I have a shower tub with kohler equipment. It's a simple single dial rotating to set temp only. To switch from tub to shower head you pull up on the stopper on top of the tub spout. The problem is I only get hot water out of the shower head but not the tub spout. All other faucets in the house get hot water. We have a hot water heater tank (not inline). If I start getting hot water from the shower head and switch to tub spout I get hot water for a few seconds then it goes back to cold. Not sure when this started as I never use the tub except for this one time and noticed.

Thoughts?

So this is an electric hot water tank I am assuming? You really need someone on site to check it out, but I am guessing that either your thermostat is bad, or your bottom element is burned out.

Thanks for the reply.

Why do you think it's my water heater? It's a gas water heater. Hot water is going to all other faucets. My water heater is a central water heater feeding the whole house. The problem is at the shower control as only cold water comes out of the tub spout but hot water does come out of the shower head.

I hope you realize that this is illogical, because the water basically goes from the valve, to the spout and back up to the shower head. So any hot water at the shower head should ALSO come out of the tub spout

Yes, I agree it's illogical which is why I posted the issue. The only thing I can think of is there is some pressure balance issue. Maybe the pressure for the shower head to work "opens" up the hot water where the pressure at the spout does not... But not sure how that could happen.

while taking a shower, the flow is limited to 2.5 gallons per minute, and say 2/3 of that is hot water. An unrestricted tub spout may be doing triple that flow. If you are getting sufficient hot water everywhere but the tub, then your system can keep up with the 1.6 gallons per minute of hot water demand, but can't keep up with anything much higher. If it is a gas water heater, and isn't tankless, then I have to assume that the bottom of your tank is full of sediment and it can't heat the incoming water fast enough. Since gas water heaters get most of their heating directly from the bottom of the tank and very little from the flue down the center, even a sixteenth of an inch of mineral deposits cause serious performance issues as it insulates the water from the heat.

It couldn't and it is not a problem with the heater either, unless it only happened after a long shower and the stored hot water was depleted. Your shower valve has a "pressure balancing unit" so if something reduced the hot water pressure, the same thing would happen to the cold water flow.

Is it a two-handled faucet for the tub - one hot, one cold? Is the shower activated by a lever on the tub faucet or does it have its own on/off valves or what?

I'm leaning toward a bad valve.

My option is the only one that makes sense. Hj, as you stated above, if it was pressure balancing, the cold water would drop in pressure as well. I know you like to argue, but let's be realistic here… The OP's water supply can't provide hot water at flow rates above what is needed for a 2.5 gpm shower head, but can maintain anything less than that. On a gas hot water tank, the only 3 options are that
1) the heater can't produce the heat
2) the heat can't reach the water
3) the water is bypassing the hot zone and not getting heated

It could be a restricted gas flow, preventing the required fuel for normal operation, but that would most likely starve the pilot light and shut down the heater.

The best explanation for the second option is that sediment has built up and is acting as insulation.

The third option would indicate that the tank is either plumbed backwards, or has a deteriorated dip tube.

There are other possibilities, but nothing that is anywhere as close to being as likely as the above options, given the poster's limited information is accurate.

quote; 1) the heater can't produce the heat
2) the heat can't reach the water

I AM being realistic, which means NEITHER of those would be a factor until the tank started cooling down, because to start with the tank is full of hot water and the burner does not operate until later.

So you realize that it could in fact be the dip tube and you made a mistake by saying it couldn't be the water heater earlier in the thread? I accept your apology and agree that it is likely that the water heater is the the most likely culprit.

quote; So you realize that it could in fact be the dip tube and you made a mistake by saying it couldn't be the water heater earlier in the thread? I accept your apology and agree that it is likely that the water heater is the the most likely culprit.

BOY! Did you ever extrapolate a lot of stuff into that reply. I did NOT accept that it could be the dip tube, because if it were, the hot water would NOT return when he went back to the shower. I definitely did NOT apologize, because it would be a rare time when I had to. AND I do NOT agree that the water heater it culpable. SO, THERE!

hj, the one thing you do have to apoligize for is that poor excuse you have for a baseball team.
at least the red sox know how to go from last to first to last. boston fans ( of which i am not one) never know what to expect. GO CUBS..
BTW, do they do ice sculptures where you are for news years eve?

quote; BTW, do they do ice sculptures where you are for news years eve

Yes, but we call them "buckets of water".

Hello. So I was reading, because this is EXACTLY what is happening to a Tenant. Did you ever figure out what it was?? All the Ego's got in the way of finding an answer, rather than complete ridicule. Crazy! Anyways. Its happiness. Same flipping thing! Can't figure it out. All other options are fine!!! Frustrating! Please lmk if you figured it out.

I have the exact same problem. And I have a gas tankless water heater. Please let me know if anyone is figure this out. I have hot water everywhere. Except my bathtub. This includes the showerhead that is in the same tub. I switch the water to the tub it goes cold within a few seconds, I such a back to the showerhead and it was warm. Again I have a tankless water heater, and it is gas and I have very very hot water everywhere else.

I am having the same issue. The shower is hot but the tub is not. I have installed a new tankless heater, 5 moen single handle cartriges and re-plumbed the hot side of my bath room, still nothing. I came across something on the internet that stated the shower head is low flow restricter (EPA save water stuff) but the tub is not because it would take forever to fill. In short the shower flows at roughly 2.5 gallons per minute but the tub could flow at 3.5 GPM possibly up to 5 GPM. So the water flows quicker and the water heater simply cannot heat the tub water quick enough as it can in the shower that is low flow. I am going to install an in line water pressure regulator. The pressure sholud be between 35-55 PSI to work properly. You probably live in a city that actually has decent water pressure, Many do not. I will try and repost after i install the regulator and share the results.


P.S. not 100% sure about the pressure going from memory. Point is shower is restricted tub is not. If you come up with anything, I am all ears



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I am having the same issue. The shower is hot but the tub is not. I have installed a new tankless heater, 5 moen single handle cartriges and re-plumbed the hot side of my bath room, still nothing. I came across something on the internet that stated the shower head is low flow restricter (EPA save water stuff) but the tub is not because it would take forever to fill. In short the shower flows at roughly 2.5 gallons per minute but the tub could flow at 3.5 GPM possibly up to 5 GPM. So the water flows quicker and the water heater simply cannot heat the tub water quick enough as it can in the shower that is low flow. I am going to install an in line water pressure regulator. The pressure sholud be between 35-55 PSI to work properly. You probably live in a city that actually has decent water pressure, Many do not. I will try and repost after i install the regulator and share the results.

P.S. not 100% sure about the pressure rating, going from memory. Point is shower/faucets are restricted tub is not.High pressure and the water coming into the house is Just to cold this time of year.Anything rated high efficient/energy saveris code for JUNK, Less powerful. My old dish washer, furanace and water heater worked way better than the newer stuff.Pay more get less. If you guys come up with any solutions, I am all ears



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