Suburban DSI Water Heater Issue Solved

[OldJarHead]

I picked up our new Rockwood Signature Ultra Lite TT 8328BS on 6/23/17. During our first time out while using the LP mode for the water heater, the HI-LIMIT switch on the LP side of the water heater tripped. The water was very hot compared to our last TT, a Trail Bay, that had an Atwood WH. After using some of the hot water, I reset the HI-LIMIT, turned the water heater back on in LP mode and it started up, stayed on until the HI-LIMIT tripped again.

By the way, the by-pass valves were in the correct position. I checked that the day I picked the camper up. I also purged the air at the relief valve and the faucets.

On 7/5/17 I was able to troubleshoot the problem. After connecting shore water, I started up the water heater and monitored the water temp periodically at the faucet while it was heating up. The thermostat should stop the heating process at about 130°; however, once the temp reached 160°, I turned off the water heater and purged all the hot water. I didn't wait for the HI-LIMIT to trip as I know it works.

I checked to ensure that the thermostat & HI-LIMIT sensors were tight against the water heater tank and making good thermal contact.

So, obviously the thermostat on the LP side (12V) was defective.

By the way, I tested the 120VAC mode of the water heater and it cycles normally.

To verify that the thermostat was indeed defective, I tested the removed thermostat assembly by applying heat with a heat gun to the mounting plate of the part while monitoring the temp with an attached thermometer & an ohm meter across each thermostat. Both were closed before any heat was applied. The HI-LIMIT thermostat opened at approximately 240 degrees (my thermometer only goes up to 220 degrees). The operating thermostat never opened.

I contacted the dealer and they immediately sent out a replacement thermostat (PN: 282232). They even paid the return shipping for the defective one.

I've done technical work (electronics/electrical) for 40+ years, so I didn't mind replacing the thermostat, which took all of about 3 minutes.

Hope this helps in the future if someone else experiences this issue.

BTW, the same part on Amazon Prime would've cost about $18.

Dan

[wmtire]

Good Post, Dan. Welcome aboard.

[modaholic]

Where is this thermostat located ?

[OldJarHead]

Originally Posted by modaholic

Where is this thermostat located ?

It's behind the reset buttons in the photo. Remove the 2 screws of the black cover and you'll see them. The one on the right is for 12VDC/LP mode, while the one on the left is for 120VAC/electric mode.

Dan

[Mewcasa]

You are VERY lucky! I'm a tech guy too! Dometic would not send me a circuit board for my refrigerator... period! I had to drag my trailer 120 miles to an authorized repair center, where it sat for weeks before it was even looked at. They came up with the same solution I did using the same service manual! Now I'm waiting for the part to come in! There's another week gone. I have a trip pre planned and paid for starting next week. There are no refunds for reservations... or scheduled vacations... Everyone else could care less! I'm holding my breath!

[OldJarHead]

Wow! That sucks! Hope all works out for your plans.

[CaptnJohn]

Originally Posted by Mewcasa

You are VERY lucky! I'm a tech guy too! Dometic would not send me a circuit board for my refrigerator... period! I had to drag my trailer 120 miles to an authorized repair center, where it sat for weeks before it was even looked at. They came up with the same solution I did using the same service manual! Now I'm waiting for the part to come in! There's another week gone. I have a trip pre planned and paid for starting next week. There are no refunds for reservations... or scheduled vacations... Everyone else could care less! I'm holding my breath!

Dometic should have used an authorized mobile tech. You would have had to pay about $50 for the service call but it would have been done sooner. IF there is an authorized tech in your area.

[New2minilite]

Originally Posted by OldJarHead

I picked up our new Rockwood Signature Ultra Lite TT 8328BS on 6/23/17. During our first time out while using the LP mode for the water heater, the HI-LIMIT switch on the LP side of the water heater tripped. The water was very hot compared to our last TT, a Trail Bay, that had an Atwood WH. After using some of the hot water, I reset the HI-LIMIT, turned the water heater back on in LP mode and it started up, stayed on until the HI-LIMIT tripped again.

By the way, the by-pass valves were in the correct position. I checked that the day I picked the camper up. I also purged the air at the relief valve and the faucets.

On 7/5/17 I was able to troubleshoot the problem. After connecting shore water, I started up the water heater and monitored the water temp periodically at the faucet while it was heating up. The thermostat should stop the heating process at about 130°; however, once the temp reached 160°, I turned off the water heater and purged all the hot water. I didn't wait for the HI-LIMIT to trip as I know it works.

I checked to ensure that the thermostat & HI-LIMIT sensors were tight against the water heater tank and making good thermal contact.

So, obviously the thermostat on the LP side (12V) was defective.

By the way, I tested the 120VAC mode of the water heater and it cycles normally.

To verify that the thermostat was indeed defective, I tested the removed thermostat assembly by applying heat with a heat gun to the mounting plate of the part while monitoring the temp with an attached thermometer & an ohm meter across each thermostat. Both were closed before any heat was applied. The HI-LIMIT thermostat opened at approximately 240 degrees (my thermometer only goes up to 220 degrees). The operating thermostat never opened.

I contacted the dealer and they immediately sent out a replacement thermostat (PN: 282232). They even paid the return shipping for the defective one.

I've done technical work (electronics/electrical) for 40+ years, so I didn't mind replacing the thermostat, which took all of about 3 minutes.

Hope this helps in the future if someone else experiences this issue.

BTW, the same part on Amazon Prime would've cost about $18.

Dan

So I've got a 2018 2509s that the water heater trys to light and sometimes does on lp but only runs for a bit then kicks off then trys again and same thing it's got plenty of propane no air in propane system any leads would be great

Originally Posted by OldJarHead

It's behind the reset buttons in the photo. Remove the 2 screws of the black cover and you'll see them. The one on the right is for 12VDC/LP mode, while the one on the left is for 120VAC/electric mode.

Dan