Noticed last week my furnace alert light was on. Turned off then back on. 3 seconds later light came back on. Came back an hour or so later and tried again. It worked!
So symptom is that when cold WH comes on and runs until hot. When system water is used and/or cools enough to call for a relight the relight fails. Power cycling switch, light goes out and back on 3 to 4 seconds after power cycle.
Things I've tried...
- Used compressor to blow out propane orifice & flu
- Disconnected and connected connectors to controller
- Checked thermistor (good continuity)
- Replaced thermistor with spare
- Replaced both thermostats (amazon $14)
- Replaced controller board (ebay $75)
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None of the above worked. Still have exact same symptoms. :(
Only component left is the propane solenoid. What brothers me is that when cool the solenoid works fine. When water hot but cool enough to call for a re-light and I have the DW power cycle I hear nothing at the water heater. Seems like I should hear a click. Which mades me think electrical. As you can probably tell I'm a little stumped here and the DW is getting a little tired of having to remember to turn on the WH 20 mins before she needs it. DW not happy nobody happy!
Before I throw more money (ebay $75 gas valve) at this repair. Does anyone have any ideas?
see ya
ken
Ken
Try a new clean ground. Screw it to the top of the case (not the back, as the screw can go into the tank). Sand the case for good contact.
You say $75.00 for board off ebay. Was it used. I bought a used one once, did the same thing.
If you have a manometer, you can check the LP pressure at the allen bolt on the gas valve, that will tell you if the valve is working, before you throw parts at it.
Sometimes just one of the 2 solenoids goes bad. They are replaceable. I probably have a good used one.
Did you change the thermo cut out, when you replaced the thermo's? Those go bad. You can remove it to test, but don't permanently leave them out:
Amazon.com: Atwood 93866 Thermal Cut Out Switch 2 Pack: Automotive (https://www.amazon.com/Atwood-93866-Thermal-Switch-Pack/dp/B00OA7UJPK/ref=asc_df_B00OA7UJPK/?tag=hyprod-20&linkCode=df0&hvadid=385217038031&hvpos=1o15&hvnetw=g&hvrand=8448041812286004692&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029625&hvtargid=pla-799818135598&psc=1&tag=&ref=&adgrpid=79334632300&hvpone=&hvptwo=&hvadid=385217038031&hvpos=1o15&hvnetw=g&hvrand=8448041812286004692&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029625&hvtargid=pla-799818135598)
Chris
What "brand" replacement board did you use? If it wasn't a DINOSAUR you don't have the right one. Their replacement boards are significantly better in quality/function than any other brand, including a genuine Atwood factory board.
Dinosaur Electronics Home. High quality circuit boards for RV appliances. (https://www.dinosaurelectronics.com)
What he said! It's just best to replace the factory board, even if the furnace/hwh is brand new! :facepalm:
Ditto for my furnace and hot water heater. My old system had intermittent ignition, probably due to low voltage or micro-cracks in the ceramic insulator. The new Dino boards must have had a higher voltage spark, but since I replaced the ceramic insulators/ignitor assemblies, it was hard to tell.
I wasn't fooling around because during freezing weather I replaced both major ignition components: Dino and ignitor. I didn't want the water to freeze in the rig.
kenhat wrote: "Only component left is the propane solenoid. What brothers me is that when cool the solenoid works fine. When water hot but cool enough to call for a re-light and I have the DW power cycle I hear nothing at the water heater. Seems like I should hear a click. "
Take a voltage reading across the solenoid coils, when cold and when hot. That will tell you if there is a change in resistance for one reason or another. Remember E=IR, voltage equals current times resistance. For comparative measurements just make the resistance equal to 1. Makes the math easier.
Or, turn on the hot water heater and when it tries to light smack the valve with a hammer. The valves are disks sitting on top of tubes with the aid of light springs and gas pressure. If the valve opens the electromagnets are weak.
I'll check ground tomorrow. Don't know why I didn't think of that. Should have been the first thing.
The controller was a new Atwood from an RV dealer.
Don't have a manometer. :( But when it does fire it has a good strong flame. Don't think pressure is an issue.
Didn't know there were 2 solenoids in the gas valve. Was looking at replacing the whole unit. I'll take another look in the morning.
I did replace the "thermo". That's what I'm was calling the thermistor in items 3 & 4 above.
thanks
ken
A voltage reading across the solenoids is a good idea. Would at least tell me if it's upstream or downstream of the gas valve.
When making my list of actions I left out 7. Tried impact adjustment on gas valve. Unfortunately didn't help. :(
thanks!
ken
Just to be certain that we're on the same page here, when I said take a voltage reading across the coils, I meant on the hot and ground leads. Any voltage there indicates resistance in the coils. If you use the current value printed on the tag you can determine the resistance of the coils in use. E=IR. You stated that the valve doesn't open when warm, if you take the same measurement when the hot water heater is trying to start and see a different voltage, you know the resistance changed with temperature and by how much.
In the recent past, when we needed to do so, our hot water heater started behaving the way yours is right now. I took the measurements, did the math and re-did the math for twice the current draw. Using a spool made from a bolt and some washers in my cordless drill I unwound enough magnet wire to give me the resistance value calculated. Lynn did the soldering, and the hot water heater was still working when I sold the Rockwood onto its new owner.
Now? I'd just buy a new valve, checking that the coils were 1/2A draw instead of the 1/4A.
Is that your original unit, Ken?
Mike I replaced the WH about 4 or 5 years ago.
I found my problem. As usual it was mostly dumb me.
I let the WH cool down and took voltage readings at the T-stat and saw 11.9v and at the ECO 10.9v. WH lit and ran fine. Waited for it to fail and took readings. 11.9v on T-stat & 0v on ECO. On a whim I reversed the thermo switch on the ECO and T-stat. It lit and ran fine! Did some research and found out the thermo switches are set at different temps. The T-stat is set for 140º and the ECO is set at 180º. Duh! I had watched a youtube on replacing the thermo switches and it didn't mention that they are set to different temps and the switches look identical. Went back and read the Amazon description and it does say the 180º goes on the left (ECO) and the 140º goes on the right (T-stat). It wasn't till after I read this that I found out what ECO stood for (Emergency Cut Off). The switches are marked 60c and 82c.
My assumption is that the original problem was the ECO went bad, was kicking in early, and stayed that way until it cooled.
Moral of story: do some damn research before slapping parts in!
After 9 years on the road I'm still making rookie mistakes. :(
see ya
ken
You already know the 140° thermostat is the service temperature, the 180° thermostat is a level of safety to prevent the hot water heater from turning itself into a bomb. The pressure relief valve is a temperature and pressure sensitive device. Larger boilers with have a fusible plug between the water and the fire as a final safety if a low water condition occurs.
Congratulations on a successful repair and learning experience. What doesn't kill you makes you smarter.
The Feynman Technique: The Best Way to Learn Anything (https://fs.blog/2012/04/feynman-technique/)
Art Joly
Interesting, because the spade connectors are different sizes, not sure how you reversed them. Glad it is fixed.
Chris