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Electrifier
Electrifier, Mechanical Inspector
Category: HVAC
Satisfied Customers: 1633
Experience:  24 years as a Mechanical Inspector and years designing and building car wash equipment
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My tank-less water heater goes from very hot to cold.

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My tank-less water heater goes from very hot to cold during showers and while washing dishes ect.. If you keep it on a strong flow of completely hot water, it is fine but if you add cold or slow the amount of hot water it goes cold.

Electrifier :

Do you have a book with troubleshooting that came with your instantaneous water heater? Is the heater gas or electric? Do you know anything about a flow switch that is built into the water heater that tells it to turn on or off depending on water flow?

JACUSTOMER-e8d4l522- :

I don't know where my book is. My heater is gas, I don't know about the flow switch. I think this has something to do with the adjustments

Electrifier :

If you give me the make and model number of the heater, I'll see what I can find for you, so we can solve your problem.

JACUSTOMER-e8d4l522- :

Ok, I`ll look for it

Electrifier :

Great. I'll get to it when you give me the info.

JACUSTOMER-e8d4l522- :

Model number is GWH2400ENG SERIAL NUMBER FD78602912

Electrifier :

What is the brand name?

I have it, Bosch, HERE is the manual for your heater. Let me look through it to find what I need.

JACUSTOMER-e8d4l522- :

Bosh Tank less water heater

Electrifier :

Page 34 section 6.6 tells of your problem. Does your shower have a temp balancing assembly to ensure you don't get water that is too hot in the shower? If the water is set too hot at the heater, it won't take enough to keep the heater fired. It must have .8 gal per minute to fire the heater.

JACUSTOMER-e8d4l522- :

I think the shower doesn't pull 8 gallons per minute but the heather pushes out 8 gallons per minute. Does there have to be a perfect balance in metering for the heather???

Electrifier :

It is .8 gpm not 8 gpm. Notice the decimal point. Do you have the metering valve in your shower?

Electrifier :

Does it prevent water from being too hot?

JACUSTOMER-e8d4l522- :

No

Electrifier :

Did you get the manual link I gave you above? Did you download it?

JACUSTOMER-e8d4l522- :

Yes

Electrifier :

Did you go to page 34 and read section 6.6? It actually starts on page 33 but that part isn't so near your problem.

JACUSTOMER-e8d4l522- :

for our sink if you got to a lower volumen of water it goes cold. we need to shut it off and turn it on again to get the water the water hot again. it takes several minutes.

Electrifier :

Have you turned up the heat on the unit at any point?

JACUSTOMER-e8d4l522- :

It is set up at 135

Electrifier :

What was the factory setting for it?

JACUSTOMER-e8d4l522- :

Yes

Electrifier :

Have you checked the inlet screen?

JACUSTOMER-e8d4l522- :

Factory setting was 115 to 140

JACUSTOMER-e8d4l522- :

For the air???

Electrifier :

I would turn the temp down to 115 and see how that is working. It will mean you need more hot and less cold to get the desired temp. This may be all it needs.

JACUSTOMER-e8d4l522- :

We will give it a try

Electrifier :

You may have low flow faucets and it may not flow enough water through the heater to keep it going. It sounds backwards to turn the temp down to get hotter water.

JACUSTOMER-e8d4l522- :

You are right. It does sound backwards but I think you got the problem. We will try it. Very good advice. We would like to keep you at our finger tips. We will accept your suggestion thank you very much.

I would want to have a way to contact you if I need help later.

Thank you

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