Water Pump To Boost Pressure

[ronswelters2]

Typical Japanese made pressure-boosting pump in house. Seems not right to me, cycles on/off every 10 seconds or so when the water is on.

Is this a malfunction or usual behavior?

Is it adjustable?

Thanks,

Swelters

[Crossy]

Assuming the pump has a pressure tank chances are it's lost its air pocket, this is a common cause of short-cycling.

If you don't have the pump instructions, it should go something like this:-

Turn off the pump power

Turn off the incoming supply (should be coming from a tank not the mains)

Somewhere on the bottom of the pump should be a drain valve, open it.

On top of the tank should be an air bleed valve, open it.

Water should come out of the drain.

When it stops close the drain and bleed.

Turn on the water

Turn on the power

QED hopefully

[Lantern]

Agree, but could be other causes, hole in diaphram, diaphram not inflated to correct pressure. or leak in piping somewhere.

[rgs2001uk]

I dont know what the op means by,

"cycles on/off every 10 seconds or so when the water is on"

Does he mean the pump is on at the mains, but there are no taps running, or does he mean the pump cycles when pumping water?

If its the latter, thats what its supposed to do.

If its the former, then he has a problem, water leak somewhere, usually a leaking tap or a flapper valve in the toilet.

[Crossy]

I'm assuming that it cycles when he's using water, if this is the case short-cycling is usually caused by loss of tank air.

If it's got a decent sized pressure tank it shouldn't cycle every 10 seconds.

[PETERTHEEATER]

Coincidentally, I have the same problem.

When water is turned on in the house (Any tap or toilet flush) the pump starts and runs for a second or two but then starts short cycling; ON/OFF every second and so water delivery is in pulses. If I use a garden hose only the pump runs normally most of the time (higher demand?) but then short cycles.

I had a similar problem last year and fixed it by adjusting the on/off contacts on the Pressure Switch on top of the tank but adjusting - even over the full range - (apart from the point where the pump wont start at all) makes no difference. If the pump is run for a long period (garden watering) the motor overheats (no surprise there!) and the Thermal Cut-out operates isolating the motor until it cools down.

I am trying to source a new Pressure Switch but any other pointers from our Forum experts will be welcomed.

PS: Yes, I have drained the tank!

Edited January 20, 2010 by PETERTHEEATER

[Crossy]

Peter. After you drained the tank did the pump work properly at all and then go back to short-cycling?

[PETERTHEEATER]

No, only long enough to prime the pump and recharge the tank then it was on/off as usual.

[ronswelters2]

Thanks all, gents.

The genius of Thaivisa!

Cycles when the water is on, I'll try the suggestions.

Ron

[PETERTHEEATER]

Today, after some searching, I found a shop which had a spare Pressure Switch near-enough match to the suspect switch on my pump. The seller was adamant that it would do the job even though it is marked as operating at lower ON/OFF pressures. Not an original manufactures spare but it must be good; it's marked JAPAN.LOL

I will try it this evening but I'm not holding my breath!

Edited January 23, 2010 by PETERTHEEATER

[T_Dog]

There is one more reason that no one has mentioned, that being the one-way valve. On the input side to the pump there is a one way valve, usually a small piston with a rubber seal. Its purpose is to not allow the pressure from the pump accumulator tank to discharge backwards through the pump and into the head-less supply line.

My pump just started cycling on-and-off every 20 seconds yesterday and I found a crack in the rubber seal of the one way valve. Have not yet been able to find a replacement for it either so might be cutting my own out of rubber in a few days....

If anyone knows of a Makita pump supply house in Chiang Mai, please let me know.

[PETERTHEEATER]

I tackled the job of replacing the Pressure Switch on my pump this morning. Isolated the pump electrically, removed the Drain Plug and opened the Priming Cap to drain the pump then disconnected the Pressure Switch electrically and uncrewed it from the top of the tank at which point water gushed from the tank drain!

At this point, I realized that my operation to 'drain' the tank a couple of days earlier inline with Crossy's advice had been incomplete. There is no other 'cap' or valve on top of the tank on my pump and I had assumed that removing the Priming Cap and seal would suffice but I now see that the tank was only partly drained.

Giving the suspect Pressure Switch the benefit of the doubt I fully drained the tank and re-installed the original switch. Reconnected everything, primed the pump with a little water and switched on. Voila! Problem fixed. Pump runs sweetly and normally.

So, as suggested by Crossy, the first fix for a pump which is short-cycling, that is switching on and off rapidly on normal demand., is to completely drain the tank and re-fill.

[Richb2004v2]

My next door neighbors pump has been picking on and off almost permanently for the past three years. He doesn't seem bothered and I've gotten used to it. TIT

[Artisi]

"So, as suggested by Crossy, the first fix for a pump which is short-cycling, that is switching on and off rapidly on normal demand., is to completely drain the tank and re-fill. "

Don't refill the tank.

Ideally your pump should be fitted with an isolating valve on the inlet pipe to the pump and the outlet pipe leading to the house. Close both of these valves and drain the tank - replace the drain plug and then open the 2 valves, this gives you an air cushion in the tank. You might need to reprime the pump prior to start-up but this is done thru the priming port.

Some installations need this proceedure done on a regular basis, others seem to require it only occassionally - I think it has to do with the pressure on the pump inlet - the higher the pressure the more often it needs doing.

[Eff1n2ret]

I'm not sure what is the "tank" on the pump that posters are referring to. On my pump (Makita) there is on the inlet side the motor and above it a block containing 2 bleed valves (presumably one going in and the other coming out of the motor chamber). Then there's the adjustable pressure switch and below it a horizontal cylinder domed at one end - is this the "tank"? There is nowhere I can see to drain it, but there is a little cap on the dome, which unscrews for access to a valve similar to that in a tyre. I've tried depressing it both with the pump running and switched off, but nothing comes out.

The pump does have intermittent periods of 'cycling' when there is no water running, which I have suspected may be because of a leak somewhere downstream, but I reading this thread I also wonder if the pump itself is functioning properly.

[Crossy]

The pump does have intermittent periods of 'cycling' when there is no water running, which I have suspected may be because of a leak somewhere downstream, but I reading this thread I also wonder if the pump itself is functioning properly.

If it's cycling when no water is in use, you probably have a leak

If it cycles during water use, likely you have a pressure tank issue

That cylinder with the pressure switch is the pressure tank, if it has a car-type valve chances are it's a bladder tank (theoretically more reliable). There should be instructions somewhare on how to top it up, but if it's working ok leave well alone, "if it 'aint <deleted>, don't fix it"

[rideswings]

I was having a similar problem to this, cycling every second when the water is on but not running or cycling when the waters off. When it was first installed, I got the pump and holding tank combo and the pressure was great in all faucets and it would cycle every 10 seconds which sounded like it was doing its job. Since then, we have had the guys from Toolpro out here 4 times and we have been told that our pipes are too small to maintain the kind of pressure that our Mitsu is putting out. They told us that if they try to keep the pressure high it will break one of the pipes in the house. So they turned down the pressure and now I am back to low water pressure in the house which is where it all began, 15,000 baht later. What a waste of money

At least it doesnt cycle as much now, but I just dont have high pressure the way I like it.They said that they could replace all the piping in the house for a few thousand baht, but I have a feeling it too would be a waste of money.

Edited March 15, 2010 by rideswings