Need help with auto water pump

[Kenny202]

Have one of those little self contained Hitachi auto water pumps. Right next to the tanks so no problem with supply etc. Unless I am imagining things, when we first got it a few weeks ago we'd turn a cock or the shower on and the pump would basically run until you turned the cock off again. Every things fine, pressure seems constant etc but now it seems to be cycling on and off in about 3-5 second intervals. Just seems like the differential maybe need adjusting or something or maybe thats how it should work and I am dreaming.

[Crossy]

Short cycling like that suggests a waterlogged pressure tank, was the pump new?? If so get the supplier to have a look.

[Kenny202]

Yes new pump mate. Have it directly connected beside 2 interconnected 1000L tanks outlet at the bottom going into the pump. Is that too much pressure coming in maybe? Have a non return check valve just past the pump so water can not run back into the front of the pump.

[Litlos]

Are you sure you do not have a leak somewhere? If there is an isolation valve downstream of the pump shut it off and see what happens. If the short cycling stops, then then likelihood of a leak downstream is higher. It could also be a leaking check valve within the pump allowing the pressure to escape backwards, do you have a filter upstream of the pump?

If you have a model number on the pump would be helpful as there is a couple of different types of Hitachi pumps and how they operate is a little different.

Cheers

[Kenny202]

Model is WM 150 X2

No leak anywhere. Our pipes are all visible and everything is dry.

You may have misunderstood me. The pump isn't coming on all the time (as in the case of a leak). It only comes on when we turn on a cock but cycles on and off in 3 sec intervals. I had a look in the manual doesn't look like there's any adjustment. Maybe that's how it's meant to work? When I open a tap normally what would I expect to hear from the pump?

[Forkinhades]

sounds like an air lock to me

[IMHO]

Are you sure you do not have a leak somewhere?

+1 for the leak. When something stops working right, the first question you need to ask is "what changed?" - given that a bad PVC joint is about as common as a hot summer's afternoon, that's where I'd be looking first.

As noted, if you have a valve that shuts off all water to the house after the pump, close it. If the cycling stops, you know you have a leak.

Edit: Just read your update, see below instead

Edited March 15, 2015 by IMHO

[IMHO]

Model is WM 150 X2

No leak anywhere. Our pipes are all visible and everything is dry.

You may have misunderstood me. The pump isn't coming on all the time (as in the case of a leak). It only comes on when we turn on a cock but cycles on and off in 3 sec intervals. I had a look in the manual doesn't look like there's any adjustment. Maybe that's how it's meant to work? When I open a tap normally what would I expect to hear from the pump?

How is the water flow when it's doing this? Is it pulsing/surging, or does it seem more or less stable?

Edited March 15, 2015 by IMHO

[Kenny202]

It surges just slightly when the pump kicks in but ever so slightly. It's hardly noticeable. The flow is strong and constant. If it had an air lock where would that be? In the line somewhere or in the pump. The tanks are only about 20% full now where before they were chockers. Maybe not having the pressure of the full tanks going into the pump has made a difference?

Like I said before. What shud I expect to hear when I open a cock?

[IMHO]

It surges just slightly when the pump kicks in but ever so slightly. It's hardly noticeable. The flow is strong and constant. If it had an air lock where would that be? In the line somewhere or in the pump. The tanks are only about 20% full now where before they were chockers. Maybe not having the pressure of the full tanks going into the pump has made a difference?

Like I said before. What shud I expect to hear when I open a cock?

I'm not familiar with the WM 150 X2 pump (never heard of such a model), but I can only guess it's a bladder type pump, which explains the cycling (the bladder helps pick up the 'slack' to provide near constant pressure).

If you have an air lock in your pipes, the simplest way to get rid of it is to open all taps. If the air lock is at the pump, open the priming lid and add some water (disconnect from power first, and be careful as the lid might have a bunch of air pressure behind it).

The other thing to check is that some pumps have a spring that needs to be installed in the check valve if the supply head is less than a couple of meters down (i.e. always needs to be installed in a tank scenario) - otherwise you can get "water hammer' - check your owner's manual.

Edited March 15, 2015 by IMHO

[Litlos]

You should hear nothing for a few seconds until the pressure drops, then the pump starts. The accumulator is initially supplying the pressure and once the pump starts the accumulator is recharged by the pump. The minimum cycle time I would expect would be 10 seconds, anything shorter is a problem.

I downloaded the manual from Hitachi Thailand and it is in Thai/English. Either your draw volume is way to small, the accumulator has lost charge or the 'Life Safe" unit is contaminated, They specifically say if you adjust the pressure switch the warranty is void.

The only real troubleshooting options I could see as per the manual are to cleanout debris from the "life safe" unit, it is under the pressure switch. Or the accumulator has lost charge and needs service. If relatively new I would try the service option, maybe someone local can come out?

Cheers

[ripstanley]

Go and check all outlets. Especially bum guns and showers. I had the same problem and found a bum gun leaking.Good luck

[Kenny202]

Your 100% with all that. Mine doesn't have the optional check spring but the model that pumps from under has that (steel tank) . Mine is the bladder type. I guess if I did have an air lock there wud be noticeable surging

[Kenny202]

Thanks for all that. Like I said and correct me if I'm wrong if there was a leak the pump would be cycling on randomly when nothing was or shud be turned on. I'll try for air locks and check the life safe unit is clear tomorrow. Failing that I hope they have a service team :-( i hate the thought of returning anything here they make you feel like a criminal and assume you are either making a false claim, u are a total idiot or it was Ur fault. Bought it at home pro so I guess no dramas with warranty but we only have tank and pump now. Probably take a month to fix.

[wayned]

If you have an "accumulator" type pump, the one with the tank attached it might just be normal operation.

I am currently using a Mitsubishi WP-255Q3 pump.

Situation 1: If I turn the hose faucet full on the pump will turn on and run until just after the faucet is turned off. What is happening is that the tank pressure switch activates the pump when it reaches the lower pressure limit and does not turn it of until after the faucet is turned off because it can not increase the pressure in the tank to cut off pressure until then. So the pump runs all of the time. This is normal operation.

Situation 2:If I turn on the same faucet 1/4 on the pump will cycle on and off every few seconds the frequency will depend on how much the faucet has been opened. What is happening is the tank pressure switch activates when it reaches the lower pressure limit and then turns the pump off when it reaches the upper cut off pressure since the pump can now increase the pressure in the tank to the cut off pressure turning off the pump. So the pump cycles on and off every few seconds. This is normal operation.

My house is plumbed with 1/2" pipe and all of the faucets "had" sediment filters and the standard flexible hose connections. When a faucet is turned on the water demand is insufficient to to cause the pump to run all of the time as explained in Sit. 2 above. When more than one faucet is turned on at the same time or the toilet is filling the pump might run all of the time since there is enough demand as explained in Sit1. above.As I said I removed all of the sediment filters from my fixtures as we have very hard water and they would clog frequently aggravating the situation.

It could also be a "water logged" pump as said above which can be easily corrected by turning off the input water supply to the pump and draining the tank fully and reverse the process, but I don't think so. Don't mess with the pressure switch as that's not the problem if there actually is one.

If you have a leak, the scenario would follow situation 2, but unless it was bad the pimp would cycle on/off for a few seconds and then stay off for a while. Leaky toilet valves are quite common.

If yon have a "constant pressure" type pump all that I said above is garbage and I should hev stayed in bed.

[Kenny202]

I'm getting the same symptoms as if the flow is slightly restricted. I bled all the line for air this morning, ran the pump dry. Maybe some crap is restricting the inlet slightly. The flow is still strong but I do remember it being slightly stronger 3 weeks ago wen I installed it

[wayned]

If the pump is waterlogged, running it dry won't cure the problem. You have to remove the drain plugand drain it completely letting some "air " into the tank.

[Kenny202]

Went away for three days and come back and pump working fine. All a bit of a mystery

[farmerjo]

If it relates mainly to your shower,check the little filter in the shower unit.

[Kenny202]

No was every outlet

I'm starting to think maybe there was a blockage or something that's cleared itself