| [GMCnet] Water Heater Pop-Off [message #273307] |
Sun, 08 March 2015 10:52 |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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I wouldn't worry about it, George. I just replaced the water heater in the Clasco and both the pop off valve in the old, stock water heater and the new one I purchased for the new water heater are labeled the same (212K and 150PSI as I recall). The amount of crud in the old stock water heater was amazing. It turns out the water leak that showed up under the bed was coming from the drain fitting at the bottom of the old water heater. It had rotted all the way off and the only thing that kept water in that tank was crud. I have no idea how long it was like that but I am glad all that junk was stout enough to contain the heat and pressure.
There is so much heat loss in the heater hose that runs to the heat exchanger (mine were covered in pipe insulation but there were lots of gap everywhere the clamps held the hoses to the underside of the coach) that I can't imagine the water temp in the heat exchanger ever reaching anything like 212K. Plus, the heat exchanger is a separate tube that slides into a slightly larger tube welded into the water heater so heat transfer there is not going to be perfect either. I inspected the hoses and found them far better than I expected so did not change them, just re-insulated them with new pipe insulation. I also put in ball valves up by the engine so I can isolate the heat exchanger if one of the pipes ever does go south.
Net, net, from what I can see the heat transferred by the heat exchanger will likely never exceed the pop off temp and the pressure in the system will likely never exceed the pop off pressure unless something goes dreadfully wrong with the thermostat that controls heat on the electric side.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Message: 2
Date: Sat, 07 Mar 2015 17:38:19 -0700
From: George Beckman
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Water Heater Pop-Off
Message-ID:
Content-Type: text/plain; charset="utf-8"
cbryan wrote on Wed, 04 March 2015 17:56
> George,
>
> I can't find that series of posts that recommend putting a Canadian spec pressure-temp valve on the water heater because of the problem you
> indicate.
>
>
> Somebody will remember about the Canadian valve. They allow hotter hot water heaters up there.
>
> Best,
>
> Carey
To follow up on replacement valves. I happened to have the bathroom under sink panel out so I looked at the replacement valve I bought in Canada a
couple of years ago. On the box it says it is a heat and pressure valve. It has 212F on the box but I could find no pressure listed.
I will say I don't think I am going to put that one in as I often go over the Grapevine and usually one trip East a year, over the Rockies. It is not
unusual to see 220 and even 230 (once) when pulling a long hill in warm weather. The coach does not boil but of course antifreeze and the (albeit low)
pressure pressure cap hold things in check.
But, tell that to a 212 pop-off in a tank where over 212 boils.
In addition to the stock restrictor, I am beginning to think I need a thermal valve on the engine water return from the water heater that would shut
off at 212. Is there such a thing?
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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Jerry & Sharon Work
78 Royale
Kerby, OR
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