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-   -   Old expansion tank leaking (http://www.diychatroom.com/f17/old-expansion-tank-leaking-122817/)

KE2KB 11-08-2011 04:32 PM

Old expansion tank leaking
 
Hi;
I need to replace the expansion tank on my hot water system. It is 30 years old, and has started leaking (drips occasionally, but not an emergency yet).
The tank is an Extrol model 30. There is no valve between the boiler and the tank (should there be a shutoff?)

I am assuming I will pretty much need to shut down the system, cut off water supply, and at least partially drain so that no water comes out when I remove the old tank.

When doing this, should I also replace the air purge valve (it is also 30 years old, and has some corrosion around the air vent on top). That valve is an American no. 700.

When installing the new expansion tank and air vent, should each have its own valve to isolate it from the system when it needs replacement?
That said, if the original ones lasted for 30 years, the next replacement will probably include the entire furnace, and maybe more...

Thanks for your advice

FW

how 11-09-2011 06:49 PM

Shut the water feed off for the boiler, turn off its elect power, shut off any gate valves around the boiler to minimize how much water you'll need to drain, and open the drain valve to reduce the water pressure to 0. Tape the threads of the new expansion tank. Put a towel down to catch the bit of water that will come from the boiler and old exp tank when you switch one for the other. The weight of the fully waterfilled old expansion tank may suprise you. Arrange for a place to rest the old tank upright during the swap so it doesn't drain out over your floor. One off and the new one threaded back on just takes a few seconds.
Some nice systems have a valve that can isolate the exp tank but it's not common.

KE2KB 11-14-2011 09:39 AM

Quote:

Originally Posted by how (Post 767513)
Shut the water feed off for the boiler, turn off its elect power, shut off any gate valves around the boiler to minimize how much water you'll need to drain, and open the drain valve to reduce the water pressure to 0. Tape the threads of the new expansion tank. Put a towel down to catch the bit of water that will come from the boiler and old exp tank when you switch one for the other. The weight of the fully waterfilled old expansion tank may suprise you. Arrange for a place to rest the old tank upright during the swap so it doesn't drain out over your floor. One off and the new one threaded back on just takes a few seconds.
Some nice systems have a valve that can isolate the exp tank but it's not common.

Thanks how;
Season is just starting, so now is the time to get this job done.

FW

biggles 11-14-2011 10:23 AM

just going to say ...:wink:if your on a one level home and the baseboard runs the perimeter of the walls and if your boiler is not in the basement but also on the main floor?then you can remove the exsisting pressure drain down below the blow off...and do your flip :thumbsup:add a ball/gate valve on the riser to the tank and if you can get a tank with a draincock on it...so during the dead of winter you can shut the expansion tank drain it off and reopen it you'll feed a little make up water with the pressure out of the X tank butit will re pressurize right back up off the system..again this all happens if the boiler is on the same level as the baseboard with no upstairs

KE2KB 11-15-2011 10:00 PM

Quote:

Originally Posted by biggles (Post 770899)
just going to say ...:wink:if your on a one level home and the baseboard runs the perimeter of the walls and if your boiler is not in the basement but also on the main floor?then you can remove the exsisting pressure drain down below the blow off...and do your flip :thumbsup:add a ball/gate valve on the riser to the tank and if you can get a tank with a draincock on it...so during the dead of winter you can shut the expansion tank drain it off and reopen it you'll feed a little make up water with the pressure out of the X tank butit will re pressurize right back up off the system..again this all happens if the boiler is on the same level as the baseboard with no upstairs

It's a 2-level home with the boiler in the basement.
I ordered the tank today from PexSupply.com. About the same price (including shipping) as would have cost locally, without the hassle of the highway run.

FW

REP 11-15-2011 10:17 PM

Used to be against code to have a valve in the expansion tank line.You should check.

hvactech126 11-16-2011 06:03 AM

Quote:

Originally Posted by KE2KB (Post 766774)
Hi;

When doing this, should I also replace the air purge valve (it is also 30 years old, and has some corrosion around the air vent on top). That valve is an American no. 700.


FW

I would replace the auto air vent at the same time. I like the
Honeywell Braukmann


EA122A1002 Automatic air vents because you can shut them off and open up and replace/clean the guts of them. The important thing to be aware of when replacing this auto air vent and your EXP tank is to use the hex head provided and a wrench for tightening, do NOT use the body of the part you are replacing to tighten by hand!

chiefswabjockey 11-16-2011 06:40 AM

Quote:

Originally Posted by REP (Post 772251)
Used to be against code to have a valve in the expansion tank line.You should check.

I'm having my tank replaced and they specifically recommended that a valve/drain be installed in line with the new tank so in the future it's not such a pain to service the tank. They are a rather large hvac company doing everything to code with licensed technicians so I assume that, at least here, if it was once code to not do this it isn't any more.

Normally I'd make an attempt at swapping tanks myself but we have a newborn in the house and for one I don't have the time or patience for this kind of stuff right now and for two, I can't afford to freeze the house out with the little guy in it because I did something dumb. :P


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