Is our Atwood 10G water heater supposed to do this?

Hi All!

A quick update and maybe resolution to the problem (although I'm not quite sure how)

Here is an image of the water heater:



I went in there today to try and clean up the wires and the contacts. The control board is in the top right corner and the thermostat controls are just above the gas tube to the burner. The wires and contacts going to the t-stat were very badly corroded and some whiteish residue on the wires and connecting terminals. I could not pull the wires off of the terminals at the t-stat as they just wouldn't come off and they seemed very, very rubbery and weak - like they were ready to break off or pull right through the cover. I brushed to contacts as best as I good with small brushes and straightened out the wires and closed the heater up for the time being until I could figure out how to better tackle the wires to get them off and properly cleaned up. I went back in the RV and just for grins and giggles I flipped the gas switch back on and I haven't heard a peep from the gas side since. I'm going to hit the showers shortly here and I will turn off the electric side and see if the gas kicks in to reheat the water as it depletes from the shower. Either I fixed it or I wrecked it??

I'll keep you posted for sure!

Cheers!

Mike

dougrainer wrote:

Old-Biscuit wrote:


Use the electric only and see if electric cycles on/off.

Still think you issue is with spark electrode assembly/flame proving vs t-stat
T-stat would affect both heating sources

OK, without an amp meter, how will he know if the 120 electric short cycles also?????????????????? Also, I read his post again. He states it runs for a few minutes when showering or heavy hot water draw then shuts off. What I think is happening is, he has a center bypass valve ON and the hot water is bleeding with cold and he is not getting all the hot water out of the tank and that is why it short cycles. Doug

Simple plug in Voltmeter will show electric heat element turning on/off (voltage drops/increases)

Have one in my RV and it will clearly show when it turns on/off


Cold water mixing and therefore the propane turns on/off ???????????????????????
OP Stated The water is hot and plentiful so no worries there"



Propane cycling.........
Flaming proving is being lost after a few minutes of use. Circuit board drops gas valve.....refires cause t-stat is still closed
Main flame lights off.....then after few minutes flaming proving signal lost repeat again (doesn't lock out cause flame proving is established and burner fires for a few minutes)

Old-Biscuit wrote:

Mike LeClair wrote:
Thank you all for your insightful and helpful feedback. Last night I switched off the electric side to see if it would make a difference in the behaviour of the gas side. No change, the gas still cycled for a few seconds on a frequent and irregular cycle. Today I am going to attempt to check all of the T-stat connections and fitment to the tank. I will also clean up the spark electrode assembly and check it's orientation and placement per the factory service manual. Since this is my first adventure with an Atwood water heater there is a learning curve for me and I don't want to bugger anything up. It is pouring rain here right now as I type this post. Hopefully it will quit and I can get outside to work on things.

I will keep y'all updated as I work on this. Many thanks again for you help.

Cheers!

Mike

Use the electric only and see if electric cycles on/off.

Still think you issue is with spark electrode assembly/flame proving vs t-stat
T-stat would affect both heating sources

OK, without an amp meter, how will he know if the 120 electric short cycles also?????????????????? Also, I read his post again. He states it runs for a few minutes when showering or heavy hot water draw then shuts off. What I think is happening is, he has a center bypass valve ON and the hot water is bleeding with cold and he is not getting all the hot water out of the tank and that is why it short cycles. Doug

Mike LeClair wrote:
Thank you all for your insightful and helpful feedback. Last night I switched off the electric side to see if it would make a difference in the behaviour of the gas side. No change, the gas still cycled for a few seconds on a frequent and irregular cycle. Today I am going to attempt to check all of the T-stat connections and fitment to the tank. I will also clean up the spark electrode assembly and check it's orientation and placement per the factory service manual. Since this is my first adventure with an Atwood water heater there is a learning curve for me and I don't want to bugger anything up. It is pouring rain here right now as I type this post. Hopefully it will quit and I can get outside to work on things.

I will keep y'all updated as I work on this. Many thanks again for you help.

Cheers!

Mike

Use the electric only and see if electric cycles on/off.

Still think you issue is with spark electrode assembly/flame proving vs t-stat
T-stat would affect both heating sources

Sounds like a faulty T-Stat.

I will describe one T-Stat or two that I have seen or tore down

I just put an "open Switch" type T-Stat on my Furnace (long story omittee) when the thing opens a small magnet holds the switch open so it take quite a bit of "PULL" to close it,, likewise other things help hold it closed when it's closed so more pull is needed to open it.

This causes the furnace to run "For a while" not "blink" on and off.

Another type uses a bi-stable bi-metal spring bar, it "Snaps" open and closed and again there is a "Gap" between open and closing temp's

That's the kind Atwood uses.. Practically they both work the same but the magnet one is easier to see (it is the 20 dollar one from ACE if you'd care to take a look)

Yours has lost that "Gap" is my guess so instead of waiting say 5 Degrees to turn back on it's waiting 0.5 Degrees.

Thank you all for your insightful and helpful feedback. Last night I switched off the electric side to see if it would make a difference in the behaviour of the gas side. No change, the gas still cycled for a few seconds on a frequent and irregular cycle. Today I am going to attempt to check all of the T-stat connections and fitment to the tank. I will also clean up the spark electrode assembly and check it's orientation and placement per the factory service manual. Since this is my first adventure with an Atwood water heater there is a learning curve for me and I don't want to bugger anything up. It is pouring rain here right now as I type this post. Hopefully it will quit and I can get outside to work on things.

I will keep y'all updated as I work on this. Many thanks again for you help.

Cheers!

Mike

Both electric and propane are using the same set of t-stats for heating cycles so if t-stat was issue the electric would be going on/off along with the propane and water would not be getting hot due to the short cycling


The propane is cycling because it is NOT 'proving' main flame is lit (or proving it is staying lit)
That is a function of the spark electrode and grounding

Flame proving.....milivot signal from 'ionization' so circuit board keeps DC Voltage on gas valve UNTIL t-stat opens

Spark electrode assembly suspect.
Clean & reposition

KCFDCapt wrote:
Check the connections at the thermostat. Clean and tighten them with a pair of pliers. It could be poor contact on those slip on connections.

I agree it is likely related to the thermostat, but on my 6 gallon Atwood they are only a 1/4 turn to install/remove.

Check the connections at the thermostat. Clean and tighten them with a pair of pliers. It could be poor contact on those slip on connections.

12th Man Fan wrote:
I suspect the problem is caused by running both the gas and electric.

I use both for the original start up but after it has reached the proper temp I cut off the gas and the electric handles the recovery just fine.

Cut off your electric and see if the gas doesn't work more like you are expecting it to then.

Doug

LP and 120 uses the same tstat. NO, it should not do that. As another poster stated, odds are the tstat is not tight against the LP aluminum tank. If it is tight, then replace the tstat. Doug