Tempering valve? No hot water in tub...

[Lynn Bryan]

House is 5 years old and hot water to master tub has gradually gotten cooler. Hot water works well everywhere else. Plumber came out and replaced cartridge. Still not hot. He is wanting to do an exploration for crossed lines. Does this make sense? We are talking a LOT of money.

 

[FullySprinklered]

Is this a tub-shower unit, or a large tub with Roman valves? Had a call on one this week with the same symptoms.

 

[Sponsor]

 

[FullySprinklered]

Garden tub had a dedicated tempering valve under the lavatory sink. It was defective and adding too much cold water to the hot supply for the tub. I removed it.

 

[Lynn Bryan]

Is this a tub-shower unit, or a large tub with Roman valves? Had a call on one this week with the same symptoms.

A large roman jetted tub. Picture attached of Moen faucet.

 

[Terry]

Garden tub had a dedicated tempering valve under the lavatory sink. It was defective and adding too much cold water to the hot supply for the tub. I removed it.

That sounds right. Recent code calls for a tempering valve for two handle faucets on tubs. Normally I see them under lav cabinets near where the tub is located. The showers have their own balancing valves and don't require the tempering valve, but the Roman Tub does.

 

[Lynn Bryan]

That sounds right. Recent code calls for a tempering valve for two handle faucets on tubs. Normally I see them under lav cabinets near where the tub is located. The showers have their own balancing valves and don't require the tempering valve, but the Roman Tub does.

Nope, no tempering valves under any of the sinks in the house. The tankless water heater just has a temp set digital panel.

 

[hj]

get a better plumber. Crossed lines would have been a problem from the very beginning, NOT a "gradual change".

 

[Lynn Bryan]

Could the problem be that there is not a tempering valve under the sink connected to the tub?

picture added by Terry Love to show what a tempering valve looks like installed under a lav.

 

[Jadnashua]

Could the problem be that there is not a tempering valve under the sink connected to the tub?

No...while today's code may require one, not having one wouldn't prevent hot water from getting to it.

Some valves when worn, allow hot and cold to mix even when they are not turned on. That could be the issue. If it's say the lavatory faucet...try turning either the hot or cold shutoff off, and see if the problem goes away. It's more common with some shower valves, but those often do not have their own shutoffs, so it's harder to isolate. A defective tempering valve could be stuck, preventing hot from getting as hot as designed.

 

[Lynn Bryan]

So, it sounds like it could be a tempering valve? Is there one within the faucet or handle itself?
And I should try turning off the cold water under the tub to see if that affects the hot water to the tub?
I did take off the front panel to feel the hot water tubing to the tub and it only got warm, not hot, so the problem has to be in a tempering valve somewhere, which I cannot find.

 

[Jadnashua]

A cross-over between the hot and cold supplies somewhere will dilute the hot water further down the line. Fluids are weird...like many things, they take the path of least resistance...if you have a defective valve somewhere that allows it to mix hot and cold, that warm water will then supply things along that path of least resistance. Essentially, to eliminate that, you need to try to isolate that cross-over point. To do that, if you can shut off either the hot or cold going to a valve, it can not cross-0ver. It wouldn't be in the tub/shower valve unless it is a thermostatically controlled valve, then the cartridge could be bad. If there is another shower in the home, it could be that one. With the shower running, if you feel the cold supply lines of the other fixtures (vanity, kitchen sink, etc.), if one is warm, that valve is probably leaking (crossing over) between the hot and cold.

One thing some people do is put a Y-connection at their washing machine to always get warm...this creates a cross-over.

 

[Lynn Bryan]

Jadnashua,

Water heater was flushed about 4 months ago.
Checked Y union behind washer. There is one. Turned off cold water. Still lukewarm in tub.
Turned off cold water at water heater as far as possible. Wall is in way. Water kept running at all faucets in house.
Turned off hot water totally at water heater. Hot water stopped at all taps but tub water which continued running at same pressure but entirely cold - not lukewarm as has been.
Turned off all water at turn on/off switch in wall under water heater thermostat and all water turned off in house, tub included. There is a mixer valve/sleeve with notches on it with warning label in there that is white. See pictures of valves in water heater and the mixer sleeve.

 

[hj]

quote; It wouldn't be in the tub/shower valve unless it is a thermostatically controlled valve,

On the contrary, there are MANY single handle tub/shower valves which WILL crossover even when the valve is in the OFF position.

 

[Jadnashua]

quote; It wouldn't be in the tub/shower valve unless it is a thermostatically controlled valve,

On the contrary, there are MANY single handle tub/shower valves which WILL crossover even when the valve is in the OFF position.

But, it wouldn't be the one in use! It would be one elsewhere, which is what I think I said.

Regarding the pictures posted...that thing with a white handle on the bottom is a tempering valve. It may be shot. When you are using hot water, feel the hot inlet and compare it to the outlet (the third connection is cold, which mixes with the hot to hold the desired outlet temp). If the outlet temp is only warm, and the inlet is hot, one of two things: the tempering valve may be set too low (change the dial to make it warmer), or it is defective.

 

[Lynn Bryan]

Ok, but kind of obvious question here....if this tempering valve is shot or set wrong, why is it only affecting the tub?

 

[Jadnashua]

Ok, but kind of obvious question here....if this tempering valve is shot or set wrong, why is it only affecting the tub?

Can't tell for sure where it is in the scheme of things...if it literally feeds everything, then it's not the problem.

 

[Terry]

Normally a tankless comes set at 120 degrees and wouldn't require a tempering valve. It looks like you have one though. Is that tempering valve only for the tub? If so, you can run the tub and put your hand on the pipe and feel how hot it is on the output. If it won't adjust up high enough, you may need to work on that.

 

[Lynn Bryan]

I don't know if you can tell but is it like tightening or loosening a screw to where turning to the right will make it hotter?

 

[fakingit]

quote; It wouldn't be in the tub/shower valve unless it is a thermostatically controlled valve,

On the contrary, there are MANY single handle tub/shower valves which WILL crossover even when the valve is in the OFF position.

I have such a single-handle shower valve. It allows crossover in both directions when OFF (i.e., if I turn off just the hot water shutoff leading to the shower valve, cold water slowly trickles into the hot line; and vice versa). The shower head vs handheld diverter is also OFF.

Question: This shower valve is brand new (wall is not even closed yet, luckily). Is this new valve defective? Is crossover when the valve is OFF common and acceptable? Pretty sure the answer is NO, but maybe I'm missing something. Thanks!

 

[Lynn Bryan]

I don't know if you can tell but is it like tightening or loosening a screw to where turning to the right will make it hotter?

Ok, I am back and still have not resolved my hot water problem. I have tried all suggestions.
My Koehler Whirlpool tub has stopped delivering hot water to my tub-only lukewarm. I have changed the cartridge in the faucet and have had a plumber out who cannot find the problem in the plumbing. He wants to do an exploratory search in the house to find the problem. We get hot water everywhere else in the house so I am not letting him do this. It seems to me that the problem must be in the tub system.
As the tub is more than 5 years old I am sure there is no warranty in effect any more. I’m thinking I need to call a whirlpool repair service.