Water pump pressure loss ?

[Andrew Dwyer]

Okay, so I have a Hitachi constant pressure pump for 2 1/2 years, it has always run for a split second a few minutes after a shower or toilet flushed etc ( as if the pressure has dropped slightly and it pulses to get back up to pressure ? ).

Notice it at nighttime only as it’s right outside our bedroom window.

 

Now it pulses for a split second various times a day, maybe once an hour , even when no water has been drawn recently.

 

I checked for any dripping taps/showers/bum guns etc also checked the toilets are not letting any water down the pan and all is good.

 

I’m thinking a very small leak somewhere or maybe a problem with the pump ( possibly the bladder tank ).

If it’s a leak it is tiny and going to be very hard to find so i’m suspecting the pump.

 

The pump looks like this:

 

Anyone had similar or any suggestions to try ??
 

TIA

Andy

 

 

[sometimewoodworker]

2 hours ago, Andrew Dwyer said:

Now it pulses for a split second various times a day, maybe once an hour , even when no water has been drawn recently.

Almost certainly a cracked pipe or joint failing.

 

2 hours ago, Andrew Dwyer said:

I’m thinking a very small leak somewhere or maybe a problem with the pump ( possibly the bladder tank ).

A failing pressure tank will not have those symptoms 

 

2 hours ago, Andrew Dwyer said:

If it’s a leak it is tiny and going to be very hard to find so i’m suspecting the pump.

Interesting logic ???? but likely to be flawed.

[bankruatsteve]

8 hours ago, Andrew Dwyer said:

I’m thinking a very small leak somewhere

Yup.

[Momofarang]

Bum guns are my favorite culprits.

[Rookiescot]

Possibly the check valve (non return valve) has become slightly worn and is passing. This allows pressure built up in the pump outlet to drain back slowly into the water source.

You can test this if you have a manual valve fitted on the pump inlet.

 

1 Run a tap for a few seconds until the pump starts.

2 Close the tap and allow the pump to bring the pressure back up.

3 Close the manual valve on the pump INLET.

4 Wait and see if the pump restarts within an hour.

5 If the pump restarts then you have a leak somewhere in the house.

6 If the pump does not restart then you have a passing check valve.

 

Note. Do NOT allow the pump to run for more than a few seconds with the manual valve on the inlet closed. This can damage the pump and indeed case a fire.

Do not use any water in the house while carrying out the test. That includes people flushing the toilet.

Edited January 15, 2020 by Rookiescot

[Surelynot]

Haven't read all the responses, but had a similar problem. Had a ball cock leak inside a hot water tank that drained into a common overflow pipe. Is the overflow bone dry?

[Lacessit]

The bladder inside the pump may have become more permeable, and the leak is there, Rubber does degrade over time.

[CGW]

Running once an hour is nothing, that wouldn't even be noticed in my establishment! could be anything, even compression or heat expansion in lines etc.

I would wait till it gets worse before investigating further, one thing I have noticed is that problems always get worse, never better!

[Artisi]

2 hours ago, Rookiescot said:

Possibly the check valve (non return valve) has become slightly worn and is passing. This allows pressure built up in the pump outlet to drain back slowly into the water source.

You can test this if you have a manual valve fitted on the pump inlet.

 

1 Run a tap for a few seconds until the pump starts.

2 Close the tap and allow the pump to bring the pressure back up.

3 Close the manual valve on the pump INLET.

4 Wait and see if the pump restarts within an hour.

5 If the pump restarts then you have a leak somewhere in the house.

6 If the pump does not restart then you have a passing check valve.

 

Note. Do NOT allow the pump to run for more than a few seconds with the manual valve on the inlet closed. This can damage the pump and indeed case a fire.

Do not use any water in the house while carrying out the test. That includes people flushing the toilet.

Cause a fire, extremely unlikely to the point of impossible. 

[bankruatsteve]

8 minutes ago, Artisi said:

3 Close the manual valve on the pump INLET.

4 Wait and see if the pump restarts within an hour.

5 If the pump restarts then you have a leak somewhere in the house.

6 If the pump does not restart then you have a passing check valve.

A passing check valve could certainly be the problem here but how does closing the pump inlet (which is almost always connected to a tank) help determine that?  My thinking is that the house would need to be isolated such that the check valve (and any other valves) are the only factors remaining.

 

Apologies for not quoting from the source.

Edited January 15, 2020 by bankruatsteve

[Rookiescot]

4 minutes ago, Artisi said:

Cause a fire, extremely unlikely to the point of impossible. 

Tell that to my ex wife who managed to set fire to the outhouse by dry running a water pump.

[Rookiescot]

Just now, bankruatsteve said:

A passing check valve could certainly be the problem here but how does closing the pump inlet (which is almost always connected to a tank) help determine that?  My thinking is that the house would need to be isolated such that the check valve (and any other valves) are the only factors remaining.

 

Apologies for not quoting from the source.

Because with the manual valve closed then the pressure being passed by the check valve has nowhere to go. If the pump restarts then the "leak" is either within the pump or in the house.

If the pump does no restart then the check valve is passing.

[bankruatsteve]

53 minutes ago, Rookiescot said:

Because with the manual valve closed then the pressure being passed by the check valve has nowhere to go. If the pump restarts then the "leak" is either within the pump or in the house.

If the pump does no restart then the check valve is passing.

This would be for the NRV intrinsic to the pump.  (?)  A leaking NRV in the "bypass" is more often the culprit when nothing else is obvious.

[Rookiescot]

33 minutes ago, bankruatsteve said:

This would be for the NRV intrinsic to the pump.  (?)  A leaking NRV in the "bypass" is more often the culprit when nothing else is obvious.

Yes that would be the NRV on the pump. (So much better to call it a non return valve than a check valve but that term seems unique to the UK for some reason).

The OP makes no mention of a bypass so I assumed there is none.

[sometimewoodworker]

4 hours ago, Lacessit said:

The bladder inside the pump may have become more permeable, and the leak is there, Rubber does degrade over time.

While true it’s irrelevant as that would not produce the symptom, even if the airspace filled completely it would not cause the pump to cycle.

[Andrew Dwyer]

2 hours ago, Rookiescot said:

Yes that would be the NRV on the pump. (So much better to call it a non return valve than a check valve but that term seems unique to the UK for some reason).

The OP makes no mention of a bypass so I assumed there is none.

Yes, no NRV on the bypass ( only a ball valve ).

 

Did your check this morning Rookiescot and it did restart so am back to looking for any signs of a leak , although it is a very small leak and probably won’t visibly appear until it gets worse ☹️

[bankruatsteve]

Check the stop valves for toilet, bum gun, sinks, etc.  Feel around for any dampness.  A leak that small could be dissipating into the wall instead of dripping to the floor and making it difficult to see.

[bankruatsteve]

2 minutes ago, jasjones said:

1 Run a tap for a few seconds until the pump starts.

2 Close the tap and allow the pump to bring the pressure back up.

3 Close the manual valve on the pump INLET.

4 Wait and see if the pump restarts within an hour.

5 If the pump restarts then you have a leak somewhere in the house.

For your first post, you copied from someone else's post?  Great start there newbie.

[Rookiescot]

2 hours ago, Andrew Dwyer said:

Yes, no NRV on the bypass ( only a ball valve ).

 

Did your check this morning Rookiescot and it did restart so am back to looking for any signs of a leak , although it is a very small leak and probably won’t visibly appear until it gets worse ☹️

OK my next guess would be the ball valve in a toilet cistern passing slightly. Leaks from bum guns and taps are obvious so its unlikely to be that.

 

[Andrew Dwyer]

9 minutes ago, Rookiescot said:

OK my next guess would be the ball valve in a toilet cistern passing slightly. Leaks from bum guns and taps are obvious so its unlikely to be that.

 

Checked the toilets with some tissue paper ( a small trickle of water can be difficult to see ) and they are dry.

 

Did see a little bit of water from this tap running down the wall and out the drain.

Tiny little trickle !!

Banged some tape on it, now playing the waiting game.

[Rookiescot]

58 minutes ago, Andrew Dwyer said:

Checked the toilets with some tissue paper ( a small trickle of water can be difficult to see ) and they are dry.

 

Did see a little bit of water from this tap running down the wall and out the drain.

Tiny little trickle !!

Banged some tape on it, now playing the waiting game.

OK flush the toilet, let it fill up and mark the water level with some electrical tape or something.

Leave it for an hour and see if the level has gone up. 

[Andrew Dwyer]

6 minutes ago, Rookiescot said:

OK flush the toilet, let it fill up and mark the water level with some electrical tape or something.

Leave it for an hour and see if the level has gone up. 

Sorry, I don’t see the significance in doing this  ??

[Rookiescot]

Just now, Andrew Dwyer said:

Sorry, I don’t see the significance in doing this  ??

If the ballcock valve in the cistern is passing you will see a rise in the water level.

You probably have the ballcock set to stop about an inch or two from the top of the overflow pipe.

This means if the valve is passing there is a reservoir there for it to fill. Losing 2 liters or so from the pipework into the cistern will cause a pressure drop and the pump will kick in to maintain it.

However because of the slow level rise you would not see any leaking from the toilet or the overflow being used.

 

I'm trying to help you identify where the water loss is occurring.

[sometimewoodworker]

1 hour ago, Andrew Dwyer said:

Checked the toilets with some tissue paper ( a small trickle of water can be difficult to see ) and they are dry.

 

Did see a little bit of water from this tap running down the wall and out the drain.

Tiny little trickle !!

Banged some tape on it, now playing the waiting game.

That is most likely to be the culprit, a trickle that can be seen will be enough 

[Andrew Dwyer]

5 minutes ago, Rookiescot said:

If the ballcock valve in the cistern is passing you will see a rise in the water level.

You probably have the ballcock set to stop about an inch or two from the top of the overflow pipe.

This means if the valve is passing there is a reservoir there for it to fill. Losing 2 liters or so from the pipework into the cistern will cause a pressure drop and the pump will kick in to maintain it.

However because of the slow level rise you would not see any leaking from the toilet or the overflow being used.

 

I'm trying to help you identify where the water loss is occurring.

Okay thanks, I get you now.

[rvaviator]

Sorry to but in .... I have a somewhat

 

Does anyone have any experience with a Walrus 500 pump ?  I am trying to find out what the 'stop pump' / 'start pump' pressure is (factory setting)

[Rookiescot]

Just now, Andrew Dwyer said:

Okay thanks, I get you now.

It might be the small leak you have already identified but with these things its often a culmination of small leaks which equate to a larger one.

Its a process of elimination.

[Andrew Dwyer]

4 minutes ago, sometimewoodworker said:

That is most likely to be the culprit, a trickle that can be seen will be enough 

Yes, I put some paper down and it is not leaking there anymore.

I haven’t heard the pump pulse again but to be honest I only hear it in the bedroom at nighttime when there is no water being drawn off.

 

[Rookiescot]

Just now, rvaviator said:

Sorry to but in .... I have a somewhat

 

Does anyone have any experience with a Walrus 500 pump ?  I am trying to find out what the 'stop pump' / 'start pump' pressure is (factory setting)

http://www.walrus.com.tw/en/pdfdownload/business/TPH-Q/TPH-Q-IM-EN01.pdf

 

Any help?

Remember though when it comes to pump pressures you have to allow for the head pressure coming from the source. 

[Fruit Trader]

Short cycling automatic pumps

 

Helps avoid lots of guesswork and dancing :-