I have plenty of hot water in my sink faucets.
The hot water in the shower is hot when the water is first turned on, but then cools off. The shower has one knob to turn it on and to control water temp.
I have an oil burner w/ a tankless hot water heater. I have tried turning up the thermostat on the burner, but that has not helped. Any ideas?

Shut the water off, and take the control apart. Turn the water on briefly allowing it to flush out any junk in the line. If that doesn't do it, check the water heater to see if it is heating when you are getting cold water in the shower. I looked at tankless hot water heaters, but decided they weren't for me. They are great for delivering high volumes of hot water, however as I understand the description, they need a minimum flow to heat water. With a single, low flow shower head, the heater may shut off once you cut back to a moderate temperature.

The control for the shower or the heater? I assume put in back it back together before turning the water back on.
I'm no expert, but it would seem the volume of water coming out of a sink faucet would be less than that coming out of a shower head. I can get hot water at any fixture at any time although it does take time to heat up.

Quote:

---

Originally Posted by briang30

I have plenty of hot water in my sink faucets.
The hot water in the shower is hot when the water is first turned on, but then cools off. The shower has one knob to turn it on and to control water temp.
I have an oil burner w/ a tankless hot water heater. I have tried turning up the thermostat on the burner, but that has not helped. Any ideas?

---

Labman gave you instructions on flushing any crud out of your hot water supply. Sounds like you've pulled some trash up into the hot water inlet port of the cartridge. Did you check the openings? When you still had the cartridge out and turned the hot water on for a minute did you have a full stream come out? You might want to pull the shower head and pry out the small neoprene washer, with the holes around the edge, and toss it. Let us know how you make out? Tom

Not one of my better answers. I think Tom's answer covers the idea I meant the shower control. I was thinking of a different style water heater. Yours should always provide hot water as long as the water is flowing.

No hot in the shower and no hot water in tub... but OK at the sunker no water coming fm the shower I mean hot water cold water is OK... I did before pretty hot water to me look like there some is junk in the hot water line.. no water also there is one knob for hot and cold with two adj srew...

Titco60, this post has been dormat for 3 years. Why not start your own post by clicking on "ASK" at the top of this page. Fix your typos before posting so we will understand you better.