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.

likablenap

https://forum.heatinghelp.com/discussion/comment/1729782#Comment_1729782

So I did call amtrol as I ran into this same issue, hopefully someone finds this useful. I need about 4.5gal of expansion in my system it currently has an EX-30 on it, and I'm gonna need to goto EX-90 as the 60 won't cut it.

TLDR EX-60 is for 3 story houses and EX-30 is good for 1-2 story houses.

The person at Amtrol said it is not a typo but the EX-60 is good for higher pressure systems whereas the EX-30 is good for lower pressure systems that need similar acceptance volumes. He said low is 10-12 PSI, and 15 or more would be high. He also said they used to have something between the 60 and 90 but it didn't sell well so they don't make it anymore.

So to breakdown what he meant and why the EX-60 would be good for a higher pressure systems I'll my own system as a data point. My system needs to be at 16psi, 30ft of rise +3psi for the inducer pump. I need 4.5-5gal of expansion volume but assume I only needed 2gal which is in the acceptance range of what both the EX-30 and EX-60 can do.

So using ideal gas P1*V1=P2*V2 we can estimate the system pressure at both cold P1 and hot P2.

P2 = 16psi*V1/V2

For the EX-30 V1=4.4gal V2=4.4-2=2.4gal so P2 = 29.33 psi which is really darn close to the pressure relief valve setting on a residential unit. Now imagine if you needed just a bit more expansion, it'll still expand into the tank but you'll exceed the 30psi limit, and have leaking.

For the EX-60 V1=6.7gal, and V2=6.7-2=4.7gal so P2 = 22.8psi which is well within the limits of a residential boiler unit.

Now if I only needed my system at 12psi cold, then with the EX-30 my pressure is only 22psi which also works fine.

So to sum it up if you have a 3 story house and you only need a couple gallons of expansion use the EX-60 if you have 2 stories or less and the same expansion needs use the EX-30.

hot_rod

You can gang multiple tanks together. Two #30 tanks will be more expansion than the #60 and less $$. Just be sure to pre-charge them both the same.

Here is the deal on the #60. The upper most ring is where the diaphragm is crimped inside the tank. So both the #30 and #60 have the diaphragm in the same location. So the same acceptenance.

The two weld spots shows where the extra ring is welded in the #60, maing it longer, more air space, compared to the #30.

The #60 has a much larger air space. While acceptance is the same, pressure increase will be less, or slower due to the larger air cushion.

Screenshot 2024-10-16 at 3.30.10 PM.png

likablenap

I considered ganging up two 30's but it seems like a pain, it'd require redoing plumbing vs just installing the bigger tank in the same spot. It also seems like more of a maintenance headache to make sure they are both charged to the right pressure.

JohnNY

Back in the '80s I took all the I=B=R courses that came around. We used to spend the whole time (2-3 days) doing manual calculations for heat loss, fin-tube lengths, total developed head, gpm, and expansion tank sizing. We students were often surprised at how frequently the number 15 expansion tank would meet the system's requirements. Since then I am very conservative with my tank selection and I can't recall ever having regretted it.

JUGHNE

I recall reading on one of Dan's books that there were some old systems with no expansion tank.

The top floor radiators were not completely bled of air. These were the expansion chambers.

You lost some expansion area by bleeding the upper rads. That may have made the difference.

delcrossv

leonz

Speaking as a novice homeowner;

Your home probably had a hand fired coal boiler that used the radiators as part of the compression system by maintaining an air charge in the radiators.

I agree with Alan from California Radiant that the previous owner added the baseboard.

Your boiler needs a lot of work, the near boiler piping should be stripped back to the boiler and replaced with black iron pipe and the proper sized piping and the circulator layout should be installed to pump away from the boiler. You need a separate low water cut off switch.

I am not sure if the pressure relief valve should be plumbed the way it is with a circulator pumping water by it into the boiler.

The boiler needs to be examined more closely to see why there is rust above the burner mounting plate. You may very well have a bad flange gasket that is leaking exhaust gas and causing corrosion.

A steel compression tank with a gauge glass would be ideal for your system as it would have 10 or more gallons of water to maintain the point of no pressure change and a much larger air cushion of 5 gallons of air or more. You could pipe it from the vent tapping in the air scoop to the tank at a longer distance away allowing for a more gradual slope to the airtrol valve under the tank but only if the tapping in the air scoop is 1/2".

You could reuse your air scoop to divert the air bubbles into the steel compression tank with an amtrol valve very easily if the tapping is large enough.

I would not add a second amtrol tank in the short term UNLESS you supported the two tanks by using a Tee'd connection with longer pipe nipples that were secured to the adjacent piping to hold them up using pipe strapping.

I would suggest that you invest in three of Mr. Holohans excellent books on hot water heating which are "CLASSIC HYDRONICS", "PUMPING AWAY" and "HOW COME" from the heating help bookstore as they would be the books you need to solve your boiler and heating issues.

delcrossv

Don't even needs a sight glass in the tank.. Just a compression tank and an Airtrol tank fitting out the top of your scoop. Note Airtrols take 3/4" out of the scoop- 1/2" into the tank.

EdTheHeaterMan

@leonz said: Your boiler needs a lot of work, the near boiler piping should be stripped back to the boiler and replaced with black iron pipe and the proper sized piping and the circulator layout should be installed to pump away from the boiler. You need a separate low water cut off switch.

The three points listed therein Not actually needed. As a seasoned professional I have connected many Hot Water boilers with copper. I wouldn't do a steam boiler in copper, but a water boiler is always done in copper inless someone wants to build a specific manifold with some strength to support several circulator pumps or other specific assemblies. I have often started the first fitting out of a water boiler with a copper by male adaptor.

A circulator pumping away from the expansion tank that is located on the supply pipe is also not a necessity. I have worked on 50 year old boilers where the expansion tank of any type was connected directly to a return pipe and the circulator. Others where the circulator was installed on the return pipe. Some of them were put on the return by the manufacturer and pre-wired. And finally the LWCO that may be built into that Aqustat Relay is all that is needed to pass inspection. I was never a fan of that Hydrostat/Beckett control but it was a correct way to do the job.

And the fact that this original post was from December of 2022 makes me wonder where this new found interest is coming from? I am sure that @ryan242 has moved on to more important stuff by now like adding dish soap to the boiler water, or operating 2 circulators with one thermostat.