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Pressure valve on cold water intake to heater replaced 3 times...bad leaks still

Pressure valve on cold water intake to heater replaced 3 times...bad leaks still

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  #1  
Old 01-16-14, 02:11 AM
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Pressure valve on cold water intake to heater replaced 3 times...bad leaks still

Townhouse in Florida.

I've done the best I can to follow all plumbing from the street to the water heater, and I see only shutoffs. No Pressure Reducing Valve that I can find, no expansion tank, etc.

Typical pressure measured at outside spigot around 70psi. Pressure relief valve (not variable) set at 75 psi.

Each time, it blows out after a few months, and just starts pouring out water. I'm not sure if this is just a hot water expansion issue, or partially due to constant construction around me (first leak didn't occur until they started putting up buildings around me.)... possible spikes.

Anyway, I'm not entirely sure that an expansion tank alone would fix it. If so, not quite sure where or how to install one with given dimensions. Would I also need to install pressure reducing valve?

Also, read somewere that I might need to make sure there's some air in the hot water heater since air compresses and water does not, which would allow the system to handle fluctuations in pressure due to water heating. If this is true, is there an optimal way to do this?

Leaking out all over my back yard again (drain line coming off of pressure relief valve), so looking to fix this for good rather than just replacing it for a 4th time.

thx
 
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  #2  
Old 01-16-14, 03:25 AM
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In my opinion the best thing to do is to remove that pressure relief valve and drop kick it as far as possible. Install a proper expansion tank that has the air side charged to the same pressure as your water supply to the same connection now used for the relief valve. If you are concerned about high pressure then you could use a tee fitting and install a 90 or 100 psi relief valve AND the expansion tank. The expansion tank does not have to screw directly to that fitting but may be mounted nearby and connected with a flexible connector.

What is happening is that your water meter has a built-in backflow prevention check valve and the thermal expansion from heating cold water is raising the pressure to the point where the relief valve opens and drains off the excess pressure. Since water is incompressible it only needs to relieve a few drops to allow it to again close. This repeated open-drain-close action is simply wearing out the valve innards causing the leak. Installing the expansion tank (and higher rated relief valve if you do so) will let the expansion move into the expansion tank rather than raising the pressure abruptly.
 
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Old 01-16-14, 06:56 AM
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The typical residential T&P relief valves I have seen were all 150 PSI rated and installed directly in the water heater tank. This one from Watts is about as typical as it gets. I haven't seen one installed in the piping in many years.

0556000 - Watts 0556000 - LF100XL-4 3/4" Lead Free Self Closing T & P Relief Valve
 
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Old 01-16-14, 08:04 AM
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OK, well, these are new townhomes, the plumbing in all of them looks just like this, and as near as I can tell, the local Lowes and Home Depot only sell replacements set to 75 psi in local stores. Sales people weren't very helpful except to note that they do not carry higher psi rated or variable psi similar type relief valves in store.

If I do need an expansion tank, am I then correct in reading that it REPLACES the relief valve, so I then have no relief valve on the cold intake? If so, without a pressure reducing valve, I really have no protection from spikes, and could end up with unsafe pressure in the heater, or leaks in the house, right? I'd rather make sure I don't end up causing a more expensive problem down the line.

Are these skinny cheap fleshy colored pipes ok with a pressure above 75?

If I were to put in a pressure reducing valve along with the expansion tank, is there a preferred configuration that makes sense with the above geometry?

Anything to this air in the heater concept? Should there be some air there?
 
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Old 01-16-14, 01:07 PM
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OK, so trip to Lowes, some more research, digesting responses, and...

If I need the expansion tank, then OK, but I'm left wondering... isn't my real problem that the incoming pressure and the release pressure are so close together... I mean, with 70psi average coming in, and a valve set to blow at 75, it's not tough to see why it starts leaking.

Now, if there are no incoming spikes, the tank might just smooth that out, but if there are, I'm looking at much more costly leaks inside walls or wherever else... which necessitates a relief valve... which has to be higher because it's so close to incoming pressure,

SO....

Isn't my real problem the relief pressure setting? Yes, a tank could expand and contract with the minor variations around 70psi, but is that really helping if the relief doesn't blow until 100 or so anyway?

What about just getting a relief valve set at 90 or 100? Wouldn't that be enough of a margin to deal with the heating expansion without needing the tank?

Would this put the rest of the system under more pressure or the same as if the tank was there? Can the system take a higher relief pressure? If not, isn't it potentially subject to the higher pressure anyway with a tank there if the relief is raised?

Just trying to understand. I'll get the tank if necessary, just not sure it is if I have to get higher relief valve anyway.
 
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Old 01-16-14, 03:57 PM
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...isn't my real problem that the incoming pressure and the release pressure are so close together...
That IS part of the problem but not the only problem. It is doubtful that you are getting any pressure surges incoming from the water utility so you can forget that part. The main problem is that you have a closed system when no water is being used. The water meter will not allow a backflow from the house to the utility main and therefore no pressure relieving capacity that direction. You DO get pressure increases when you heat cold water to hot from thermal expansion and since water is virtually incompressible that pressure rises quite rapidly.

What about just getting a relief valve set at 90 or 100? Wouldn't that be enough of a margin to deal with the heating expansion without needing the tank?
Maybe, but probably not. My own home has a nominal water pressure of 60 psi and without an expansion tank (but with large air chambers at several fixtures) I can get pressure increase to over 90 when I use a significant amount of hot water.

Are these skinny cheap fleshy colored pipes ok with a pressure above 75?
Yes. CPVC piping used in residences is rated to 100 psi at 180 degrees F. Since the temperature would be less than 180 under all but a serious fault condition the pressure rating is even higher.

Anything to this air in the heater concept? Should there be some air there?
Theoretically yes but on a practical basis no. Air is soluble in water and any air cushion in the tank would quickly be absorbed by the water leaving no cushion. Further, because of the design of the heater it is all but impossible to even have an air cushion.

The relief valve you have was installed instead of an expansion tank and was done so only as a cost saving measure in the original construction. The relief valve cost the builder maybe five dollars where an expansion tank would have been a minimum of twenty-five dollars. A twenty dollar savings on each of 200 homes is four thousand dollars clear profit to the builder.
 
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Old 01-16-14, 05:20 PM
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The relief valve you have was installed instead of an expansion tank and was done so only as a cost saving measure in the original construction.
Actually its code to install a lower value relief valve when pex or cpvc is installed...

Most inspectors make me change out the water heater relief valve also on top of that added one. The added one is pressure only..

With that said code here says 100psi relief valve.. IMO that may have been what was there. But since you can probably get that flavor only at a supply house or on line it was changed with the box store special..

The main problem is that you have a closed system when no water is being used. The water meter will not allow a backflow from the house to the utility main and therefore no pressure relieving capacity that direction.
How do we know they have that type of meter???


IMO with cpvc I would absolutely want an expansion tank.. Especially if that is flo gaurd gold, which it looks like.. read the name off the pipe...


It is doubtful that you are getting any pressure surges incoming from the water utility so you can forget that part.

Oh I dont know about that... Ye,s day time when water is used in the community, you can have a steady 70psi... At night it can increase.. I have seen it in certain community's because of small mains...

Like I said IMO PRV and expansion tank. Change both the heater relief and that pressure unit to 100 psi varietys..

Put this in the 75's place...

0190001 - Watts 0190001 - 1/2" 53L Poppet Type Pressure Relief Valve (100 psi)

And this for the heater...

0121357 - Watts 0121357 - LF100XL-Z11 3/4" Lead Free T & P Relief Valve (100 PSI, 180 F)

PRV..

0009257 - Watts 0009257 - 3/4" LF25AUB-Z3 Pressure Reducing Valve (Threaded F Union Inlet x NPT Threaded F Outlet)
 
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Old 01-17-14, 10:39 AM
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Was able to verify a few things:

Yes, it's FloGuard Gold piping.
Yes, the city has a backflow preventer inline on their end.
Yes, the current TPV is also rated at 75 psi.

Well, I've got a very tight space. There are some very significant and rock solid shelves built up just a couple feet from the heater with extensive bracing. Trying to figure out at this point where to put everything.

Between the wall and the T-junction (where the shutoff valve is) the is no room to splice anything at all. So... that's where a PRV would have to go, right?... or could I somehow trace back the pipes to a whole other location and stuff it there?

Not sure how to get the TPR out of there, but I'm sure there's a diy vid on that somewhere. Mainly, I'm just not sure where or how to fit the tank. Does it have to be facing a certain way? Might I need to build some sort of bracing from the wall to hold it so it doesn't stress the joints?

That's 3/4 in at the T-junction on in to the relief valve and 1/2 in on down and out, btw.

Looking at tanks online now... I guess it's by size and incoming pressure, right? So... size on side of my heater says 55gal, and incoming pressure would be the 70 I'm reading at the meter on the spigot, right?
 
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Old 01-17-14, 03:09 PM
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You need to remove the currently installed relief valve and using the appropriately sized fittings (most likely 3/4 inch pipe size) install a brass nipple (hex nipple if I were doing the job) and 3/4 inch brass tee. Install the new 100 psi relief valve in one of the remaining ports of the tee and connect the expansion tank to the last port of the tee using whatever means works best for you.

The expansion tank can be mounted in any position. The connection to the tee can be with a flexible water heater connector or copper tubing using either flared or compression fittings. The tank can be mounted anywhere you have sufficient room. Remember that when the tank fails (probably many years from now) it will be full of water and heavy so mounting it high in the overhead is not the best plan if a lower location is available.

Most important is to pre-charge the air side of the expansion tank to the same pressure as the incoming water pressure.

BTW, that plastic ball valve you now have for turning off the cold water feed to the water heater is a very poor excuse for a real valve. Don't be surprised if it sticks open when you most need it. I personally would cut it out and install a real brass ball valve when you do the other work.
 
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Old 01-17-14, 04:22 PM
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Also the expansion tank needs the precharge adjusted to the incoming pressure from the street... Most tanks are set to 40psi... Since your psi is 70psi thats what you need to adjust the tank to before you install it.....
 
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Old 01-19-14, 11:33 AM
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I'm assuming not this actual one since it has warnings about not to be used for potable supplies:

0190001 - Watts 0190001 - 1/2" 53L Poppet Type Pressure Relief Valve (100 psi)

I've located a few others, but they raise questions. For instance, is there a reason for the poppet style? Also, some say cold use only. Does this qualify since it's on the cold intake side or not since it's dealing with expanded water from heater?

For instance (cold use only):

Pressure Relief Valve 100 psi Lead-Free 3/4" MIPT - FreshWaterSystems.com

And I believe I saw this one locally the other day which would be ideal... but wondering if the variable thing is "one more thing to go wrong"... and not sure what "Not ASME approved" implies.

3 4" Calibrated Pressure Relief Valve 50 175 PSI Adjustment Watts Series 530C | eBay
 

Last edited by dominican joe; 01-19-14 at 12:08 PM.
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