Air Separator degradation...

kcopp

I have seen over time that some Air separators seem to lose their ability to filter out the air in a system.

Typically, you can swap out the head if there is a float vent. Sometimes some models have media that can be cleaned, some you can clean and others you are out of luck.

Im having an issue w/ a Caleffi discal 1.5" that seems to not be grabbing any air. System is newer (5 yrs), cap was replaced 2 yrs ago.

issue is that the indirect zone is the first zone off the loop and appears to in the last couple months be getting air locked from time to time.

System is piped "pumping away".

I find it odd that that would happen after 6 years of pretty good performance.

Is it possible the media inside could lose the ability to scrub?

Water quality of the system is decent. Better than normal.

leonz

Have you tried turning the heat up to eliminate any trapped air in the system and then simply shut the water feed off and then capping the Calefi unit?

kcopp

System temp is at 180F. That should be hot enough. System pressure is at 25 psi. Was hoping to get any air back into solution. I didnt want to cap the air sep as any chance of air getting out would be gone…

I suppose the next shot it to add dishwashing detergent into the system and see if that would help or add another 3/4" air separator to the indirect zone..

Should need to do that as its a super short run. 6' tops

hot_rod

Its a brass version, correct?

I would take the small cap off to check the needle valve and hinge assembly.

Next open it at the big joint to get to the media inside. Its a glass reinforced nylon media. It should not deteriorate from water. We have seen them plugged with sludge, teflon tape and in one case a brown cotton glove in a large steel separator

kcopp

It is the brass version. Ill look at the cap again. Thanks

yellowdog

How close is your indirect circ to the air separator? I've seen them pull in air when piped too close.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1831381#Comment_1831381

Yes, the expansion tank connection inn relationship to the circs could cause air to be pulled into an auto vent. An example here, which expansion tank location is preferred?

Screenshot 2025-01-02 at 7.51.26 AM.png

yellowdog

@hot_rod I would prefer the one on the left for this reason.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1831478#Comment_1831478

If that was a high pressure drop mod con, a coil type, and a high pressure drop indirect, one with a 3/4" coil. Here is what can happen.

The blue horizontal line is the static fill pressure, call it 12 psi.

The red dotted line is the pumps ∆. Notice on the left drawing, pressure drops below the static fill. Whereas the right hand drawing with the exp tank location moved, dynamic pressure never falls below static. Under some conditions you could pull a negative pressure in points of the piping. The example below, shows a -3 psi at the circs inlet..

Screenshot 2023-10-23 at 10.13.29 AM.png

It gets complicated when multiple circulator locations, types, and flow resistance are considered.

This is just a continuation of B&G and Dans teachings of "Pumping Away" But with a few of todays high pressure drop components thrown into the mix.

Now you would need to define and calculate all the components, to know this, or throw some gauges on the system along those piping paths.

Screenshot 2025-01-02 at 7.51.43 AM.png

GroundUp

I've had a number of the Caleffi and Webstone air eliminators that the vent/float assembly was bunged up from the factory and needed to be rearranged. Much like the needle and seat in a carburetor if you're familiar. But then again I've also had a few plugged up with teflon and/or excessive flux from install. First thing, pull the cap off the vent and poke at it like you're letting the air out of a tire. If anything comes out, the float assembly isn't doing its job correctly.

kcopp

It is a short run but not that short. 4-5 feet.

Indirect is 3/4" off a 1 1/2" copper line. Boiler is a Trio 3 pass oil unit.

Not a lot of velocity here.