Protech

Yeah, but not when the bladder fails and then goes unnoticed for 10 years.

The pressure relief valves are adjustable. You just set them 10 pounds above the static pressure or at 75psi. The pressure WILL NOT go above 80psi. As far as one failing closed.......I don't think so. It's not mounted on a steel tank like a t/p so I don't see any galvanic fouling happening. As long as the thing is installed with a down hill drain nothing is going to get clogged in the spring ether. Impossible no, highly improbable yes.

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Redwood

I'm not to sure where your coming from Protech...

The initial pressure control on the system here would be a PRV we have hills and pressure variations...

The thermal expansion tank would be piped on the cold side providing the thermal expansion protection with a temp range of 35-70 feeding the water heater...

The T&P providing safety only...

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Protech

Let me suppose the following then to make it clear:

You have a house at the bottom of a hill with a street pressure of 175psi.

You have a PRV at the main regulating it down to 60psi.

You have a bladder tank on the heater inlet.

The bladder goes bad. No one knows since homey doesn't check his pressure on a regular basis.

Thermal expansion causes the pressure to shoot up to 150psi.

A toilet supply line bursts from the high pressure flooding the house.

The end.

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TheMaster

An exspansion tank needs to be checked atleast once a year. I still think your valves will be slow to act and or fail and leak all the time. I dont think they are as reliable as a tank if the tank is maintained. I dont think that valve has a stamp that our code requires either but thats a lame ass arguement as far as I'm concerend. Some people have hard water and it'll ruin that valve because of its possible intermittant use. Some very active closed systems never get high pressures or not for long because all it takes is alittle drip somwhere to control it and alot of people have leaks. That little drip going through your valve can clog it up,its small compared to a 3/4 valve. Thats another reason why they dont want the pipe size reduced on a 3/4 t&P valve because if it dribbles on and off for along time it can close itself off and then all you may need is a sticking thermostat for the consitions to start getting right for the fireworks. The way I see it atleast we both are doing somthing to control the problem and I have no real proof other than I've seen T&P valves hold 200# and over from thermal exspansion and I even replaced the T&P and did another test and it held too for about 15 minutes before it started to dribble.

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Redwood

Hey it's not my problem you buy the junk plastic ones that look like stainless steel braid at the depot...

T&P opens venting just like your relief valve would

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Protech

Lets try that again with a relief valve instead of a tank:


You have a house at the bottom of a hill with a street pressure of 175psi.

You have a PRV at the main regulating it down to 60psi.

You have a pressure relief valve set to go off at 75psi on the heater inlet.

The valve goes bad. Homey ether notices the big puddle of water at the relief drain and calls the plumber out to check things out OR homey gets a high water bill and call the plumber out to check things out.

Plumber replaces the valve and checks out the PRV as well.

Plumber gets paid. The house is not flooded.

The end

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Protech

Fine, you get lucky and there are no cheap supply lines in the house. Fixtures all start failing prematurely and/or a ball cock shears at the threads or a laundry hose bursts. Or any number of other bad cenarios.

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Redwood

Or the customer gets his water bill for $15k and says what the heck and finally finds a relief valve discharging into a drain and asks on some on-line plumbing forum WTF is this thing finally discovering how the rest of the world does it...

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Redwood

I think your data is a tad bit skewed...

I'm just saying...

A relief valve in a ballcock isn't the brightest idea ever hatched...
It is to easily circumvented by replacing a ballcock with one that doesn't have that feature...

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Protech

I'm with ya 100% there.

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