My Big Fat Water Heater @ Liberty Coach

[flloyd]

Well, it's done. I have a new water heater.

We arrived at Liberty Coach on Tuesday and spent the night in their lot. They had good power and a tall, barbed wire fence around the lot. We felt secure being at the home where our baby was born.

Our service manager, Bill Daughtery is the most knowledgable and professional person we've ever dealt with regarding our coach. There wasn't a question about it that he couldn't answer. While he agreed that our water heater needed replacement, evident by it's 2" top-to-bottom bulge, the reason wasn't immediately clear.

While we were at the factory, we elected to have two other items fixed: a broken cabinet handle (mirrored lucite), and our left side ammeter which was totally inaccurate. Although the water heater job was completed on Wednesday, they need another half day to button everything up. We took a day to visit Chicago and play tourist. All was well.

So, aside from the heater being 13 years old, what caused it to fail? Upon careful inspection of its remains, it was found that the pressure relief valve was of a type that Bill hadn't seen before. It was similar, but not quite the same as the one on the new heater. I had noted before the repair that the valve worked fine and so we couldn't blame it for tank bulge. It became apparent that one of the coach's previous owners had replaced the tank's original pressure relief valve. The replacement valve was of high quality and it was rated the same pressure as the tank itself - 150 PSI. ... Ooops.

The factory pressure relief valve on the new unit was rated at 75 PSI. Thus the cause of the bulge. Lesson learned.

We're very happy that the original tank never burst or leaked. Also, the water from the new tank was noticeably hotter. After going down the road for a few hours, it was downright scalding from the exchanger heat. All is well and the wife is happy with the extended shower time now available.

I highly recommend Liberty Service. Bill is the man if you ever need expert advice.

[Jon Wehrenberg]

Fred,

Let me be the first to tell you the tank did not fail exclusively because of the water pressure relief valve.

I will guarantee that at some point the accumulator tank (the blue one on the LH side) had zero bladder pressure. As the water expanded, most likely from the higher temps of engine coolant heating the contents there was no room in the accumulator tank for the expansion so your water heater bulged.

Some one, some where along the line failed to recognize the subtlety of ownership where it is the little things that will bite you in the ass.

[JIM CHALOUPKA]

Fred,

Let me be the first to tell you the tank did not fail exclusively because of the water pressure relief valve.

I will guarantee that at some point the accumulator tank (the blue one on the LH side) had zero bladder pressure. As the water expanded, most likely from the higher temps of engine coolant heating the contents there was no room in the accumulator tank for the expansion so your water heater bulged.

Some one, some where along the line failed to recognize the subtlety of ownership where it is the little things that will bite you in the ass.

My tank looks to have the original P/R valve as installed by Liberty, it is rated at 175 PSI.

Do you think it should be changed to 75 PSI as suggested?

There is a 75 PSI which is listed as, RV75, maybe aimed at the RV industry.

I don't think anyone changed yours Fred. I think it came that way when new.

It is possible the RV75 was not available in 1997 and that the way of thinking about the system changed and a new P/R valve was created to better serve the RV industry.


JIM

[Jon Wehrenberg]

From the Raritan Web Site:

A6 The pressure relief valve on my water heater keeps dripping. What is wrong?

The rubber seal in the pressure relief valve may have failed with age. Replacement part #WH3.

The pressure relief valves used in Raritan water heaters are set for 75 PSI or 210° F. If water temperature or pressure inside the tank exceeds these limits, the valve will unseat.

If engine coolant is being used in a Raritan water heater with heat exchanger, some of the engine coolant may have to be diverted via a bypass valve, to insure that the water in the tank does not exceed the limits of the pressure relief valve.

Review the owner's manual or contact Raritan Technical Support.

If the relief valve is greater than 175 it was changed according to the statement above which was copied from the Raritan web site list of FAQs.

Any expansion in a Liberty system is handled by the accumulator or expansion tank as long as the bladder has 20 to 30 PSI. Once the bladder air pressure in the accumulator or expansion tank is gone, the entire plumbing system no longer has the pnuematic pressure provided by the bladder, but now is a closed system, not unlike a hydraulic system and expansion of the water due to heating increases system presssures since the expanded contents of the system have no where to go except out the 75 PSI bypass valve, or if held in the system by a heavy pressure by pass valve such as the 175 PSI valve that was/is installed then the excess pressure just builds until something has to give.

[flloyd]

From the Raritan Web Site:

If the relief valve is greater than 175 it was changed according to the statement above which was copied from the Raritan web site list of FAQs.

Any expansion in a Liberty system is handled by the accumulator or expansion tank as long as the bladder has 20 to 30 PSI. Once the bladder air pressure in the accumulator or expansion tank is gone, the entire plumbing system no longer has the pnuematic pressure provided by the bladder, but now is a closed system, not unlike a hydraulic system and expansion of the water due to heating increases system presssures since the expanded contents of the system have no where to go except out the 75 PSI bypass valve, or if held in the system by a heavy pressure by pass valve such as the 175 PSI valve that was/is installed then the excess pressure just builds until something has to give.

I'd say unequivocally that anybody having a 175 PSI valve should replace it immediately. The 75 PSI valve protects the entire system, regardless of whether there is a functional expansion tank.

Nobody knows what pressure was reached in my tank, or if the 175 psi valve ever vented on its own. It is clear, however, that enough pressure existed to deform the tank, which by all accounts would have been considerable, even if less than 175 psi. Going by the area-rule alone, the end of a 20" tank would be subjected to about 55,000 pounds of pressure at 175 per square inch.

My tank didn't rupture, but it did deform vertically by 2". What surprises me is that the plumbing held whatever pressure did result, and no part of the system leaked. That's quite remarkable for plastic plumbing, IMHO.

http://lh4.ggpht.com/_QkzN2-KPKAg/TH5PZPoFrwI/AAAAAAAABrs/6pDYU627x_8/s512/IMG_5659.JPG
The bulge

http://lh6.ggpht.com/_QkzN2-KPKAg/TH5PZ93Aa6I/AAAAAAAABr8/bPJfbJ7wzNs/IMG_5660.JPG
Note top cap in place, bottom cap separated. This heater lasted 13 years.

http://lh5.ggpht.com/_QkzN2-KPKAg/TH5PZTxVb3I/AAAAAAAABrw/vIZnnC3M3cs/s512/IMG_2867.JPG
Mysterious stain behind heater - still unidentified.

I wasn't able to watch the actual heater replacement so I gave my camera to Bill Daughtery who took the photos. I would have loved to participate in the repair, but alas, I have no garage of my own. I do envy John's barn...

[JIM CHALOUPKA]

Fred, what was it that made you aware of your water heater trouble. What was/were the telltale symptoms.

JIM

[flloyd]

Fred, what was it that made you aware of your water heater trouble. What was/were the telltale symptoms.

JIM

To this I have to credit Jim Elmore, who showed me the water heater in his 2000 Liberty. At the time, his was leaking. The key indicator was the separation of the bottom outer cover and the fact that the whole assembly had raised about 2". Normally the tank is 24" tall. Mine was 26" tall after the bulge-out. Rather than risk a leak, I elected to go ahead with the replacement. There was a lot of stress on the pipes, both plastic and copper, while it was in the bulged condition.

[JIM CHALOUPKA]

I have that same condition.:(:(:(:(


JIM

[Ray Davis]

Wow! Fred may have just saved you a lot of damage, before that darn thing explodes!

[Jon Wehrenberg]

While a split or fracture of the water tank is possible, an explosion is not likely. Since it is hydraulic pressure creating the bulged tank condition, as soon as the pressure is relieved via a leak through a crack in the tank the pressure drops almost immediately.

That of course doesn't recognize the ensuing water damage.

If I had a tank that has bulged, but not failed to hold water I would do nothing but make sure my accumulator tank has the proper bladder pressure, and make certain the pressure relief valve is the appropriate rating. The hot water tank is not going to bust as long as the pressures are down to our normal range of around 40 to 60 PSI. So Jim, if all else is OK don't worry about the tank. If the accumulator tank will not hold the bladder pressure (checked when the water system has zero pressure and a faucet is open) then that needs to be replaced before heading down the highway.

[JIM CHALOUPKA]

I have just replaced the bladder tank and the pressure relief valve and will live with the bulged hot water tank until it is convenient to R&R it.

Raritan states they are behind in production and could not fill an order for about two weeks anyway.

My plate is already tooooo full trying to get ready to go on the road at the end of Sept. :eek:

JIM:)

[Ray Davis]

Probably a poor choice of words on my part. I meant that the tank might rupture and a lot of hot water down there wouldn't be a pretty site.

[Jon Wehrenberg]

I think your words were probably correct in the context that if a seam did split it would likely produce a fair amount of noise, followed by a significant rush of water. They served the purpose in illustrating the problem associated with an excessively high pressure relief valve.