Shower is Cold

PaulSeward

I have a 35 year old tub filler with diverter flapper for shower. Over the years the water has got cooler and cooler. At this point, the cold water is not turned on at all and only the hot water valve is opened when in use. The max temperature it will reach is too cold for me. Meanwhile 6 feet away, the lavatory has water hot enough to scald you if cold water is not mixed in. This is the same for all fixtures in the house. Any ideas on this? It has been suggested that cold water is leaking into the hot water stream. How could this be if the cold water valve is shut off?

EdTheHeaterMan

Have you considered replacing the "35 year old tub filler with diverter flapper for shower"

That sounds like the place where the problem is taking place.

Of course, the other solution might be to stop taking showers there.

hot_rod

A two handle tub filler valve?

Larry Weingarten

Hi, Is it a single lever or knob sort of control? If so, there could be leakage through the body of the valve. How do you shut off the cold water? Where is that valve and do we know if it really works? If you can take a photo or two, that would help.

Yours, Larry

HomerJSmith

Over the years the water has got cooler and cooler. At this point, the cold water is not turned on at all and only the hot water valve is opened when in use. The max temperature it will reach is too cold for me.

This doesn't make any sense to me, could you re-phrase your situation?

Jamie Hall

Would it be fair to say that you have the cold water feed to the shower turned off (preferably with the fixture service valve, should you be so lucky to have one) and when you turn on the hot water int he shower it's cool or cold?

If so, then somewhere on the line between the bathroom feed (I recall you said you got hot water at the lavatory?) and the shower there has to be a cross connection.

The most likely spot, if this is a single handle mixing shower faucet, would be in the shower control -- but if the problem persists with the cold water service valve to the shower turned off, it can't be there, can it? Another possibility is the lavatory faucet, if it is a single handle mixing faucet. You can check that with the lavatory cold service valve -- turn that off too. Make any difference? Working back, what happens if you turn of the cold shutoff valve (likely in the basement) to the entire bathroom stack?

PaulSeward

Both the tub filler and the lavatory are two-handle units

HomerJSmith

So, you're saying that you turn off the cold water knob on the shower/tub and the water that comes out of the hot knob is too cold for you? If so, You don't have enough hot water at a temperature that can be blended with the cold water.

How do you heat your hot water? Have you got a re-circulation sys on the water heater?

How do you heat your hot water?

Yes it can happen if there is a crack between the cold side and the hot side of the two knob valve. Depend on the design. What happens when only the cold knob is open and the hot is closed? Does the cold water get warmer? Pics, please.

PaulSeward

Homer, This makes no sense to me either. With two handle units and the cold handle shut off and there was a cross connection at the faucet, then cold water would drain out of the faucet when not in use. That doesn't happen. If there is a cross connect in the system, then why did it take 30 years for it to manifest itself?

The very first item in the plumbing system is the kitchen sink which is a single lever. It is brand new. The problem stated long before the kitchen faucet was installed (5 years?). The second item is the bathtub and the third is the lavatory.

Jamie Hall

Step back a moment and do this one step at a time. Plumbing isn't mysterious.

Step one. Close whatever service valve you can find on the cold water line which eventually makes its way to the cold connection on the tub faucet. Open the cold faucet. Do you get water when you open the cold handle and only the cold handle?

Note the resule.

Now do exactly the same thing on the hot water side (open the cold valve you closed first). Do you get water when you open the hot handle and only the hot handle.

You shouldn't, should you, in either case. You closed the cold water feed but still got at the cold connection. You closed the hot water feed and still got water at the hot connection. Therefore, somewhere between that cold water valve or hot water you closed and the cold water or hot water connection at the faucet there is a way for water to get to the faucet -- which doesn't belong there.

You now have a very short distance of pipe and a fixture to examine.

It passed the above test? OK, great. Now do exactly the same thing, only instead of closing the cold or hot valve to the shower, you close the ones to the lavatory and the shower, but repeat trying the shower.

Problem? Something in the lavatory between the service valves and the shower feed.

Still passing? Go to the sink and repeat, only closing the sink service valves.

Somewhere along here you are going to find that you close a valve and somehow water is getting around it. Now start tracing pipes and fixtures. There are very few possibilities...

HomerJSmith

Plumbing isn't mysterious.

Hmmm! Everytime I do plumbing, I have to sacrifice a chicken in a pentagram in a circle and keep my fingers crossed for good measure. I learned that in plumbing school.

Larry Weingarten

Hmmm, Plumbing just knows the laws of physics, and follows them. People have to learn and then understand those laws. It’s often hit and miss, so we call it magic. 🤡

Yours, Larry

neilc

where is the clothes washer in this scenario?
or the steam dryer?

PaulSeward

-The hot water at the lav is hot enough to scald you
-domestic hot is heated with a boiler and a triangle Tube tank-in-tank
-No recirc.
-when running the cold water, it does not appear to get warmer
-additional isolation valves are gates that are frozen open
-the washing machine is downstream from the tub
-No steam dryer
-I know where I can get a chicken...

Larry Weingarten

Hi @PaulSeward , Here's a pretty straight-forward test that will shed some light. Shut off the cold supply to the water heater and go open any hot tap. Does it stop running in a few seconds or keep running? If it keeps running, is it just a dribble or a volume of water?

Yours, Larry

Mad Dog_2

The guys are right with the good troubleshooting steps, but I'm cutting that
Mud- puppy out and putting in a modern and safe anti-scald shower body.  Mad Dog 

archibald tuttle

very weird if the sink is hot a few feet away and you only run the hot only in the shower and don't get anything like that. @HomerJSmith has seen more than me if this could actually be internal problem to two handled valve. is this bathroom on a first floor where you can follow the piping connections in unfinished basement? copper piping? just looking at your simple options, e.g. shark, and run some pex or a decent hose on the floor to the water heater kind of thing bypassing existing piping to test-esp. if a lot of your isolations are frozen.

all of that is easiest if you have access to the piping (never hurts to consider where to put a strategic access if pipes are behind finished surfaces.)

brian

Jon_blaney

I suspect the valve cartridges are bad. They are not opening properly even thought the stem is turning.

JUGHNE

Jon, if the cold is off and the hot flows any amount it should get hot as the sink.

Is this the temp coming out of the tub spout or the shower head or both?

Do you have any faucets in the basement for laundry tub, shower etc.?

JUGHNE

If you run the hot on the sink for a long time, and nothing else open anywhere, does it cool off any?

Or if you run the tub hot only will the hot pipe out of the WH get cool/cold?

rick in Alaska

Does your toilet have warm water piped to it, and does it seem like it is getting too warm? Also, is there another sink with the hot and cold lines tied together to make warm water?
Rick

JUGHNE

FWIW:

Is it possible that the WH dip tube is cracked at the top?

On low flow to the lav the crack remains mostly closed and hot water is taken off the top of the tank.

On high flow to the tub the crack is forced open and the cold water scoots across the top of the tank and out the hot delivery pipe.

If the dip tube broke completely off then it would be obvious.