Does this look right to you?

[That1Guy]

OK, my question is about my house boiler/furnace. It's a weil McLane "boiler" but water temp is right at 180*F so... no boiling in this boiler. My issue, or question, is about the air separator (or lack thereof) on this home boiler. It does technically have a separator but it is basically useless because of where they located it in the system. Again, keep in mind these are my NONPROFESSIONAL opinions so whatever that's worth. And yes, I did try the search option but didn't really come up with anything usable....

You can see in the pictures below that the air eliminator is between the fresh water valve and the rest of the boiler. As new water is introduced to the boiler, it passes the combo check valve / pressure relief valve, past the pressure reducing valve, past the shut-off valve and into the Tee where the air separator is. Unless I'm mistaken, the water will only pass by this separator one time - as it first enters the boiler - and never again.

It seems like there should be a big ol 4900 series eliminator installed in the 1" pipe coming out of the top of the boiler, past the Tee for the control box, past the valve and elbow where it turns horizontally. In the short horizontal section of pipe, I'm seriously considering tucking an air eliminator right there. The small OE eliminator has been sticking open and causing a lot of corrosion. I dropped the ball this past Spring and didn't clean and grease the boiler when I took it out of service - my bad. As I was looking it over it occurred to me that it's no wonder there is always air in the system since the water only passes over it once with this current setup.

I am replacing 3 of the zone valves because our water is so hard and mineral dense, these valves don't last but maybe 10 years if I'm lucky. Since I'll be sweating new valve housings on, maybe it'd be a good time to introduce a real air eliminator to this system while I'll have it apart anyway. Again, I'm no professional and I know just enough to be dangerous - but I do enjoy doing the DIY thing whenever possible - whether it saves me money or not. I just like DIY. I just wanted to hear from others to see what all ya'll thought. Maybe there's a reason for such a poorly placed eliminator - I dunno. On some of the slat-finned registers, the elbows have a tiny bleeder valve that is all but useless. Of the countless times I've used these bleeders, seldom has there ever been any noticeable air bled off from these bleeders. Even so, I drain them every year - very frustrating.

So, looking at the pictures, can anyone explain this setup for me? Maybe it's nothing, but maybe it's something after all. I just dont want to add an air eliminator if it's going to either reduce the efficiency or have no effect at all. Either of those situations is a big waste of time and money.
Maybe it's not supposed to have an eliminator - I dunno. Any input is appreciated.

 

[PoorUB]

That is an air eliminator. It is not the best place, but it should work. Any air that makes it to the boiler should get expelled. Not much different from having it in the pipe some where. You can add another any where in the system if you like. Best on a straight run of pipe, away from an elbow.

If you are replacing the zone valves I would put in a good air eliminator, something on the line of a Spirovent ,These are all I installed for years. Avoid installing anything right over the boiler that may spit water out from time to time. It just makes a mess like you have now!

 

[That1Guy]

My point about the original install location is that it will NOT work as the water only goes past the "eliminator" once - ever! All the air that comes out of solution after hitting the boiler will just be caught in the system forever as it has been doing since it was installed - except for the few tiny microbubbles that get vented via the elbow bleeders twice a year. Not even so much as an up-pipe on those elbows to collect the air until it's vented - totally useless.

 

[yeldogt]

I would try and hunt down the manual for the boiler ....... see how the manufacturer wants things piped.

Where is the safety valve --- T&P valve for excess pressure/ temp ?

What you really have there is a "vent" ..... any air in the system will bubble to the top as it goes through the boiler and find its way to the vent. I agree it's not the best location as it may not be in the best spot on the boiler to get any air. It is open to the system -- these is where the manual would help if it shows air elimination at that location. My fear is it looks like a nice spot for the T&V valve .. and I;m nit seeing one.

Old time boilers used a scoop type air eliminator --- it's just a cast iron hunk with an internal air foil design. As water flows through it -- the water sloes a bit as it enters the larger pipe and any air will go to the top and be vented --- they have vent like you have on that pipe,

One of the biggest problems with older setups is the pump. In the USA the pump was placed on the return ... not the best spot. Ideally you want the pump on the supply "pumping away" . Check to se where yours is.

Today --- your boiler would have a Spirovent on the supply pipe out of the boiler -- then it would go to a modern "smart" pump and then to the zone valves. The pump would understand when valves open and close and adjust flow. the spriovent would be getting the hottest water from the boiler (best place to remove air) . The Spirovent has a fitting for the expansion tank. The expansion tank sits at that spot and works together with the pump. We get into fluid engineering. Most times you place a tee at the expansion tank and use that for the water feed.

Prior to cutting and starting any changes -- I would do a full review.

 

[PoorUB]

My point is all the water for the heating system goes through the boiler. Air should rise to the top of the boiler and escape through the air vent, but depending on how the boiler is sectioned off, maybe not.

Add another vent if you like, it will not hurt anything. If you have had trouble with air in the system the existing air vent is not doing the job.