Bad water hammer in house while zone switches

[Watersoftenerhelp]

Hi, I've been in this house for 2 summers and this summer i'm having a problem with my sprinkler system. During the winter I discovered my expansion tank for my well (4.8 gallon) was bad so i replaced the well. I ended up blowing out my owner sprinkler system during the winter as well.

This summer, when my sprinkler change zones, I get a really bad water hammer whenever a new zone opens. I thought maybe the zones were opening too rapidly so what I did was put a minute delay inbetween each zone.

I have a BF20 constant well pressure controller, with a 33GPM Goulds 2 HP well pump.

When my valve is open for my sprinkler system I can tell I have a leak. My gauge will go from 75PSI to 68 PSI bleed *I have a 4.8 gallon expansion tank* that will end up bleeding out in a matter of 10 minutes.

I dont know if this problem is a new problem or not.

I also checked my valve boxes and I did have a few leaking valves that I had repaired. But i still have a leak in my system somewhere to bleed out every 8-10 minutes.

When the zones change my pressure gauge drops to 40PSI rapidly and my gauge dances around for a while. That ends up seeming to cause water hammer and my expansion tank doesn't like that. (it seems to only happen when my sprinkler have sit for more than a few hours, i'm guessing the water has enough time to bleed out of the pipe leak?)

My question is, could my problem be the main sprinkler line bleeding out or having air in it and everytime it has to change zones it has to fill that entire pipe up again and my zones?

I've been looking for 4 days straight (10 hours a day) for a wet spot, fungus, sinking, bubbling soil. I also filled the zones up with air and walked my property to see if i can hear any hissing.

I'm kind of at a loss at this point. Could my expansion bladder also be too small for my system?

 

[Deurgo]

Good morning,

What i suspect may be happening is that your non-return valve is leaking (either debris is stuck or lodged in the seat of the valve or it has deteriorated) and when this happens the pressure that's built up on the outlet side of your pump will seep back into your water tank thus resulting in a gradual pressure drop and causing the pump to cycle even though there seems to be no valves open.

Check this and report back but I have a feeling this may be what's causing your system to cycle.

Also relating to the water hammer - maybe just confirm you have the correct amount of air pressure in your tank? If you're using a typical pressure switch setup, set the PSI in the tank 10% LOWER than that at which your switch is set to turn on at. Example, switch turns the pump on at 40PSI therefore the tank pressure should be 36PSI.

See how you go and good luck. Looking forward to hearing back from you.

 

[Sponsor]

 

[Valveman]

A 4.5 gallon size pressure tank only holds about 1 gallon of water between 40 and 60 PSI. So for it to bleed down from 75 to 68 in ten minutes means you are losing about 1/4 gallon every ten minutes. I agree it is probably a leaking check valve. They even make special check valves now for those variable speed type pump systems like the BF20. Seems they have discovered check valves don't like the swirling water and low flow chatter caused by the VFD controller. So now they make special check valves that can better handle the abuse from a variable speed drive.\

Also some expansion tanks have a very small water opening. This is ok as an expansion tank, but won't let water in and out fast enough to work for a well pump. If the opening in the tank is only about the size of a pencil, you need a regular well tank instead of an expansion tank.

Water hammer usually happens when the bladder in the tank hits the bottom. So you want a little less air pressure in the tank than the lowest pressure you see from the system. If the tank has 40 PSI air charge, and pressure drops below 40 PSI while you are waiting on the variable speed controller to pick up speed, when the bladder hits the bottom of the tank at 40 PSI it causes water hammer. So put 5 PSI less air in the tank than the lowest pressure you see while the system is working.