No hot water in shower

Joe_141

Hi all, not a heating guy by any stretch, so here's the details. Oil furnace, tankless water heater (i think- because there's no hot water heating tank) provides hot water baseboard heat in our small ranch. When I use the hot water in the kicthen or bathroom sink, its plenty hot! But the shower can never seem to get hot. I thought it was maybe just the mornings, being the time we both take showers, but it's any time of the day. Some days are warmer than others,(and some are just plain cold) but why is the hot water coming out of the sinks and not the shower??? Any help woould be GREATLY APPRECIATED!!! Thanks in advance.

ed wallace

shower

is the ranch on a slab?is the shower farther away from boiler then the kitchen? both issues can cause lack of hot water if you have a single handle shower valve it could be the problem you do not say how soon you run out of hot water when doing dishes if you lsack hot water in kitchen sink then its a tankless problem

Paul MacDougall

Its most likey the shower valve itself, if you are getting hot water every where else. Single handle shower valves usually have a cartridge that controls both hot and cold water flow, and eventually will seize up and get stuck, allowing only cold water to flow. What type of shower valve is it?

jackchips_2

Joe

I would suggest you turn your thermostat to 90 and have someone run the hot water in the sink while you, carefully, hold onto the mixed water pipe coming out of the tempering valve on the boiler.

This valve should be dropping down a few inches from the tankless coil near the top half of your boiler and have a hot (from the tankless coil), cold and mixed pipe attached.

If it is hot, then have someone run the shower valve and see if the temperature drops. If it does, then feel the hot pipe going into the mixing valve to see it that pipe has cooled down. If it has, this would indicate the tankless coil is not keeping up probably because of lime deposits built up inside the coil. You would then need the coil serviced.

If the pipe into the mixing valve from the coil remains hot while the outlet to the fixtures drops in temperature then the mixing valve is the culprit.

If the water coming out of the mixing valve remains hot then it probably is your shower valve, especially if it is a single handle, pressure balance type.

Good luck and remember to turn your thermostat back down.

Jack

Joe_141

Okay, thanks for the tips guys, I think it may be the shower valve. The house is not on a slab, there is no real distance difference in location of the shower to the furnce. We have one of those rainfall shower valves with an attached handheld sprayer mounted on the wall, so water can be going to either one of both at any time. But the kicker is even when we're just running the bath (no shower hookups) we still get lukewarm to cool water. Not sure, should I detach the whole hookup and/or what am I looking for? Its a fairly cheap shower faucet setup we bought for $75.

ed wallace

shower valve

what is the brand name of the shower valve?

Ken Field

Moen

valves seem to have this problem most often in my experience. Don't worry about the diverter, focus on the control valve itself.

Ken

Joe_141

I think the brand name is actually Rainfall

kevin_60

hot water

It could be limit stop not adjusted for enough hot water if it is a pressure balance/anti scald valve. The anti scald limits max hot temp. I see this alot when valve was calibrated in warmer months. Cold water is colder in winter.