My GWH 635 ES tankless water heater is now 5 years old, and from day one, it has made a squeeling noise...I called the factory technician and did some things to it, but it still squeels. I have had several problems with it, and now the technicians in town want $75.00 just to come out and dignoise the problem, and then charge me for fixing it...What can I do to fix this problem...I paid over $900 for the heater, and it still doesnt work like is should...what can I do???

SOURCE: Keep getting error codes and have to reset too often

This paticular problem your having is specific to the jumper in the heater. The jumper is for condensing heaters. Your heater does not have the specific wiring or computer for condensing. So they added a jumper in the wiring. It is failed or failing. It should ohm out at about 120ohms. sometimes its just a loose connection. Check this out, and called 1-800-642-3111, they have been very busy, but leave them a message and they will call you back.

SOURCE: Bosch Pro tankless water heater overheating

The vent pipe you use is the correct size for the heater.Longer runs require bigger pipe.I also would check to see if the water is getting to hot.

SOURCE: Looking for Outdoor Tankless propane water heaters

it will tell you right on the box if it for indoors or out doors either way they have to have a cover over them,,

SOURCE: rheem gas tankless water heater with error code c4 13

problem is inside burner compartment o2 sensor dirty or block..need to have a qualify technician clean it.

SOURCE: Paloma tankless, gas, water heater, error code C7 76

My Paloma tankless water heater had a code of C7 - 76. I called the service center at 866-720-2076 and they stated this code showed a communication error between the Water Heater and the thermostat; they stated it was still under warrantee and they would replace it for free. Also, I found out there was a recall related to the door properly shutting. To make it work while waiting for the repair, I would turn off the thermostat, wait 2-3 minutes, and turn it back on. Usually it would work for enough time to shower.