backflow preventer

jaybee

What is the purpose of the backflow preventer and where should it be placed in a system.Thank u guys for answering my questions unfortunenately i dont have many anwers yet.Thanks once again.

kevin coppinger_4

Its to protect the drinking ...

water in the house from the stagnant boiler water....put it right before the boiler fast fill....ie. watts 1156f

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DaveGateway

Occasional drips from backflow preventer vent

I've had 2 installed and both drip water on occasion from the vent outlet. Watts says that this is normal when pumping from a well because the supply pressure can vary by more than 20%. In my case the, supply pressure varies from 40-60 psi. Evidently the combination of the backplow preventer and the fast fill pressure regulator will track the supply pressure during a fill and will lock in at the point where the fast fill regulates (somehow holding that pressure). If the supply drops sufficiently below that point, the backflow preventor will then release to vent.

Weezbo

on a domestic well...a check infront of the back flow....

is my recommendation. to maintain water pressure on the supply side of the backflow when the pump experiences larger pressure drops .it is sop with me.

psd_3

Nice!

Protecting for supply variations is not clearly stated in the Watts 9D backflow preventor product literature. Had to call them to find out what was up after the original and then the replacement leaked the same way within weeks. Wish more folks took the time to find out what the real problem is, rather than just replacing parts. Thanks for the solution, I'll recommend it next time around ... although, sometimes advice from a lay person isn't always well received .

Big John

Pressure relief valve

Have a problem and need some advice. Client has a circulating hot water boiler. Relief valve keeps dripping. Backflow preventer is watts 909, the pressure reducing valve has been replaced, the waterlogged expansion tank has been replaced, the boiler pressure is 12 psi and the relief valve is set for 30 psi but it keeps dripping. I am tempted to recommend replacement of the boiler relief valve because it may not be seating correctly. I will check the size for the expansion tank again. Anything else you folks would recommend looking into. Thanks for your help.

Kenny

Pressure Relief Valve

Big John,

How high is the pressure in the boiler going based on the guage? I assume it is being regulated correctly by the fill valve and expansion tank and is holding somewhere between 12psi (cold) and 20 psi (hot)? If so, then the pressure relief valve is shot. Sometimes they reseat correctly, but other times the don't ... sort of depends on the water quality in the system. I have one that I'm about ready to replace on my domestic well because it's been leaking for about a year, slow at first and now faster.

todd s

extra check valve

Are you saying to put an additional checkvalve before the backflow preventer? isn't that like 3 check valves in a row? It seems like a good idea but would look strange.

Jack, CVMS

PRV

It's not uncommon to have to replace a pressure relief valve, especially when they start dripping. Even with deionized water and propylene glycol in a system (rather than cruddy well water) I've seen installations where they start leaking in less than a year.
Have had much more trouble with the Watts valves than other brands. Switching to Conbraco seems to have helped.

Weezbo

replace the valve.if it leaks,keep the valve You Know Its ...

Good. then replace the boiler:).............sorry its a bad habit i have. well, if the coil was leaking youd have some indication on the idiot gauge on the boiler ...if it was any good:)
i save the ones that read 12 lbs at 170 or so....:) then i can always replace one that isnt working right with one that might be right oncein a while:)))) sorry seriously though the seat probably has some sediment lodged in it taqp the top with a screwdriver handel open the valve and turn the lever another direction and give it another swift tap. if it still leaks it ready for the bone yard:)

will smith_2

Back flow preventers are also used to protect the potable water from the street-which is why you need a diaphragm tank on hot water heaters as well;lack of usage of your hot water (like in commercial buildings over a weekend) can cause the pt relief to pop