Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,041
I had picked up a gas water heater with circulator pump at ReStore (Habitat for Humanity's thrift store), planning to use it for solar thermal water storage. So, it was on-hand when I just needed a replacement water heater. The Kenmore that came with my house when I bought > 21 years ago finally failed. Water leaking from a hose fitting so I replaced that, but still leaking; tank had failed. Two leaks at once? My guess is the stainless braided hose failed, and dripping water rusted through the glass-lined storage tank on the outside.
After removing door frame to shoe-horn in the replacement 60 gallon tank, I hooked everything up. I did have to mess with tank support and exhaust pipe to fit things correctly. This one has a piezo ignitor, no more looking for a match. It lit, but then I realize that after gas valve opened, it never shut off. This unit had been stored outside for years, and something gummed it up.
Water heater gas thermostats are an available item, $80 to $150 or some much more.
These are interchangeable for most models. In fact, the one on the Kenmore had been working fine ... Just three smaller fittings and rotate the body to unscrew 3/4" pipe thread from tank. All the fittings matched, and water heater rumbled to life.
That was a few weeks ago. Yesterday, shower didn't warm up enough. Water heater was off. I re-lit it and it rumbled to life again. Later, off again and not hot enough. So I googled the topic. I've had a bad thermocouple elsewhere in years past, but due to more sealed assembly, wanted to test this one before replacing.
I was aware of 750 mV thermostats (for furnaces) and larger thermocouples which power them. But looking up water heaters, turns out these produce just 20 to 30 mV. That's enough to drive a solenoid?!
I first tested thermocouple from old water heater (Besides transferring the thermostat, I pulled out the burner, pilot, and thermocouple assembly before junking it. Did I say I'm a pack rat?) On the stove, sure enough, I got 27 mV. Current setting, a quarter amp! Not a lot of watts, but impressive amount of current.
Testing "new" water heater's thermocouple in situ, similar voltage but only 60 or 70 mA.
For this semi-sealed unit I ended up removing four torx screws an sliding burner assembly out part way to access thermocouple body, and twisted it back and forth until I worked it out. Installed old thermocouple as replacement and reassembled. It now heats the tank properly and stays lit.
Here's the faulty thermocouple being tested on stove:
After removing door frame to shoe-horn in the replacement 60 gallon tank, I hooked everything up. I did have to mess with tank support and exhaust pipe to fit things correctly. This one has a piezo ignitor, no more looking for a match. It lit, but then I realize that after gas valve opened, it never shut off. This unit had been stored outside for years, and something gummed it up.
Water heater gas thermostats are an available item, $80 to $150 or some much more.
Rheem PROTECH OEM Natural Gas Control Thermostat SP20166B - The Home Depot
The Rheem PROTECH Gas Control Replacement Kit contains everything that you need to replace the Gas Valve on your Rheem gas water heater. The part is required anytime the cag control is damaged or needs
www.homedepot.com
These are interchangeable for most models. In fact, the one on the Kenmore had been working fine ... Just three smaller fittings and rotate the body to unscrew 3/4" pipe thread from tank. All the fittings matched, and water heater rumbled to life.
That was a few weeks ago. Yesterday, shower didn't warm up enough. Water heater was off. I re-lit it and it rumbled to life again. Later, off again and not hot enough. So I googled the topic. I've had a bad thermocouple elsewhere in years past, but due to more sealed assembly, wanted to test this one before replacing.
I was aware of 750 mV thermostats (for furnaces) and larger thermocouples which power them. But looking up water heaters, turns out these produce just 20 to 30 mV. That's enough to drive a solenoid?!
Water Heater Pilot Won't Stay Lit? Do This - Plumbing Sniper
If you water heater pilot going out as soon as you release the button/gas valve? Here is how you can troubleshoot and fix the problem fast
plumbingsniper.com
I first tested thermocouple from old water heater (Besides transferring the thermostat, I pulled out the burner, pilot, and thermocouple assembly before junking it. Did I say I'm a pack rat?) On the stove, sure enough, I got 27 mV. Current setting, a quarter amp! Not a lot of watts, but impressive amount of current.
Testing "new" water heater's thermocouple in situ, similar voltage but only 60 or 70 mA.
For this semi-sealed unit I ended up removing four torx screws an sliding burner assembly out part way to access thermocouple body, and twisted it back and forth until I worked it out. Installed old thermocouple as replacement and reassembled. It now heats the tank properly and stays lit.
Here's the faulty thermocouple being tested on stove:
Last edited: