My cooling towers are overflowing and need help

[srl1994]

I am from the UK and have 4 x cooling towers which overflow only when the pump turns off.
I have isolated the make up to ensure that it is not a float valve issue, and i have also isolated the flow to the top of the towers to ensure the water doesnt 'backfill into the system should there be a failed NRV.
me and my colleague drained down the towers to 2 inches below the overflow and once again when the pumps shut off they overflow.

Could someone please steer me in the right direction?

KR
Shane

[moideen]

maybe the undersized equalizer line caused the overflowing. equalize line to be sized 15% more capacity of single tower flow rate. please check and update

[ehsx]

New or existing older job?
How much of the condenser water piping is higher than the tower basin? Type tower, model? Iso?

[RyanWAIDB7778]

Also check your chemicle treatment lines. I have had siphon effect thru the lines after pump is off and it would literally empty the supply to tower into basin after about 30 minutes.

[pecmsg]

Also check your chemicle treatment lines. I have had siphon effect thru the lines after pump is off and it would literally empty the supply to tower into basin after about 30 minutes.

3/8" or even 1/2" chemical feed lines are going to take quite a while to move several hundreds of gals of water!

[RyanWAIDB7778]

3/8" or even 1/2" chemical feed lines are going to take quite a while to move several hundreds of gals of water!

Didn't know how fast it was leaking back. Triple duty not checking? Or you're supply piping is above your tower inlet

[Chillertech4]

I would look at the check valves


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[srl1994]

I would look at the check valves


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I isolated the main flow going over the top of the towers to 'simulate' a valve shutting as the pumps went off, the ponds still overflowed, not sure where the additional water would be coming from?

[srl1994]

New or existing older job?
How much of the condenser water piping is higher than the tower basin? Type tower, model? Iso?

The cooling towers are existing and probably over 15 years old, i have no O&M or schematics for the condenser water circuit, the Towers are EVAPCO LPT but i do not have the model number.
In regards to the piping, the only pipes that are higher than the basin are the flow pipes going the spray nozzles, i initially thought it may be a failed check valve but to simulate this i isolated the flow valve just as my colleague turned the pumps off. and it still overflowed

[srl1994]

Didn't know how fast it was leaking back. Triple duty not checking? Or you're supply piping is above your tower inlet

The overflow ( 2") literally gushes out whenever the pumps shut off, our dosing system is located in the basement

[pecmsg]

Check valve in or out of the pump is leaking by.

[WAYNE3298]

It's starting to sound like the your makeup water control is putting too much water in the basin. With the system running how high is the water level in the basin?

[HYP1278]

There is a running level for towers listed in their manuals. Usually A buildings running level is too high to hold hot box water After shut down. Piping also can contribute if a long horizontal run also drains in to tower at shut down.