Water Pump Problem?

[PMK]

Small rented house with water pipes above ground - it is easy to check for any water leaks and I don't see any including the toilets. The landlord recently installed a second hand water pump. It seemed okay for a while, but now cycles on for a fraction of a second every 15 seconds or so. Could it be an internal problem - bad seal or something, inside the pump?

Thanks.

[Crossy]

Does the pump have a pressure tank?

If it does try draining all water from the tank (there needs to be an air space). How you do this depends upon the pump but there'll be a drain of some sort at the lowest point on the pump and some means of getting air in at the top of the tank.

Power and water off before trying the above.

Once drained close everything up and turn the water back on followed by the power.

[PMK]

Does the pump have a pressure tank?

If it does try draining all water from the tank (there needs to be an air space). How you do this depends upon the pump but there'll be a drain of some sort at the lowest point on the pump and some means of getting air in at the top of the tank.

Power and water off before trying the above.

Once drained close everything up and turn the water back on followed by the power.

Thanks, Crossy.

Pressure tank - I have no idea! It is multi (3) point, which personally I've never seen before, and taller than the tanks in my experience. Other than that it seems like the common type of tank you see for 5-8,000 baht. There is a screw cap on top which I assume is to prime it. I don't see any drain bung at all. I suppose turning the inlet water off and the pump on would more or less drain it.

Does that help?

[Pib]

If it's the kind of pump with no pressure tank, a leak of only a few drops can cause this problem. Or, as Crossy talks about above, if a pump does have a tank but the tank is water logged (i.e., lost its air charge) a small leak any where will cause the pump to cycle on frequently. In cases like this, it takes very little leak-wise to cause the pump to kick-on for a very brief run period very frequently.

Just last week my neighbor had a similar problem and she asked me about the problem. I already knew what type of pump she had....it was a Mitsubishi constant pressure pump that utilizes a liter size screw-in pressure tank. About every 30 seconds the pump was kicking-on for about a half a second. I told her she needs to be sure there is no faucet leaking, no commode refill leak, no water hose leak, just no leaks, etc. She said she was pretty sure there were none. I said I would be over in about 15 minutes to take a look. As soon as I pulled the plastic weather cover off the pump assembly I saw the problem. The little black hose that connects between the pump output connector to the constant flow control valve had a small leak...there would be about one drop every three seconds or so. Fixed that small leak...problem fixed...pump back to operating normally.

Now, if you have one of those pumps that sets right on top of small pressure tank, if that tank is water logged (i.e., lost its air charge) "and" there is a small leak it will kick on briefly & frequently. But if the tank is not water logged, it should take several minutes at least before it would kick on and run about 5 seconds to refill the tank and then cut off. This is due to the stored energy in the compressed air in the tank which will continue to push out water without the pump being on, until the pressure drops off so much. Exact same principle for a standalone pump which is connected to a large pressure tank a few feet away (and I'm not talking a water storage tank). If you think the pressure tank is water logged, cut power and water to the pump, turn a faucet on for a few seconds to drain off water pressure, and then unscrew the drain plug on the bottom of the tank. Now if the tank is "not" water logged, as you remove the drain plug the water will come out VERY force-ably for a few seconds if you didn't drain off enough pressure with the faucet; if it just kinda flows out under very little to no pressure then your tank was probably water logged (i.e., lost it aircharge).

But once the tank has completely drained which will allow air to rush-in through the drain plug, put the drain plug back in, turn on water to the pump, and then turn on the pump power. It will take about 5-10 seconds for the pump to refill the tank...and while the water is being refilled it is also compressing the air in the tank which creates a "stored energy cushion/spring" which allows X-amount of water to be pushed out without the pump having to kick on. When X-amount of water is pushed out / flows out (usually around a liter) the pump kicks on and the cycle continues until the water flow from the faucet, hose, etc., is turned off. If you have a large/separate pressure tank, this it would take more liters of flow before the pump would kick on.

Now, with these types of pump-on-tank designs they should not have lost their air charge/became water logged because they have a "air charger valve" feedback loop to keep the air charge in the tank at the proper level. If the rubber diaphragm in the air charger valve is ruptured, it will no longer operate properly by adding a very small amount of air to the tank every time the pump cycles on and off. And since air is naturally & slowly absorbed by the water in the tank, without a very small amount being added back, the air charge disappears since it is slowly/naturally absorbed into the water since there is no bladder or diaphragm in the tank to separate the water and air. This air charger valve is normally mounted on the top of the tank or water input manifold assembly and has a small PVC hose coming out of the top of the air charger valve going back to the manifold's water input side.

Now, if its a pump design with a completely separate pressure tank, follow Cossy's instructions. If the problem is then fixed, then you need to consider once again why the tank lost its air charge. If it's a plain steel pressure tank that does not use a bladder or diaphragm to keep the air and water separated, then unless there is an air charge/air control automatic system installed, you'll just have to periodic follow drain the tank, allow air to rush in, or possibly be able to pump in some air through Schroeder valve (a.k.a., car time valve) on top of the tank. If it is a tank that uses a bladder or diaphragm, well, it would take a long time (probably years) for the tank to lose any significant amount of air unless the schrader valve is leaking or some other minor air leak is occurring, or the bladder/diaphragm is rupture which basically turns the tank into a plain steel tank with no water/air separation and the process of air being naturally absorbed into the water begins...and this process works fairly fast...after just a few weeks the tank can get water logged.

Good luck.

Edited January 24, 2011 by Pib

[PMK]

Thank you for the detailed response.

I did some research on pressure tanks, and no, I don't have one.

I know a very small leak can cause this cycling problem - been through that before in another house, but everything is as dry as bone - no hint of a leak anywhere. I would still like to know if it is at all possible the problem is within the pump itself. I know it is unlikely and on the other end of the scale, anything may be possible, but realistically is the idea even worth considering?

There is no what I would call a back-pressure valve on the inlet side. Never was, and this is a new problem, so I suppose doesn't have anything to do with it, but how important is that? Also, I tried turning off the inlet valve just now, and the pump started cycling furiously within 10 seconds. Do you think that is significant?

[Crossy]

Is there a pump OUTLET valve you can turn off? That should isolate where (if any) the leak is.

Are you pumping directly from the supply main (a big no-no) or do you pump from a reservoir tank that fills from the main?

It's possible (as the pump is a used one) that the pressure switch has been 'adjusted' (read messed about with) which could be leading to your issues.

Any chance of posting a photo or two of your set-up so we can see exactly what you have?

[PMK]

Is there a pump OUTLET valve you can turn off? That should isolate where (if any) the leak is.

Are you pumping directly from the supply main (a big no-no) or do you pump from a reservoir tank that fills from the main?

It's possible (as the pump is a used one) that the pressure switch has been 'adjusted' (read messed about with) which could be leading to your issues.

Any chance of posting a photo or two of your set-up so we can see exactly what you have?

There is a water tank. I feel like an absolute idiot for not checking myself with the outlet valve shut. Yep, it is still cycling when shut. Do you think there is an adjustable pressure switch on the pump? I always have a lot of problems uploading photos here. You can see them at http://s41.photobuck...1/Water%20pump/

Thanks a lot!

[Pib]

You do indeed have a pressure tank...it the red tank the pump/manifold assembly is setting on.

The pressure switch is on the left side of the picture (looks like a small gray can)...if you remove the screw holding the switch's plastic cover on, you can remove the cover and see if there is one or two screw adjustments on the top of the switch which adjust the pump cutoff pressure and pressure range between the cut-on and cut off pressures. But don't attempt adjusting the switch pressure unless you have a pressure gauge, and the cap you removed shows what the cut on and cut off pressures are suppose to be, which are probably going to be around 2.8bar & 2.1bar (pump off/pump on) or 1.9bar & 1.4bar depending on the size/wattage of your pump.

Also, have you tried draining the red tank yet? I see the drain valve on the low left hand side. Be sure to cut off the pump power and pump water inlet & outlets before draining...and be sure to "completely" drain the tank because until all the water drains out the air can't rush in.

[PMK]

You do indeed have a pressure tank...it the red tank the pump/manifold assembly is setting on.

The pressure switch is on the left side of the picture (looks like a small gray can)...if you remove the screw holding the switch's plastic cover on, you can remove the cover and see if there is one or two screw adjustments on the top of the switch which adjust the pump cutoff pressure and pressure range between the cut-on and cut off pressures. But don't attempt adjusting the switch pressure unless you have a pressure gauge, and the cap you removed shows what the cut on and cut off pressures are suppose to be, which are probably going to be around 2.8bar & 2.1bar (pump off/pump on) or 1.9bar & 1.4bar depending on the size/wattage of your pump.

Also, have you tried draining the red tank yet? I see the drain valve on the low left hand side. Be sure to cut off the pump power and pump water inlet & outlets before draining...and be sure to "completely" drain the tank because until all the water drains out the air can't rush in.

Pib,

I drained it and it seems to be working properly! There is a reserve of pressure so the pump does not immediately kick in as soon as the water is turned on, but it does eventually.

I notice now there is a leak which was not there before. Perhaps it is the cause of the pressure tank problem. I believe it is in the same area same as your neighbour's - the constant flow control valve. It is from the area the lower end of the black tubing is attached to on the right side of the pump.It looks like it is from a small black rubber pip in the center of the inside (pump side) of that vertical valve. I can take a photo if necessary. What can I do about getting that repaired or replaced?

Thanks very much for the assistance!

Edited January 24, 2011 by PMK

[PMK]

I uploaded another photo to the same album.

[Pib]

That's your air charger valve on your particular model. Assuming the red arrow on the picture is pointing to the leak area I would say the rubber diaphragm inside your square shaped air charger valve has ruptured/developed a hole, which means it's probably no longer working which means your pump cycling problem will come back as the air charge is absorbed into the water. Or, since the valve also probably has one or two very small check valves (nothing more than a plastic ball and possibly a spring) that work in conjunction with the rubber diaphragm to allow flow of air into the tank and keep air or water from escaping while the valve is pushing in a little air....these little check valves may be dirtry/clogged...you can clean them by removing/dis-assembling the air charger valve. But your pump looks like it got some years under it's belt and the rubber diaphragm in the valve has probably just dried up and cracked/ruptured.

Take a look at one of my earlier posts on this subject...the post deals with how my air charger valve went bad on my Mitsubishi WP series pump, and this problem caused me to pull my hair out for months as the improper pump cycling problem would always come back approx 3 weeks after I had drained/recharged the tank. Steady, constant water pressure for about 3 weeks and then the water pulsations and pump improper cycling were back. This post will give you some ideas on how to check the operation of your air charger valve (a.k.a, air volume control valve, balance valve, etc) without taking it off, by seeing if you can feel any light suction occurring from the valve vent to atmosphere and how to check the tank "draw down" the determine if it's loosing it air charge way before it become noticeable by improper pump cycling. Keep in mind your valve is shaped/constructed just a little differently than mine and it may be more difficult to do the air suction test, but the principle of operation is exactly the same.

I see so many TV posts where folks seem so happy that their pump begins cycling properly after they completely drain the pressure tank and let air back in, but I just know for many of those folks the problem comes back soon since the "root cause" problem was not fixed....and the root cause problem was probably the air charger valve. Good luck.

http://www.thaivisa.com/forum/topic/426117-why-does-my-pump-throb/page__view__findpost__p__4134744

Edited January 24, 2011 by Pib

[PMK]

The main thing for me is knowing the source of the problem - a new pump will not be very much for this house if/when it comes to that.

So, now, thanks to Crossy and Pib, I know the rapid cycling was due to no air in the pressure tank, and that is probably caused from an air leak in the air charger valve. I no longer have to search for a non-existent water leak inside the house!

Thanks for your help - much appreciated!

[powderpuff]

FYI - the isolation valve, downstream of your pressure pump system is a PVC type which I have never had much luck with. They are fine for isolating the pump to do repairs inside the house but you can never be sure they are 100% sealed.

So if you decide to replace the pump in future I suggest getting a gate valve (like Kitz) with the necessary PVC fittings. Then if you have to isolate the pump for troubleshooting you know you have a seal.

Otherwise good info from PIB.

[Pib]

The main thing for me is knowing the source of the problem - a new pump will not be very much for this house if/when it comes to that.

So, now, thanks to Crossy and Pib, I know the rapid cycling was due to no air in the pressure tank, and that is probably caused from an air leak in the air charger valve. I no longer have to search for a non-existent water leak inside the house!

Thanks for your help - much appreciated!

You are welcome. And technically, although you see some water leaking from your air charger valve its probably not leaking any air...just water from the water input/suction side of the pump. Instead, the valve is just not working anymore which means it's not adding small amounts of air to the tank which compensates for the natural process of the tank air being slowly absorbed into the water. A replacement valve will probably cost you in the 500 to 800 baht range....a lot cheaper than a new pump. Check the web page of the water pump manufacturer and you should be able to find service centers/shops that provide service and/or replacement parts....that what I did to find my replacement valve and installed it myself...install is super easy.

From my experience in tearing apart my water pump and examining individual parts when I was looking for my earlier air loss problem, I think the most likely thing to fail on these pumps is the air charger valve simply due to the rubber diaphragm in the air charger valve. One side of the rubber diaphragm is contently exposed to the water which causes it to deteriorate (and actually dry up) over years of operation, plus it is moving back and forth on each pump cycle. And if I had to guess maybe the pressure switch would be the next thing most likely to fail due to constant switching on and off and a small diaphragm inside the switch used for the pressure sensing (approx 400 to 700 baht for a new switch). Then comes the motor startup capacitor mounted in that plastic box on top of the motor...capactor size vary per motor but are usually in the 4 to 8 micro-farad range (costs about 35 baht for a replacement...aleady bought my spare 8uf cap in case of failure). I see so many of these pumps around my moobaan which are still operating and look to be around 5-10 years old (maybe older). I don't know if or how often they have broke down/been repaired, but the original tank, motor, manifold assembly, etc., all appear to be original. Definitely long lasting and reliable pumps for the most part.

[doglover]

Excellent detail Pib! There are some members who only like to recieve basic info and others like me who want all the details. Thanks to you I now have enough knowledge to tackle the issues with my Mitsubishi WP - 355Q.

You said: "But don't attempt adjusting the switch pressure unless you have a pressure gauge, and the cap you removed shows what the cut on and cut off pressures are suppose to be, which are probably going to be around 2.8bar & 2.1bar (pump off/pump on) or 1.9bar & 1.4bar depending on the size/wattage of your pump."

Too bad I didn't know about the awesome info in this forum beforehand. I've already messed about with my pressure switch without a gauge. I managed to fiddle with it and have the pump run continuously when a tap is opened. So until I read this thread I was pretty proud of myself.... as it is a better situation than a rapidly cycling pump. But now it is time to get to the bottom of the issue and it will be fun to troubleshoot (albeit fairly easy now).

It would be appreciated if you could go into some detail about adjusting the pressure switch and where you bought the pressure gauge. Also more detail about the water draw down test would be handy as well if you are inclined. Thanks again Pib!

[powderpuff]

Gate valve will look like this with the correct PVC fittings.

[powderpuff]

Any hardware store selling pumps will have gauges. Here is a picture out back of my house near my workbench.

Gauges are normally 1/4 NPT male inlets. So you need to get a 1/4 NPT X 1/2 NPT reducer to hook it up.

For those that don't know NPT is the American standard pipe fitting. T stands for "tapered" unlike BSP with is not tapered.

[doglover]

Any hardware store selling pumps will have gauges. Here is a picture out back of my house near my workbench.

Gauges are normally 1/4 NPT male inlets. So you need to get a 1/4 NPT X 1/2 NPT reducer to hook it up.

For those that don't know NPT is the American standard pipe fitting. T stands for "tapered" unlike BSP with is not tapered.

Now that's thinking.... Just permanently install the gauge in the system. I had in mind to just fit the gauge temporarily but your idea makes alot more sense. I don't like the idea of restricting flow with any reduced fitting sizes anywhere in the system however. I am using 1" PVC piping up and downstream from my pump so I will have to search for a pressure gauge with the same diameter.

*I suppose there would also be a slight reduction in flow from the resistance of the pressure gauge even when matching diameter, but I'm guessing it would be very slight given the pressures used.

*Totally agree with your comment about PVC ball valves. The gate valve in your photos is the way to go.

Edited January 25, 2011 by doglover

[Pib]

Excellent detail Pib! There are some members who only like to receive basic info and others like me who want all the details. Thanks to you I now have enough knowledge to tackle the issues with my Mitsubishi WP - 355Q.

You said: "But don't attempt adjusting the switch pressure unless you have a pressure gauge, and the cap you removed shows what the cut on and cut off pressures are suppose to be, which are probably going to be around 2.8bar & 2.1bar (pump off/pump on) or 1.9bar & 1.4bar depending on the size/wattage of your pump."

Too bad I didn't know about the awesome info in this forum beforehand. I've already messed about with my pressure switch without a gauge. I managed to fiddle with it and have the pump run continuously when a tap is opened. So until I read this thread I was pretty proud of myself.... as it is a better situation than a rapidly cycling pump. But now it is time to get to the bottom of the issue and it will be fun to troubleshoot (albeit fairly easy now).

It would be appreciated if you could go into some detail about adjusting the pressure switch and where you bought the pressure gauge. Also more detail about the water draw down test would be handy as well if you are inclined. Thanks again Pib!

I think Post 22, 40, and 42 in another topic basically on the same subject will provide the details you need, with a picture of the pressure switch that came with my WP-255...and I wouldn't be surprised if the pressure switch for your WP-355 isn't exactly the same although your pressure switch settings are suppose to be 2.8 bar for pump cut-off and 2.2 bar for pump cut-on....my WP-255 has settings/specs of 2.8 and 2.1 bar. Below is hopefully the link that will take you to the topic and post #42...post 22 and 40 are in the same topic. Lots of good info/posts in this one topic.

http://www.thaivisa....ost__p__3912170

Regarding the pressure gauge, I just bought a 0-6 bar gauge at Global House in their irrigation section and clamped on a foot long piece of water hose with a faucet connector on the end of the hose...that way the gauge can be mobile, used to carry around and check different water outlets, take it to go check the neighbor's pressure, etc. The gauge cost around a 130 baht give or take 10 baht.

If your pump is running all the time when water is on somewhere in/around the house, this probably means you have adjusted the pressure switch to such a high pressure the pump can't reach that pressure and it just continues to run...trying to reach that too high of a pressure switch setting. As you will read in above mentioned posts my pump came new with the new house, but apparently the pressure switch came mal-adjusted from the factory or the installers mal-adjusted the switch (probably the later) so the pump would put out more pressure by running longer. The pressure switch was set to cut off at 60 psi and cut on at 50 psi instead of the factory specs of 40 psi (2.8 bar) and 30 psi (2.1 bar), and the pump ran significantly longer than it's off period of time. When the pump pressure settings were set properly on my WP-255 and with one faucet running full blast (and no water logged tank), the pump would cut on for about 6 seconds, cut off for about 6 seconds, and continue at this on and off interval. Before when the pump pressure switch was mal-adjusted, it would cut on for about 10 seconds, cut off for about 2 seconds, etc. Basically the pump was being worked to death, beyond its designed, day-to-day operating specs, and it would overheat sometimes and shut itself down for about 15 minutes until the motor's thermal protection devices automatically reset itself. And this pressure switch mal-adjustment may have been what forced my air charger valve to early failure which caused the water logged tank condition. Sounds like you may have yours adjusted to even a higher pressure...and make sure your tank is not water logged.

Yeap, don't mess with the pressure switch adjustments unless you have a gauge. Cheers and Good Luck

[PMK]

Follow up question, please.

I started looking at replacement pumps as I know I'll have to change it out eventually. This is a small house, two residents, no bath, no garden, single story, minimal requirement for water pressure. I was looking at a Mitsubishi WP105Q series and I am not sure if it has a pressure tank or not. It looks exactly like my current pump - the motor sits on a large cylinder, but I don't see any drain valve. If that cylinder was a pressure tank, wouldn't it have one? If it doesn',t does it really matter in my situation?

[Pib]

Follow up question, please.

I started looking at replacement pumps as I know I'll have to change it out eventually. This is a small house, two residents, no bath, no garden, single story, minimal requirement for water pressure. I was looking at a Mitsubishi WP105Q series and I am not sure if it has a pressure tank or not. It looks exactly like my current pump - the motor sits on a large cylinder, but I don't see any drain valve. If that cylinder was a pressure tank, wouldn't it have one? If it doesn',t does it really matter in my situation?

If it is setting on a tank, that is a pressure tank...but Mitsubishi calls it a "booster" tank for its WP series. The WP105Q should have a drain valve...maybe if you were looking at a display model it was on the side you didn't look at. Sounds like a WP105Q would meet your described water "volume" needs, but keep in mind the WP105Q pump cut-on and pump cut-off pressure switch settings are 1.9 bar (27 psi) and 1.3 bar (19 psi), for an average pressure of 1.6 bar (23 psi). That is not considered a strong pressure and is going to produce a weak shower,especially through an instantaneous water heater. If you use a instantaneous hot water heater for the shower, most of these heaters require at leat 1 bar of pressure before they will operate/heating elements turn on. Since you could see a pump pressure of around 1.3 bar for a few seconds as the pump cycles, it may impact your water heater operation.

Personally, in your situation, I would get a Mitsubishi WP 205Q which has pump cut-on and pump-cut off pressure switch settings of 2.8 bar (40psi) and 2.1 bar (30 psi), for an average approx pressure of 2.5 bar (35 psi). This will give a strong shower and more water volume if needed later on. Plus it shouldn't cost much more than a WP105Q. Don't be concerned about the pressure variations between the pump cut on and pump off as they basically can't be felt or seen within the household water use environment....it just feels like constant pressure or at least my WP255Q with 2.8/2.1 bar pressure switch setting feels and looks like a constant pressure. But you definitely want to get enough "average" water pressure to suit your needs and desires.

See below attachments for more info/specs on the Mitsubishi water pumps. Note: slightly different pressure specs reflected in the two attachments regarding the WP105Q, so I used the slightly high pressure specs in my words above. Good luck.

hp2009_Q3_102726.pdf

Edited January 26, 2011 by Pib

[doglover]

Any hardware store selling pumps will have gauges. Here is a picture out back of my house near my workbench.

Gauges are normally 1/4 NPT male inlets. So you need to get a 1/4 NPT X 1/2 NPT reducer to hook it up.

For those that don't know NPT is the American standard pipe fitting. T stands for "tapered" unlike BSP with is not tapered.

Now that's thinking.... Just permanently install the gauge in the system. I had in mind to just fit the gauge temporarily but your idea makes alot more sense. I don't like the idea of restricting flow with any reduced fitting sizes anywhere in the system however. I am using 1" PVC piping up and downstream from my pump so I will have to search for a pressure gauge with the same diameter.

*I suppose there would also be a slight reduction in flow from the resistance of the pressure gauge even when matching diameter, but I'm guessing it would be very slight given the pressures used.

*Totally agree with your comment about PVC ball valves. The gate valve in your photos is the way to go.

OOPS! I just bought a pressure guage yesterday and realize how stupid my response about restricting flow is too those that have pressure guages. I didn't realize that the guage simply threads in the top of a T-fitting and there is no intrusion of any mechanical parts into the water flow. I'll be fitting mine in permanently today.

[Naam]

Totally agree with your comment about PVC ball valves. The gate valve in your photos is the way to go.

to each his own :jap: i have always preferred PVC ball valves or any brass gate valves (which will sooner or later leak as sure as a prayer is followed by "amen").

to prevent flow restriction one increases the valve size and installs it with PVC adaptors. same same but different when it concerns check valves.