Problem With Water Pump 'hunting'

[simon43]

This is a problem that has annoyed me ever since I built my small hotel in Phuket about 2 years ago!

The water supply set-up is as follows:

We have a 14 metre well that never runs dry. A standard well pump is used to pump this water up to a 3,000 litre holding tank on our water tower, at a height of about 8 metres. The well pump is working within it's specification for 'pulling' water from the well and 'pushing' the water up to the storage tank.

The water from the storage tank then is fed (via gravity) to the base of the water tower where I have a large pump that is connected to a sand filter and thereafter via pipework to our 10 hotel rooms, supplying water for the electric showers, basin and toilets.

Here is the problem.

When no-one is using any water, both pumps are automatically off. That's correct because there is no water demand.

When someone uses a shower, the large pump switches on to pump the water to the shower. But rather than remaining on until the shower is turned off, it 'hunts' or cycles, switching on for a few seconds and then off for a similar time, thereby creating a 'pulsed' water flow, (which is quite powerful but also means that the shower flow is not constant).

This problem means that the electriccal brush contacts on this pump burn out after only a couple of months, because they are cycling hundreds of times each day. The sound of the pump switching off and on every few seconds is also very annoying.

Also, whilst this is happening, the small pump that supplies water from the well also starts to act in a similar manner, since the storage tank water level is dropping slightly every few seconds, but then not dropping for a few seconds since the large pump has switched itself off!!

How can I stop the large pump hunting like this? Ideally, I would also like the storage header tank to maybe reach half-full before it is topped up again to full by the well pump.

Any suggestions much appreciated!

Simon

[Naam]

How can I stop the large pump hunting like this? Ideally, I would also like the storage header tank to maybe reach half-full before it is topped up again to full by the well pump.

to avoid that both pumps cycle on/off within seconds you need a pressure tank for each pump Simon. the bigger the better! money for a pressure tank is a good investment as it saves on pump repairs in the long run.

[Gary A]

Naam is correct. The small pressure tanks lose their air cushion and then the pump must cycle on and off because there is not enough air to push the water. Long ago I found a stainless steel tank that had a tire valve fitting on the top and a sight glass to see how much water was in the tank. Unfortunately I left it because I was too lazy to move it and really had no more use for it. I could certainly use another one now.

In the meantime, drain your existing pressure tank. That will fix the problem for a while.

[PETERTHEEATER]

This is a problem that has annoyed me ever since I built my small hotel in Phuket about 2 years ago!

The water supply set-up is as follows:

We have a 14 metre well that never runs dry. A standard well pump is used to pump this water up to a 3,000 litre holding tank on our water tower, at a height of about 8 metres. The well pump is working within it's specification for 'pulling' water from the well and 'pushing' the water up to the storage tank.

The water from the storage tank then is fed (via gravity) to the base of the water tower where I have a large pump that is connected to a sand filter and thereafter via pipework to our 10 hotel rooms, supplying water for the electric showers, basin and toilets.

Here is the problem.

When no-one is using any water, both pumps are automatically off. That's correct because there is no water demand.

When someone uses a shower, the large pump switches on to pump the water to the shower. But rather than remaining on until the shower is turned off, it 'hunts' or cycles, switching on for a few seconds and then off for a similar time, thereby creating a 'pulsed' water flow, (which is quite powerful but also means that the shower flow is not constant).

This problem means that the electriccal brush contacts on this pump burn out after only a couple of months, because they are cycling hundreds of times each day. The sound of the pump switching off and on every few seconds is also very annoying.

Also, whilst this is happening, the small pump that supplies water from the well also starts to act in a similar manner, since the storage tank water level is dropping slightly every few seconds, but then not dropping for a few seconds since the large pump has switched itself off!!

How can I stop the large pump hunting like this? Ideally, I would also like the storage header tank to maybe reach half-full before it is topped up again to full by the well pump.

Any suggestions much appreciated!

Simon

My garden water pump was often short cycling (hunting) and the sound was irritating. I found that some of the workers building an extension on my house were leaving a tap on slightly to provide a trickle of water when mixing cement. Consequently, the pump was not running continuously because the 'demand' was too low.

The point I am making is that the delivery capacity of the pump is usually selected in anticipation of high demand. For example, the family all tend to take showers/baths in separate bathrooms whilst the washing machine/dishwasher is running.

Most well type pumps have a flow reducer installed in the connection at the pump delivery port. This is a resemble a large plastic 'thimble' perforated with holes, slightly smaller in diameter than the delivery pipe. It restricts flow but not pressure.

I removed the one that I had on our townhouse pump - because that would short-cycle when just one shower was running - and it fixed the problem as well as improving the water flow from the shower heads.

Check if there is a flow restrictor in your large pump and take it out and see if that fixes it. Also, the perforations (small holes) in the flow restrictor could be partially blocked with gunge.