Is an air separator near relief valve tapping useless?

RichC901

I can't find an air separator anywhere on my system. I was thinking about putting an air separator between my relief valve and expansion tank, which are attached to the top of my boiler. I'm not sure if it's worth the effort since there is no water flow through there. Does that top tapping off the boiler collect air? Here is a description of the system along with some pics:

4 zones
-> 4 Taco 007 Circulators Pumping INTO
-> 20 year old Dunkirk PVWB-8D, top tapping off boiler with relief valve and expansion tank
-> Supply going into 4 flow check valves and out to zones

Air is not a major problem in my system (some air collects in attic radiators, but almost never need to bleed the others). So, I'm not motivated to do any major pipe work. Also, what is up with that tangle of copper above my boiler? Is it normal to have the pipes going all over the place?

hot_rod

"Tangle" is a polite way to describe that piping. A complete repipe would be a nice upgrade, too many pumps for the job, bad piping practices, no central air scrubber, etc.

But if it works and you do not have major air issues then adding a small float style at the connection wouldn't add much value or performance.

Wait until you have the motivation to upgrade and repipe the entire near boiler piping.

One ECM pump with zone valves, combine zones if possible to eliminate short cycling potential, update to ODR, maybe an indirect? Plenty of places to throw $$ at it.

STEVEusaPA

While you're upgrading, the flue pipe T and the pancake reducer (oh the tape) should be fixed too.

EBEBRATT-Ed

@RichC901 saidAir is not a major problem in my system (some air collects in attic radiators, but almost never need to bleed the others)

So if your not having air problems why do you want an air separator?/

Systems don't always need to be perfect to work .I have seen plenty of jobs that weren't piped the way I would do it yet the system works fine.

Hot water is more forgiving than warm air or Steam.

If it aint broke don't fix it

Ironman

Do you hav cast iron rad's? If so, the air in your system will make its way to the top of them and have to be bled manually.

It looks like you had a open compression tank at one time and someone replaced it with a bladder tank? If that's true, the open tank would have received air from the top of the boiler, but you'd still have to bleed rads.

Like others have said: "if it ain't broke, don't fix it.

MikeL_2

I always prefer to install diaphragm type expansion tanks below rather than on top of piping; this prevents air from entering the tank & gathering beneath the diaphragm where there is exposed iron. The bullhead tee on your return manifold is less than ideal also.......

RichC901

I read some posts about old cast iron boilers having built in venting, so was wondering if that's what the top tapping was for, and if it needed a float vent. Seems like that's not what it is.

I totally agree with you guys - if it ain't broke, don't fix it. Unfortunately, I need to put on a larger expansion tank b/c the boiler kept spilling water out of my relief after I bled out a lot of air from attic cast iron radiators. Seems like those radiators were acting like an expansion tank. I turned off the fill water (I have a LWCO and was checking pressure twice a day), and the system stabilized at a around 5-10psi when cool and 30psi when hot.

I've been reading Siegenthaler's text book and got to the chapter on pump cavitation. I got worried my system pressure was too low, so I went up to the attic and opened up the vent and let the system suck air back in up there. Now my pressure is more normal 12-15psi when cool, and does not get near 30psi when hot anymore. The height from boiler to attic rad is about 30ft.

So I'm going to mount a #60 tank on the wall and hook it up with some pex. That's why I was wondering about the air separator. Figured while I'm there might as well see if there is any low hanging fruit.

Thanks for the help guys. Love reading this forum and am obsessed with my boiler. Who knew there was something so cool in my basement?

RichC901

@hot rod, I'm dying to re-pipe the system, but it's tight in there. Doesn't look easy and I will probably mess something up. Oh, and my wife would not appreciate me spending several weekends down in the boiler room. I will probably put on a Hydrolevel 3200 this year b/c my Aquastat might be bad. Still not sure if it's controller, molex, or vent damper causing my intermittent no burner. But Hydrolevel looks like an easy upgrade regardless. I might hire a pro to re-pipe at some point, but where is the fun in that?

@STEVEusaPA said "flue pipe T and the pancake reducer (oh the tape) should be fixed too". Can you elaborate on what's wrong? The home inspector mentioned something about the venting when we bought the place, but in one ear out the other. Had a couple pros in the room to try in figure out the intermittent no heat. No one mentioned anything about the venting to me.