Posted a while ago about air in my baseboard heating pipes. Decided from the advice (thanks to all who helped!) to install some bleeders in the baseboards at the return end of each loop (where the noise was). I'm wondering if anyone can tell me how long it will take to get ALL the air out, it's MUCH better but I'm still occasionally getting a little bit more out, it's Sunday now and we finished installing the bleeders and bleeding the system late Monday afternoon. Any guess how long it should take to get all the air out would be appreciated.

it takes as long as it takes..
one hint, manually raise the system pressure to somewhere around 25 PSI. it will help purge the air. put the end of the hose in a bucket of water and watch for air bubbles.
when there are no more bubbles, you are done.
make sure the pressure gets back to 12-15 PSI.

It sounds like he is using individual automatic air vent, but possible manual ones. Unless you can figure out how the air is getting into the system and correct THAT, you will NEVER eliminate the air in the radiation. Putting the vents on the baseboard is treating the SYMPTOMS, NOT the problem.



Edited 1 times.

We bled the system in the cellar when we were done putting in the manual and automatic vents at the baseboard. I'm assuming the air is coming out of the fresh water we flushed the system with, the only noise I hear in the pipes now is at the boiler where the pump is pushing the water feed side), a slight trickling sound, not always but sometimes. No air sounds on the first floor now or second floor but I'm still getting a little air out of the 2nd floor vents on occasion. There was a lot of pipe noise on the second floor prior to putting in the vents. I really don't think air is getting in (turned the auto fill of for a few days and no drop in pressure), if you think air is getting in where should I check? Could the pump (internal, Weil McLain GV90+-4) be creating the air or sucking it in somehow? The air is getting less and less, could it just take some time for it all to gather and be eliminated?

First off, does the boiler have an "air scoop" and air vent ahead of the pump? The only "low pressure" area in the system is at the pump's impeller and seal where air could be introduced.

At the flange of the inlet side of the circulator there is a negative pressure relative to system pressure. If there wasn't you could not have circulation. If the air keeps coming back, I'd check there.

The air scoop is on the return, it has an automatic vent on top of it (Maid O' Mist).

I IS a lower pressure than the outlet side, but it is still greater than atmospheric pressure so air CANNOT "leak" into the piping. The only place that has a 'negative' pressure is in the pump's volute.

In that case the air is being left in the radiation before it ever gets to the air scoop. What @#$%& installed it. I say "@#$%&" because no rational competent installer would EVER do that, and it will NEVER work properly.

Maid O Mist = Steam Vent

One way to determine the head of an existing system involves using a vacuum gauge at the pump inlet and pressure gauge at the pump outlet. The operative word is "Vacuum".

IF there were a 'vacuum' at the inlet to the pump, the water would turn to steam. Why is there a "steam vent" on a hot water system? The two types of vents are completely different and NOT interchangeable.

maid-o-mist also make auto vents for hot water heat.
[www.maid-o-mist.com]

OK.........I had never heard of them, other than steam, but you're right. I don't like air scoops myself. If not piped according to the directions, they can be useless. Most aren't piped correctly. A SpiroVent has no placement restrictions, and is a better choice. IMO

It still has to be ahead of the radiation to be effective.

So maybe a Spirovent in the piping after it comes out of the boiler? It's driving me crazy, I would think all the air would be out by now but I'm still getting a little bit once a day upstairs.

even the Taco air scoop would work IF it is installed where the water comes out of the boiler, since THAT is where the air is coming from. EVERYTHING you did, installing vents, etc, was only trying to cure the SYMPTOM of air in the radiators, but did nothing to eliminate the PROBLEM of air getting in to them in the first place.



Edited 1 times.

So would a Spyrovent somewhere on the outlet side of the boiler (before the baseboards even start) solve the problem or if the pump is creating the air does that need to be resolved first (and is there a way to resolve the pump introducing air). I pushed up the pressure to about 20lb (would be about 25 hot)and got much less air out this morning. I can't even find anyone around here that knows enough about hydronic heating to figure out what the actual problem is. The installer said his contract was to install the boiler and he did it. He wants to use the "process of elimination" to figure out where the air is getting in and wanted to replace the 4 valves (diverter? The ones with the screwdriver slot to limit the flow on the returns) with ball valves. When he installed the heater he removed the secondary heat exchanger to get it in the door (which I don't think was necessary), could that not have been sealed properly and be introducing air or would it also leak water? It sounds expensive to keep replacing things without figuring out what the actual problem is. I don't believe the diverter valves are sucking in air or they'd be leaking water right?

Plbg staff deleted the top image due to possible copyright infringement

--



important:



==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

quote; t sounds expensive to keep replacing things without figuring out what the actual problem is

It is, and it is also the sign of a less than competent service person. ANY air eliminator on the feed side will handle the symptom of air in the system. Since yours is installed incorrectly, there is no way to tell if you are getting air "sucked" into it, or it is just normal air being released from the water. Air does not LEAK INTO a system. It has to be sucked in by a vacuum or pumped in by a compressor so the way the auxiliary tank is reconnected, OR any valves, is not the source of the air.IF they were leaking water would come out, but air could NOT get in.

for the OP:

"... on the feed side ..." is correct

HOWEVER

it refers to the feed side of the heating loop itself NOT the feed side of the boiler

in other words 'on the feed side' would be the outlet FROM the boiler TO the radiators (also known as the supply)

the above diagram IS correct for ANY brand of equipment

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

It would be an unusual boiler where you could install a 1" or 1 1/4" air scoop or air elimiator on the water "feed side" to the boiler, so the expository comment would be irrelevant.



Edited 1 times.

the radiator return piping is obvious to US but some of our nomenclature may be foreign to a DIYer



==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Then maybe he should NOT be doing the revision that is needed.

our nomenclature is, however, confusing even to 'pros'

eg.

expansion tanks

vs.

compression tanks

.

.

let us NOT start the debate



MERRY CHRIST MASS

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

You are picking at nits. A compression tank IS an expansion tank. The water COMPRESSES the air, and it absorbs the EXPANSION by compressing the air further.

So true, Brother