Atwood Water Heater won’t light

[dvmweb]

Model GE16EXT, Combo.
Worked fine a week ago. Electric and Propane.

Plenty of propane. Good 110 voltage, plugged in to 50 amp.
Furnaces’ working. Stove is working.
Water heater won’t light on propane. Only warm on 110 volt.

Started it up on propane yesterday and made a big “whump”.
Stayed lit for awhile then went off after several minutes.
Restarted, whump, stayed lit awhile again.
Now won’t start.

Again, only warm on 110.

So,
Is there a good video or algorithm to follow?
Should I just take it in?

[Old-Biscuit]

The GE16EXT has the same wiring/control scheme and components as all 6/10 gal combo standard units (since 2004) except for the T-stat & Mixing Valve



Atwood GE16EXT is a 10 gal water heater that uses a 160*F T-stat to overheat the water in tank and then has a 'Mixing Valve' on backside of WH Tank where Cold water mixes with Very HOT and regulates HOT out to 130*F


Mixing Valve clogging up is common issue....hot from tank gets scale/crud/sediment and more cold then necessary flows resulting in Luke Warm (Even just Cold) water in HOT side



Mixing Valve can be unclogged by soaking in hot vinegar etc

But can be PITA depending on amount if crud.
Can be disassembled BUT factory seal on upper knob has to be broken to access the set screw
And they can be expensive to replace.



As for propane and that 'whomp'....that is due to dirty orifice (screws into outlet end of gas valve) and/or dirty burner tube
Doesn't take much to disrupt the air/fuel mixture...even a spider web will cause issues
Remove burner tube....clean out using a small bottle brush (blowing air doesn't remove spider webs)
Remove orifice and soak in alcohol then blow it using your mouth (Air Compressor can damage the metered hole in orifice.)

[dvmweb]

Old biscuit,
Thank you for the ideas.
I’ll check the orifice.
And, see if I can unclog the valve.

Could I take the mixing valve out and put in a lower temp thermostat?

[Old-Biscuit]

Originally Posted by dvmweb

Old biscuit,
Thank you for the ideas.
I’ll check the orifice.
And, see if I can unclog the valve.

Could I take the mixing valve out and put in a lower temp thermostat?

YES...........


But you will need to purchase the Standard set (t-stat/eco---come together on shrink pack)
THEN you will need to change the T-stat Spade Connector to a small spade connector (Brown wire to t-stat)
160*F EXT t-stat uses a PIN connector vs spade.
T-stat/ECO use spade connectors (Small size on t-stat/larger size on ECO)


ECO is same...just different T-stat
Atwood Part 91447 (Standard)
(EXT ---91547)



By removing Mixing Valve and changing out T-stat you will have a Standard 10 gal WH



Will need to replumb COLD Inlet, HOT outlet and a BYPASS.
3 valves (Sharkbite/FlairFit etc) and some PEX piping

[dvmweb]

That is what I thought.
I have put a set of bypass valves in another moho.
Thank you so much.

[Tha_Rooster]

Have you pulled relief valve to see if water is really hot. If it is probably mixing valve.

[dvmweb]

It was the mixing valve.
I took it out and put in a bypass system.
It still has an inline one way valve in the hot water outlet line. I left that in.
We have lots of hot water now.
When I get a bit of time I’ll recheck the propane portion.

Thank you for the suggestions.

[Old-Biscuit]

Originally Posted by dvmweb

It was the mixing valve.
I took it out and put in a bypass system.
It still has an inline one way valve in the hot water outlet line. I left that in.
We have lots of hot water now.
When I get a bit of time I’ll recheck the propane portion.

Thank you for the suggestions.

Did you change out the T-STAT for the Atwood Standard T-stat?
EXT uses a 160*F T-stat....which WILL result in 3rd degree scald with in 0.5 seconds
Hate to hear that happen when it can be minimized so easily

[Sco70ttie]

dvmweb,

If the electric is on, the gas won't come on until there in a major draw of water. What caused the gas to come on the last time it on? It might be operating properly.

[dvmweb]

The propane portion worked just fine after it got filled with water. So should I put a 140 or 120 thermostat in?

[dvmweb]

After looking at the chart I think I will put in a 120° thermostat.

[Old-Biscuit]

Originally Posted by dvmweb

After looking at the chart I think I will put in a 120° thermostat.

Atwood doesn't have any 120*F t-stats....haven't for YEARS
They do have a 130*F t-stat which many websites list as 120*F

Standard/OEM 140*F.......part number Atwood 91447
Optional 130*F.......part number Atwood 91470
Optional Adjustable T-stat 110*F to 150*F .......part number Atwood 93105

[Tha_Rooster]

Originally Posted by dvmweb

The propane portion worked just fine after it got filled with water. So should I put a 140 or 120 thermostat in?

The way you have a large water heater is it supper heats the water then using the mixing valve to adjust temp. I removed the glue out of adjustment knob screw, took off handle then on the inside of knob removed safety tab to make it fully adjustable. Then flushed and cleaned valve and it works like a new one.

[dvmweb]

Update:
Put in an adjustable thermostat to keep grandkids from getting scalded. Pretty easy and it works.