Suburban SW6DE Water Heater - Water Too Hot Gas AND Electric...

[OR_Brewer]

So I'm having an odd issue with my Suburban SW6DE... the water is getting too hot on both gas AND electric(well over 130). If I'm understanding correctly there's a separate Hi-Limit/ECO-Thermostat for the gas side and the electric side. It seems odd to me that both would be malfunctioning (trailer is only a year old).

Am I correct that there's two Hi-Limit/ECO-Thermostats, one for gas and one for electric? If so, is there a way for me to test these? Given that both electric and gas is getting too hot, I'm wondering if maybe these are fine and there's an issue with a different part (perhaps a circuit board or something) somewhere.

Thanks for the help!

[TitanMike]

The thermostat for SW series Suburban water heaters is designed for 130 degrees. Like most anything man made it might have a range of temps above or below that it functions.

They're non-adjustable so choices are either use more cold water or replace the thermostat and hope it doesn't exceed 130 degrees.

Curious but how hot does it actually get? i've heard some accounts of 135 degrees which certainly sounds like a reasonable tolerance.

[OR_Brewer]

It's getting so hot that on occasion it has started weeping out of the blow-off valve. It's definitely not an issue of just sensitivity on my end. Something is definitely malfunctioning.

To be safe, at this point, we run only in propane mode since we can turn on and off as needed inside the trailer. Since I have to go outside to turn on/off the electric mode we've just avoided using it that way until I can fix the issue.

I just want to make sure I've properly isolated the malfunction before I start purchasing replacement parts.

[TitanMike]

Originally Posted by OR_Brewer

It's getting so hot that on occasion it has started weeping out of the blow-off valve. It's definitely not an issue of just sensitivity on my end. Something is definitely malfunctioning.

To be safe, at this point, we run only in propane mode since we can turn on and off as needed inside the trailer. Since I have to go outside to turn on/off the electric mode we've just avoided using it that way until I can fix the issue.

I just want to make sure I've properly isolated the malfunction before I start purchasing replacement parts.

Sounds like bad or shorted thermostat circuit.

Check out the troubleshooting suggestions in the manual or on Suburban's site.

[BehindBars]

This is not a direct solution, but food for thought. I've always had Atwood water heaters and also found them to generally run too hot. So, for a long, long time I've always installed an adjustable thermostat on the heater to keep the temperature well below skin damaging levels. Is an adjustable thermostat available for the Suburban?

[kenandterry]

Originally Posted by BehindBars

This is not a direct solution, but food for thought. I've always had Atwood water heaters and also found them to generally run too hot. So, for a long, long time I've always installed an adjustable thermostat on the heater to keep the temperature well below skin damaging levels. Is an adjustable thermostat available for the Suburban?

Our Atwood heater provides hotter than needed water.
Where can you get this adjustable thermostat?
Is there a specific part number ......and price please.

[Lins]

Originally Posted by OR_Brewer

It's getting so hot that on occasion it has started weeping out of the blow-off valve. It's definitely not an issue of just sensitivity on my end. Something is definitely malfunctioning.

To be safe, at this point, we run only in propane mode since we can turn on and off as needed inside the trailer. Since I have to go outside to turn on/off the electric mode we've just avoided using it that way until I can fix the issue.

I just want to make sure I've properly isolated the malfunction before I start purchasing replacement parts.

Are you sure the blow-off valve isn't just leaking? I would find out exactly how hot the water is getting to.

[BehindBars]

Originally Posted by kenandterry

Our Atwood heater provides hotter than needed water.
Where can you get this adjustable thermostat?
Is there a specific part number ......and price please.

Link below is for the Atwood part from Amazon. This is not for the Suburban, which is the subject of this thread. You can read the reviews and Q&A there. You’ll need to shop for the best price and source in Canada.

https://www.amazon.com/Atwood-93105-...-2&tag=mh0b-20

A suggestion is to set it to a just tolerable water temperature. If you set the temperature too low you just run out of hot water sooner. Ours is set cooler than the original thermostat, but with back to back showers we never run out of hot water.

[wmtire]

Originally Posted by OR_Brewer

So I'm having an odd issue with my Suburban SW6DE... the water is getting too hot on both gas AND electric(well over 130). If I'm understanding correctly there's a separate Hi-Limit/ECO-Thermostat for the gas side and the electric side. It seems odd to me that both would be malfunctioning (trailer is only a year old).

Am I correct that there's two Hi-Limit/ECO-Thermostats, one for gas and one for electric? If so, is there a way for me to test these? Given that both electric and gas is getting too hot, I'm wondering if maybe these are fine and there's an issue with a different part (perhaps a circuit board or something) somewhere.

Thanks for the help!

This link will show you what/where the thermostats are on the Suburban. Maybe make sure that both assemblies are bolted snug against the tank wall, as they sense the temp from the tank wall.



https://www.forestriverforums.com/fo...ml#post1827312

[cardwellmarty]

I replaced my Suburban water heater a year or so ago it said 130 degrees in shipment directions, l checked it with a food thermometer and it was right on 130 degrees. I have had the blow off valve to wipe on occasions, l just open and close it quickly and let it reseal, but l drain mine every 4 months to check anoid rod and to keep air regulated in the tank, we are a full-time rv family.

[cardwellmarty]

Anode rod spell correction.

[nomad297]

Your temperature and pressure relief valve isn’t dripping due to your hot water temperature being too high — it would need to reach 210 degrees Fahrenheit for that to happen. It is dripping due to the thermal expansion caused from heating cold water to 130 degrees.

You stated you measured 130 degrees (not 210 degrees), which is what it usually should be with an RV water heater, so no problem there. With your RV’s water system being a “closed” water system, thermal expansion has nowhere to go, so once it reaches 150psi (and it WILL reach 150psi), the temperature and pressure relief valve will drip until the pressure in the system is less than 150psi. No problem there, either.

Here is something from the AIRXCEL/Suburban technical service manual to validate what I just wrote. It makes no difference which brand of tank-type water heater you have in your RV; this still applies:



Of course you could always try to create an air pocket at the top of your water heater’s tank, but the efficacy and longevity of that remedy is debatable.


Bruce

[KyDan]

We're still wondering "how hot is it"??
Can you check it with a thermometer?
Need some hard data before offering guesses as to cause.

[BehindBars]

Originally Posted by nomad297

Your temperature and pressure relief valve isn’t dripping due to your hot water temperature being too high — it would need to reach 210 degrees Fahrenheit for that to happen. It is dripping due to the thermal expansion caused from heating cold water to 130 degrees.

You stated you measured 130 degrees (not 210 degrees), which is what it usually should be with an RV water heater, so no problem there. With your RV’s water system being a “closed” water system, thermal expansion has nowhere to go, so once it reaches 150psi (and it WILL reach 150psi), the temperature and pressure relief valve will drip until the pressure in the system is less than 150psi. No problem there, either.

Here is something from the AIRXCEL/Suburban technical service manual to validate what I just wrote. It makes no difference which brand of tank-type water heater you have in your RV; this still applies:

Of course you could always try to create an air pocket at the top of your water heater’s tank, but the efficacy and longevity of that remedy is debatable.

Bruce

You said the pressure “WILL reach 150psi”, but since we have never experienced any kind of pressure like that in our motorhome, it got me thinking about the water system.

We don’t know the OP’s water pump type, but if the OP has a bypass type fresh water pump, wouldn’t pressure build up from heating the water be relieved by way of the pump bypass valve opening and pushing water back to the pump inlet side? For example, a SHURflo 4008 pump, according to it’s instruction sheet, should be in full bypass at 62 PSI. It also wasn’t stated whether the OP’s system has an accumulator tank installed, which might also provide some space for expansion.

[nomad297]

Originally Posted by BehindBars

You said the pressure “WILL reach 150psi”, but since we have never experienced any kind of pressure like that in our motorhome, it got me thinking about the water system.

We don’t know the OP’s water pump type, but if the OP has a bypass type fresh water pump, wouldn’t pressure build up from heating the water be relieved by way of the pump bypass valve opening and pushing water back to the pump inlet side? For example, a SHURflo 4008 pump, according to it’s instruction sheet, should be in full bypass at 62 PSI. It also wasn’t stated whether the OP’s system has an accumulator tank installed, which might also provide some space for expansion.

I’m not sure where the bypass is on the 4008 pump, but if it is set up the way I think you are saying, if you ever hooked-up to “city” water at above 62psi, you would start filling your fresh water tank, eventually overflowing it. Depending on the size of an accumulator tank (it wouldn’t have to be too large for a 6 gallon water heater) it would most likely absorb the thermal expansion.

Bruce

[BehindBars]

Originally Posted by nomad297

I’m not sure where the bypass is on the 4008 pump, but if it is set up the way I think you are saying, if you ever hooked-up to “city” water at above 62psi, you would start filling your fresh water tank, eventually overflowing it. Depending on the size of an accumulator tank (it wouldn’t have to be too large for a 6 gallon water heater) it would most likely absorb the thermal expansion.

Bruce

I think you’re right about city pressure above 62 PSI possibly filling the fresh water tank. That is something to think about. I use a 40-45 PSI regulator on the city water line, and I guess that’s a good reason to do it.

[TitanMike]

Originally Posted by KyDan

We're still wondering "how hot is it"??
Can you check it with a thermometer?
Need some hard data before offering guesses as to cause.

Asked the same question in post #2 with no definitive response.

[Scrapper]

I believe pressure relief valves are made to a 10 percent tolerance. The temperature can range from 117 - 143 degrees and the pressure can range from 135 - 165 psi. I am not sure if the two are linear but my guess is as the temperature tolerance increases the pressure tolerance decreases.

[OldJarHead]

Here’s a post I shared in July 2017. Sounds similar. Good luck.

https://www.forestriverforums.com/fo...ed-138936.html

[nomad297]

Originally Posted by Scrapper

I believe pressure relief valves are made to a 10 percent tolerance. The temperature can range from 117 - 143 degrees and the pressure can range from 135 - 165 psi. I am not sure if the two are linear but my guess is as the temperature tolerance increases the pressure tolerance decreases.

I’m not sure about the tolerances you mention because I’ve never heard or read anything about that in all of my time dealing with T&P valves, but I’m always open to learning new things when it comes to plumbing. I do know that when after roughing in buildings and performing a hydrostatic pressure test (I have done hundreds) on the entire system with the water heater installed, the gauge on the hydrostatic pump would always stop climbing at exactly 150psi because the T&P would begin to relieve the pressure at that point. I never had one relieve pressure below or above 150psi, so I believe they are pretty accurate.

As far as the relation to the temperature measuring part and the pressure measuring part goes, there is none. They are two completely independent systems. The only part they have in common is, they both allow the same seal to separate from the valve seat. The thermostatic probe is a brass tube with a white plastic coating. Inside of the brass tube is a spring-loaded stainless steel rod/piston with a chamber of gas behind it. When the gas gets hot enough, it pushes the rod/piston up towards the seal and separates it from the seat, allowing water/steam to escape. The spring on the rod is supposed to push the rod back down into the brass tube to close the seal to the seat when it cools down enough, but it may only do this once or twice, if it does it at all, before the valve needs to be replaced. The pressure part of the valve works with a simple spring above the seal, holding it tight to the seat. When the pressure reaches 150psi, the spring begins to compress, causing the seal to separate from the seat allowing water to escape.

Bruce