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Water Heater Pop-Off [message #273036] Wed, 04 March 2015 12:12 Go to next message
George Beckman is currently offline  George Beckman   United States
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Location: Colfax, CA
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I realized I was sort of hijacking the thermostat thread so I am moving my question here.

Some times, if the water in the water heater is cold when we start, the pop-off is leaking when we arrive. Anyone else (besides my friend Max) had this problem?

I think it is pressure rather than heat, but I was thinking of changing from a 195* to a 180* thermostat. If we open the faucet for a second with the pump off before we leave (when the water heater is cold) it does not seem to happen. It does not have to be a warm day... i.e. the engine stays at 195*.

I can't seem to get a definitive answer as to whether our ('74) water heater pop-off is temp and pressure or just pressure. (I think the latter.)

Anyway, two or three times, we arrive and the pop-off is leaking and I have to flip the little toggle thingy to get it to seal.

Perhaps my answer is to change that puppy out... but I just helped my friend Randy get the anode rod out of his '77 and there was not an impact wrench big enough. (PB, let it sit. Bigger impact, etc.) We finally took the heater out and used BIG pipe wrenches and cheaters (six plus feet of cheater) I had not used for years. It finally came out, screeching all the way. I hope the pop-off in mine is not like that. It looks sort of newish. I have had a new one lying back in there, next to the heater, since Amana.


'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: Water Heater Pop-Off [message #273049 is a reply to message #273036] Wed, 04 March 2015 16:58 Go to previous messageGo to next message
wally is currently offline  wally   United States
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Registered: August 2004
Location: Omaha Nebraska
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George Beckman wrote on Wed, 04 March 2015 12:12
I realized I was sort of hijacking the thermostat thread so I am moving my question here.

Some times, if the water in the water heater is cold when we start, the pop-off is leaking when we arrive. Anyone else (besides my friend Max) had this problem?

I think it is pressure rather than heat, but I was thinking of changing from a 195* to a 180* thermostat. If we open the faucet for a second with the pump off before we leave (when the water heater is cold) it does not seem to happen. It does not have to be a warm day... i.e. the engine stays at 195*.

I can't seem to get a definitive answer as to whether our ('74) water heater pop-off is temp and pressure or just pressure. (I think the latter.)

Anyway, two or three times, we arrive and the pop-off is leaking and I have to flip the little toggle thingy to get it to seal.

Perhaps my answer is to change that puppy out... but I just helped my friend Randy get the anode rod out of his '77 and there was not an impact wrench big enough. (PB, let it sit. Bigger impact, etc.) We finally took the heater out and used BIG pipe wrenches and cheaters (six plus feet of cheater) I had not used for years. It finally came out, screeching all the way. I hope the pop-off in mine is not like that. It looks sort of newish. I have had a new one lying back in there, next to the heater, since Amana.

We had the same deal and swapping to a 180 stat cured it. I don't know if our relief valve was on the low spec for temperature but it's been fine this way. I've been hoping I wasn't the only one.


Wally Anderson
Omaha NE
75 Glenbrook
Re: Water Heater Pop-Off [message #273058 is a reply to message #273036] Wed, 04 March 2015 19:43 Go to previous messageGo to next message
77Royale   United States
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
Senior Member
Replaced mine a while back, Mine is for an Atwood, but I think they are all the same, Had to go to Amazon to get it, Local places dont carry that size anymore 1/2 inch, All I could find was 3/4 with the shorter annode rod.

Like 12 bucks shipped. Mine was not leaking but was from 1977 and had seen better days.

hope it helps.


77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy. Mid Michigan
Re: Water Heater Pop-Off [message #273059 is a reply to message #273036] Wed, 04 March 2015 19:56 Go to previous messageGo to next message
cbryan   United States
Messages: 451
Registered: May 2012
Location: Ennis, Texas
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Senior Member
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. However, Rob Mueller did post this, indicating that it was not unheard of. His message #264278:

"G'day,

One of the problems a coach that has rubber lines back to the water heater runs into is that the water temp in the water heater gets
heated to the same temperature as the engine cooling water. When the water pump is turned on water flows out of the temp / pressure
relief valve until the temperature of the water in the water heater is reduced below the setting of the temperature relief valve.

At first it thought using metal lines wouldn't be a good idea as you would lose heat through the lines, however, that might be a
good thing.

Rick,

Let us know if you experience the problem noted in the first paragraph."

I can't find the discussion, but the solution might be a higher temp PT valve, available only from Canada. I also while looking for the link, stumbled across a link showing we ought to keep our water heaters over 140 Fahrenheit because of Legionella, the bug that causes Legionnaire's disease. Not specifically to your point. 180 degree tank water sterilizes the little troublemakers, right away, 140 after 22 minutes.

Somebody will remember about the Canadian valve. They allow hotter hot water heaters up there.

Best,

Carey


Carey from Ennis, Texas 78 Royale, 500 Cadillac, Rance Baxter EFI.
Re: Water Heater Pop-Off [message #273085 is a reply to message #273059] Thu, 05 March 2015 09:11 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
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Registered: October 2008
Location: Colfax, CA
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Senior Member
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. However, Rob Mueller did post this, indicating that it was not unheard of. His message #264278:

"G'day,

One of the problems a coach that has rubber lines back to the water heater runs into is that the water temp in the water heater gets
heated to the same temperature as the engine cooling water. When the water pump is turned on water flows out of the temp / pressure
relief valve until the temperature of the water in the water heater is reduced below the setting of the temperature relief valve.

At first it thought using metal lines wouldn't be a good idea as you would lose heat through the lines, however, that might be a
good thing.

Rick,

Let us know if you experience the problem noted in the first paragraph."



Somebody will remember about the Canadian valve. They allow hotter hot water heaters up there.

Best,

Carey


Cary,

This is most interesting, because when I first had trouble we were touring Banf and the area. So the replacement I got, and have not installed, is Canadian or at least from a Canadian hardware.




'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: Water Heater Pop-Off [message #273094 is a reply to message #273036] Thu, 05 March 2015 11:43 Go to previous messageGo to next message
cbryan   United States
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
Senior Member
George,

I found a post by Emery Stora which may shed light on which valve you have. Quoted below:

"There was recent posting about the temperature/pressure water heater safety valve and someone posted that it was just a pressure valve.
You are both right but it depends on which water heater you are talking about.

The early GMC motorhomes used the Type 1 water heater which was in a rectangular box. This one did use a temperature/pressure valve.

However, the Type 2 water heater which was in a round cylinder case only used a pressure safety valve.

Emery Stora
77 Kingsley
Frederick, CO"

HTH.

Carey


Carey from Ennis, Texas 78 Royale, 500 Cadillac, Rance Baxter EFI.
Re: Water Heater Pop-Off [message #273140 is a reply to message #273094] Thu, 05 March 2015 19:36 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
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Location: Colfax, CA
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Senior Member
cbryan wrote on Thu, 05 March 2015 09:43
George,

I found a post by Emery Stora which may shed light on which valve you have. Quoted below:

"There was recent posting about the temperature/pressure water heater safety valve and someone posted that it was just a pressure valve.
You are both right but it depends on which water heater you are talking about.

The early GMC motorhomes used the Type 1 water heater which was in a rectangular box. This one did use a temperature/pressure valve.

However, the Type 2 water heater which was in a round cylinder case only used a pressure safety valve.

Emery Stora
77 Kingsley
Frederick, CO"

HTH.

Carey


Carey and Emery,

This does help. I have a '74 (square model). The valve may not be new, but perhaps it is still temp and pressure. If so, I may go back to the 180*. I know there is supposed to be a reducer in the output at the head, but I am afraid that when going cross country even a slower flow will get the water "too" hot.




'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: Water Heater Pop-Off [message #273188 is a reply to message #273036] Fri, 06 March 2015 10:27 Go to previous messageGo to next message
thesmith is currently offline  thesmith   United States
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Registered: February 2015
Location: Cary, NC
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Senior Member
Would not a valve like this in the water line from the engine to the heater fix this problem? Simply dial in what heat you want the tank to heat to and it shuts off the water flow when it reaches temp desired?



http://www2.spiraxsarco.com/resources/steam-engineering-tutorials/control-hardware-sa-actuation/typical-self-acting-temperature-controls-and-systems.a sp



Pete


Cary, NC 1978 Center Kitchen Royale.
Re: [GMCnet] Water Heater Pop-Off [message #273190 is a reply to message #273188] Fri, 06 March 2015 10:55 Go to previous messageGo to next message
powwerjon is currently offline  powwerjon   United States
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Registered: March 2013
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Senior Member
Pete,
Cinnabar - http://www.thegmcmotorhomepeople.com Offers a complete kit that includes a 12 VDC solenoid, temperature sensor, wiring and a switch. The kit allows the temp switch to shut off the the flow of coolant to the hot water tank and prevent the tank water from getting too hot. I think that Rob has a picture of the unit from the Cinnabar newsletter. I have the kit in my shop and will be installing it this spring. Kit runs a little over $60 and considerable cheaper than the industrial style temp controls, which I have specified and bought as my previous life as an instrument engineer. Good find, but not a good application for the cost.

J.R. Wright
30' Buskirk Stretch
Michigan
On Location in Tucson

> On Mar 6, 2015, at 9:27 AM, Pete Smith wrote:
>
> Would not a valve like this in the water line from the engine to the heater fix this problem? Simply dial in what heat you want the tank to heat to
> and it shuts off the water flow when it reaches temp desired?
>
>
>
> http://www2.spiraxsarco.com/resources/steam-engineering-tutorials/control-hardware-sa-actuation/typical-self-acting-temperature-controls-and-systems.a sp
>
>
>
> Pete
> --
> Cary, NC
> _______________________________________________
> GMCnet mailing list
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Re: Water Heater Pop-Off [message #273195 is a reply to message #273140] Fri, 06 March 2015 12:10 Go to previous messageGo to next message
cbryan   United States
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
Senior Member
Quoting your last message, George,

"This does help. I have a '74 (square model). The valve may not be new, but perhaps it is still temp and pressure. If so, I may go back to the 180*. I know there is supposed to be a reducer in the output at the head, but I am afraid that when going cross country even a slower flow will get the water "too" hot."

Thinking about how hot is "too" hot. I wonder if just replacing the Pressure Temperature valve on your rectangular water heater with just a pressure valve and depending on not boiling the water there using your radiator to keep below an estimated say, 220 degrees F at the engine, wouldn't hurt you. And if it did boil, it would vent on the pressure valve as designed. You might have to be extra careful at altitude. At 9500 feet at Telluride, Colorado, the boiling point of water is 195.5 degrees F. The electric setup there on your water heater has a limit switch on it for the electric side, as well as a thermostat. Then, you would have an in effect, an unscientifically estimated slightly (8%) larger water heater and one that would keep water hotter for a little longer if that means anything to you. I know Johnny Bridges would appreciate both, as he washes dogs while boondocking in dog show parking lots.

There is a scalding issue with both the engine coolant-heated water heaters at the washroom and shower. I would rather spend money on a thermostatically controlled mixing valve than on the other paraphernalia. There is also a cheap solution where a pair of Tee connections near the shower head between hot and cold with a restriction automatically kept the hot water from scalding. However, at the last dregs of heat from the water heater when boondocking, that mixing would still occur unless manually shut off, which would mean we forget the next time and scald anyway.

I know Dan Gregg went to the 195 thermostat in winter for increased front heater performance and changed out to 180 in summer, just what he did. I plan to go with 195 if we travel much in winter. JWIT.

Carey





Carey from Ennis, Texas 78 Royale, 500 Cadillac, Rance Baxter EFI.

[Updated on: Fri, 06 March 2015 12:20]

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Re: Water Heater Pop-Off [message #273227 is a reply to message #273195] Fri, 06 March 2015 20:43 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
Senior Member
[quote title=cbryan wrote on Fri, 06 March 2015 10:10

Thinking about how hot is "too" hot. I wonder if just replacing the Pressure Temperature valve on your rectangular water heater with just a pressure valve and depending on not boiling the water there using your radiator to keep below an estimated say, 220 degrees F at the engine, wouldn't hurt you. And if it did boil, it would vent on the pressure valve as designed. You might have to be extra careful at altitude.

There is a scalding issue with both the engine coolant-heated water heaters at the washroom and shower. I would rather spend money on a thermostatically controlled mixing valve than on the other paraphernalia. There is also a cheap solution where a pair of Tee connections near the shower head between hot and cold with a restriction automatically kept the hot water from scalding. However, at the last dregs of heat from the water heater when boondocking, that mixing would still occur unless manually shut off, which would mean we forget the next time and scald anyway.

Carey

[/quote]

Carey,

We do have a thermostatically controlled mixing valve for the shower. That was the best upgrade I made. Ruth thinks it is the best thing since sliced bread. I will say that after a long day of driving in warm weather the shower was "warmer" that the setting usually delivers. I think the hot water was hot and the "cold" water tank was warmer than usual.

But you are right. That valve is great. A bit pricy but well, well worth it. I am going to plumb it to the bathroom sink as well as sometimes the water gets hot quickly. (My installation did away with the divider valve.)


'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: Water Heater Pop-Off [message #273245 is a reply to message #273036] Sat, 07 March 2015 05:50 Go to previous messageGo to next message
rcjordan   United States
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
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Senior Member
I bought the Chinese/Ebay mixing valves recommended in the previous thread. I plan to install them at the water heater outlet to protect the whole coach.

SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
Re: Water Heater Pop-Off [message #273281 is a reply to message #273059] Sat, 07 March 2015 18:38 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
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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
Re: Water Heater Pop-Off [message #273282 is a reply to message #273281] Sat, 07 March 2015 19:00 Go to previous messageGo to next message
Hal StClair   United States
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
Senior Member
Just a little thought here. If you have the coach water pump on with pressure in the system, I doubt you'll be able to boil the water in the HW tank. For approx every one pound of pressure you should increase the boiling point three degrees. You should have in the area of at least 30 lbs in the tank so the boiling point will far exceed the temps you can create. Now the pressure side is another point all together, one you'd have to investigate. And the extreme temps of out flow could boil or scald. A tempering valve may be in order.
JMHO,Hal


"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane." 1977 Royale 101348, 1977 Royale 101586, Diesel powered, 1974 Eagle Bus 45',w/slideout, Rio Rancho, NM
Re: Water Heater Pop-Off [message #273295 is a reply to message #273036] Sat, 07 March 2015 21:12 Go to previous messageGo to next message
Rick Staples is currently offline  Rick Staples   United States
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George wrote:
"Some times, if the water in the water heater is cold when we start, the pop-off is leaking when we arrive. Anyone else (besides my friend Max) had this problem?"
George,
I suspect you're not overheating your water at all. What happens is that the water in your heater expands as it is heated, and has to go somewhere. In fact, there was a service bulletin (76-TM-4) concerning this expansion pushing hot water back into the cold water system. Of course, this is even more pronounced if you start off with cold water in the water heater.
Usually there is some air in the water heater that can compress to accommodate this expansion. However, if you seldom drain your plumbing and water heater, it may have become "waterlogged" as they used to say about well tanks before they had captive air bladders.
Try completely draining your water heater, and refill it. Another fix might be to add an expansion chamber of pipe fittings (only a cupful is needed) on the outlet side of the water heater, AFTER any check valves. HTH.
Rick Staples


Rick Staples, '75 Eleganza, Johnstown, CO "Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
Re: Water Heater Pop-Off [message #273313 is a reply to message #273227] Sun, 08 March 2015 12:12 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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George Beckman wrote on Fri, 06 March 2015 21:43
Carey,

We do have a thermostatically controlled mixing valve for the shower. That was the best upgrade I made. Ruth thinks it is the best thing since sliced bread. I will say that after a long day of driving in warm weather the shower was "warmer" that the setting usually delivers. I think the hot water was hot and the "cold" water tank was warmer than usual.

But you are right. That valve is great. A bit pricy but well, well worth it. I am going to plumb it to the bathroom sink as well as sometimes the water gets hot quickly. (My installation did away with the divider valve.)

George,

There is a water control used on some boat that use engine heat for house hot water. I will be deep in catalogs for the next few days (buying parts for a client's spring job), and if I find one, I will ship you the link.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: Water Heater Pop-Off [message #273319 is a reply to message #273313] Sun, 08 March 2015 16:26 Go to previous messageGo to next message
George Beckman is currently offline  George Beckman   United States
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
Senior Member
Matt Colie wrote on Sun, 08 March 2015 10:12




There is a water control used on some boat that use engine heat for house hot water. I will be deep in catalogs for the next few days (buying parts for a client's spring job), and if I find one, I will ship you the link.

Matt


That would be great. Thanks.


'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
Re: Water Heater Pop-Off [message #273320 is a reply to message #273036] Sun, 08 March 2015 16:39 Go to previous messageGo to next message
rcjordan   United States
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
Senior Member
This what you had in mind, Matt?

Marine mixing valves

http://www.go2marine.com/product/387709F/torrid-marine-3-way-3-4-mixing-valve.html

http://www.cyber-bridge-marine.com/Quick-hot-Water-mixing-valve.html


SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
Re: [GMCnet] Water Heater Pop-Off [message #273323 is a reply to message #273320] Sun, 08 March 2015 18:09 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
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Location: Americus, GA
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Senior Member
I want to be sure I understand the concept/plan here: Do you install the
mixing valve at the output of the water heater so that the Hot faucets all
receive the moderated water, with the Cold unaffected? That should, I
presume, allow one to control the water temperature, up to the mixing valve
setting, at any faucet.

It's probably time I did something like this.

Ken H.


On Sun, Mar 8, 2015 at 5:39 PM, RC Jordan wrote:

> This what you had in mind, Matt?
>
> Marine mixing valves
>
>
> http://www.go2marine.com/product/387709F/torrid-marine-3-way-3-4-mixing-valve.html
>
> http://www.cyber-bridge-marine.com/Quick-hot-Water-mixing-valve.html
> --
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: Water Heater Pop-Off [message #273328 is a reply to message #273036] Sun, 08 March 2015 19:00 Go to previous messageGo to previous message
rcjordan   United States
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
Senior Member
That's what I'm going to try, Ken. In looking for Matt's marine tempering valves, I ran across an article or two that confirmed that plan. Also, a few marine water heaters come with the tempering valve installed, apparently.

SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
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