Water Pressure Reducer and Backflow Prevention Valve Woes


Old 09-26-07, 11:05 PM
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Water Pressure Reducer and Backflow Prevention Valve Woes

Sorry for the long post, but I want to be as precise as possible.

My forced water heating system has the above-mentioned pressure-reducing valve (PRV) between the water supply and the boiler. Just ahead of the PRV is a backflow prevention valve (BPV). After bleeding the system, the following occurs:

1. If I set the PRV to the "fast fill" mode (lever up) I can only attain about 13-14 psi in the system with the water supply valve turned on.

2. If I put the lever down (normal regulated position) and leave the water supply valve turned on, water will begin to drip out of the BPV when the psi rises above about 13.

3. If I then close the water supply valve, water stops flowing out the BPV but the system pressure very slowly drops to about 10 psi. There are no leaks anywhere in the water distribution system inside the house.

Both the BPV and the PRV were replaced about 4 years ago. The PRV is an Apollo (Conbraco) Series 35 and all the literature that I was able to find states that can be adjusted from 10 to 25 psi; however, I can find no adjustment screw or locknut. How does one adjust it??

And what would cause the BPV to open when the water supply is turned on?
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Old 09-27-07, 05:57 AM
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Join Date: Jun 2007
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Water pressure doesn't just drop unless the water is cooling off after the fill, you must have a leak somewhere, it could actually be in the valves after the pressure reducing valve. That would allow water to leak out a weak seal on the pressure reducing valve.
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