Per the advice of this forum, I purchased a B&G inline air seperator for my boiler system. I am getting all of the parts together, along with a plan of attack for the installation process. the one thing in which I noticed, is that in a conventional system, the expansion tank pipe needs to connect to the top outlet on the air seperator. This is where the question occurs. What needs to be done with the outlet from the boiler that currently connects to the expansion tank?? Can it simply be capped off, or does something else need to be done with it???
IMAG0062.jpg picture by cheinemann_605 - Photobucket

While looking at this picture, there are two pipes that go from copper to steel connections, that go down into the boiler. The smaller pipe, is the one that currently goes to the expansion tank. What needs to be done with this connection, once the air seperator is installed???
Here is the link to the air seperator that I am installing

Thanks for the advice, it is much appreciated.

 

That small 3/4" pipe coming out of the boiler is there because you have a built in air separator in the boiler When i hook up a boiler like yours i run that 3/4 pipe up and use a 90 degree vent tee, put tank at a horizontal and a auto bleeder straight up in the vent tee. This way it takes the air out of the system. If you are going to move the tank than i would leave 1 foot of pipe coming up and put a auto bleeder there. Or you could leave the tank where its at but put a auto bleeder up there also. Then out of the top of the new air separator put about 1 foot of pipe and a auto bleeder. If you don't have a bleeder on that 3/4 line coming out of the boiler than the air can't get out of the system. Paul

 

the reason in which I bought this particular air seperator, is that I have a conventional type expansion tank. Then by design, the top outlet of the air seperator would go to the expansion tank. Could the line coming from the boiler go into the bottom of this air seperator, then all air would be seperated out, and go into the expansion tank??

 

Disconnect the pipe from the boiler and plug the tee.
The pipe to the tank comes off the top of the IAS to the tank and plug the bottom of the IAS.
Make sure the pipe to the tank is 3/4" and any valves are in the vertical. The valve must be a full port ball valve not a stop and waste valve. The pipe must be pitched uphill all the way. Do not ever install auto air vents on this type of tank application.
Make sure the make-up water is connected between the IAS and the tank.

Look at the lower half of this link
Expansion Tank Information

 

Just wondering why not go to a bladder type exp. tank? Add an air vent there at the new air seperator on top and the expansion tank installs below. Then leave 12" of pipe where the current exp. tank is tied into and add a air vent there.

Mike NJ

 

We all have opinions. I prefer the older style tank as it is a no maintenance tank which lasts a lifetime i,f as anything is applied properly. Never needs drained or air charged. Bladder type tanks require annual to semi-annual checks. You need to drop pressure to check the air charge and than bring the system pressure back up. How do we do that? Most say by adding water back to the system. I disagree we do it by adding oxygen, chemicals and minerals.....oh, that is water.
If we drain water from the system to check pressure on a bladder type tank and it is low what do we charge it with? Air? Hmmmmm.....since most bladder tanks are charged with nitrogen today should we charge again with nitrogen? How do we charge the customer for the amount of nitrogen used? Maybe not use nitrogen lets add air. Air is 20.9% oxygen. The diaphragm is oxygen permeable which means some of the oxygen in our air charge will end up in the system causing rust and corrosion. I guess option two is charge the customer to replace the tank due to being low on charge. Thanks, but I will keep the old steel compression tank when possible.

 

Pretty funny rbeck!

Tires are O2 permeable also. That's why we need to check and add air continuously. Them little O2 molecules can sneak through the tiniest of inter-molecular structures! Many tire shops are now using Nitrogen in auto tires... ever see a tire with a GREEN cap on the valve? Nitrogen in that tire.

So yeah, what are we supposed to do? carry a nitrogen tank on the service truck? Heck no! just do what most service guys do... NEVER EVER properly check/charge the air in a bladder tank! (yes, tongue is in cheek, but it's still a sad fact that MOST tanks are never given a second look until the relief valve opens... on Christmas Eve... Sunday... in a 30" blizzard... it's -10F outside... and it's 3 AM...)

 

so, first of all, I simply want to confirm that the 3/4" line coming from the boiler, that goes to the expansion tank can be capped off??? Secondly, reading the article that rbeck supplied regarding steel tanks, why does the expansion tank isolation valve need to be on a vertical pipe, as opposed to a horizontal pipe??? Is it hurting anything having that valve on a horizontal pipe? I am not sure that I would have enough clearance to add in a vertical pipe to accomodate a isolation valve. Thanks.

 

The reason for a valve on the vertical pipe is due to resistance to flow. A valve is equal to an equivalent feet of pipe. If worst comes to worst put it in the horizontal and try to get a bit more pitch.

Trooper,
Ye is right oh great one.
I just decided to not replace the tanks all the time when I learned as a service manager the benefit of steel compresion tanks. We left hundreds of tanks in place and did not have problems when properly piped and no maintenance.

 

So, I read at the beginning of this thread that the weil mcclain boiler that I have already has a built in air separator? Can anyone prove or disprove this? SEcondly, if it does have a built in separator, I am guessing, that this built in unit is placed poorly, or the unit itself is not that great? What are your thoughts on this?

 

There was a few manufacturers that tries this, using the larger volume, slowing down the water to eliminate the air. It worked just not great so they all eliminated it. I do not know if your boiler has it or nor. Just because the tapping is there does not mean there is an air separator. Many tech's will pipe the tank there thinking it has a built in air separator it is only a tapping for the relief valve.....no separator. If it works so poorly you are better off using an external air separator.

 

As others say we all have opinions. Your set up is fine. Why are you changing anything? If you are having air issues possibly the air trol is not working at the tank. But If you ripping everything apart I would do a bladder tank. Thats just me.

Page 17 on this link shows the water piping for bladder or closed type exp. tanks. Page 23 identifies it as an air seperator. I think they are placed ideally, are still used, and work fine.

http://www.weil-mclain.com/en/multim...1-009_0107.pdf

The boiler air vent is all my boiler has had for 30 plus years. I dont have one of those fancy spirovents and have a bladder type tank.

Mike NJ

 

well, first of all, it appears that lawrosa is correct:

According to the manual for my boiler, it appears that there is an internal air seperator. Which, this unit does work to a certain extent, like you said rbeck, it works ok, but not great. Secondly, I was doing a little looking at the piping going up to the tank. not exactly sure what happened here, but I noticed that the pipe to the expansion tank is level, or slightly below level. I am not sure if this was due to the poor initial installation of this unit, as it was totally screwed up and piped backwards when I bought this house, or if over the years, this old steel tank has started to sag. Either way, the tank probably needs to be lifted, and re anchored, if not also shortening the vertical pipe, so that the horizontal pipe that runs over to the tank is at the correct pitch. But since this fall, after I added some additional piping for baseboards, I have since never been to get all of the air out of the system, and the burners will always shut off early, and it just dont seem to heat my house like it used to. I seemingly can bleed the system until I am blue in the face, but once the system gets hot, and I stand next to the unit, it never fails, I can still hear occasional "swishing" from the air working its way through the lines. On that note, when on the main floor, and second floor calls for heat, I can hear the occasional "bong" as some air must be working its way past a 90, on its way to second floor. It just seems to make sense to me to put an external air seperator in, so that all air will be isolated before it hits the zone piping, reducing the need for bleeding at baseboards etc. It also seems to be the answer to creating a self-maintaining, and maintaince free system. Thoughts anyone??? Is there something that I missed, or am not understanding here?? I ask you guys, since you are the professionals in this industry. Thanks.

 

On a second note, regarding the expansion tank and piping, it appears that the tank may have started to sag slightly, but when I lift up on it, the tank will hit the subfloor, and the pipe going to the expansion tank is still pitched downwards, leaving me to conclude that the initial installation was done very poorly. But since I have to tear into everything anyhow, may as well add the inline seperator, right???

 

Hi paul here. Please pay attention to what lawrosa is telling you. He has taken the time to show you the manual and the manual shows you how to pipe that tank. Leave the 3/4 line coming from the boiler air separator going to the tank. You can fix the line so it does go up hill to the tank. It is ok to put the air separator in you feed line, but put a pipe a foot hi in the top of it and a auto bleeder on the top of the pipe. I sold Weil- Mclain for 40 years. and i have a Mi. 3B boiler license which goes up to at least 10,000.000 BTU in lo and Hi water
pressure, both lo and hi pressure steam. Paul

 

This is ok to do on a steel tank system?.... the way I understood, is that you don't want auto vents on a steel tank system, as they will let all the air out of the system, including the air charge in the steel tank....???

 

No air vents closed exp.tank

Air vents bladder type.

Its what you want to do but follow install instructions...

Mike NJ

 

Correct no auto air vents if using the steel compression tank. The piping to the tank is some of your problem with air elimination. If you install the air separator you will get better air elimination die to the agitation the separator creates.
The reason you hear air after purging until you are blue in the face is all the water you are purging with has oxygen in it. Heat water and drive out the oxygen.
Many tanks are piped from an air separator and the top of the boiler tying the pipes together with a Tee.

 

is there any major benefit to having two connections to the expansion tank like you mentioned?

 

Not really. With a good air separator you will have the same benefit.

 

Yesterday, I did look at the piping going up to the expansion tank. I cut the pipe as seen here:



Upon doing this, I noticed that the tank hangers were loose, tightened them up, and got the pipe at the correct pitch, as shown here:

Now, with it put back together, it appears that the internal seperator is making an attempt to work and air can actually be heard running into the tank. After looking at this, and how it was piped, whomever installed it did a very poor job, or did not care about the quality of the installation. Any thoughts on this?

 

The second pic doesn't look much different than the first?

I think I might be inclined to run it that way for a while and see what happens... maybe it's all you needed to do?

 

well, that is certainly an idea. It seemed like the seperator was working when I first ran the pump, so I will give it a week or 2 and see what happens.

 

No one said they did not work. They do work just not as well as an air separator. The built in air aspirator is nothing more than a small lip in the iron. The thing that makes it work at all is the water in the boiler moves slowly as compared to the piping and is getting heated up.

 

I always thought that the boilers that advertised a 'built in air removal' had a 'dip tube' on the supply out of the boiler that takes the water from an inch or two below the top of the water level... and that the so-called 'air vent' was simply a tapping into the top of the boiler. Air bubbles float up and out the vent pipe, the water going to the system from a few inches below the surface is relatively air-free... yes? no?

 

Just an open pipe to the outside? All the water would come out of the system if that was the case.

 

Who said that?..................

 

Trooper
The cast iron boilers did not have a tube they were a lip and then sloped up to the supply tapping. I will try to locate a picture. The down side of these were the early ones trapped air at the top of the boiler.