1 zone doesn't heat after some repairs

tryingtobeaplumber

Hi all,

I had a pressure relief valve that was leaking and I traced it back to a bad expansion tank.

So I went ahead and replaced the expansion tank, the pressure relief valve, as well as the air vent while I was at it.

Before performing the replacement I naturally had to drain the water out of the system. The replacement went well (except for someone tightening the expansion tank way too much) and then I went ahead and purged the system.

I have 4 zones on 5 return pipes, and 3 of the zones + hot water work well. I also haven't noticed any more water coming out of the pressure relief valve so far after the repairs (yay).

Unfortunately, one of the zones isn't heating at all. I manually opened the Taco zone valve in case it's bad, but that didn't help. I also, swapped a known good zone valve with the zone that isn't heating, and still no luck.

While it's cooler out, it's not cold enough to freeze pipes. One guess is maybe I didn't purge that zone well enough. The water flow seemed a bit weak on the offending zone.

Below is my setup and I don't seem to have that many shutoff valves to isolate zones well enough, but this is also the first time me doing this. The way I purged was by opening each of the 5 return drain valves, one after the other while also using fast flow on the inlet. I also turned off the hot water inlet/outlet to isolate zones.

The boiler pressure is around 12 psi when cold, so the inlet pressure valve seems to work as expected.

Any suggestions on what to do? Appreciate any help with this.

neilc

I think you need to go again,
this time with all the returns closed, and all the supply side open,
if you had all the returns open then water could have short circuited and missed your cold zone,

this time, open one purge bib at a time and then fast feed till that one zone flows air free,
manually open the zone valve(zv) for a bit and burp any air under the zv, close zv,
air free?, yes?, shut off the fast feed, close that purge bib, and switch to next,

repeat process at each zone,
on the right there I see a couple extra ball valves, when you get to that zv, manually open zv, and burp each ball valve as above,

EBEBRATT-Ed

Close all your zone valves. Put the hose on the zone that doesn't heat above the zone valve and purge the two zones that don't heat one at a time. Putting the outlet of the hose in a bucket with some water in it and purge until you see no bubbles. Have someone monitor the boiler pressure and use the fast fill to keep teh pressure between 15-25 psi.

When you are done purging if the zones that won't heat are the 2 with the ball valves close those valves otherwise leave them open. Then put the hose back on one of the zones that don't heat and open the zone valve to purge from the boiler return. Then close that zone valve and do the other zone back purge the other zone

Again if the zones that won't heat are the two with the ball valve open that zone valve keeping the two ball valves off and back purge those zones one at a time using the ball valves

tryingtobeaplumber

Thanks for your replies. I think a bad purge was the issue. The zone that didn't have heat was the far left one in the picture.

I'm not sure if this is normal, but when I open a purge valve, the boiler pressure goes to 0, even with fast feed on (is that normal?). I have my own well, so maybe there isn't as much pressure compared to being connected to city lines? I ended up building up a little extra pressure in the boiler (not enough to trigger the relief valve, < 20psi) and then opening and closing the purge valve. Is there a better way to do this, or does that seem reasonable. I also tried not opening the purge valve all the way to also help a little with extra pressure in the system to get the air out.

Anyway, I do get heat now in that zone, but not sure if the purge is perfect yet.

Thanks again for your help.

neilc

No, that's not normal,
well water, and time, may have taken its toll on the fill valve,
it should probably get replaced,
you also have a backflow up there, they clog too,
both of these have screens which you might try to get to and clean,
is there a manual valve further upstream, and is it closed, but leaking by, for a low pressure feed?

you could try a hose from the HW tank, to the boiler drain, and throttle it as a "Fast Fill",
you'll need a female to female clothes washing machine hose

EBEBRATT-Ed

What @neilc said feeder may be clogged.

tryingtobeaplumber

Seems like more things to fix

There are no immediate valves further upstream. There are others on the same line that go to external hookups but I don't see any obvious leaks.

I also noticed that the boiler pressure looked low when I just checked. My understanding is that it shouldn't really go below 12psi, or ?

What do you think is the level of effort/difficulty to clean or replace the feeder valve / back pressure valves? I added another picture below. Does it require any welding from what you can tell?

Edit: I found this for the feeder valve: https://s3.amazonaws.com/s3.supplyhouse.com/product_files/0386423-install.pdf
Seems like as a first step I can just remove the Fast Fill Lever and Cap Assembly.

EBEBRATT-Ed

If the back flow preventer is ok leave it alone.

You can buy a kit to rebuild the feeder. With what contractors charge they just replace the whole thing not worth it labor wise it would be more costly to rebuild,

. But its your own go for it, should be fairly easy

tryingtobeaplumber

Looks like the repair kits are discontinued https://www.watts.com/products/plumbing-flow-control-solutions/repair-kits/rk-1156f/rk-1156f-12

Is disassembling and rebuilding with the same parts a reasonable option?

EBEBRATT-Ed

@tryingtobeaplumber

Probably not. You will find the inside gunked up with rust. That's the reason other than cost why no one rebuilds them.

tryingtobeaplumber

Alright, I guess replacement it is. Final question (hopefully) Can anyone tell what model feed valve I have. The tag is missing and the markings are not very helpful. I'm guessing the Watts TB1156F or SB1156F but it doesn't look exact. The top shows a RMP 44 I think. And the bottom has 66 or 99 on it.

EBEBRATT-Ed

Yours is sweat. The first letter tells you s ...sweat t...threaded. They are the same except for the supply nut the outlet is threaded on both

tryingtobeaplumber

Many thanks. Darn that it's an Sweat one since that is more difficult to swap for me (assuming it will require soldering). However, I'm thinking I can just buy a new one and use the parts to rebuild, so I don't have to remove the existing one. Appreciate all the help!

tryingtobeaplumber

Wow that was pretty easy to replace. Didn't need to soder, nice!. However, I noticed that when purging with the new feed valve, I can't use fast feed. It seems like it's already using max pressure. Could that be an indication that the backflow valve also needs to be cleaned or is that normal?

neilc

when you changed the PRV, did you open the service valve, while the PRV was out, and see if there was a good flow to the PRV?
yeah, it could be the backflow, but that looks rather new, it could be the service valve, it could be well junk in either,
take out the PRV again and see what you have for flow,
then take off the backflow and see what you have,

tryingtobeaplumber

I found the issue. There was a lot of debris in the mesh/filter from the backflow valve which reduced the water pressure to the feeder valve. Cleaned everything up and it works as intended. What a project. I do wonder now if I need to check something else from the cold water supply. I've found a lot of debris in other outlets, like the washer (hot and cold water), but maybe that's just build up over many many years of no maintenance.