Check Valve on " Air out " and extrol tank ??

Rick143

Hey guys, I just had a boiler installed and they put 2 check valves on the extrol tank and on the air vent " to be able to quick change them out ".. Is this a common practice ? The thing that worries me is I didn't hear any air come out of that vent at all and my system still has air in it even after purging several days ago. The tank doesn't seem to be expanding with the heat pressure as I can feel no heat on it like before they did this. In my mind, in order to make the check valve work there must be something pressing against it to open the valve but there isn't so how can it work ??

hot_rod

A very nice addition and the next person that works on the system will appreciate them being there.

What even vent, or connection you screw into those service checks will push open the valve.

Here are a couple examples.

I'm not a huge fan of the cast iron air scoops for efficient air removal, and that float vent will only release air when it fills the chamber, it is not a constant release.

Does the system sound quiet and air free when you heat it up?

Jamie Hall

Er… um... a check on the expansion tank? No. An isolation valve, perhaps -- that is nice to have -- but a check valve? No. Consider that the whole purpose of the expansion tank is to allow a small amount of water into the tank when the system heats up, and to let that water back out when the system cools off. There is no way to install a check valve without defeating one of those two purposes.

Sorry about that.

Rick143

@ the boiler yes but not through the system, that's the problem. I purged it my self also and also tried doing the vents on the rad elements. Seems like when the pump kicks on I hear a quick surge of water like something flushing for a short moment.

EBEBRATT-Ed

Get those check valves out now.

A check valve on the expansion tank defeats the purpose of the expansion tank.....in effect you have no expansion tank.. water needs to move back and forth between the tank and the system.

The one on the air vent is not going to do any good. Installed backwards it will not allow the vent to work no air will get out. Installed with the flow toward the vent it will restrict the ability to vent and will not allow the vent to be changed with the system pressurized

Rick143

I thought so !!!!! That's why I have so much air !! Thanks guys !

leonz

Think of it this way, The expansion tank allows the water under low pressure to expand. The bladder with the air charge expands with it and it cannot contract with the check valve in place. The water cannot exit the expansion tank and reenter the system to add the small amount of water back into the system.

The automatic air vent may not be able to fully vent the air bubbles in the hot water.
The check valve spring is the resistance in the system that will limit or stop the air bubbles from entering the automatic air vent.
The automatic air vent uses a simple weight on a hinge to counter the water pressure in the system.
The automatic air vents ballast weight is enough to allow to allow the small micro bubbles to exit the water flow that enters the air scoop that naturally rises into the air chamber in the air scoop. Any trapped air in the riser portion of the air scoop casting then enters the automatic air vent or can be fed into an airtrol valve at the base of a steel compression tank that has a 1/3 air 2/3's water volume in the steel compression tank.

I have a B+G Internal Air Separator(IAS) combined with an airtrol valve and the 15 gallon steel compression tank to control the air that is in my system.
The steel compression tank just sits there hung in the ceiling silently doing its job of letting the airtrol valve plumbed into the bottom tapping of the steel compression tank.
The steel compression tank uses the available heat in the system to allow the air bubbles to enter the cooler water blanket in the horizontal steel compression tank and then dissolve slowly as the water that came in with it cools down.
Eventually the cooler water drops by gravity back into the system as needed to add water and pressure to the system without a bladder as the system continues to removes the microbubbles in the water stream.

You should remove the check valves and add back long pipe nipples and reducing bushings to allow you to use 1/4" ball valves to isolate the automatic air vent and the bladder tank under the air scoop so that you can replace the automatic air vent as it will fail and need to be replaced eventually.
If you do the same thing for the bladder tank you will be able to change the bladder tank if it fails without shutting the system down and allowing it to be drained out to avoid having a huge mess of water to deal with and clean up after.



.

Rick143

leonz said:

You should remove the check valves and add back long pipe nipples and reducing bushings to allow you to use 1/4" ball valves to isolate the automatic air vent and the bladder tank under the air scoop so that you can replace the automatic air vent as it will fail and need to be replaced eventually.
If you do the same thing for the bladder tank you will be able to change the bladder tank if it fails without shutting the system down and allowing it to be drained out to avoid having a huge mess of water to deal with and clean up after.



.

Thank You so much for that info !! Could you please tell me the parts/sizes I would need to do this by looking at the pic I have or would you need another ? Thanks again, I knew in my gut this wasn't right and they told me they put them on EVERY system they install !!!

hot_rod

Gentlemen, those are not check valves, they are called "service checks", maybe not a good name. Look at the pic I attached above.

They open, as shown when you screw the tank into them, or an air vent. They close when you remove the tank or vent for service.

We sell 10's of thousands of them and some wholesalers order and stock all their air vents with that option. They also are included in our Boiler trim kits.

They are also included in all solar expansion tank kits. The solar ones do double duty, the isolate the system and also trap pressure in the tank so you can take it outside to relief a water logged tank.

I prefer them to ball valves as some un-knowing person can turn off a valve. Remove handles if you use ball valves to isolate tanks!!

Rick143

hot rod said:

Gentlemen, those are not check valves, they are called "service checks", maybe not a good name. Look at the pic I attached above.

They open, as shown when you screw the tank into them, or an air vent. They close when you remove the tank or vent for service.

We sell 10's of thousands of them and some wholesalers order and stock all their air vents with that option. They also are included in our Boiler trim kits.

They are also included in all solar expansion tank kits. The solar ones do double duty, the isolate the system and also trap pressure in the tank so you can take it outside to relief a water logged tank.

I prefer them to ball valves as some un-knowing person can turn off a valve. Remove handles if you use ball valves to isolate tanks!!

Thanks for the reply @ hot rod, are you absolutely sure that's what they are ?? Because the expansion tank doesn't get warm at all like it used to, I could tell before at least 1/4 of the tank would be hot and have water as I could knock on the tank and tell the density that water was there but not now with this setup, and I cant get the air fully out of the system.... something just doesn't seem right.

STEVEusaPA

Yes I agree with @hot rod. Everyone who now realizes it's not an actual check valve will (should) make the correction.
The tank shouldn't get warm at all.
Knocking on anything to determine volume is... (you pick the adjective).

leonz

I take it that the plumber did not leave any literature about these valves with you?

FWIW, The water side of my old amtrol expansion tank always warmed up when the system was hot.

I guess it will be up to Rick143 whether he leaves them in or not.

Before you go to the plumbing supply warehouse be sure to check and see if the automatic air vent has been closed.
If the cap is fully tightened the air vent is closed and will not release any trapped air(if there is any trapped air).
Let the heating system work for a while and then decide whether to remove them.

I hated spending $20.00 a year to replace the two failed automatic air vents I had and now I do not have any nor do I have air locking in my system anymore.

Jamie Hall

Aye, well the OP said "check valve" and I took them at their word. Sorry...

Rick143

leonz said:

FWIW, The water side of my old amtrol expansion tank always warmed up when the system was hot.

Yes that's what mine did on the old system also, as it expands water is allowed in and it will get warm where the water is in the tank and you can tell Density knocking on the tank from bellow the bladder and above the bladder if water is in there the sound will change from hollow to dense.
I made sure the cap was loose on the top vent.. I may hold off as you suggest and see if I can purge more of this air out myself over time.. I just hope that's what these are on my system.

hot_rod

The expansion tank may or may not get warm, depending on system volume, temperature differential and what the pre-charge and what the system cold pressure was.

It could be the old tank was under pre-charged so it always allowed some water in?

What does the system pressure read cold, and at high temperature? It should vary a few psi, if it approached the 30 psi relief setting either the tank is too small, waterlogged, or not pre-charged properly.

If the tank were to get hot every time the boiler ran, it would be a radiator Probably not where you need or want a radiator.

Rick143

@ hot rod The boiler pressure seems to be steady under both circumstances. So I would assume if the service valve were blocking the expansion to take place I would have a much higher reading at operating Temp ?

hot_rod

Rick143 said:

@ hot rod The boiler pressure seems to be steady under both circumstances. So I would assume if the service valve were blocking the expansion to take place I would have a much higher reading at operating Temp ?

Exactly! If the tank was not "seeing" the system you'd probably pop the relief valve.

EBEBRATT-Ed

My bad. Should have known that @hot rod would know. What I thought was a bad idea now seems genius. learn something new every day

hot_rod

Service checks are not at all new.

Many hydronic manufacturers have offered them over the years, still do, 20 maybe 30 years now?

Honeywell Braukmann built them into some of their air vents, 1/4 turn to activate, allows the vent to be disassembled. Those got turned off by mistake often.

Maybe the original design was Italian, or they produce them for other brands as OEM

STEVEusaPA

I'd add, if you install one, you should hang a tag on it to let the next tech know.

hot_rod

STEVEusaPA said:

I'd add, if you install one, you should hang a tag on it to let the next tech know.

Good advice to label it, not many would identify what it is doing or capable of.

We build a ball valve with a spring check inside, that really throws troubleshooters for a loop