Purging/Bleeding Air out of a Gas Water/Radiator System (pics)

JayPoorJay

Good Day All...

Newbie! I think this is my third or forth post here (getting MORE help than I would have imagined from a member about my DIY Central AC System project!) and I have a couple of questions about bleeding/purging air out of my hot water radiator system.

Not long ago I did a little rerouting of the PEX lines feeding two zones in the rad heating system. It was daisy chained where the last 2/3 rads (on both floors) in the chain would never even get up to temp and the furnace would run a long ol time barely being able to get the thermostat up to the desired temp.

I split the lines near where they were coming out of the two zone pumps and made some shorter runs to what WERE the last 2/3 rads in the system on floors 1 and 2. Then, a little rearranging on the returns. AMAZING difference in the way the heating works. Thanks to Y'all! Anyways,,,

I introduced a lot of air into the lines doing that and want/need to purge them.

I have some photos of the system and am hoping someone can tell me (with arrows?) what valves to close and which to open, where to connect a garden hose to push out air OR whether I can just use the auto fill valve for that and, an order of operations - that sort of thing?







I have watched some YOUTUBE videos and read some, but its tough when the examples don't look EXACTLY like what you are working on - if you know what I mean?

I'll be SUPER grateful for a bit of guidance...
Thanks in advance

neilc

turn the boiler power off,
are the air vents open? on the boiler? and on the air sep? open them and let them vent,
close the red return ball valve going into the boiler next to your expansion tank,
connect your hose to that red handle bib right there,
close the 2 ball valves (blue/black) on the returns above the tank,
set your system pressure up to 20~25 psi,
open the hose bib and maintain 20~25,
open one of the return ball valves (blue/black) till the hose runs bubble free,
when the hose runs bubble free, open and close the red ball valve at the purge hose a couple times to burp any air that might be there,
bubble free hose?
close the return ball valve (blue/black) that was open, and open the other,
same deal, run it to bubble free, then burp that lower valve,
you want to maintain the higher 20~25 pressure thru all this,
when the 2nd zone is air free, start closing the purge bib hose,
and let your system pressure back down to 12~15 that you want,
close the hose bib and remove the hose,
open all 3 ball vavles,
power up the boiler,

enjoy the heat,

JayPoorJay

@neilc

Hey there. Thanks. I got a little impatient last night and went ahead and did exactly and pretty much what you said (thanks for the detailed explanation,,, amazing!) EXCEPT the air vents. I'll include a picture with what I think might be the "sep"... Then, if you're willing, give me a hint on where to locate vents on the boiler itself.

The vent circled (if that's what it is) seems to have a cap of some sort on the valve on the back side. When I was running water through it last night I took the cap off and got a short but real burst of air. Lasted a second. Can I leave the cap off a day when it runs and see if it will let any remaining air out?

Again. Super appreciative.
All ears.

Thank you! 

neilc

picture?

you have one vent on the boiler behind the supply pipe coming out of the top,
that little 1/4 cap should be loose so air can escape,

then further up that supply pipe, you have that larger brass assembly, the air separator, (your tank connects to it's bottom), off the top of that assembly, that little dogleg, that too is an air vent, that's another cap there, right?
make it loose also, that's your main air separator(sep)

JayPoorJay

"sep"! = separator. Got it. 

Awesome! Thank you. I'll get to looking.

This is the photo I meant to include. 

Yes. It's a little 1/4 inch brass cap on the rear of what's circled. When I released it I got a short but sharp blast of air. But then I tightened it back down fully not knowing. 

If there is a photo out in the world, an example of the dog leg separator, I'll take it.

Thanks much. 

neilc

unless that separator vent starts to leak water, leave the cap loose so the sep can do its job and let / get air out,
check the cap on the boiler also

JayPoorJay

Will do, and thanks for the guidance!

I'll guess that the boiler valve is what's circled in red in the photo?

Not that it's guaranteed, but all the bits and bobs are fairly new, so I'll trust that they're functioning properly and doing their thing, for now ...

I love forums!

The thing is already sounding much better after running a lot of water thru it. Winter is coming 😊

Be well

neilc

red circle is your boiler VENT, (not valve)
glad to have helped

hot_rod

Looks like there has been some condensation running down the vent diverter hood, to the right of the blue circle?
Is this boiler connected to cast iron radiators?

JayPoorJay

@hot_rod

They are cast iron...got some new worries fur me 😆