Water Heater Pressure going too high

[Mmfh]

I noticed a few days ago that the T&P valve on top of my water heater was leaking. Moving things around in the garage and I found a nice wet area as if its been leaking for a while.

I replaced the valve and figured all was well again. Yesterday floor was all wet again, so I put a pressure gauge on the hose fitting toward the bottom of the heater and opened the valve for that fitting, and left it open all night to see how high the pressure would get.

This morning now the gauge is leaking and the tattle-tale indicator on the gauge says the pressure last night went over 200psi. Of coarse now I know that the T&P valve I replaced was not the problem.

Normal pressure every other time I've checked it is about 70 psi. I noticed with the gauge hooked up that flushing the toilet brings it down to about 50 psi. My temp is set to the normal line and the gas valve, temp feels normal while doing dishes and taking shower.

Why is my pressure going so high? I've read I could put in a thermal expansion tank but don't understand why. I've never in any other house needed to do this before, so what's up with this place?

Any Idea's??

By the way, its a 50 gallon gas unit about 10 years old.

Thanks very much!

Mm

 

[pattenp]

Re: Water Heater Pressure going to high

There's no reason for the water pressure to go that high other than your temp is getting too high making the pressure rise. Replace the thermostat.

Are you on city/county water?

 

[Mmfh]

Re: Water Heater Pressure going to high

I was doing some reading and seems some people are having problems with excessive pressure after a new water meter has been installed. Old style meter doesn't have a back flow valve, new style meter has a anti-back flow valve and will not allow pressure to go back into the system.

We had the meter replaced about a year ago, new fancy thing with three gauges and solenoids and wires. No idea what all of it does but its not like the meters I've always seen. We were not having a problem with the old one, they decided to change it out because we were at the start of a run, or something like that. Don't remember for sure. Could this have anything to do with it?

As far as temp goes, and going to high, I have not noticed any changes in temp unless its for some reason only doing it at night when nobody is using the water?

Could the thermostat be going stupid at night when its been idle for a while? And we are on City water.

Mm

 

[BD1]

Re: Water Heater Pressure going to high

hi, 200 pounds

;if that was right your faucets,toilets, and piping should have blown up by now. I think you need another gauge. City water pressure can increase and decrease depending, but 200 pounds cannot be right . I would not want to be the one turning the faucet on .
If thermostat goes that high you would have FLAMES coming out of faucet. Actually, you got your moneys worth from the heater. On some installations they do require a expansion tank on piping. That 200 pounds is not right. You can call water department and verify what their city pressure is and I would think no more than 60 pounds, maybe 80 during night but that seems high.

 

[Mmfh]

Re: Water Heater Pressure going to high

I just thought of something, I had my gauge hooked up to the faucet outside and left water on overnight. The tattle tale needle on the gauge didn't go above 70 psi.

When I hooked the same gauge up to the drain fitting on the bottom of the water heater and left it on over night, it went to over 200 psi.

Seems like if the pressure was getting this high in the house the faucets would be leaking hot water?? Have never noticed any faucets leaking in the house.

Just thought I would throw that in.

Thanks

 

[BD1]

Re: Water Heater Pressure going to high

I just thought of something, I had my gauge hooked up to the faucet outside and left water on overnight. The tattle tale needle on the gauge didn't go above 70 psi.

When I hooked the same gauge up to the drain fitting on the bottom of the water heater and left it on over night, it went to over 200 psi.

Seems like if the pressure was getting this high in the house the faucets would be leaking hot water?? Have never noticed any faucets leaking in the house.

Just thought I would throw that in.

Thanks

Yes, that's what I said about pressure. 200 pounds on a residential house system would turn it into a swimming pool. Your piping should be leaking somewhere not to mention what happens when you flush the toliet or take a shower. You would have a whole house pressure washer Try calling the city water department .

 

[katmat]

Re: Water Heater Pressure going to high

You may need to put a expansion tank on your system. When the water is heated it expands & with the new meter, the additional volume has no wear to go.

 

[A_Pmech]

Re: Water Heater Pressure going to high

You may need to put a expansion tank on your system. When the water is heated it expands & with the new meter, the additional volume has no wear to go.

Bingo.

Your new water meter has a check valve in it. When a large amount of cold water is admitted into the water heater (such as a bath before bed) and then heated overnight the system pressure builds because the expanding water has nowhere to go. Installing an expansion tank gives the water a place to go. The expanding water compresses air within the expansion tank rather than working against the relatively inelastic piping in your plumbing system.

 

[Spareparts]

Re: Water Heater Pressure going to high

a lot of city's require an expansion tank and backflow valve to prevent your system from getting into the city;s water system, katmart nailed it, with the backflow valve either at the meter or in your system it is locked in and no where to go but increase the pressure. If the backflow valve is at the meter it is going to take longer to build up the pressure, over night. I had to install the expansion tank in my house to eliminate the same problem. I installed mine in the cold water supply to the water heater (cut the pipe that goes to the heater and install a "T" and threaded ****** then screw the tank to it vertically) problem solved.

 

[nehog]

Re: Water Heater Pressure going to high

...

This morning now the gauge is leaking and the tattle-tale indicator on the gauge says the pressure last night went over 200psi. Of coarse now I know that the T&P valve I replaced was not the problem.

Normal pressure every other time I've checked it is about 70 psi. I noticed with the gauge hooked up that flushing the toilet brings it down to about 50 psi. My temp is set to the normal line and the gas valve, temp feels normal while doing dishes and taking shower.
...

Actually this is perhaps easy to explain. I will guess that your water system either doesn't have an expansion tank, or your tank is defective. That 200 PSI reading is likely due to 'water hammer' which sends shock waves through the pipes.

If you have an expansion tank, check to make sure it is charged, the diaphragm has not failed, that it is working correctly. If you have no expansion tank--time to get one!

 

[Frank The Plumber]

Re: Water Heater Pressure going to high

You need to put a thermal expansion tank on your system. You have a system that is not allowing the expansion created by the heating of the water to expand back into the water source.
Until you correct this turn off the heater. You have the potential to flatten the home with 200 psi of pressure in a water heater. If this is beyond your scope please call a professional to install it for you.

Do not just assume anything here, this is serious stuff, I do not want to read of the family tragedy here.

The dripping T and P valve is telling us this is the problem.

Thank you.

 

[BD1]

Re: Water Heater Pressure going to high

You need to put a thermal expansion tank on your system. You have a system that is not allowing the expansion created by the heating of the water to expand back into the water source.
Until you correct this turn off the heater. You have the potential to flatten the home with 200 psi of pressure in a water heater. If this is beyond your scope please call a professional to install it for you.

Do not just assume anything here, this is serious stuff, I do not want to read of the family tragedy here.

The dripping T and P valve is telling us this is the problem.

Thank you.

I still cannot believe that he could have 200 pounds in this system. The relief should have blown since it is new; not to mention that some where on the piping, faucets, toilet tank valve, the house would become a water part without the slide

 

[Mmfh]

Re: Water Heater Pressure going to high

Of all my years on this planet I've never run into a expansion tank before. Until I searched for this problem I didn't really know they existed.

What I found was that the new water meter most likely has a back flow device that isn't letting my pressure go back to the system like it did with the old meter. That would mean this has probably been leaking for the last year or so since the meter was put in.

Seems like the water company that installed the meter should have told me that now because of this new type of meter, I'm going to need an expansion tank or I'm going to have problems.

Sure looks like this is the answer. I'm going shopping for a tank to get this problem solved.

I haven't searched yet, but where is the best place in the system to install the tank? On the Hot or cold side of the heater?

Thanks very much

Mm

 

[pattenp]

Re: Water Heater Pressure going to high

I wouldn't have thought about the anti-backflow on the meter. But as you are hearing that's got to be the problem. The placement of the expansion tank can be where ever it's the easiest to install and service.

 

[Steve from Socal]

Re: Water Heater Pressure going to high

I had a T&P valve start leaking on a nearly new water heater, I call the company and they sent me a new one same results. Short story my pressure regulator needed an overhaul kit. I live in the hills and in fire country, our water pressure is between 150-170 unregulated, my water heater has an expansion tank. The problem was the regulator was not sealing well.

Steve

 

[djjsr]

Re: Water Heater Pressure going to high

What's the pressure of the T/P valve? I have a BIG water heating system, 850,000 btu with a 600 gallon tank and it has 3 T/P valves. They are all 125 psi. You can't build up 200 psi with a 125 valve.

 

[Mmfh]

Re: Water Heater Pressure going to high

What's the pressure of the T/P valve? I have a BIG water heating system, 850,000 btu with a 600 gallon tank and it has 3 T/P valves. They are all 125 psi. You can't build up 200 psi with a 125 valve.

The original T&P valve and the one I replaced it with are both 150 psi.

 

[BillK]

Re: Water Heater Pressure going to high

The original T&P valve and the one I replaced it with are both 150 psi.

Then you cant have 200 lbs because the valve should pop off at 150.

I know all of us here love to fix everything ourselves, and I am no exception, but in this case I would be calling a plumber or the city water department and have somebody look at it before somebody or something gets hurt badly

 

[Charles (in GA)]

Re: Water Heater Pressure going to high

You may need to put a expansion tank on your system. When the water is heated it expands & with the new meter, the additional volume has no wear to go.

It took someone seven posts to mention this. Code in most places requires the anti-backflow valve and expansion tank.

Charles

 

[Charles (in GA)]

Re: Water Heater Pressure going to high

I haven't searched yet, but where is the best place in the system to install the tank? On the Hot or cold side of the heater?

Thanks very much

Mm

Probably best on the hot side (if the tank is rated for the temp) as I assume you have a shutoff valve on the heater tank cold water inlet, and you want the tank to still protect the system if you were to close that valve.

Charles

 

[Mmfh]

Re: Water Heater Pressure going to high

Then you cant have 200 lbs because the valve should pop off at 150.

I know all of us here love to fix everything ourselves, and I am no exception, but in this case I would be calling a plumber or the city water department and have somebody look at it before somebody or something gets hurt badly

My pressure gauge might not be the most accurate thing around, but its telling me the pressure is way to high and I've got water everywhere, lets say its at 150 then.

Unfortunately I will be doing this myself, there just are no funds for this and I've never paid anybody to help me before so why start with something fairly basic as this.

I did call the Water bureau people and they are going to come out in the morning and double check my pressure readings and see what they think.

Worst case, install a tank and maybe a thermostat. Not sure yet.

I've been wanting to move the water heater, this might be a good reason to get it done.

Mm

 

[Mmfh]

Re: Water Heater Pressure going to high

Probably best on the hot side (if the tank is rated for the temp) as I assume you have a shutoff valve on the heater tank cold water inlet, and you want the tank to still protect the system if you were to close that valve.

Charles

Yes, I do have a shutoff valve on the cold side of the heater. Installing it on the hot side where I'm apparently having a problem makes sense anyway.

Strange thing now is, putting the gauge on the drain at the bottom of the heater, I checked it and gauge said 120 lbs. This poor gauge can't handle the pressure as the water is now leaking from the inside of the gauge.

So, 120 at the heater, go inside and all the faucets seem to have normal pressure. Almost looks like some kind of restriction in the line after it leaves the water heater? Excess pressure in the tank, but normal pressure inside the house. I've got some more reading to do before I call this diagnosed.

Mm

 

[pattenp]

Re: Water Heater Pressure going to high

As an example the instructions from the Watts manufacturer say to install on the cold inlet side of the water heater.

 

[BillK]

Re: Water Heater Pressure going to high

Almost looks like some kind of restriction in the line after it leaves the water heater? Mm

A restriction in the line will only affect volume, not pressure. When the system is closed (no water running) the pressure will be the same everywhere, restriction or not.

When you are checking the pressure at the faucets, are you allowing it to sit for several hours to allow the pressure to build up, or checking it after opening the faucet to attach the gauge ?

 

[71flh]

Re: Water Heater Pressure going to high

If there's no water flowing, shouldn't the pressure be about the same throughout the system?
I'm guessing there's no real problem.
I've never even heard of, let alone seen an expansion tank.

 

[Mmfh]

Re: Water Heater Pressure going to high

A restriction in the line will only affect volume, not pressure. When the system is closed (no water running) the pressure will be the same everywhere, restriction or not.

When you are checking the pressure at the faucets, are you allowing it to sit for several hours to allow the pressure to build up, or checking it after opening the faucet to attach the gauge ?

The time I was referring to was where I saw the gauge on the water heater reading 120 lbs, then I went into the house and cracked the kitchen faucet. I thought it was going to come blasting out but it seemed normal.

I'm going to the depot today to get another gauge, just to double check, I'm getting inconsistent readings and symptoms.

The water bureau should be here today as well. I'm thinking a tank and thermostat will be my fix.

Mm