Random Backflow Preventor + Shutoff Valve??

AnthVale

Anyone know what this if for? My first thought was for when I drain the system I can open this valve so air can escape? I also put a diagram of my current plumbing system so you can see where this is located (bottom left right after Feed)

mattmia2

No idea. Kind of looks like they were going to put the prv there then went a different way. Or the PRV was there before they made some changes. The check valve should be after the shutoff since if they fail they can leak and you would want to be able to shut it off without shutting off the water to the whole house. Any chance there was a second boiler at some point in the past?

AnthVale

Hmm, unaware of a second boiler. Bought the home in December. I'm wondering…since my other check valve from the other Forum Thread you were helping me with is all corroded, if I should take this one and use it in place of the other one. But, how do you know if they are in working order?

Or, how do I know this isn't put in place for some other reason?

I'm also considering just getting a combo like this and rebuilding the entire PRV/Check Valve section with the ByPass added in.

Thanks again @mattmia2

https://www.supplyhouse.com/Caleffi-573012A-1-2-573-Backflow-Preventer-and-AutoFill-Combination-w-Pressure-Gauge-NPT-x-NPT

mattmia2

The check valve will either leak out the vent or not pass water if there is something wrong with it. The prv itself usual fails by not sealing all the way and the pressure in your system slowly creeps up. You could replace all of it, you could replace none of it, you could rebuild the prv you currently have. I like that callefi one, it does auto fast fill even though the one I have had the check valve crust itself shut.

AnthVale

I may just get the Callefi one since I am doing all my own work I feel I can spend the money and just redo the check valve and prv section there. Still debating the manual bypass

mattmia2

Probably fine without the manual bypass, from the look if your system I initially thought it was radiant but baseboard usually isn't hard to purge enough to start flow so you should be fine without it. The caleffi valve also does auto fast fill so you don't have to deal with a fast fill lever. I would leave the by pass out.

AnthVale

Ok, great. Thanks again!