Water pump pulsing

[Andrew Dwyer]

Not sure if I have a problem or not really, but here goes.

 

Have lived in this house for nearly 2 years now, the pump, tank and pipe work was fitted just before we moved in .

I have noticed that the next door neighbours pump pulses ( 2 sec on 2 sec off ) when I assume he is showering.

Ours never did that, or I never noticed it anyway, pump always on.

 

This week had tiling done outside and lifted the pump and tank by 10” onto a steel frame, pipe work modified for height but exactly same as before.

 

Now when showering I can hear the pump pulsing ( 3 sec on 3 sec off ) something I never noticed before, if another tap is opened or toilet flushes the pump stays on constantly.

I mentioned it to the gf , she said that now that the pump is on the steel frame it is louder ( which it is ) and nothing has changed. ( will also look at some rubber material to reduce the pump noise, steel frame has rubber feet).

 

It does seem logical that the pump delivers more water required for just the shower hence it turns on and off and stays constant when an additional tap open/toilet flushes calls for more water.

 

Or am I missing something obvious here, as the pump and tank were drained to lift them do I need to prime the pump or something of this nature. ??

 

Am convinced that it has changed since lifting up !!

 

Couple of photos of the pump.

 

 

[Puchaiyank]

Man, I wish I had your problems...????

[carlyai]

I could be completely wrong, but is that the correct pump to use for your application? It seems to have a very small pressure tank, but there again the specs say it is a constant pressure pump.
At the back/side near the filler cap looks like your pressure switch. You can adjust the switch (with an insulated handled screwdriver) so the pump stays on during shower.
Maybe best first thing to empty all the water out and recharge it again.See if that makes a difference.
I put a pressure meter on my pumps to see what's going on.

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[Ahab]

I have the same pump, with the same issues. Our pump issues started after our tank ran dry one day. Kind of annoying but not a big issue. It probably has something to do with the pressure regulator or more likely the bladder tank. The manual says to replace the bladder tank. 

WP_WT-P_WM-P_GX2.pdf

[Andrew Dwyer]

I have the same pump, with the same issues. Our pump issues started after our tank ran dry one day. Kind of annoying but not a big issue. It probably has something to do with the pressure regulator or more likely the bladder tank. The manual says to replace the bladder tank. 
WP_WT-P_WM-P_GX2.pdf

Thanks Ahab, does your pump run constantly now even opening one tap or flushing a toilet etc ?

[sammieuk1]

Look at the rubber flap on the cisterns of your toilets if they are leaking like mine they cause the pump to turn on and off to compensate ????

[Andrew Dwyer]

Look at the rubber flap on the cisterns of your toilets if they are leaking like mine they cause the pump to turn on and off to compensate [emoji848]

Thanks but I meant when a tap opened/ toilet flushes/shower running etc the pump runs intermittently and not constantly ( as I think it did before).

 

When no water is being used the pump stays off I.e. all night.

[Langsuan Man]

Have / had the same problem and have isolated the problem to a couple of cheap plumbing fixtures.  Specifically any that mix hot and cold water at the discharge point.

 

The expensive shower fixture in the main bath does not cause a pulse, but the cheaper one in the guest bath does.  Replaced the cheap one and it's no longer pulsing.

 

But have noticed that the main bath fixture pulses if not opened fully, which leads me to believe these problems stem from lousy packing in the fixtures since the expensive one is showing it's age

 

I would try and isolate the problem before proceeding further  

[Andrew Dwyer]

Have / had the same problem and have isolated the problem to a couple of cheap plumbing fixtures.  Specifically any that mix hot and cold water at the discharge point.
 
The expensive shower fixture in the main bath does not cause a pulse, but the cheaper one in the guest bath does.  Replaced the cheap one and it's no longer pulsing.
 
But have noticed that the main bath fixture pulses if not opened fully, which leads me to believe these problems stem from lousy packing in the fixtures since the expensive one is showing it's age
 
I would try and isolate the problem before proceeding further  

I guess that problem is related to the amount of water flow.
For example: a large shower head will call for a larger volume of water causing the pump to run constantly whereas with a cheaper/smaller shower head the volume will be too much causing the pump to pulse ( on a few secs off a few secs).

This is where my question is based:

Should the pump pressure remain constant and pulse on and off depending on volume requirements ??

Or should the pressure adjust automatically to compensate for different volumes requirements and the pump run constantly ?? ( I guess that’s where the bladder comes in to adjust for varying volumes as in Ahabs post ?? ).

[Fruit Trader]

This compact series of pumps are fitted with a tiny bladder tank and pressure switch with a close on/off differential (around .4 Bar). This can result in rapid cycling at low flow.

Be sure to release all air from the pump and around the house after draining.

[Ahab]

5 hours ago, Andrew Dwyer said:

Thanks Ahab, does your pump run constantly now even opening one tap or flushing a toilet etc ?

No it does not run constantly, but when it is running the pressure varies up and down. As soon as a faucet or toilet is flushed the pump kicks on and runs until the flow stops (just the pressure is not steady).

[Andrew Dwyer]

No it does not run constantly, but when it is running the pressure varies up and down. As soon as a faucet or toilet is flushed the pump kicks on and runs until the flow stops (just the pressure is not steady).

Ok thanks.

Can I ask you where you bought the bladder tank ?

That’s got to be the prime suspect as there is nowhere ( that I can see ) to drain water or air, only the hopper for priming, which I guess once it’s up and running is not necessary to mess with .

The pressure switch I’ve never touched so would be unlikely, IMO, that the pressure needs adjusting.

[Fruit Trader]

1 hour ago, Andrew Dwyer said:

Ok thanks.

Can I ask you where you bought the bladder tank ?

That’s got to be the prime suspect as there is nowhere ( that I can see ) to drain water or air, only the hopper for priming, which I guess once it’s up and running is not necessary to mess with .

The pressure switch I’ve never touched so would be unlikely, IMO, that the pressure needs adjusting.

The bladder tank is very low capacity maybe 1 litre draw down at best. You cant expect a pump of that capacity not to short cycle on low demand with such a small bladder tank and up to 36L/min available. Its possible the bladder has lost some of its pressure and shortened the cycle a little. These small bladder tanks are often nitrogen filled have no service valve and are built to last.

 

You can add a larger capacity bladder tank to the outlet if cycling at low flow becomes annoying.

[steve73]

Easiest is to adjust the pressure switch setting (with an insulated screwdrivers as others have said) a little so it shut's off at a slightly higher pressure (I.e. it'll keep running at lower flowrates - to suit your shower).

 

Need to ensure it still shut's off when all the taps are closed or the pump will never shut-off and damage itself... It can be quite tricky getting it set just right, especially if your electricity supply voltage is prone to variation (a lower voltage will make the pump run slower, and it will never shut off - and damage itself on no flow).

 

If the bladder tank does fail it'll cycle very rapidly (less than 1 sec).  You can easily add a little more surge capacity with a 2m length of 2" pipe mounted vertically with a valve at top and bottom to drain it occasionally... no need of a rubber bladder.

 

 

[sometimewoodworker]

15 hours ago, Andrew Dwyer said:

Now when showering I can hear the pump pulsing ( 3 sec on 3 sec off ) something I never noticed before, if another tap is opened or toilet flushes the pump stays on constantly.

I mentioned it to the gf , she said that now that the pump is on the steel frame it is louder ( which it is ) and nothing has changed. ( will also look at some rubber material to reduce the pump noise, steel frame has rubber feet).

 

It does seem logical that the pump delivers more water required for just the shower hence it turns on and off and stays constant when an additional tap open/toilet flushes calls for more water.

It is probably normal, if you get a shower unit that has a greater flow rate it will not happen.

 

Do ignore any suggestions to change the pressure switch settings, the will make no difference at all as it is the flow rate that is affecting the pump, also from the instructions 

 

You might possibly have a problem with the flow switch (life saver)

 

[Ahab]

18 hours ago, Andrew Dwyer said:

Ok thanks.

Can I ask you where you bought the bladder tank ?

That’s got to be the prime suspect as there is nowhere ( that I can see ) to drain water or air, only the hopper for priming, which I guess once it’s up and running is not necessary to mess with .

The pressure switch I’ve never touched so would be unlikely, IMO, that the pressure needs adjusting.

The pump has a small bladder tank attached. I don't know where you would buy a new one but the tech manual recommends replacement for the symptom. The tech manual also recommends not adjusting the pressure switch (and if you do adjust it any warrantee would be voided). If I can find a replacement I will report back whether it fixes the problem or not.

[Andrew Dwyer]

The pump has a small bladder tank attached. I don't know where you would buy a new one but the tech manual recommends replacement for the symptom. The tech manual also recommends not adjusting the pressure switch (and if you do adjust it any warrantee would be voided). If I can find a replacement I will report back whether it fixes the problem or not.

Okay thanks, I thought you had changed the bladder tank, I just re-read your first post and realised you hadn’t changed it only referring to it as a possible problem, sorry, my bad !

Yes, although annoying I don’t think it’s that bad, possibly affects the life of the pump though so would be grateful if you do find a tank, I’ll have a look around also .

[carlyai]

I go back to my origional post.

Have a look at the automatic water pumps for sale, they have a larger pressure tank. I think you have the wrong pump. Yours has a very small tank. But, don't change the tank as it was working.
Close off the valves and empty out all the water. Then refill it, see if this fixes the problem.
Next, take the cap of the pressure switch, be carefull live power around, get a texta marker and mark the position of the screw adjust so you can restore it to that mark. With an insulated screwdriver (the screw slot is live) screw it a bit clockwise and anticlockwise quickly then return it to the mark. Turn your shower etc on and see if any change. If not, with the shower etc on, adjust the pressure switch until the pump stops cycling.

So I wouldn't think about changing parts until you had a bit of a fiddle.

Again I could be wrong but I think your booster pump is more for getting water up to the top of a multi-floor townhouse etc.



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[Andrew Dwyer]

I go back to my origional post.

Have a look at the automatic water pumps for sale, they have a larger pressure tank. I think you have the wrong pump. Yours has a very small tank. But, don't change the tank as it was working.
Close off the valves and empty out all the water. Then refill it, see if this fixes the problem.
Next, take the cap of the pressure switch, be carefull live power around, get a texta marker and mark the position of the screw adjust so you can restore it to that mark. With an insulated screwdriver (the screw slot is live) screw it a bit clockwise and anticlockwise quickly then return it to the mark. Turn your shower etc on and see if any change. If not, with the shower etc on, adjust the pressure switch until the pump stops cycling.

So I wouldn't think about changing parts until you had a bit of a fiddle.

Again I could be wrong but I think your booster pump is more for getting water up to the top of a multi-floor townhouse etc.



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I have a small leak ( only a drip really ) from a fitting so while fixing will drain the pump and have a look around for any signs of dirt ( pvc shavings could have got inside ) or anything floating around in there.
This time I will prime the pump, something I didn’t do last time, as per the manual.

I think you could be right about the bladder tank, I worked on some machinery ( many moons ago ) with a hydraulic clutch, a nitrogen bladder tank was used to boost the initial burst of oil pressure to the clutch, after that the pump maintained the pressure.
But as it worked perfectly for two years, I don’t think the pump application is wrong maybe more than is needed for a bungalow but that can’t be a bad thing. Plus I’m sure it’s the same unit used on the other houses in the moobahn.

I seem to think that before it was like this:

Watering the garden, showering, flushing toilet or opening a tap fully would start the pump and pump would run constantly until water/tap was closed.
Pump would only pulse if a tap was opened partially.

now

Watering the garden, flushing toilet or tap fully open causes constant pump running.
Showering causes the pump to pulse.

So, restricting the flow ( shower head ) causes the pump to turn on and off as too much water is being delivered for shower fittings. ( I even cleaned both shower heads last night ).

Sounds like adjusting the pressure switch for the showers would resolve my problem, and I will probably have a play with this after I check the pump out for any obvious dirt and prime it .

P.S. probably sounds like I’m obsessed with this but I do admit to being ocd [emoji51] and as the pump is right outside my bathroom I can hear the pump turning on and off quite clearly and it’s doing my head in !!

[carlyai]

Sorry, I missed the comment about not changing the pressure switch. It's up to you.

The way I see it is that you have changed nothing in your setup. The shower head is the same, everything is the same. I can't see how it would hurt if you changed the pressure to see what would happen.

I have adjusted pressure switches before and replaced faulty pressure switches but I can't remember the exact fault as there have been a few.

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[Fruit Trader]

1 hour ago, carlyai said:

Sorry, I missed the comment about not changing the pressure switch. It's up to you.

The way I see it is that you have changed nothing in your setup. The shower head is the same, everything is the same. I can't see how it would hurt if you changed the pressure to see what would happen.

I have adjusted pressure switches before and replaced faulty pressure switches but I can't remember the exact fault as there have been a few.

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A do not adjust pressure switch warning is written into most automatic pump user manuals because people attempt to adjust the range screw without first establishing if differential setting has gone out of spec using a pressure gauge. It is possible to adjust range and differential in these compact switches but most people just hit the range screw above the spring and end up shifting a bad differential around.

 

Bladder tanks are charged to match pressure settings and its best to check cut in and cut out pressure before looking at adjusting or changing the pressure switch.

 

Hitachi 150XS

Cut in - 20 psi

Cut out - 25.5 psi

Pressure tank draw down - 1.2L

[carlyai]

A do not adjust pressure switch warning is written into most automatic pump user manuals because people attempt to adjust the range screw without first establishing if differential setting has gone out of spec using a pressure gauge. It is possible to adjust range and differential in these compact switches but most people just hit the range screw above the spring and end up shifting a bad differential around.
 
Bladder tanks are charged to match pressure settings and its best to check cut in and cut out pressure before looking at adjusting or changing the pressure switch.
 
Hitachi 150XS
Cut in - 20 psi
Cut out - 25.5 psi
Pressure tank draw down - 1.2L

Yes you are correct of course.

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[Fruit Trader]

10 minutes ago, carlyai said:

Y 


 

A rare sight but essential if you want to health check your pump.

[carlyai]

A rare sight but essential if you want to health check your pump.

I've got then on my jet pump as well. I've got 2 jet pumps, one I never have trouble with, and the other one, with the pressure indicator, is the one I sometimes have trouble with.

It took a while, but to know what's going on I needed them.

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[Mike45]

I've got the same issue when requiring low water flowing (like at the kitchen sink) water pulses and the pump quick cycles on and off.

I'd like to fix it so that I can get a constant water flowing at low and high flow rate.

[sometimewoodworker]

2 hours ago, Mike45 said:

I've got the same issue when requiring low water flowing (like at the kitchen sink) water pulses and the pump quick cycles on and off.

I'd like to fix it so that I can get a constant water flowing at low and high flow rate.

The only way with a small domestic pump like that is to get a large (100 litre +) pressure tank, it's still going to pulse if you are running the the kitchen sink tap for a long time but at a much slower rate.

[Fruit Trader]

4 hours ago, Mike45 said:

I've got the same issue when requiring low water flowing (like at the kitchen sink) water pulses and the pump quick cycles on and off.

I'd like to fix it so that I can get a constant water flowing at low and high flow rate.

 

Those are very short cycles and not normal even for a pump with small pressure vessel. I suggest you look into why the cycles are so short.

 

If you want to eliminate noisy cycling altogether then consider a  constant pressure pump.

[steve73]

Pumps produce both pressure and flow... the higher the flow rate, the lower the discharge pressure, but as the flow is choked back by throttling the outlet somewhere, the pressure increases, until there is no flow and the pump is what's called "dead-headed".   This pressure vs. flow relationship is called the pump curve.

 

The pressure switch is designed to shut off the pump when it operates at a low flow to prevent it dead-heading since it will continue to run but with no flow to cool it, it will rapidly overheat and damage itself.  

 

The difference in pressure between low flow and no flow (say 5-10% or rated capacity) is usually very flat, so the setting of the pressure switch to shut off the pump is very critical.  Set it too low and the pump will cycle, set it too high and the pump will never switch off (and damage itself).  But you can usually improve the factory settings, and allow cycle free operation at lower flowrates than "as supplied".... but you do risk damaging the pump.

 

One problem especially here in T/L is that the supply voltage can vary a lot.. higher voltage make the pump run faster (and so generate a higher pressure, which makes it more prone to cycling), or if the voltage drops a little. the pump will run slower and can never generate enough pressure to shut itself off - i.e. overheat and damage. 

 

If you do suffer with low voltage, you can adjust the switch setting to make it shut off at a little lower pressure, (but it will tend to cycle more when the voltage is normal). 

 

If excessive cycling does bother you, and you can't increase the set pressure due to occasional periods of low voltage, you can install a flow switch on the pump outlet.  This will then shut off the pump when it detects no flow regardless of the pressure, and will switch the pump on when it detect a falling pressure (such as when you open a tap).. But they are expensive (c. 2-2,500 bt) and can easily be damaged with voltage surges (I got through 3 of them in a year before I replaced them with a simple pressure switch.)  

[Andrew Dwyer]

Pumps produce both pressure and flow... the higher the flow rate, the lower the discharge pressure, but as the flow is choked back by throttling the outlet somewhere, the pressure increases, until there is no flow and the pump is what's called "dead-headed".   This pressure vs. flow relationship is called the pump curve.
 
The pressure switch is designed to shut off the pump when it operates at a low flow to prevent it dead-heading since it will continue to run but with no flow to cool it, it will rapidly overheat and damage itself.  
 
The difference in pressure between low flow and no flow (say 5-10% or rated capacity) is usually very flat, so the setting of the pressure switch to shut off the pump is very critical.  Set it too low and the pump will cycle, set it too high and the pump will never switch off (and damage itself).  But you can usually improve the factory settings, and allow cycle free operation at lower flowrates than "as supplied".... but you do risk damaging the pump.
 
One problem especially here in T/L is that the supply voltage can vary a lot.. higher voltage make the pump run faster (and so generate a higher pressure, which makes it more prone to cycling), or if the voltage drops a little. the pump will run slower and can never generate enough pressure to shut itself off - i.e. overheat and damage. 
 
If you do suffer with low voltage, you can adjust the switch setting to make it shut off at a little lower pressure, (but it will tend to cycle more when the voltage is normal). 
 
If excessive cycling does bother you, and you can't increase the set pressure due to occasional periods of low voltage, you can install a flow switch on the pump outlet.  This will then shut off the pump when it detects no flow regardless of the pressure, and will switch the pump on when it detect a falling pressure (such as when you open a tap).. But they are expensive (c. 2-2,500 bt) and can easily be damaged with voltage surges (I got through 3 of them in a year before I replaced them with a simple pressure switch.)  

Thanks for the info Steve.

My pulses , or cycling is probably a better word I’ve learnt, are nowhere near the frequency of Mike45’s and probably around 3 seconds on, 3 seconds off.

I’ve decided not to play with the pressure switch and live with the cycling in fear of buggering something up !!
Both my immediate neighbours have the same pump and i can hear a similar cycling occurring on some occasions , presumably when using the shower as it is a restriction.

As I said in the OP I’m not sure that this wasn’t happening before when the pump was sitting on concrete, now it’s sitting on a steel frame ( with rubber feet ) and a tiled walkway and it does seem much louder, but i am obsessing about it now [emoji51].
It’s in exactly the same position, albeit around 11” higher, and the pvc pipework is the same.
So, maybe some rubber or felt material under the pump will dampen some of the sound and in time I’ll forget about it, I have noticed the plastic cover does make the pump noise increase significantly but don’t want to leave it uncovered.

[steve73]

If the pulsing bothers you when showering (eg. if the resultant temperature varies too much) simply open a tap slightly, and the combined flow should allow the pump to run continuously.... but of course you will waste some water...