What is causing a hot water system to get water logged?

Sateesh Cherukuri

At our apartment building, the HW system is getting water logged in less than a week after draining the expansion tank.

Any suggestions on causes and remediation would be appreciated. Thank you

ed wallace

water logged

you need a new expansion tank or if you have a a hot water indirect or tankless it might be leaking and over pressurizing the boiler also the auto water feed could be leaking by and slowly adding water

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Dick Charland

How do you know?

Can we assume you are familiar with the system? You are draining the expansion tank because the pressure is going up and the relief valve is relieving at or about 28-30 PSI. You say the system is water logged after draining the tank, The system should be full of water. If you have an expansion tank, it should have a charge of air in it as well as water from the system. An indication that the air has been depleted is a buildup in pressure in the system when the burner operates to heat the sytem. With no cushion, there is no room for expansion as the water gets heated.
With an expansion tank, it must be drained completely, to do so requires shutting the valve off between the system and the tank, opening the draw off at the tank and then providing some means of introducing air back into the tank to prevent a vacuum which would hold the water up in the tank. There maybe a tank drainer on the tank to which the draw off is attached with an 1/8" plug that allows air to enter the tank through a tube that goes to the top of the tank. If there is a stop and waste valve as a shutoff to the tank and the waste is on the tank side, you may remove the cap and allow air in through that. Or you may try to add air through the hose into the tank by blowing into the hose(always good for a mouthful of tasty water).

Once all of the water is out, close the drain, cap or plug tank drainer and or stop and waste if used, then open the valve from system. Water will enter tank, hopefully feeder is working properly, operate system to see if pressure remains steady. If you have drained the tank as described, and it gets water logged again (indicated by water held in tank by vacuum) check for air leak on tank and or replace tank. If tank is holding charge of air and pressure is building without the burner running, check for feeder leaking by (shut feeder off) or possible leak in tankless coil if installed as described by Ed.

All of this assumes system installed correctly, sized properly. If not familiar, find a "Professional".

[Deleted User]

Articles...

addressing this very topic...

http://www.contractormag.com/articles/column.cfm?columnid=45

http://www.contractormag.com/articles/column.cfm?columnid=60

http://www.contractormag.com/articles/column.cfm?columnid=75

And a link to ALL of the articles I've written for Contractor Magazine, if you're bored out of your gourd...
http://www.contractormag.com/articles/columnist.cfm?columnistid=6

Enjoy, and NEVER stop learning.

ME

oil-2-4-6-gas

> addressing this very

> topic...

>

> http://www.contractormag.com/articles/

> column.cfm?columnid=45

>

> http://www.contractormag

> .com/articles/column.cfm?columnid=60

>

> http://www

> .contractormag.com/articles/column.cfm?columnid=75

> And a link to ALL of the articles I've written

> for Contractor Magazine, if you're bored out of

> your

> gourd... http://www.contractormag.com/articles/co

> lumnist.cfm?columnistid=6

>

> Enjoy, and NEVER

> stop learning.

>

> ME



--a couple of reasons for this situation --pressure reducing valve bad overfilling or in the wrong part of the piping of the system ,expansion tank(maybe air charged and the bladder is bad or -compression tank no air charge --BUT it must be drained and refilled the correct way --if you have a domestic coil in the boiler it may have a pinhole leaking domestic water into the boiler system --if you have a watermaker with an exchanger -it may have a pinhole leaking domestic into the boiler system any other -exchanger on the system --by-pass feed valve or manual fill valve may not be seated all the way --or some Genius piped in a feeder /low water cutoff and it is leaking --i'll bet you with a detailed picture of the boiler room --piping i could give you the steps to remedy your stuation lobster dinner or 12-pack of Sam Adams --would do

oil-2-4-6-gas

--a couple of reasons for this situation --pressure reducing valve bad overfilling or in the wrong part of the piping of the system ,expansion tank(maybe air charged and the bladder is bad or -compression tank no air charge --BUT it must be drained and refilled the correct way --if you have a domestic coil in the boiler it may have a pinhole leaking domestic water into the boiler system --if you have a watermaker with an exchanger -it may have a pinhole leaking domestic into the boiler system any other -exchanger on the system --by-pass feed valve or manual fill valve may not be seated all the way --or some Genius piped in a feeder /low water cutoff and it is leaking --i'll bet you with a detailed picture of the boiler room --piping i could give you the steps to remedy your stuation lobster dinner or 12-pack of Sam Adams --would do