Replacing pressure tank. Do I need to worry about trapping air?

[Bugeyed]

My existing pressure tank has failed & I I have a replacement on hand. It looks like I will have to cut the PVC to remove the old one. There is no drain or pressure release in the circuit, so I am wondering if I have to worry about trapping air in the tank. This question probably exposes my ignorance of how the system works, but I promise I can learn things & I have an understanding of physics & mechanics .

 

[Reach4]

No. You do have to set the air precharge to match your pressure. With a submersible pump, set that to 2 psi below the cut-on pressure.

The pump will be empty on the water side of the diaphragm before water pressure is applied.

The old failed tank may have water trapped on the air side of the diaphragm, so the tank will be heavy. You may drill some big holes to let the trapped water out to make it lighter.
If that is a Pentair WellMate pressure tank, those have a bladder instead of a diaphragm, and they are more likely to fail sooner. The bladders in theory are replaceable, but that seldom happens. Pentair WellMate tanks are good for other purposes, but not so durable as pressure tanks.

You might be able to remove the bladder from up top. Then suck water out of the tank with a wet-dry vacuum or a suction pump. I have never done it.

Normally you put a drain valve low at the tank entrance. That lets you clean out sediment periodically, maybe annually.

 

[Sponsor]

 

[Bugeyed]

No. You do have to set the air precharge to match your pressure. With a submersible pump, set that to 2 psi below the cut-on pressure.

The pump will be empty on the water side of the diaphragm before water pressure is applied.

The old failed tank may have water trapped on the air side of the diaphragm, so the tank will be heavy. You may drill some big holes to let the trapped water out to make it lighter.
If that is a Pentair pressure tank, those have a bladder instead of a diaphragm, and they are more likely to fail sooner. The bladders in theory are replaceable, but that seldom happens.

You might be able to remove the bladder from up top. Then suck water out of the tank with a wet-dry vacuum or a suction pump. I have never done it.

Normally you put a drain valve low at the tank entrance. That lets you clean out sediment periodically, maybe annually.

Thanks for your response. It IS a PentAir WellMate tank & I think the bladder comes out the bottom after releasing the nipple assy at the top. I don't know if it is much cheaper to replace the bladder as the only sourch I have found so far was $250. for the 47 gal. tank. That sounds high to me.

 

[Reach4]

Thanks for your response. It IS a PentAir WellMate tank & I think the bladder comes out the bottom after releasing the nipple assy at the top. I don't know if it is much cheaper to replace the bladder as the only sourch I have found so far was $250. for the 47 gal. tank. That sounds high to me.

Since bigger pressure tanks are in short supply, maybe that could be worth considering if you did not have the replacement already. What tank did you get?

If you went the new bladder route, one thought would be to get the next size up. But I am not sure that would buy more life.

Replaced from the bottom? I don't think so. With that tank, the bladder holds air, and the water at the bottom is in contact with the tank. One of the contributors here would bury those tanks in the yard and be able to replace the bladder from above. Tank does not take above-ground space, and is protected from freezing. That would have been brilliant if the bladders were more durable.

 

[Bugeyed]

There is a horrible video of the bladder replacement here.

I bought an A.O. Smith 52 gal tank from Lowe's. The WellMate was a 47 gal. Hopefully that will be easier on the pump?? Probably going to put the new tank in today instead of waiting for info about the replacement bladder for the WellMate.

 

[Reach4]

That A O Smith from Lowes looks like a good choice to me, at least based on the specs. Butyl diaphragm and more. I am not sure if will be a good choice in in the long term, but it is what I probably would have gone with today.

 

[Bugeyed]

That A O Smith from Lowes looks like a good choice to me, at least based on the specs. Butyl diaphragm and more. I am not sure if will be a good choice in in the long term, but it is what I probably would have gone with today.

Thanks

 

[Bannerman]

One option would be to install a Cycle Stop Valve, thereby eliminating the need for a large pressure tank. For most single residential applications, a CSV and 4.5-gallon pressure tank will be all that is needed to preventing pump cycling and to provide constant water pressure.

https://cyclestopvalves.com/