Back Flow Preventer ?

Danscrew

A watts 3/4 back flow preventer is leaking water out of the discharge port every once in a while. When the system ( radiant loop) is on ( Last years problem ) is it the Back flow or the Expansion Tank? Thanks Dan

MikeSpeed6030

Is the relief valve dripping? What is the boiler pressure?

I would just replace the backflow preventer. I think Watts makes a rebuild kit, but I believe that the price of the kit is close to the price of a replacement.

hot_rod

What type of water pressure on the inlet? On city water or a well? Do you know if the main water has a back flow device, maybe at the meter, if you are on city water.

Does the home ever experience water hammer, maybe when a wash machine shuts off the fill cycle, or a lawn sprinkler solenoid, a faucet turned off quickly.

What can happen when flow is stopped quickly a shock wave develops and may cause a high pressure condition, followed by low. Sometimes referred to a elastic shock.

If the low side pressure drops enough the back flow will quickly open the first check and cause a spit. If this happens over and over eventually the seal is compromised and the drip all the time.

A water hammer arrester can prevent it, or a thermal expansion tank connected at the water heater can act as an absorber for that shock.

When we get calls where the BFD has been replaced numerous times, different brands used and the same problem returns, something in the system is causing the valves to fail. It is rare to have 3 or 4 different brands with defective checks.

If the BFD drips immediately after being installed and turned on, a piece of crud is stuck inside the main passage seal. They can be disassembled and cleaned, usually they get replaced and condemned as a faulty valve.

JUGHNE

Perhaps the best solution is a valve on each side of the BFP which are both shut off until you need fill. However a LWCO is highly recommended with that situation .

cableman

I had a leaking bfp and my plumber bud said they install one with out the part that drips, is this wrong to do?
This is on mine now

Danscrew

Thanks to all
I'm going to have him watch the BFP when the washing machine goes thru a cycle to see if it spits when the water shuts off

hot_rod

cableman said:

I had a leaking bfp and my plumber bud said they install one with out the part that drips, is this wrong to do?

This is on mine now

cableman said:

I had a leaking bfp and my plumber bud said they install one with out the part that drips, is this wrong to do?

This is on mine now

More of a dual check than a BFD in my opinion. From what I hear it does passcode in some areas, when used on a boiler feed valve.

Jamie Hall

hot rod said:

cableman said:

I had a leaking bfp and my plumber bud said they install one with out the part that drips, is this wrong to do?

This is on mine now

More of a dual check than a BFD in my opinion. From what I hear it does passcode in some areas, when used on a boiler feed valve.

While it at may pass code in some areas such a device is not a backflow preventer. If what is needed or required is a backflow preventer, it won't do.