Need to replace leaking expansion tank. (Pictures included)

[hoboyobo]

I noticed my expansion tank was leaking over a week ago and have just had a bucket under it to catch the water. I was hoping to replace it myself and purchased the same Fill-Trol 109 Expansion Tank With Fill Valve (2.0 Gal Volume). I am not sure how to cut the water supply so I can actually swap out the tank. I have attached some pictures of the system. Any advice or suggestions would be welcome. I am on a very tight budget so I would really like to do this myself.

 

[Dana]

How good are your plumbing skills?

While it's in a topologically reasonable location relative to the pump (it's pumping away from the expansion tank, right?), hanging it horizontally is a recipe for early failure, since it has the vibration of the pump and the moment-arm lever of the tank imparting significant stress at the tee.

There appears to be enough room that if you moved the pump to the far end of horizontal pipe it's pumping toward currently it would be possible to install it hanging vertically, preferably on the underside of an air-scoop with a vent, with at least 6" of straight pipe on both sides of he air scoop:

If that's not possible, putting the expansion tank on the return side of a cast iron boiler isn't a disaster, since the pumping head of cast iron boilers is pretty small and isn't likely to induce cavitation at the pump impeller. Even if you have to move it over to the return pipe to the boiler to get it to hang vertically it would be better than where it is now, since by hanging on it's side like that it's guaranteed to fail again.

But first you'll have to figure out where the valves are that can isolate the tank from the rest of the heating system so that you don't drain the whole system to swap out the tank, and read up on how to purge air from the system once you've buttoned it all back up. If you end up re-plumbing the tank & pump locations, it's worth installing a ball valve on both ends that run so that you can easily swap out or re-charge the tank, or swap out the pump when it eventually fails.

When the pump fails there are some pretty good ECM drive smart circulator pumps that would use less than half the power that Tac0-007 or whatever uses. They're twice the money, but pay for themselves in power use within a normal pump lifecycle. The pump looks pretty fresh compared to the rest of it, so it might be awhile. It may be worth swapping out ahead of time if your electricity is more expensive than average.

 

[Sponsor]

 

[BadgerBoilerMN]

If you are having trouble taking the XT off you may want to reconsider re-piping the system. A good idea, just not a DIYer.

The pump is ahead of the expansion tank. Have it removed and re-pipe the XT upstream of the pump. If you have to move them both to the one side or the other of the boiler, so be it.

You have now and will always have "air in the pipe" until you have the boiler piped as Dana's illustration suggests. It is most likely that your tank is rusted out from the oxygen available, entrained and not.

I would installed a separate fill valve and connect between primitive "Air Purger" and new XT.

 

[hoboyobo]

Thank you both for your advice and honestly I would not want to attempt any re-piping by myself. I am just really short on cash these days and was hoping a temporary fix would be to simply swap out the expansion tank. I picked up the same model for about $50. From the pictures would I be able to just turn off the power to the boiler, and turn off that red ball valve right in front of the expansion tank and unscrew the old tank and screw on the new? Looking at the system I just can't see where to turn the valve off to isolate the expansion tank.

I do get air in the pipes and have to bleed the system this time of year. Once my kids are out of daycare I would love to get a plumber in and repipe the system and fix the problem more permanently.

Thanks again. I realize there is a right and wrong way to do these things but hopefully you understand my position.

 

[Dana]

I'm not sure exactly what that red handled valve is, but what it ISN'T is a ball valve. I doubt that it's capable of isolating the tank, since it's hooked up to both the boiler (which isn't isolated), and the system plumbing (which isn't isolated.)

There is usually other valves in the near-boiler plumbing to be able to isolate at least some of it so that you don't need to drain down the system to work on things, but your pictures are less than complete.

BTW: BadgerBoilerMN has it right- looking at the orientation of the shiny-new pump, it's pumping toward the expansion tank, not away, which can reduce the lifespan of the pump. Whomever replaced the pump SHOULD have corrected the near-boiler plumbing, but as a quick swap on a tight budget that error may have been ignored (assuming they had a clue in the first place, which isn't always a good assumption.) DON'T just flip the pump around when swapping the tank, since that would screw up the boiler, and boiler efficiency, which is designed with a preferred direction of flow.

When re-plumbing, make sure that the pump is in a straight line from the pipe from the air-scoop/expansion tank, not pulling against a right angle turn. The turn in the plumbing induces turbulence, which increases the amount of cavitation at the pump impeller, reducing pump life. You'll get better flow and longevity out of it if you follow a few simple rules.

 

[hoboyobo]

The new pump was put in last year under the same circumstances that given the budget we would just fix the part that is causing the problem. When I was at the plumbing supply store they were telling me similar things about the XT being in the wrong place and that the system should be reconfigured. I would definitely want to get a professional to handle that.

I would just really like to unscrew the current tank and pop in the new one, stop this leak and then plan to get the system reconfigured in a year or so. Do you think that is possible? I looked for valves on the other side of the boiler but I cannot see any.

If the system is cold (off) and the water pressure is stable would removing the tank cause water to pour out of the connection or is there a pressure valve that would close that connection until the pressure in the system rises? Hope that makes sense.

 

[Dana]

At the very least turn off the fill valve to the boiler, and any other valves you can find anywhere on the system. Be prepared to get wet/mop-up and be prepared to purge the major air from the system. This should not be done with the system on, or with the boiler still at temperatures above 115F (to limit scalding risk.) Worst case you drain the system down to the level just above the tank using that hose-bib port visible in the picture of the tank, just above and to the left of the valve with the red handle. Turn both the power and the gas off to ensure there is no WAY it can fire up while the system is open.

Don't just assume the plumber re-configuring the system knows what they're doing either. Print out the image of the pump and XT location, and mark it up with minimum distances. You want a straight 6"-12" between the expansion side and the sucky side of the pump, and at least 6" (more is better) to the nearest ell or tee on the input side of the air scoop, since turbulence hampers it's efficacy at removing air from the system.

 

[BadgerBoilerMN]

And don't forget the teflon tape!

 

[hoboyobo]

Thanks for all your advice. I will hang on to the diagram and what you said so I can show it to the plumber when I am in a position to have the work done.

Thanks again.

 

[Terry]

I will add my picture here too. Sometimes the rubber bladder leaks and then water can get to the steel tank from the inside. Eventually it can rust through, normally starts with a pinhole leak.

It's why I always replace the expansion tank with a new water heater.

 

[Reach4]

Eventually it can rust through, normally starts with a pinhole leak.

Date code Thursday, February 24, 1994.

 

[Terry]

Date code Thursday, February 24, 1994.

1994? The water heater was 2009. How funny. That lasted a lot longer than most. The condo was built in 1994.
The sad part was when I picked up the new tank, and I felt like I should pick up two in case one was bad. My logical self made fun of me and I only got one. I go to the job, and it only threads part way down and has a small weep. I cut out the female adapter and solder on a new one. Same thing, still leaking. I drive down to Issaquah and pick up a second tank, run back and this one threads down into the fitting much better and holds. Premonitions.