No hot water in bathroom

Hi guys--

I've got a devil of a plumbing problem that I just can't seem to get a handle on. I had a plumber come out today, and he can't figure it out either. Anyway, here's all the info... it's a lot, so thanks for bearing with.

1. No hot water in either tub or sink of guest bathroom. Plenty of pressure; just not hot.

2. No problem with hot water anywhere else in the house, including other bathroom. Both bathrooms are upstairs; water heater downstairs.

3. For a long time, the hot would "come and go" -- fine for a couple of months, then it would disappear, then mysteriously come back a week or two later. This time it's been out for a month, and shows no sign of returning.

4. Galvanized pipes, 35 years old.

5. Brand new (electric) water heater; hasn't affected the problem one way or the other.

6. Moen fixtures. Replaced shower cartridge less than a year ago. Seemed fine for a while; now the problem is back. In other words, doesn't seem to have made a difference.

7. No TMV valve.

8. To test, I turned off the cold at the angle stops; still plenty of pressure, but it just won't get hot. (Plumber didn't think the problem is debris, because pressure is good.)

9. When it works, it's great--plenty of hot water, arrives after only 15 or 20 seconds. It just doesn't seem to want to work anymore.

The plumber said he would have to give it some thought, but he's never seen this problem in his decades of plumbing experience. (Not a comforting thought!)

So there it is. Anybody have any ideas?

Thanks!

Interesting problem, first, what is the TMV? Mixing valve? Some questions, are the bathrooms next to each other, sharing a plumbing wall? where is the laundry in relation to the other fixtures? Was one of the bathrooms an addition?

You might have an older Moen cartridge in lav sink somewhere that is bad and allowing it to mix hot with the cold. Find other Moen cartridge fixtures and turn the valves under it off. Then try the shower.

More on hot problem

Thanks for responding, guys.

Brent, I believe the TMV would be the mixing valve. But I don't seem to have one (or if I do, I have no idea where it would be -- it's not next to the water heater). The bathrooms are not next to each other... separated by a bedroom. The laundry room is also upstairs, but is not next to either bathroom. And nope, none of the bathrooms is an addition.

"Plumbernj", I turned off the water to the sink (both hot and cold), but still no hot in the shower. But the sink does have an old, corroding Moen fixture. Do you think replacing it might make a difference?

Thanks again for the suggestions.

dave

moveeguy said:

"Plumbernj", I turned off the water to the sink (both hot and cold), but still no hot in the shower. But the sink does have an old, corroding Moen fixture. Do you think replacing it might make a difference?
dave

Click to expand...

No sense replacing it if you tested it by turning off the hot and cold.
Somewhere there is mixing going on.

Look for a mixing valve going to the toilets.

Follow the lines as far as you can from the water heater output and make sure.

Depending on how it is hooked up, sometimes a washing machine can end up mixing hot and cold. Do you have any other single handle faucets anywhere in the house?

And more...

I have single-handle faucets in the other bathroom (shower and sink) and kitchen (sink). The washing machine has separate hose bibbs for hot and cold.

Don't see any valves going to the toilets other than the angle stop. The only valve near the water heater before the pipes disappear into the wall is a knife-type valve that says "Honeywell Braukman Model B200." I'm assuming that's just a shutoff. Am I wrong?

I hope you guys don't think I'm delusional...

thanks