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Thread: Runaway stacking problem with water heater

  1. #1
    DIY Senior Member Melissa2007B's Avatar
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    Default Runaway stacking problem with water heater

    I mentioned this before. We have a modular house with a gas water heater that has stacking problems. The overflow temp pressure valve is working, in that it closes when the temp gets low enough, but when the water gets too hot and it opens, it creates like a stacking loop, where the burner runs more and it overheats the water and the valve stays open at a trickle, causing cold water to come in the bottom and keep the burner on, while the top is scalding hot. I wish they had water heaters with a circulating pump to avoid this problem and keep the water a uniform temp throughout the tank.

    But I've turned this down to the lowest setting, to try to break the cycle and the water is still scalding and the valve is still trickling.

    This is getting really frustrating, because the house is too humid from the hot water in that pan and it's causing condensation on my bathroom skylight and too much humidity in the house.
    Melissa
    Denver Process Servers
    http://DenverProcessServers.net/

  2. #2
    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by Melissa2007B View Post
    I mentioned this before. We have a modular house with a gas water heater that has stacking problems. The overflow temp pressure valve is working, in that it closes when the temp gets low enough, but when the water gets too hot and it opens, it creates like a stacking loop, where the burner runs more and it overheats the water and the valve stays open at a trickle, causing cold water to come in the bottom and keep the burner on, while the top is scalding hot. I wish they had water heaters with a circulating pump to avoid this problem and keep the water a uniform temp throughout the tank.

    But I've turned this down to the lowest setting, to try to break the cycle and the water is still scalding and the valve is still trickling.

    This is getting really frustrating, because the house is too humid from the hot water in that pan and it's causing condensation on my bathroom skylight and too much humidity in the house.
    Wasn't the humidifier the source of the stacking problem? If so, have you turned down the humidifier settings?

  3. #3
    In the Trades Gary Swart's Avatar
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    It sounds to me like you need a thermal expansion tank. I suspect you have a pressure regulator valve that prevents the water expansion from being absorbed by the city water main. The creates too much pressure in the heater and causes the T/P valve to trip and relieve the excess pressure. (that's what it is supposed to do) Much has been written on this forum about expansion tanks and a little searching will find plenty of data.

  4. #4
    Moderator & Master Plumber hj's Avatar
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    1. The relief drain line is NOT supposed to empty into the pan.
    2. If it were the temperature function opening it would open FULLY and not stop until the tank temperature had dropped. This would overflow the drain pan in a matter of seconds and flood the area.
    3. Only the pressure side will "drip" and allow a small amount of water to exit, and that assumes that the pressure build up is such that a small amount of water will relieve it. Otherwise, it would also run until the pressure was reduced causing the same flooding.
    4.You have misdiagnosed the problem and therefore are making the wrong corrections.
    Last edited by hj; 02-13-2012 at 05:02 AM.
    Licensed residential and commercial plumber

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    Quote Originally Posted by hj View Post
    1. The relief drain line is NOT supposed to empty into the pan.
    2. If it were the temperature function opening it would open FULLY and not stop until the tank temperature had dropped. This would overflow the drain pan in a matter of seconds and flood the area.
    3. Only the pressure side will "drip" and allow a small amount of water to exit, and that assumes that the pressure build up is such that a small amount of water will relieve it. Otherwise, it would also run until the pressure was reduced causing the same flooding.
    4.You have misdiagnosed the problem and therefore are making the wrong corrections.
    Have you considered the relief valve may not be working properly? Just because its trickles water doesn't mean the tank is not getting too hot. The valves are by no means "perfect".

    Sure it could be just pressure at first but then as cold water enters the tank it can cause the burner to fire and cause stacking.

    She may be having several issues. She needs to call a professional.

  6. #6
    General Engineering Contractor ballvalve's Avatar
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    Its not "stacking" but a bad water heater that needs replacement, at least a bad thermostat.

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    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by Runs with bison View Post
    Wasn't the humidifier the source of the stacking problem? If so, have you turned down the humidifier settings?
    It's been down, but I found out what the cause is, last night. I turned the water temp WAY down and the valve still trickles, even with water temp of 135, so the valve is bad. I gotta replace it. Thanks guys.

    By the way, I need a big long handled plumber's wrench. Where's the best place to find a used one for less money? Like a pawn shop?

    Update 4:39 PM: I stopped by a couple of pawn shops but they only carry bigger stuff like electric saws & sanders, not hand tools. So I went to Home Depot. They had a medium sized Husky pipe wrench, made in China, but lifetime warranty. Came to $16 with tax. Took it home ( I'm 7 minutes from there. ) and turned the water off, opened the tap for a few minutes, then unscrewed the old valve. It was hard to turn. Even with the weight of that heavy pipe wrench, I had to really lean on it, but eventually it loosened. So I unscrewed it until it was loose, then using a rag ( it was hot ) unscrewed it the rest of the way until it popped out...releasing a few gallons of scalding water down on my hand. !@$# Took the old valve & went back to Home Depot. They had two, one in a box for $8.97 and the other in a blister pack for $14 and change, but the guy tells me they're the same! I thank him, he walks away, and I compare numbers. Watts XL100, both of them! $5 more for the fancy blister pack. Am I moron? NO. I take the $8.98 one.

    Take it home, teflon tape it, screw it in good and tight with the slip joint pliers and finally the pipe wrench, connect the vertical pipe to it, turn the water back on, I'm done. Total cost, about $26!

    I would have GLADLY hired a plumber for $50, parts & labor, but they screw themselves out of work with the union thing. They woulda charged $75 just to tippy toe through the door, then another $75 an hour, one hour minimum, plus the part?

    I ran cold mountain snow melt Denver tap water over my left index finger, it's fine thanks.

    By the way, the water heater was built by Rheem and installed in this modular house that wasn't on the lot and occupied by us until Jan of 2005. How come the valve went bad that fast?
    Last edited by Melissa2007B; 02-13-2012 at 04:13 PM.
    Melissa
    Denver Process Servers
    http://DenverProcessServers.net/

  8. #8
    General Engineering Contractor ballvalve's Avatar
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    You said earlier that at the lowest setting the water was still scalding.... sure you don't have a thermostat problem? What made the temp finally drop down?

  9. #9
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by ballvalve View Post
    You said earlier that at the lowest setting the water was still scalding.... sure you don't have a thermostat problem? What made the temp finally drop down?
    "Scalding" to me is "ouch". I think we can get scalded technically at only 117 degrees?

    Hmm, it's apparently a function of time: http://www.mwke.com/personal-injury/...lding-Injuries

    "The temperature for domestic hot tap water must not exceed 120 Fahrenheit, according to the International Plumbing Code, known as the IPC Standard. Most water heaters can push the temperature up to 140 degrees, but that will burn a user. ( My note: Yeah if they're dumb enough to hold something under it. )

    People might not expect to be at risk of injury from a tap, but a water heater malfunction may occur suddenly in a home or commercial system.
    Lower Tap Temperatures to Prevent Water Scalding Injuries

    The risk of water scalding injury rises significantly if the water temperature exceeds 120 degrees. It would take 8 minutes of exposure to water heated to 120 degrees to sustain second degree burns, and 10 minutes to sustain third-degree burns.

    A water heater that has raised the temperature to 150 degrees can cause third degree burns in just one second. At 130 degrees, it would take about 30 seconds to sustain comparable injuries."
    Melissa
    Denver Process Servers
    http://DenverProcessServers.net/

  10. #10
    In the Trades Gary Swart's Avatar
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    I glad you solved your problem, but before we leave this, I would like to point out a couple of things related to your comments about the high price of hiring a plumber. First, you are right, they are not cheap. But why should they be? They have equipment to buy and maintain, insurance to cover their business and employees, they are not paid if they are not on a job, going to and from the job takes time and gas, and finally, they certainly deserve to make a decent living. On the other hand, the reason many of us DIY is to spare this expense if it is a job within our abilities. Certainly changing a T/P valve is a task that almost anyone should be able to handle, but other tasks are not so simple. As you found out, even the simple task of changing out a T/P valve required you to buy a tool. So, try to see the other side of the cost of hiring a professional.

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    Plumber jimbo's Avatar
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    Quote Originally Posted by Melissa2007B View Post
    I would have GLADLY hired a plumber for $50, parts & labor,
    So he has $10 wholesale price, plus cost of inventory, so the valve is worth $20 on his truck. And you very generously would give him $30 to schlepp out to your place, pay gas and insurance on his van, workers comp, and by the way BOTH sides of the 15% social security tax, and who knows what kind of business license tax the city has, plus what it cost him yearly to keep the plumbing license, and oh by the way...CE classes to keep the license...and etc!

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    Quote Originally Posted by Melissa2007B View Post
    It's been down, but I found out what the cause is, last night. I turned the water temp WAY down and the valve still trickles, even with water temp of 135, so the valve is bad. I gotta replace it. Thanks guys.

    By the way, I need a big long handled plumber's wrench. Where's the best place to find a used one for less money? Like a pawn shop?

    Update 4:39 PM: I stopped by a couple of pawn shops but they only carry bigger stuff like electric saws & sanders, not hand tools. So I went to Home Depot. They had a medium sized Husky pipe wrench, made in China, but lifetime warranty. Came to $16 with tax. Took it home ( I'm 7 minutes from there. ) and turned the water off, opened the tap for a few minutes, then unscrewed the old valve. It was hard to turn. Even with the weight of that heavy pipe wrench, I had to really lean on it, but eventually it loosened. So I unscrewed it until it was loose, then using a rag ( it was hot ) unscrewed it the rest of the way until it popped out...releasing a few gallons of scalding water down on my hand. !@$# Took the old valve & went back to Home Depot. They had two, one in a box for $8.97 and the other in a blister pack for $14 and change, but the guy tells me they're the same! I thank him, he walks away, and I compare numbers. Watts XL100, both of them! $5 more for the fancy blister pack. Am I moron? NO. I take the $8.98 one.

    Take it home, teflon tape it, screw it in good and tight with the slip joint pliers and finally the pipe wrench, connect the vertical pipe to it, turn the water back on, I'm done. Total cost, about $26!

    I would have GLADLY hired a plumber for $50, parts & labor, but they screw themselves out of work with the union thing. They woulda charged $75 just to tippy toe through the door, then another $75 an hour, one hour minimum, plus the part?

    I ran cold mountain snow melt Denver tap water over my left index finger, it's fine thanks.

    By the way, the water heater was built by Rheem and installed in this modular house that wasn't on the lot and occupied by us until Jan of 2005. How come the valve went bad that fast?
    Modular home? You mean a trailer home? Does it have axles under it?

  13. #13
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by Gary Swart View Post
    I glad you solved your problem, but before we leave this, I would like to point out a couple of things related to your comments about the high price of hiring a plumber. First, you are right, they are not cheap. But why should they be? They have equipment to buy and maintain, insurance to cover their business and employees, they are not paid if they are not on a job, going to and from the job takes time and gas, and finally, they certainly deserve to make a decent living. On the other hand, the reason many of us DIY is to spare this expense if it is a job within our abilities. Certainly changing a T/P valve is a task that almost anyone should be able to handle, but other tasks are not so simple. As you found out, even the simple task of changing out a T/P valve required you to buy a tool. So, try to see the other side of the cost of hiring a professional.
    Oh I agree with you Gary, especially since I'm a professional process server by trade and have roughly the same kinds of expenses. Sorry if I offended any pro plumbers, but you're right.

    We see people try to do it themselves, to save a few bucks and royally screw things up. I've done nearly 10,000 serves since 2006 and know what I'm doing. Then we get calls from people who are shopping around for lowest price, not realizing that they're not buying a name brand TV set and that all of us aren't the same. AND Colorado isn't even regulated in the process serving industry, so there are perjurers and thieves out there as well.

    I certainly appreciate someone who knows what they're doing, though I can't always afford them.
    Melissa
    Denver Process Servers
    http://DenverProcessServers.net/

  14. #14
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by Hackney plumbing View Post
    Modular home? You mean a trailer home? Does it have axles under it?
    No, modular means one that's factory built and put on a foundation. Supposedly we saved money that way, but I'd never do it again.
    Melissa
    Denver Process Servers
    http://DenverProcessServers.net/

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    Quote Originally Posted by Melissa2007B View Post
    No, modular means one that's factory built and put on a foundation. Supposedly we saved money that way, but I'd never do it again.
    Thats good. Some people swear by the modular built. I think it comes down to quality control.

    Dont be surprised if you have another problem with the relief valve. If you do the chances of the relief valve being the "real problem " are slim,its just doing its job. Your pressure may be high and that can cause the spring to get weak. A spring under tension holds a stem with a rubber washer against the relief valve seat to seal.

    The spring is held in place with a metal insert that is pressed in place from the top of the valve. The temp probe is a plastic coated copper tube with a silicone rubber type material inside that surrounds a metal rod. When the temp goes up the rod expands and opens the valve.

    I have found many new relief valves that would not open at 150 psi. One didn't open until over 250 psi.

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