Amtrol expansion tank size

ryan242

I think I may have just wasted my money on an extrol ex60 expansion tank. I originally my system had an ex-30 on it when I moved in here, my house is a ranch house with cast iron radiator and baseboard, when it would get extremely cold the boiler would run enough to bring it up to high limit and the relief valve would pop, I narrowed it down to an undersized expansion tank and changed it out to an ex-60 but looking at the specs, it says max acceptance volume 2.7 gallon vs 2.5 for the 30, so barely a difference? Am I correct on this? Seems like it stil builds pressure just as much as before, I guess I should’ve went with the ex90? I don’t understand the minimal difference between the 30 and 60, what a waste of money 

EBEBRATT-Ed

your right never noticed that. You should check the bladder pressure before installing they are supposed to be pre charged to 12psi. Has to be done with no water pressure on the bladder

hot_rod

You can put multiple tanks together if you still have the #30

Alan (California Radiant) Forbes

My guess is that it's not a problem with the expansion tank. It has to do with the pipe and fittings between the expansion tank and the system as sometimes a clog of debris between the two will prevent the system from "seeing" the expansion tank.

Take some pictures to show us how the expansion tank connects to the system.

Mad Dog_2

Yes. There is a big jump in physical  size when you jump two sizes.  Don't beat yourself up, like Hot Rod said, gang up two of them.  When in doubt, I go the next size up - it will never hurt.  You might want to dial down the aqaustat a few notches - you shouldn't be popping the relief valve even at the top end.  Mad Dog

Alan (California Radiant) Forbes

Very curious:

So, the tank holds more water, but the volume on the air side of the bladder is the same? It seems an unnecessary model.

BTW, how may square feet is your house?

hot_rod

Yeah, why build a 7 gallon tank for that small acceptance?

ryan242

My house is 1400 square feet, I have cast iron baseboards in 2 rooms and cast iron radiators in the other 5 rooms, I did lower the high limit from 180 to 170 so maybe that will help, it’s not real cold here now so I’m going to wait until next week when the temp drops again and see how it does, I did also bleed some air out of 2 of the upstairs radiators so maybe that will help too

Alan (California Radiant) Forbes

The EX-15 tanks should work for you.  Something else is going on.  Some pictures would help. 

ryan242

A couple quick pics of it that I took, the primary circuit has the black taco circulator on the return, that’s what feeds the 5 large radiators and then the secondary circuit which is teed in on the relief valve port has the red grundfos circulator on the supply with Pex tubing to feed an addition to the house that has 2 Burnham base ray cast iron baseboards on it

Alan (California Radiant) Forbes

So, the radiator circuit is pumping water toward the x-tank and the BB circuit is pumping away from the x-tank. Pumping away is good for pressure stability; pumping toward is bad.

Did you get a lot of water coming out of the air eliminator when you changed out the x-tanks? I would remove the x-tank and make sure that there's no buildup of corrosion inside the bottom of that air eliminator.

It looks as though the previous owner added the BB. And it looks as though the installer took the easy route as both heating loops should come off the copper main after the air eliminator.

Do you have a home warranty plan that you got when you purchased the house? Or any recourse with the previous owner to fix something that is a problem now?

EBEBRATT-Ed

Someone should call Amtrol. I am betting that is a TYPO

ryan242

Alan (California Radiant) Forbes said:

So, the radiator circuit is pumping water toward the x-tank and the BB circuit is pumping away from the x-tank. Pumping away is good for pressure stability; pumping toward is bad. Did you get a lot of water coming out of the air eliminator when you changed out the x-tanks? I would remove the x-tank and make sure that there's no buildup of corrosion inside the bottom of that air eliminator. It looks as though the previous owner added the BB. And it looks as though the installer took the easy route as both heating loops should come off the copper main after the air eliminator. Do you have a home warranty plan that you got when you purchased the house? Or any recourse with the previous owner to fix something that is a problem now?

Yes water poured out of the eliminator when I changed tanks, I tried to be as quick as possible so I didn’t lose much water. And no I have no warranty or anything and I’ve actually lived here for 6 years now, really the system worked fine when the weather is of normal low temps for around here, it usually only gets down into the high teens at night. So the boiler will only reach around 140-150 to maintain the set temp in the house, just last week we had a record cold few days where it got to -5 out for an extended period of time with 30 mph winds and it had to run quite a while longer which brought it to the high limit of 180 and that’s when I noticed it opened the relief valve briefly 

Paul Pollets

As Alan said, you're pumping towards the expansion tank which will cause air bubbles at the ends of the runs. The air purger also does not have the minimum distance (16") required to the inlet. The boiler fill should also be piped to the location of the expansion tank. I would repipe the zones to the supply header with the pumps pushing away from the expansion tank, replace the air purger with either a Caleffi air/dirt mag seperator or Spirovent and relocate the boiler fill. You won't have air problems or pressure rises. Dan's book "Pumping Away" describes the reasons why. The near-boiler piping errors are common and the cause of continuing grief.