[finish line]

ok,please bear with me,as I am a carpenter with minimal plumbing knowledge,i have an on demand water heater that is misfunctioning,it takes a few minutes to warm up and after it does it becomes cold after a few minutes,is there anything I can try to fix this myself?im very handy but don't even know where to begin,any help appreciated my wife is about to kill me!:laughing:

 

[Robie]

Not that I can help but it may help those who can to know if it's electric or gas.

 

[rselectric1]

Those things sometimes take an absurd amount of amps to power. Check your circuit breakers. That's all I can think of for now.

 

[muskoka guy]

Had a similar problem with mine at home. I am a carpenter not a plumber. What I figured out was it was a flow problem. The screen on the tap was partially plugged with iron and was restricting the flow. The initial hot water was just what was present in the line when I turned it on, then returned to cold. I removed the screen off the tap and the flow increased. It fixed the problem. I cleaned the screen and all was well. One of the plumbers might chime in but I am guessing that the heater requires a certain flow rate before it will operate. Try removing the screen [ aerator} and see if it works. Hope this helps. To add as an edit, it was only happening on one of my taps, not all them.

 

[Golden view]

This sounds like the behavior of a small-tank type on demand heater, like a Toyotomi or Quietside.

 

[Matt-2013]

ok,please bear with me,as I am a carpenter with minimal plumbing knowledge,i have an on demand water heater that is misfunctioning,it takes a few minutes to warm up and after it does it becomes cold after a few minutes,is there anything I can try to fix this myself?im very handy but don't even know where to begin,any help appreciated my wife is about to kill me!:laughing:

If it's gas what brand and btu. Takagi's were the rage ten years ago. If yes on gas, and similar to a takagi tk-2 than you need a dedicated gas line. The problem back then is most companies would slam one in and tee off the gas line, wont work.

Is there return line with pump?

You could have crossover in the shower. little more detail, and I can prob come up with something to diagnose.