Loud click/thud, then loss of water pressure - need to reset (Constant Pressure System)

[Steve Ball]

Hi All -

Great forum - and I would like some help.

I got fitted with a new Constant Pressure System in January, and all was working until a few weeks ago.

System is all new: new small 1 gallon tank, reading 39PSI, new Goulds pump down around 135ft and a new Aquavar Solo 3AS20 controller.

Water pressure is set to 70PSI, with a 5PSI pressure drop.

In 1 out of every 2 showers / dishwasher cycles / washing machine cycles, the dashboard lights up with fault F02 and two blinks - this indicates low well pressure/dry well condition. This is a pain, but resetting it and everything fires up and on I go ... until the next time...

What happens is that when we put on the shower, either the controller & pump keeps up (staying around 70PSI) *OR* there is a loud/click (slap/thud/whack in the pipe), the pressure immediately drops around 10PSI and then as the shower keeps running, pressure drops slowly (presumably as water coming out of small expansion tank) until the 'dry well' condition sets and we lose all pressure. With our old system (which was replaced), we had a 30-50PSI tank and mechanical pump on/off, and never once ran out of water - so I do not suspect an actual dry well condition. System was replaced as pump got burned out due to cracked line from well to house when it was -15 back in winter. Insurance paid for this.

So something makes a noise, and something stops water pressure. It is as if there is no water coming up from the well - as if the pump is not running. It would be great to know if the controller is actually trying to fire the pump. I have had my wife run the shower while I'm watching the controller and waiting for the click... if I immediately reset the fault code, the water rushes up (you can hear it) and pressure builds up again and we wait until the next time it happens...

OK - I have looked through and I've tried all the things in the manual (bleeding the system, altering the current over-current setting, setting it to a 20PSI drop instead of a 5PSI drop etc.). I haven't touched the pressure in the tank (as it was reading 39PSI).

I'm stuck!

I'd much rather try and understand this myself (even if the work may be in warranty).

Does anyone have any ideas / things I could try??

Thanks all

Steve

 

[Valveman]

Those variable speed type pumps like the Aquavar are made to make money for the pump companies, which is the opposite of a good thing for the homeowner. Make them warranty it every time it blinks. Then when the warranty is up go back with the old pressure tank/pressure switch system that lasted so long and worked so well in the past.

 

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[Steve Ball]

Thanks, Cary, and I like your cycle stop valves too, so may switch to those at some point - and also grateful for your many posts about water hammer and valves in general. I have been reading and reading all about the issues with the variable speed pumps, and I will go back to the simpler pressure tank/pressure switch in the future. But for today... I would like trouble-shoot what is wrong with my setup.

I have looked into it more: at 70PSI, faucet on a little, all fine. Faucet on full (or shower etc.), it is 50-50 whether we'll get the issue or not. The pump is commanded (there is current of 3.5A and blinking light on the controller also indicating it), but after 5-10 seconds, if we get the issue, we hear the hammer (it's not so loud - about the same as normal hand-clap)... and then the pressure drops by around 10PSI. With the faucet still running, the PSI continues to drop slowly, maybe 1 PSI a second or two (as if there is little/no water being pumped) yet there is still current and driving of the pump. At a certain point, usually around 50-45PSI, the controller detects and sets the low-well condition and stops. I have watched this happen, and as soon as the fault is set, I reset it and instantly the pump is re-commanded (this time at 4.5A) and PSI whooshes back to 70 PSI (you can hear the whoosh in the pipe and expansion tank)...

I'm going to pull the pump next weekend: the shoe pitless adapter fitting needs a 1" threaded pipe which I'll get to pull it up, and 135ft should be pullable, I hope!

I am scratching my head thinking about what sort of check-valve or physical flow scenario would cause this. The hammer does not seem to coincide with pump turning off, as it occurs about 3-5 seconds *after* a commanded pump. The whack is clearly present, as is the instant 10PSI drop, and then it seems the pump isn't commanded to pump more / or is commanded, but isn't pumping more or much, and then it drops slowly ...

Anyway, until I pull the pump I don't know the full setup...

 

[Valveman]

If you pull it yourself it will probably void the warranty. You paid big bucks for that thing, make them warranty it. Water hammer is either a check valve slamming shut or a diaphragm in the tank hitting bottom (to much air). But either or both of these things can be caused by the VFD controller reacting too slowly. Let some air out of the tank and increase the ramp up speed.

 

[Steve Ball]

This forum is very, very helpful. After reading and learning, I guessed what the problem is and have resolved it.

The connection is:

PVC pipe from well -> Elbow -> Check Valve -> Small bladder tank -> Pressure Relief Valve -> Manual Pressure Gauge -> Pressure Transducer for Constant Pressure Controller -> Ball Valve shut-off ===> House

The Check Valve was broken: the spring, washer and bolt were all off, and loose in the inlet side of the valve - so I re-connected them, bolted it with red thread seal tightened it up - and now the system works as before - no banging, no cut off. Without the spring bolted on, the check valve was sort of loosely seated - so it may have worked a little (pressure would have seated it somewhat), but clearly it was not aligned, guided, and not fully working. So for whatever reason, it was shutting prematurely causing little/no-flow past it, thus appearing to the controller that the pump was low/dry. That makes sense to me, anyway.

I have read about whether or not that check valve should even be there (wonder if New York State code requires it?) - but for now, since it was there, but broken, I have at least put it back to the state that it was in when fitted.

Anyway, hope this helps anyone searching for this type of issue.

Thanks again to Cary whose answers (and other posts) are very informative and very useful.

 

[Valveman]

Yeah anytime a check valve comes apart the poppet can stick in the outlet and stop or reduce the flow. They make special check valves to use with those VFD or variable speed systems. Just another negative side effect of varying the speed. The check valve spins and chatters at low flow from a VFD, which is probably why it came apart.

 

[Valveman]

When you turn off power to a VFD wait at least ten minutes to be safe. The capacitors and still shock you for about 10 minutes after the power is off.