Remove air from heating pipes

kh23

Hi,

I'm having some issues with my pipes making loud metal noises. Not sure if it's just air in the pipe or something else.

I tried reading up on bleeding out the pipes and watching online videos but their pipes are a little different from mine. I'm not familiar with fixing this but willing to give it a try to learn from it. Have a lot of questions and tried to do some research online before I registered on this site for assistance.

My gas boiler is a GWA-070-N-T model. This is dedicated mainly for my second floor so it's not shared/split.

I posted a picture of the gauge. For the PSI, I've seen it get close to 30 before. Should it ever get past 30? From what I read it will cause a leak where the valve (see #5 in red) should have restricted it to 30 PSI and will need to be replaced. Is there anything I can do to lower that or is that normal to reach over 20 when the heat is turned on? Is the bottom temperature for the furnace itself or the temperature of my hot water for use in the house? What's the red vs white hand?

From what I read, I have to do the following (see pictures below for numbers I posted next to each knob/handle/valve):

1. Shut down the boiler which I see a switch for on the side of the unit.
2. Close the knob #1 (see #1 in red).
3. Plug a hose to where knob #2 is and have a large bucket or two ready with the hose inside. This is to watch for any bubbles if any coming out.
4. Turn knob #2 on to allow water to come out of the hose.
5. Flip the lever on the valve (see #5 in red). This supposedly increases the pressure coming from the city pipe.
6. When there's no more bubbles in the water from the hose, flip the lever back down on that valve (#5).
7. Turn off knob #2.
8. Turn knob #1 back on.

Will I cause any damage doing any of the above steps?

My main concern is that my set up seems to be different from what I've read online and what I've watched on some of the help videos. Do I need to turn off knob #3 also? That pipe is also hot just like #1. What about that expansion tank knob (#4 in red)? Do I need to turn that off also? My initial thought was to turn the knob off for the expansion tank after step 3 above before turning on knob #2.

Thanks in advance. Sorry for all the newbie questions. Trying to learn but don't want to make things worse. Please let me know if any additional pictures are needed if any are not clear.

neilc

where are you? do you need 200F to stay warm?
that's expansion/contraction acting on the pipes and fasteners,
and probly switching on and off,
could you get away with 180? 160? and run a more steady temp and circulation?

or are you hearing rushing water? air in the water? and need to purge?

yeah, you don't want to reach 30psi, and 25 is getting close,
your tank looks , , , older,
there's an air stem on the bottom, give it a quick depress and see that no water comes out, if so, it's shot, close that isolation valve(4) first,

if no water, with the boiler off, and #4 off, you would want to check and set the air pressure in the tank,
but the tank needs to be disconnected from the heating water system,
unscrew it slowly, so it can leak thru the threads, till no more water comes,
then slowly again, and be prepared for that 10~15 gallons of water weight,
take tank from system,
and adjust air pressure to 12~15, which is to match your cold fill pressure,
reattach tank, and slowly open #4 ball valve, turn on boiler,

or do you need to purge

hot_rod

Sure looks like a couple rust holes in the tank? Or is something dripping on it?

kh23

Thanks for the replies.

Do I set the temperature be removing the cover? Do I need to turn it off first before opening the cover? I can decrease it if that's causing the issue. I think 180 should be enough.

I can definitely hear water going through the pipes. It's been like that for years and I'm not surprised if the contractor who worked on this did it incorrectly. Would air in the pipes cause the loud banging noise? Was ok until more recently when the heat was used more often.

The expansion tank was replaced last year with a new one. I think there's a leak somewhere. I took a closer look at both sides where the rust is and it's on the outer layer. Not sure what this is, but it's a little wet and above the expansion tank.

ethicalpaul

That black part is just the cap. Unscrew that and under it is a "Schrader valve" like on a car or bike tire onto which you can push a tire gauge

kh23

I pushed it and only air came out.

Is there any harm in purging? If not, I want to try that next. Do I need to do anything different than what I have listed on the steps on the first post? Don't need to turn off any other levers?

Thanks

neilc

kh23 said:

I pushed it and only air came out.

but just a quick Pssst, you didn't let all the air out, correct?

kh23 said:

Is there any harm in purging? If not, I want to try that next. Do I need to do anything different than what I have listed on the steps on the first post? Don't need to turn off any other levers?

so you've got air,
I think you have a good understanding of your purge in your 1st post, just watch that you don't go over 25psi when you trip the fastfill lever,

kh23

Correct. I pushed it for less than a second. Pushed a second time to confirm it's still dry, then recapped it.

Great. I'll give it a go tomorrow and will report back.

neilc

consider before, or as purging, to let the system pressure drop and check that air pressure in the tank,
let the system go down to 8, then check and set the air to 12~15, then purge as you know how to, 20~25psi.
after purging set the system to your back to 12~15,

kh23

Thanks. I will monitor and increase/decrease to those ranges you mentioned. Will wait a day to see if it resolved the issue.

kh23

Great news. Looks like that solved the problem. Thanks for all the help. I was caught off guard initially when the PSI dropped so suddenly to 10 PSI but quickly increased the pressure valve to keep it around 20-25 PSI. Would there be issues if it dropped to 0 PSI?

That expansion tank was replaced last year so I'm concerned that I see some rust build up. I'm sure it's not the tank itself. It looks like it might be that automatic air valve. It seems to be the main component that's a little wet. Do I close the main water valve and all the other valves I see open, then drain all the water out before replacing that part? Seems to be similar to what I did before but need to close all the valves this time? Also, anything I can do to remove the rust on the expansion tank or prevent it from getting worse?

Slowly learning but hope I can fix some of the simple problems.

Thanks

neilc

to change that air vent,
you would drop the water pressure to 0,
have the new vent taped and ready to go,
pull the old one and quickly and calmly instal the new one,
added bonus points, put a ball valve between the separator and the vent,

kh23

That makes sense. So the ball valve will eliminate the need to close any other valves or dropping the pressure to 0? Guess it's to make it easier to replace air vent in the future? Is there an attachment piece or specific name for that ball valve? The ones I'm finding seems to show the larger 3/4 valves similar to the drain pipe size. The air vent is a smaller connector.