Expansion tank

George76

Hi my contractor install the new hydronic boiler. He installed an air separator. It has the old steel bladderless x tank with no Airtrol air eliminator. The tank is water logged and my pressure is up to 25 pounds per square inch. I heard it's better to not have an air separator which he installed with the old style x tank. Should I leave the separator and put in new bladder tank or install a b and g eliminator at the tank and keep old tank? Pumps are at the return side.

George76

Attached please see the connection to old x tank connection(missing Airtrol fitting), boiler room piping, and supply side piping(air separator and x tank branch). The installer is coming tomorrow. Thanks for your advice.

Jamie Hall

Well... you can either install a new, bladder type tank and keep the air separator, or you can get rid of the air separator and keep the old expansion tank (recharge it properly!). Take your pick..

mattmia2

You either need an air separator that returns the separated air to the conventional tank or to replace it with a bladder tank. If I were replacing a boiler, it would remove the conventional tank and install a bladder tank and microbubble air separator.

HomerJSmith

Yes, replace the bladderless tank with a bladder tank. Either a Fil-trol 110 or Extrol 30 depending on current setup.

hot_rod

You could also run a tube from the air separator up into that steel tank to turn it back into an air management system.

But I too would go with a diaphragm style tank. It will be much smaller and less hassle.

HomerJSmith

"hot_rod", you can also hook up your horse to a buggy. Steel tanks had its day. There was a valve that did exactly that, add air to the steel tank.

Since I can't remember whether I had breakfast this morning, I can't tell you what the valve was.

George76

Thanks for the advice!

The installer said he's gonna drain the old x tank and see if a new one will even fit in the available space.

He didn't really seem to understand the disadvantages of having both an air purger and an old x tank(the purger will purge air in tank and waterlog it after a while). Is this always the case, or just a rule of thumb?

He also said he will drain the x tank and drain the system a little bit to get the pressure down. I told him tank doesn't have isolation valve-- he said he could do it anyway. <--I guess he'll probably just recharge it and close drain valve before it refills.

hot_rod

Well if he is willing to learn...
This book explains the difference between air management and air elimination systems.

Tinman

Bladder tank w air separation.

George76

I saw something that said B&G Airtrol never worked that well. I think I'll remove drywall and remove the old tank and put a bladder tank there if it doesn't fit under ceiling. The air separators already on there so hopefully this will work well with it.

Now I just have to figure out what the Public works guy is referring to when he asks for test results on the backflow preventer. He says it's for EPA compliance. My HVAC guy says hes not aware this is something that is typically and even his supplier has no idea how to test it.

JUGHNE

New boiler, new air separator and probably a new bladder tank....but the pumps are still on the return side?

If you have cast iron rads it is easy to install a bladder tank that is too small.

How about pictures of your new installation showing the old tank also if possible?

mattmia2

Normally boiler water is considered low risk, it isn't dangerous to human health so the backflow requirements aren't very strict, it is usually just a double check backflow preventer. Backflow preventers designed for system containing water hazardous to human health like a water powered sump pump or a lab have a test procedure and test ports and usually are required to be tested on a schedule by a licensed plumber and a certificate of compliance signed by that plumber.

hot_rod

More and more cities and public water providers are requiring testable back flow devices. We had the City of Milwaukee back flow inspector do a webinar for us recently. They are very strict on testing yearly and fines for non compliance, both commercial and residential.

Their concern is someone, someday might put a toxic fluid in a boiler or any system direct connected. Like EG by mistake, or on purpose!

A backflow on the supply to a building protects the public system, that will always be a testable device. A BFD on the boiler protects everyone in the building.

More and more we see installers using fill tanks instead of fill valves. The yearly inspection fee, $150.00 or more goes away and you can better monitor boiler intake

George76

@hot_rod Thanks. Talked to the city official. He recommended some certified testers/plumbers in the area. I dont think he put antifreeze, I don't think it gets cold enough in Chicago and building doesn't go unmonitored for extended periods of time obviously.

@JUGHNE The rads are all baseboard fin type. Copper piping. So hopefully can get away with a reasonably sized bladder tank.
Attached are photos of entire boiler room, connection to rafter-hung expansion tank, and area above boiler. I think the 1-yr old cast iron boiler has about 7 sections.

Thanks again.

mattmia2

The antifreeze is usually polypropylene glycol with nontoxic additives for this exact reason.

you calculate the needed tank volume from an estimated system volume. a bladder tank can be much smaller than a conventional tank for a given system size.

If it is the city of chicogo i can see them having unusually strict cross connection requirements (although i think they were still installing lead services in to the 80's)

JUGHNE

That is a busy corner there.
Is the copper connected to the top of the boiler (and it looks like the only supply out) the same size that all the zone valves have connected to them?

A new expansion tank would usually connect to the bottom of an air separator. Although there are better air separators than that one. The tank can be piped away to anywhere in the room.