she has a more modern valve, but the pressure balancing module needs replacing.

Yes, post good clear pics of the handle and trim plate.
And list the brand if there is a name on it.

 

[Shel]

Yes, it sounds like a shower valve that is older style, not anti-scald or pressure balanced. I have this same exact issue in my condo shower, 50 year old Moen shower valve.

Or she has a more modern valve, but the pressure balancing module needs replacing.

Yes, post good clear pics of the handle and trim plate.
And list the brand if there is a name on it.

I'll try to get pics today.

The sink in the kitchen of the big house also has temperature fluctuations. The apartment is on the same water system, but there is no temperature issue in either the bathroom or the kitchen. Hmm ... haven't checked the laundry down in the garage. Should probably do that.

Both showers in the big house have the problem. There's not much more I can say or do right now, but I'll get pics later today.

 

[Shel]

Does the apartment get its hot water from the same hot water source as the big house ? Are both on the same recirculating loop ? mixing valves at the water Heater ?

Yes to the first 2 questions. Don't know what a mixing valve is or where it might be located.

[QUOTE}I’d start at the shower faucet that’s giving the problem. What type is it ? Pictures ? Could be it’s pressure balance spool or cartridge.[/QUOTE]

According to the tenant, both showers and kitchen faucet have fluctuations.

Unplug the pump and turn off the cold water to the water heaters inlet. Go to a hot water faucet and open it. The pressure should drop either immediately or after a few seconds. If water continues to flow and the valve to the water heater is working then you have a cross connection.

I'll try to do that today. We've had a plumber doing the work ... we're seniors and physically can't do some of the things you suggest. I'll see about getting him to come out again.

Any recommendations for a skilled, competent plumber in the East Bay area of San Francisco?

[...]

If your pump circulation doesn’t run continuously 24/7 then it will require a check valve to prevent cold water from entering the hot system. This would be a cross connection and would cause your trouble.

The pump is on a timer. However, it's been on a timer since installed several years ago, but it's only been recently that the temperature problems have manifested.

 

[Shel]

Just a guess. If there’s a valve at the circulator pump.......turn off the power to the pump and close the valve. In that order.

See if your problem goes away.

But this could be as simple as the faucet is not pressure balanced snd when others are using water in the house the pressure is changing at the shower valve......when the pressure changes so does the ratio of hot to cold mix resulting in a change in outlet temperature.

The answer to that is a pressure balancing valve.

I'll present this to our plumber. Thanks!