Replacing leaky backflow preventer (and fill valve)?

hydroNicolas

Hey there,

I have an oil boiler with 2 heat zones and a 3rd primary zone that runs our showers/taps.

I just replaced the expansion tank because there was water coming from the Schrader valve when I pressed it in.

I also have a slow drip of cold water from the backflow preventer that I haven't addressed.  I currently have a bucket catching it, and close a ball valve just upstream before I go to bed the last few nights.  

To make things more complicated the second floor zone valve has been sticking mostly closed I think.  I think I need to replace both of those zone valves as the baseboards feel warm in the summer when we take a shower.  I wasn't able to manually open the second floor zone valve with the lever last night, so after doing some googling I jumped the two wires behind the thermostat and then I was able to pull the lever down.  I'm going to prioritize replacing these zone valves, but at the moment, having the first floor zone kicking on the circulator and sending water upstairs is not a bad thing.  We're always home.

Anyway, my zone valve issue aside, I'd like to address the backflow preventer leak.  Is it worthwhile to replace both the backflow and fill valve at the same time?  Fill valve seems to work, although I'm wondering if it's getting stuck open and causing increase in pressure.  When manually using fill lever, the lever should flip back down automatically once desired pressure is reached? Or does the fill lever stay where it's been positioned?  

I see they sell the combination fill valve backflow preventers that would potentially make my life a bit easier.  Am I able to spin my existing valves off independently?  Seems like one of the npt sides would tighten if I unscrewed the opposite side?
Cutting the whole thing out and putting a new one on seems way easier, but maybe it would just thread off after.i unscrewed the downspout?

Thanks for any guidance!

hydroNicolas

I'm learning what a union coupling is and that should make this part easily serviceable.  100 bucks for a new one. Sheesh.

Mad Dog_2

I highly Recommend the Calleffi Combo unit. It has an EASILY adjustable handle you can turn, a pressure gauge for the downstream (heating side) and a Backflow preventer attached. When I have to change an expansion tank I often change the feeder valve AND the Relief valve it its been running awhile. If you don't do them all, you often wind up back there a few days later. Feeder valves get clogged up with minerals too. Show us a picture when you're done. Did you check tank pressure before you installed it? Mad Dog

DJD775

There doesn't appear to be an isolation valve after the fill valve so that makes the process harder as you will need to drain and refill the system if you add a new bfp/fill combo.
BTW, what's going on with the draft regulator? That tape does not look proper and the flapper looks like it might be stuck open.

hot_rod

Often when BFDs drip, debris is stuck under one of the checks. Easy to disassemble and check

If you are lucky the fill valve has a check also so you could remove the BFD without dropping pressure 

The Caleffi fill valves have checks on the outlet.

Chronic or frequent BFD drips can sometimes be fixed with a swing check upstream or water hammer arestors