Air in Radiators After Air Separator Install.

Sweet_Lew

Greetings Heating Helpers!



A couple of months ago, I had my system drained to remove a radiator out of our bathroom for a remodel. While the system was drained I had a Caleffi air separator installed due to constantly having to bleed the 2nd floor rads all winter. So everything was installed\reinstalled and the system was filled, all rads bled, cold pressure is 12.



Fast forward to last night. Woke up to use the facilities and heard trickling water in the bathroom. My toilet does that if you don't "jiggle" the handle a few times. Upon further inspection the trickle was coming from inside the 2nd floor bathroom radiator. Once the boiler shut off, the trickle stopped. Curious, I ended up bleeding all the top floor rads at 2am and ALL 4 rads had air in them. The boiler kicked back on and the trickle sound disappeared. Woke up this morning and bled the rads again. More air came out.



Why would I still have all this air in the system with an air separator installed? I thought the whole purpose of one was to remove air from the system? The A/S was installed on the supply (hot) side of the boiler. Also, while bleeding the radiators, when water finally came out, it barely made it out. One of the taller radiators couldn't even push water out. The hissing went away and no water. This morning I was able to get water out of it.



Thanks for reading. Any thoughts and\or feedback is greatly appreciated.



Cheers,



Lew

Ironman

Air

Lew,

If I recall correctly from your older posts, you have a converted gravity system. That means that you're not gonna be able to maintain enough velocity to force air back down the return lines and through the MBR. It can only remove what passes through it. And, despite the claims of some manufacturers, I've yet to see one that will get everything on the first pass.



This means that once air goes up the pipes, it ain't coming back down. Even if you had smaller lines, the velocity would still slow dramatically in C.I. Rads and the air would go to the top.



A couple of suggestions:

1. Make sure the circ and boiler are off when bleeding

2. Increase the cold static fill pressure. Should be 18# for 3 stories.

3. Check for, and repair any leaks.

4. Do you have a bladder or old style compression tank? If it's the old non-bladder style, then remove the air separator or the old tank and replace it with a bladder tank. The two are not compatible.

5. Is the circ pumping away from where the tank connects to the system or towards it? It should be pumping away.



Any or all of these may be your problem, but with large pipes and C.I. Rads, air will always go to the top and have to be bled from there. You shouldn't have to do it constantly though.

Sweet_Lew

Answers...

Hi Bob,



Thanks for your reply. Here are answers to your questions:



A couple of suggestions:

1. Make sure the circ and boiler are off when bleeding

**I always bleed the radiators when the system off.



2. Increase the cold static fill pressure. Should be 18# for 3 stories.

**Thanks. Will make the change tonight.



3. Check for, and repair any leaks.

**So far, I have not seen any leaks or signs of leaks



4. Do you have a bladder or old style compression tank? If it's the old non-bladder style, then remove the air separator or the old tank and replace it with a bladder tank. The two are not compatible.

**I have a WATTS bladder style tank.



5. Is the circ pumping away from where the tank connects to the system or towards it? It should be pumping away.

**If I recall correctly, the pump is pumping into the heat exchanger and then the hot water comes out of the top of the boiler and then into the air separator. I can take a pic of my setup tonight and post it.



Any or all of these may be your problem, but with large pipes and C.I. Rads, air will always go to the top and have to be bled from there. You shouldn't have to do it constantly though.



**It was never this bad when I didn't have the separator. It would maybe be two of the four radiators that had air in them and it wouldn't be much. It would maybe bleed air for a few seconds before water would spew out. Will do what you suggest and report back. I also have a call into the contractor who installed the air separator.



Cheers,



Lew

Sweet_Lew

Setup

Here is a pic of my setup before the air separator was installed:



As you can see the hot water comes out of the right side where the aquastat is located, goes up, makes a 90 degree , then up and then another 90 degree turn. Right after that turn is where the air separator is installed.



Hope that helps.

Ironman

Pump location

Lew,



The circ IS pumping away from the Point of No Pressure Change (PNPC) with the expansion tank on the return as you have it. No need to change in and of itself.



Try bleeding some more with the higher static pressure and see how it goes.



After that, try closing the bleed cap on the air separator. With all the other variables, it's possible that it could actually draw air in with your piping arrangement.

Sweet_Lew

Thanks Again!

Appreciate the help Bob. Will let you know if the up in pressure or closing the bleed cap helps.



Lew

Ironman

Air Separator Location

Lew,

Can you post a pic showing the air separator and the top of the boiler?

Sweet_Lew

Pic

Bob,



I'll get a pic of the air separator and post it up later tonight.

Sweet_Lew

Here you go!

Few pics of the Air Separator:

Sweet_Lew

Bleed cap

Well, the bleed cap on the air separator was screwed down all the way! No air was getting out. I unscrewed it a little and heard air rush out. It's open now and I'm slowly trying to get the cold pressure set to 18. It's in the 60s today and tomorrow so I should be able to get the pressure set after trick or treating is over.

Ironman

Keep an Eye on It

I don't like the placement of the MBR right above the aquastat. Caleffi makes a great product, but any float type air vent can get fouled and leak water.



I'd leave it open for few days, then close it off and re-open it periodically until you gett a feel for how often it's trying to release air.

Ironman

Swing Joint

The piping forms a swing joint and you should be able to rotate it slightly to where the MBR would not drip onto the aquastat.

Sweet_Lew

Placement

Thanks Bob,



It's not directly above the aquastat, but I understand what you're saying. Maybe I can get it rotated away from it a little more.



Cold pressure this morning was 19, so I let some water out of the boiler. The gauge is slow to adjust to change so by the time I get home from work I should be at 18 or a little below that. I also backed off the reducing valve screw as well.

Unknown

one of the

One of the worst boiler on the market piped wrong