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My water pump won't turn off!


AdamG

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Hi

My water pump started playing up. That is, the flow was irregular and, as I have a Rinnai instant water heater, that meant taking a shower was either dodging the over-hot water or dodging the freezing cold water!

Tonight, I removed the pump, took it apart, cleaned it up and re-installed it. But now it won't turn off! I recognise that there is a bit of an air-lock going on and I've had all taps open to try to release it. But that hasn't worked.

I also think I understand that it will switch off when the back pressure is sufficient - have I got that right?

But, I've left it running for a good 5 minutes or so, to allow the pressure to build up and it still doesn't turn off.

Do I need to leave it running for longer or is my pump ready for the scrap heap? A new pump is only about £50 and I'm happy to pay that, but what if I have the same problem with the new one?

Can anyone advise please?

Cheers, Adam

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1 minute ago, Richard10002 said:

Could there be a water leak somewhere? I know it would be a coincidence for it to happen at the same time as you have been fixing the pump, but it's possible.

No, I don't think so. Other than removing the pump and re-fitting it nothing has changed...

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9 minutes ago, AdamG said:

Hi

My water pump started playing up. That is, the flow was irregular and, as I have a Rinnai instant water heatdeer, that meant taking a shower was either dodging the over-hot water or dodging the freezing cold water!

Tonight, I removed the pump, took it apart, cleaned it up and re-installed it. But now it won't turn off! I recognise that there is a bit of an air-lock going on and I've had all taps open to try to release it. But that hasn't worked.

I also think I understand that it will switch off when the back pressure is sufficient - have I got that right?

But, I've left it running for a good 5 minutes or so, to allow the pressure to build up and it still doesn't turn off.

Do I need to leave it running for longer or is my pump ready for the scrap heap? A new pump is only about £50 and I'm happy to pay that, but what if I have the same problem with the new one?

Can anyone advise please?

Cheers, Adam

Depending on what pump you have, it should have a built-in pressure switch will will turn off the pump when the pressure in the system reaches a certain level. 

So assuming all taps are off and you have no major leaks, it could either be a faulty pressure switch, or you possibly didn't put it back together correctly 

 

Also worth checking the prv valve if you have one. 

Edited by rusty69
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6 minutes ago, AdamG said:

Hi

My water pump started playing up. That is, the flow was irregular and, as I have a Rinnai instant water heater, that meant taking a shower was either dodging the over-hot water or dodging the freezing cold water!

Tonight, I removed the pump, took it apart, cleaned it up and re-installed it. But now it won't turn off! I recognise that there is a bit of an air-lock going on and I've had all taps open to try to release it. But that hasn't worked.

I also think I understand that it will switch off when the back pressure is sufficient - have I got that right?

But, I've left it running for a good 5 minutes or so, to allow the pressure to build up and it still doesn't turn off.

Do I need to leave it running for longer or is my pump ready for the scrap heap? A new pump is only about £50 and I'm happy to pay that, but what if I have the same problem with the new one?

Can anyone advise please?

Cheers, Adam

I used to mend pumps but have not done so for years they are now built down to a price and if I get 3 years out of one I consider it a bonus.

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i don't know how old the pump is. As it was playing up in the first place, I'm guessing that you are probably right in that the pressure switch is not working. I re-assembled it very carefully, so I don't think it's that - but who knows?

Whilst we're on the subject, when I fully open the hot tap I get a 'pulsing' kind of flow - not steady. Would buying a pump with a higher PSI make a difference of do I need a small expansion tank? The current pump is a 30 PSI Shurflo with roughly 11 litres/per/second flow...

2 minutes ago, AdamG said:

i don't know how old the pump is. As it was playing up in the first place, I'm guessing that you are probably right in that the pressure switch is not working. I re-assembled it very carefully, so I don't think it's that - but who knows?

Whilst we're on the subject, when I fully open the hot tap I get a 'pulsing' kind of flow - not steady. Would buying a pump with a higher PSI make a difference of do I need a small expansion tank? The current pump is a 30 PSI Shurflo with roughly 11 litres/per/second flow...

11 litres per minute! Not second! That would be ridiculous!

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6 minutes ago, AdamG said:

i don't know how old the pump is. As it was playing up in the first place, I'm guessing that you are probably right in that the pressure switch is not working. I re-assembled it very carefully, so I don't think it's that - but who knows?

Whilst we're on the subject, when I fully open the hot tap I get a 'pulsing' kind of flow - not steady. Would buying a pump with a higher PSI make a difference of do I need a small expansion tank? The current pump is a 30 PSI Shurflo with roughly 11 litres/per/second flow...

You would have to kmow the input pressure of the water heater before going for a higher pressure pump. The addition of an acucumulator may help if set up correctly. 

 

Eta. You could also add an external pressure switch like the square d (or equivalent) if it is a faulty switch, or a replacement microswitch is pretty cheap(maplin or equivalent) 

Edited by rusty69
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Surflow pumps don't like the restricted flow when an instantaneous hot water heater is set to hot. If you turn the knob to cooler on the heater the flow should increase and the pump should work more smoothly. Whilst showering and using the hot setting you could crack open another tap a bit cold tap which should increase the flow through the pump, speed it up to run more smoothly whilst showering.  I would fit a lower pressure and volume pump, something like 15 or 20psi and 6-8 litres per min.

Edited by bizzard
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11 minutes ago, bizzard said:

Surflow pumps don't like the restricted flow when an instantaneous hot water heater is set to hot. If you turn the knob to cooler on the heater the flow should increase and the pump should work more smoothly. Whilst showering and using the hot setting you could crack open another tap a bit cold tap which should increase the flow through the pump, speed it up to run more smoothly whilst showering.  I would fit a lower pressure and volume pump, something like 15 or 20psi and 6-8 litres per min.

Thanks - good tips :D

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9 hours ago, AdamG said:

i don't know how old the pump is. As it was playing up in the first place, I'm guessing that you are probably right in that the pressure switch is not working. I re-assembled it very carefully, so I don't think it's that - but who knows?

Whilst we're on the subject, when I fully open the hot tap I get a 'pulsing' kind of flow - not steady. Would buying a pump with a higher PSI make a difference of do I need a small expansion tank? The current pump is a 30 PSI Shurflo with roughly 11 litres/per/second flow...

11 litres per minute! Not second! That would be ridiculous!

I doubt its pulsing now the pump won't turn off but if it is it suggests you have misassembled or got dirt in the valves of one or more pumping chambers. The usual pulsing as the pump turns on and off is normal. An accumulator would alter its frequency but not stop it. An expansion vessel is does a different job and is pressurised too highly to alter the pump cycling frequency.

If you want to fit a higher pressure pump it is vital that you do not choose one that is set to around 5 to 10 PSI BELOW the setting of any pressure relief valve but unless you have a calorifier as well as the Rinnai you probably do not have one. As said above do not exceed the pressure allowd by the Rinnai.

A boat without a calorifier is unlikely to have an expansion vessel but it may have an accumulator. Both are identical but an expansion vessel is usually set to a higher air pressure.

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You have filled the water tank recently, haven't you?

I don't mean to state the obvious but water pumps with pressure switches will continue to cycle if the water on the low pressure (tank) side runs out, and I always like to start with the basics first...

Edited by blackrose
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24 minutes ago, system 4-50 said:

when you cleaned the pump, did you turn any valves off that you have forgotten to turn on again?

Mine will run endlessly after an outage until any tap is turned on.

Not quite sure what you mean there, 4-50. All I turned off was the water and I turned that back on again...

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10 hours ago, AdamG said:

Not quite sure what you mean there, 4-50. All I turned off was the water and I turned that back on again...

 

10 hours ago, rusty69 said:

Probably means the isolation valve between tank and pump. 

 

10 hours ago, AdamG said:

Don't think there is one, ol' bean...

The above rather suggests to me that Blackrose may be onto something. In most simply disconnecting the pump from the inlet or taking the pump head off in situ results in water pouring all over the floor - unless the tank is empty of the main shut off valve is turned off. Depends on the exact design though. I suppose someone may have thought it was a good idea to fit the pump higher than the tank level so it needs to actually suck air before t will prime. I doubt it though.

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2 hours ago, Tony Brooks said:

 

 

The above rather suggests to me that Blackrose may be onto something. In most simply disconnecting the pump from the inlet or taking the pump head off in situ results in water pouring all over the floor - unless the tank is empty of the main shut off valve is turned off. Depends on the exact design though. I suppose someone may have thought it was a good idea to fit the pump higher than the tank level so it needs to actually suck air before t will prime. I doubt it though.

My tank is fed this way and has been for 30 years. With the tank 1/2 full, it takes about 2-3 seconds for the pump to prime. The big advantage is that if something fails in the pump, or there is a freeze that results in a burst pipe, you don't end up with a bilge full of water, and there is no chance of a failed isolating valve preventing pump maintenance. Also, there is no chance of debris clogging up the outlet hole from the tank.

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5 minutes ago, Ex Brummie said:

My tank is fed this way and has been for 30 years. With the tank 1/2 full, it takes about 2-3 seconds for the pump to prime. The big advantage is that if something fails in the pump, or there is a freeze that results in a burst pipe, you don't end up with a bilge full of water, and there is no chance of a failed isolating valve preventing pump maintenance. Also, there is no chance of debris clogging up the outlet hole from the tank.

Interesting. What pump is it? I can never get our pump to prime unless its low down relative to the tank. 

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