Replace air scoop with microbubble eliminator?

ryan242

Been having air issues with my system ever since I replaced the expansion tank last year, sounds like I have bubbles in my baseboards. It has an air scoop down at the boiler, it only has about 4 inches of pipe in front of it though which I’m told isn’t very effective, was thinking of changing it out to a microbubble eliminator instead, would it be worth it to drain the system down again and replace it or would it be a waste of time, also what are the odds of that old purger coming off there easily? Was installed in ‘97 from what I can tell.

STEVEusaPA

It would help, but you're also not pumping away from the expansion tank, and the smaller zone with the plastic pipe looks baffling to me (at best) and straight up wrong (at worse).

JUGHNE

Is the cap on top of the air vent loose?
Being that old and appearing to never have leaked, it is suspicious.

GroundUp

The distance on both sides thing; yes it's recommended, but in my lifetime I've maybe seen 3 that were actually installed "correctly" in that respect. They still work, they just take longer IMO. The bigger issue is that the black boiler circ is pushing more toward it than pulling from it, which doesn't help it function. I too am wondering about the cap on the vent- if it's tight the air can not escape it. What is the system pressure?

ryan242

The cap is loose on the hy-vent, I replaced the Hy-vent on top of the scoop when I replaced the expansion tank, however the old one that was on it had no signs of leaking, really don't want to move the circulators around if I can help it, the smaller zone with the grundfos pump is feeding an addition that is only 2 rooms and has a small baseboard in each room, the main zone is the black taco down below, its feeding a mixture of cast iron radiators and old cast iron baseboard, this thing was noise free until I replaced that expansion tank, now it gets noisy every time the water temp gets up above about 140, I did lose all my water when I replaced the tank. Im no professional but I have worked for plumbing companies in the past and would have no trouble changing out the air eliminator, just want to Make sure it would be worth it or if id be better off just leaving it how it is. My Cold psi is about 10-12 according to the gauge on the boiler, when its up at 180 on limit its up to a little above 20 psi, its set up as a cold start and rarely gets above 160, most of the time at the end of its heating cycle its 140-150

mattmia2

I think you are going to have to take apart enough piping to unscrew the air scoop and put in a new air eliminator and get the spacing right that it would only be a bit more work to move the flanges for the circulator to after the air separator.

mattmia2

You might get rid of a lot of air if you just cranked the t-stat up and let it get to 180 a few times.

HVACNUT

What's on the return piping for the main zone? Any way to purge the loop. Actually, I think you have a mono flo loop. 
Have you tried bleeding the radiators? If there's no purge station on the main zone return, that might be what you need to do. And one circulator pushing and one circulator pulling isn't helping. YouTube didn't tell you that part. 

ryan242

Yeah I have been bleeding the radiators, I sometimes get air out of 1 or 2 but not much, there’s no purge station on the return, just a boiler drain all the way at the bottom. And by the way I didn’t pipe this thing, either zone, the way it is, is the way it set when I bought the house about 5 years ago, only thing I did was replace the expansion tank and hy vent as the tank wouldn’t hold air pressure more than a few days, it was quiet before that, now I have air noise, I actually wish I would’ve just left it alone and put up with topping off the expansion tank with air every so often 

JUGHNE

One method that works sometimes is to crank up the temp, let the system run for sometime, then shut power off.
You wait for air to move to the top of the system and rads....maybe a half hour.

Then bleed from high points.
Worth trying IMO.

HVACNUT

When you replaced the expansion tank, you obviously introduced air into the system. Can't help it. A mono flo system can be tough to get the air out, and an 1/8" (or is that 3/8"?) Hy- vent is going to take its sweet a** time getting rid of it. 
Pressure is good on the boiler? 12-15 psi?
A lot of things should be done to make it right, but if you're going to change to a micro bubble exploder, then think about cutting in a purge station as well. Is there one on the other loop? What did they do, remove the boiler drain a pipe in a tee at the bottom? 

ryan242

HVACNUT said:

When you replaced the expansion tank, you obviously introduced air into the system. Can't help it. A mono flo system can be tough to get the air out, and an 1/8" (or is that 3/8"?) Hy- vent is going to take its sweet a** time getting rid of it. 
Pressure is good on the boiler? 12-15 psi?
A lot of things should be done to make it right, but if you're going to change to a micro bubble exploder, then think about cutting in a purge station as well. Is there one on the other loop? What did they do, remove the boiler drain a pipe in a tee at the bottom? 

Yep, that’s exactly what they did, they tee’d into the boiler drain for the return of the loop for the addition, no purge stations on either, the main zone is a 2 pipe system, almost looks like it may have been gravity feed at one point because the pipes are huge. I’d like to know how they got the system air free before I moved in here because it was quiet as a mouse when I moved into this place 

hot_rod

Snap a pic from back a few steps. Looks like on pump on the return, another zone pump on top of the boiler?

ryan242

hot_rod said:

Snap a pic from back a few steps. Looks like on pump on the return, another zone pump on top of the boiler?

hot_rod

Teeing the expansion tank into the copper above the black circ would get you pumping away and help air removal. But if you need to drain down, may as well upgrade to a micro bubble purger and get rid of the blue coupling, I mean air purger

The Steam Whisperer

A very effective, inexpensive and reliable alternative is the Bell and Gossett IAS. Much more effective design and is still just a hunk of cast iron. Scoops really aren't that effective.... I have the same problem on my home system, but a scoop was all that I could get quickly when I repiped the boiler with a bypass loop. I expect to be going to steam vapor soon anyway, so its not much of a problem longterm. I expect to be able to do back to back comparison of energy usage of steam versus hot water with identical systems and the same boiler ( probably a peerless 63-03L) by switching boiler trim.

mattmia2

that expansion tank may be a little bit marginal in size since it is a converted gravity system but if it only goes up to 20 psi hot it is ok.