Question For Those With Mitsubishi Ep Series Home Water Pumps

[Pib]

For those of you who use a Mitsubishi "EP" Series water pump, repeat, "EP" series, like the one pictured in the attachment, Do you get constant/steady water pressure?

I currently have a Mitsubishi "WP" Series water pump (came with the house). The WP series is where the pump motor sets on top of a small booster tank, but the design/operation of the WP Series pump is for the water pump to turn off and on as the pressure in its tank reaches approx 30 psi (pump turns on) and 40 psi (pump turns off). The specific psi pressures vary by tank model. While I get an "average" 35 psi water pressure, the pressure is always pulsating every second or two due to pump turning off and on which causes the water from shower heads, taps, hoses, filling up the commodes, etc., to pulsate. And with the commode tank refill you can clearly hear the pulsating. This is normal operation for Mitsubishi WP series pumps, and in fact, other manufacturers pumps based on the same design...a very common design used in Thailand.

Yes, I know I could also switch to jet-line type pump that feeds into a large pressure tank which would help reduce pulsating; instead of one or two second pulses I would have pressure changes/pulses which go up and down much slower. However, I would like to get a pump setup that gives me "constant/steady" pressure. The Mitsubishi "CP" series appears it might provide constant pressure (and looks very similar to a EP model), but it appears the CP series is designed to fill up tanks on top of a building where a separate sensor switch is needed to tell the CP pump to turn off....this really wouldn't work for my home setup...plus, I want a pump that is more self controlling.

The Mitsubishi "EP" series seems to fit that bill of steady pressure/flow with its built in "flow sensor" but since I see it also has a pressure switch build-in also which is designed to kick-in at at approx 30 to 40 psi (varies slightly by model), I'm concerned the EP may also provide pulsating water, but to a lower degree. This pressure switch may just be used as a safety feature or used under certain circumstances and the flow sensor does all the real controlling. Due to the language barrier and knowledge of the sales assistances in stores, I can't get an answer that confirms to me the pressure/volume from the EP series pump is constant/steady. So, it would be greatly appreciated from you Mitsubishi "EP" Series pump owners/users as to if your EP series pump provides "non-pulsating/steady/constant" pressure/flow. Big thanks.

[Beardog]

Hi Pib,

I have both the EP 205 & A EP 305 & they both pulse. The only way I have heard to remedy the pulse is a tank that can be pressurized to keep the psi up o it does not pulse. You can get the tanks at most home repair Homepro Homeworks Homemart & most of the larger mom & pops fixall shops. I am going to weld a tank setup that will do the same. I have seen the units as small as a mini barrel (beer keg) used for VW dune buggy tanks to 500 liters & up. Several members have the tanks in their setups.They will probably be kind enough to post you pic.

[JAS21]

I have the same pump, it doesn't cut in and out that often, have you made sure that the associated tank is not full or partly full of water. Try removing the drain plug..stand to the side when you do it!

If all else fails then add an external pressure tank, hopefully you will get some pictures from others.

[Beardog]

Hi Pib I tried to copy kamalabob2 diagram. but this is his I think a 500 liter air tank. They make smaller as well . It is under water tanks post 4 if use the search function you can pull up the post & see the unit.

[Pib]

Hi Pib,

I have both the EP 205 & A EP 305 & they both pulse. The only way I have heard to remedy the pulse is a tank that can be pressurized to keep the psi up o it does not pulse. You can get the tanks at most home repair Homepro Homeworks Homemart & most of the larger mom & pops fixall shops. I am going to weld a tank setup that will do the same. I have seen the units as small as a mini barrel (beer keg) used for VW dune buggy tanks to 500 liters & up. Several members have the tanks in their setups.They will probably be kind enough to post you pic.

Wow, that's strange. Wonder why Mitsubishi advertises it as a "constant pressure" water pump. Of course, since I don't always trust advertising, that's why I posted this topic.

Hopefully, the tank will work for you, but I sure know the tank that stands about 5 ft tall and 1.5 ft wide hooked up to jetline type pumps don't eliminate the slow pressure variation from X-psi to X-psi like 30 to 50 psi based on how the tank is setup...and the tanks are air pressurized properly/not water logged. But as you know these types of setups come with the pressure switch usually on the tank that switches on and off the pump at X-psi and then the water tank slowly pushes out the water when the pump is off and slowly allows a refill when the pump is on which keeps the pressure variations slow.

In choosing between the two types of pressure variations, slow like in the tank setup just mentioned or fast like my current Mitsubishi WP series pump which has the water booster tank on the bottom, I would probably prefer the slow variation, But what I really want is very little to no variation.

Thanks again. Now I'm not quite sure if I want to change out my WP series pump with an EP Series pump if I'm still going to have fairly noticeable pressure variation.

[Pib]

I have the same pump, it doesn't cut in and out that often, have you made sure that the associated tank is not full or partly full of water. Try removing the drain plug..stand to the side when you do it!

If all else fails then add an external pressure tank, hopefully you will get some pictures from others.

Thanks for the reply. So far regarding the EP series, I've had one PM that which said the EP series did not have much pressure variation, one post that says the pressure does vary/pulse, and your post which implies little variation.

For clarification, the tank on the bottom of the WP series of pumps is not a combination water and air pressure tank like you are thinking of which has air in the top and water in the bottom...and are usually completely separate tanks setting just to the side of a pump. The tank on the bottom of WP series tanks are called "booster" tanks and are suppose to be completely full of water which creates a small reservoir of water to help minimize pressure variations and to prevent the pump from constantly kicking on and off due to small leaks, etc. The drain tap on the tank is purely for drainage in case you want to clean out the water from the entire pump, maybe drain off any sediment in the bottom of the tank, make the pump lighter to move it, etc. See attached thumb nail for snapshot of the WP series and its tank.

Very common design (probably the most popular...at least in my moobaan) used in Thailand, regardless of the pump manufacturer. I'm beginning to think this design is so popular because it handles small leaks much better than tankless pumps. By handling leaks better I mean they turn off and on less to re-pressurize after a few drops/small leaks/leaky tap where a tankless pump would kick on briefly to re-pressurize. And if the leak is just the right size to cause the pump to turn off an on every few minutes that could drive a person crazy. One thing about tankless setups, a person needs to have no leaks or the pump is going to be kicking on briefly quite a lot...and it can make a person wonder why the pump kicked on because no one is using water.

Thanks again for your reply on your EP series pump.

[Pib]

I have the same pump, it doesn't cut in and out that often, have you made sure that the associated tank is not full or partly full of water. Try removing the drain plug..stand to the side when you do it!

If all else fails then add an external pressure tank, hopefully you will get some pictures from others.

Thanks for the reply. So far regarding the EP series, I've had one PM that which said the EP series did not have much pressure variation, one post that says the pressure does vary/pulse, and your post which implies little variation.

For clarification, the tank on the bottom of the WP series of pumps is not a combination water and air pressure tank like you are thinking of which has air in the top and water in the bottom...and are usually completely separate tanks setting just to the side of a pump. The tank on the bottom of WP series tanks are called "booster" tanks and are suppose to be completely full of water which creates a small reservoir of water to help minimize pressure variations and to prevent the pump from constantly kicking on and off due to small leaks, etc. The drain tap on the tank is purely for drainage in case you want to clean out the water from the entire pump, maybe drain off any sediment in the bottom of the tank, make the pump lighter to move it, etc. See attached thumb nail for snapshot of the WP series and its tank.

Very common design (probably the most popular...at least in my moobaan) used in Thailand, regardless of the pump manufacturer. I'm beginning to think this design is so popular because it handles small leaks much better than tankless pumps. By handling leaks better I mean they turn off and on less to re-pressurize after a few drops/small leaks/leaky tap where a tankless pump would kick on briefly to re-pressurize. And if the leak is just the right size to cause the pump to turn off an on every few minutes that could drive a person crazy. One thing about tankless setups, a person needs to have no leaks or the pump is going to be kicking on briefly quite a lot...and it can make a person wonder why the pump kicked on because no one is using water.

Thanks again for your reply on your EP series pump.

John45,

Based on my further research and testing, scratch what I said about the tank on the bottom of the WP series pumps "not" being a combination water and air pressure tank. The tank "is" indeed a combination water and air pressure tank. Now, as you know, there is no schradar valve to add/adjust the amount of air/pre-charge or a separate automatic air valve to automatically readd/recharge the tank on the WP series pumps...a person gets the correct air charge by cutting off power and water to the pump and letting the tank "completely" drain out like you said above.

Only when the tank "completely" drains that water drops lowr enough to allow air to enter the tank "at the drain valve." Then reinstall the drain valve and turn back on the water and electric supplies to the pump. Since air is compressable, it compresses to the pump cut off setting/pressure (example: 2.8Bar/40psi for my pump), pump cuts off, the air charge now act like a spring and pushes down on the water to continue the water flow with the pump not running and until the pressure reaches the pump cut on setting/pressure (example: 2.1Bar/30psi on my pump). As mentioned, these example pressures are just the pressures used for my particular pump...pressures vary from pump to pump. Without the proper air charge and since a liquid/water can be compressed very little (atoms to close together ...can't create the pressure spring...compared to atom spacing for air/a gas), the pump turns off and on too much in trying to compress the water vs compressing the air charge which creates a cushion/pressure spring to mininise pulsating....and as mentioned earlier, to apply pressure on the water when the pump is not running. Heck, this is basic physics and I should have known this...but I initially got some bad info regarding the booster tank.

Now that I have "recharged" my pump properly (it was apparently low on air) the water pulsating is gone...just the slow/steady pressure change from 30 to 40psi, which really ain't noticeable. The pump is about 3 years old and my guess is it air charge had slowly been absorbed in the water over those 3 years...I don't know if all the air charge had leaked off or was just low....I expect the later in my particular case. With my pump tank now having the proper air charge the pump turns off and on approx every 5 seconds with one water tap fully running/wide open (before it was about every 2 seconds for one wide open tap). I've also fixed two separate problems with the pump's pressure switch (mal-adjusted cut on and cut off pressures which I adjusted to specs plus cleaning the dirty/corroded contacts). Hopefully the pump is now good for another 3 years...it working better than it ever has. However, I will probably completely drain the tank every 6 months or so....or whenever I'm not getting that approx 5 second pump on/off interval with one tap fully open.

Summary: you were right about the WP series pump. Thanks for your info/recommendation, even though I didn't initially take it....but I came around to your wisdom.

Cheers,

Pib

[JAS21]

Pip

They are good pumps...the House Builders worker managed to 'boil' the pump at least once! and it still works reasonably well. He did mess with the pressure switch when I said it is not as good as before (you ran it dry for some hours)!!!

I changed the pressure switch...he <deleted>--ed it.

Also completely re-designed the pipework. New NRVs etc, I can now easily change any valve although I will have to cut the offending bit out. I did buy the highest quality NRVs I could find. Note that most pipes are either reasonably vertical or horizontal...obviously not piped up by a Thai plumber.................

I have an automatic watering system for the garden, you can see one of the timers in the picture. No pump suction v/v as I can always drain the tank if necessary.

Pleased that all is now sorted.....John

[WormFarmer]

At one time I had a Hitachi pump which caused alternating hot and cold water in the shower. I then installed a Mitsubishi 500W inverter pump as shown in the thumbnail and this works like magic. Water is drawn from an undergound tank and no matter how many outlets are in use (we have three bathrooms and the farang kitchen running off it for both hot and cold water) there is no alternation of hot and cold water and the flow remains constant.

[aoneseller]

Hi Pib. It's me again. After a while. I am not sure how to reach you, so I just replied to this water pump topic. 

After 3 years of struggling I finally managed to fix my water pump Mitsubishi EP-155Q2. The problem was : every year in April and May (hot months) the pump wouldn't cut off in the evenings. Maybe low voltage, not sure. But this video fix my problem. I followed the instructions in order to adjust the pressure switch. Let me know about your opinion.

 

https://youtu.be/kji2ZPR5e0khttps://youtu.be/kji2ZPR5e0k

[sometimewoodworker]

10 hours ago, aoneseller said:

Hi Pib. It's me again. After a while. I am not sure how to reach you, so I just replied to this water pump topic. 

After 3 years of struggling I finally managed to fix my water pump Mitsubishi EP-155Q2. The problem was : every year in April and May (hot months) the pump wouldn't cut off in the evenings. Maybe low voltage, not sure. But this video fix my problem. I followed the instructions in order to adjust the pressure switch. Let me know about your opinion.

 

https://youtu.be/kji2ZPR5e0khttps://youtu.be/kji2ZPR5e0k

It’s extremely unlikely that the pressure switch needed adjustment or that adjusting it solved your problem. The are cheap so a replacement is simple. 
it is much more likely that something else that you did solved the problem. 
 

[clivebaxter]

11 hours ago, aoneseller said:

Hi Pib. It's me again. After a while. I am not sure how to reach you, so I just replied to this water pump topic. 

After 3 years of struggling I finally managed to fix my water pump Mitsubishi EP-155Q2. The problem was : every year in April and May (hot months) the pump wouldn't cut off in the evenings. Maybe low voltage, not sure. But this video fix my problem. I followed the instructions in order to adjust the pressure switch. Let me know about your opinion.

 

https://youtu.be/kji2ZPR5e0khttps://youtu.be/kji2ZPR5e0k

Pressure switch thought to be the problem so puts a valve in the feed and leaves it open? Don't get that. Every time ours has a problem I take the plug at the bottom out and drain all the water then put the water back on again.

[Pib]

12 hours ago, aoneseller said:

Hi Pib. It's me again. After a while. I am not sure how to reach you, so I just replied to this water pump topic. 

After 3 years of struggling I finally managed to fix my water pump Mitsubishi EP-155Q2. The problem was : every year in April and May (hot months) the pump wouldn't cut off in the evenings. Maybe low voltage, not sure. But this video fix my problem. I followed the instructions in order to adjust the pressure switch. Let me know about your opinion.

 

https://youtu.be/kji2ZPR5e0khttps://youtu.be/kji2ZPR5e0k

 

The video basically shows how to mal-adjust the pressure switch to get the pump to turn off and on--and only god knows what those two pressure points turned out to be since the mechanic did not use a pressure gauge.   But the video does include annotation saying in "actual use" you need to use a pressure gauge to check the pressure in the output line.....see the snapshot below. 

 

And the only reason he added a shutoff valve in the output line was to ensure there was no water leaks down stream like a leaking commode, water tap, pipe somewhere, etc., that was allowing a continuously water flow....a significant leak.  But having a shutoff valves on the pump's output and input is definitely  a good thing for maintenance and testing purposes like done in this video.

 

 

 

And regarding the pressure switch adjustments....see comments and snapshot below.   

 

Screw #1  adjusts the switch on "and" off pressures....will increase or decrease both pressure points at the same time.   If I remember right turn the screw CW will raise the cut off and on pressures because you are compressing the adjustment spring; turning CCW will lower the cut off and on pressures because you are decompressing the spring.

 

Screw #2 adjust the "span" between the on and off pressure points.   Like say the factory/design specs cut on and off pressures are suppose to be 2.1 bar and 2.8 bar.  If you adjust the span screw in one direction it will change the pressure span to like 2.2 and 2.7,  1.9 and 2.6, 1.5 and 2.2, etc.....etc....etc.   I forget which way to turn the adjust to increase or decrease the span.....but if using a pressure gauge to take a measurement after an adjustment which way to turn will make it obvious....ditto when adjusting screw #1.

 

Then if you adjusted the span adjustment screw you go back to screw #1 to adjust the factory/design cut off pressure which should bring the cut on pressure back to factory specs also.   Remember, a pressure gauge is needed otherwise you don't have  clue what cut on and cut off pressures have changed to.   Maye changed to some pressures the pump is designed to handle or maybe some pressures the pump is not designed to handle.....simply outside the pump's design limits continuous long term operation.

 

But you can adjust either screw 1 or 2 too far in either direction (CW or CCW) to where the pump starts doing weird things like not cutting off, not cutting on, etc.   THIS IS WHY A PRESSURE GAUGE IS REQUIRED TO PROPERLY ADJUST THE PRESSURE CUT ON AND CUT OFF PRESSURES. 

 

And a final note, in the video it obvious the mechanic (or someone previous) had adjusted screw #1 to compress the spring almost to its limit....maybe just for purposes of making the video....or someone before tinkering/adjusting the pressure switch without using a pressure gauge.

 

Note: for your EP155 the pressure cut on and off points are 1.3 and 1.9 bar (see snapshot at bottom).  With your recent tinkering what did you set your pressures to?  Unless using a pressure gauge you will not know.  You pump pressures may now be set to pressures outside the pump's design limits, set too high, set too low, OR, maybe you got lucky in your roll of the dice and its now set pretty close to factory specs

 

 

 

[Pib]

Oh, by way, in this 11 year old thread I ask for feedback on the Mitsubitshi EP series of pumps as I was thinking about replacing my Mitsubishi "WP" series pump.   However, as of today, I still have my WP-255 pump made back in 2007/2008.   

 

But it has had repairs along the way....all of which I have accomplished. 

 

- I have replaced the tank that the pump/motor assemble sets on...replaced the tank a couple of years ago....the tank developed pin-hole corrosion leaks around the seam at the bottom of the tank....attempted to fix these leaks by spot brazing at a shop but the brazing simply wouldn't stop the leak 100%....just too much corrosion around the leak point....braze the leak but then another one appears real close to the original leak point.  Ended up replacing the tank for about Bt2000....not hard to do....just takes around 30 minutes to swap over the motor/manifold assembly from the old to new tank.

 

- Replaced the air balance valve which keeps the correct mixture of air and water in the tank....replaced this valve after about 5 years or operation....the rubber diaphragm in the value developed a pin-hole leak....with the valve now defective it allowed the tank to become water logged.  Drain the tag to reset the air-water mixture and pump works fine for a week or two, but without the air control valve working properly the pump would become waterlogged again in about 10-14 days.   And I replaced that valve again just a few weeks ago "not" because it was bad, but because I was replacing the a defective pressure switch and decided just to replace the valve at the same time since it only cost a couple hundred baht....keeping the old valve as a spare/backup.

 

-  Replaced the original pressure switch about a half dozen years ago with another Mitsubishi switch and had to replace this switch just a few weeks ago....once again, the switch lasted about a half dozen years.   So, I have replaced the pressure switch twice over the pump's 12-13 year lifespan....seems the pressure switch will last about a half dozen years before the switch's electrical contacts wear out (the 1st switch's failure point) or the pressure spring mechanism wears out (2nd switch's failure point as it electrical contacts were fine before and after cleaning/burnishing).    For the switch that failed last week, it was not possible to correctly adjust the switch to factory cut on and off specs....I tried (with pressure gauge)....simply couldn't get the span adjustment to give the correct difference between the cut on and cut off pressures without the switch  occasionally/intermittently sticking in the on position not allowing the pump to turn off until the slapping the pressure switch.  Adjust the span adjustment to eliminate the sticking problem but to do this you end up setting the pump to pressures significantly outside it's design specs.....in this case the pump was putting out about 20% more pressure than it specs....not good for long term operation.  Replaced the pressure switch and all is fine again....hopefully for another half dozen or so years.

 

--Note: and boy there is definitely a major quality difference (at least visually) between a Mitsubishi OEM switch (which costs approx Bt450) and a generic switch (which costs approx Bt200).  Visually the Mitsubishi mechanism looks solid, no plastic parts, just looks long lasting, but the generic switch has plastic parts and cheap looking springs....just gave me the feeling this new switch could break in just a few months.   I had bought this cheap generic switch as an emergency spare to have on hand for quick replacement/emergency replacement purposes.....I used this generic switch for two days pending getting an original Mitsubishi switch......that generic switch is now back on spare/emergency backup status like the still working air control valve I replaced.

-  And finally when replacing the pressure switch and air control valve a few weeks ago I also replaced the pump motor start capacitor.  The original 8 microfarad cap was still working but it was over a dozen years old, I had a new spare capacitor already, and just replaced the old cap while replacing the pressure switch and air control value to eliminate multiple maintenance down times.  The old cap was still working fine but it did measure low in capacitance at around 7.4 microfarad  which is typical as a cap ages....typically a cap either completely & quickly fails or slowly starts losing capacitance to where it will not start a motor or only allow the motor to start slowly.

 

Yeap, when it comes to the home water pump I like having some critical spare parts on-hand for quick repair....and for some parts just change them periodically before they fail.   The pressure in my moobaan soi lines is only 5-10psi....usually just enough to reach the top of the storage tank to keep the tank full....not enough pressure of usage in and around the house especially on the 2nd story of the house.   Gotta have a water pump otherwise refilling your commode tanks, taking a shower, getting water to the 2nd story, etc., just ain''t going to happen. 

 

 

[aoneseller]

11 hours ago, Pib said:

With your recent tinkering what did you set your pressures to?

I do not know as I don't have a pressure gauge. What I did is I turned the screw #1 to the left. It was only a quarter turn. The pump is working fine since. 

It is really interesting reading your pump history by the way. Can you please explain more about the pressure gauge, where to hook up and those specific pressure points that u highlighted from the spreadsheet. Do they suppose to match with the readings from the pressure gauge? 

[Pib]

11 hours ago, aoneseller said:

I do not know as I don't have a pressure gauge. What I did is I turned the screw #1 to the left. It was only a quarter turn. The pump is working fine since. 

It is really interesting reading your pump history by the way. Can you please explain more about the pressure gauge, where to hook up and those specific pressure points that u highlighted from the spreadsheet. Do they suppose to match with the readings from the pressure gauge? 

Put a pressure gauge in your output line not far from the pump's output.  Or temporarily hook the pressure gauge to a water tap close to the pump.   Then fully turn on a tap somewhere in/around the house to get the pump operating continuously....then watch/listen for the pressure switch cutting on and off.   Those points where the pressure switch click on and off should be approx plus/minus 10% of the pump's specs like shown in the spreadsheet....that is, the 1.3 and 1.9 bar settings for you particular pump.

 

Important Note: Since you have an EP model where the pressure switch and flow switch work as a team (they are interconnected) you will probably have to listen for when the pressure switch clicks for its upper pressure setti1ng of 1.9 bar  as the flow switch should keep the pump motor running and allowing an upper max pressure of approx 2.9 bars.   So, you'll probably just have to listen for that cutoff 1.9 bar pressure point as the flow switch will probably keep the pump running as long as you have the tap open.

 

The constant flow models (EP series) have both the pressure switch and flow switch whereas a WP series model like I have only have the pressure switch.  

 

For me I permanently mounted a 0-4 bar pressure gauge in my output line in a convenient location about two meters from the pump.   And I also have another 0-4 bar gauge I rigged up with a short hose and connector which allows me to go mobile with the gauge and just hook it to an water tap.....kinda like how  you use a car tire gauge.   You can buy pressure gauges pretty cheap off Lazada, Ebay, and sometimes get them in your location hardware store....but Lazada is probably you best bet for variety and lowest cost.

 

 

[aoneseller]

1 hour ago, Pib said:

And I also have another 0-4 bar gauge I rigged up with a short hose and connector which allows me to go mobile with the gauge and just hook it to an water tap.....kinda like how  you use a car tire gauge

Is it possible to hook up the gauge at the end of a water hose? Something like as shown the picture I just attached. I don't really want to cut the pvc pipe and mount it permanently. 

 

[Pib]

2 minutes ago, aoneseller said:

Is it possible to hook up the gauge at the end of a water hose? Something like as shown the picture I just attached. I don't really want to cut the pvc pipe and mount it permanently. 

 

 

Sure....that's what I meant by a mobile pressure gauge....like the one in your picture above.   Just keep in mind that the further away from the pump you get there will be pressure lost primarily due to pipe-water friction..  So, try to hookup the gauge to the water tap/outlet closest to the pump (hopefully not too many meters away) to minimize the pressure lost which adds error to the desired pressuring measuring point right at/real close to the pump.

[aoneseller]

Thanks for all the informations Pib. My garden hose is not that far from the pump, around 3 metres. I will post my reading once it's done. 

[Pib]

11 minutes ago, aoneseller said:

Thanks for all the informations Pib. My garden hose is not that far from the pump, around 3 metres. I will post my reading once it's done. 

Hook to the tap...where you hook the hose; not the end of the water hose as a 10, 15, 20 meter long hose will cause a pressure drop.

[aoneseller]

6 hours ago, Pib said:

So, you'll probably just have to listen for that cutoff 1.9 bar pressure point as the flow switch will probably keep the pump running as long as you have the tap open.

My readings is about 1.8 bar at the cut off pressure point. I attached a short video when I was doing the reading. Can you check and tell me if I am correct. Thanks. 

[Pib]

I'm not really sure what I'm seeing/hearing in the video in terms of cut on and cut off points/pressure.  I looked/sounded like "maybe", repeat maybe the cut-on pressure was around 1.8 bar ( specs call for 1.3), the cut off pressure around 2.4 bar (specs call for 1.9) and then the flow switch took control and allowed the pressure to climb to its steady max of 2.6 bar (specs call for approx 2.9 bar but 2.6 is close enough).

 

If I understand you video correctly then it seems the pressure switch is adjusted too high....instead of 1.3 and 1.9 bar its at 1.8 and 2.4 bar.   Since you already adjust the switch a little which probably lowered the pressure from even high amounts which was causing you pump problem....and the adjustment you made got the pressure range barely back within an acceptable range for the pump's design.  

 

To get a better idea of the cut on pressure (i.e., the lowest pressure...when the pump turns on).   While the pump is running turn off the tap that is running.  The pump will stop running and your pressure will be at its high point.  Now, "slightly", turn on the tap to allow a "small/slow" flow of water.....a flow that "slowly" breeds off the pressure as you watch the pressure gauge.....when the pump kicks on that will your cut on pressure....you should be able to get a better reading of the cut-on pressure that way.    

[aoneseller]

20 minutes ago, Pib said:

Since you already adjust the switch a little which probably lowered the pressure from even high amounts which was causing you pump problem....and the adjustment you made got the pressure range barely back within an acceptable range for the pump's design.  

So, I should turn srew#1 to the left more until I reach 1.3 cut on pressure? Just to get close to the pump's specifics. By the way the pump works good since I have adjusted. 

[Pib]

9 minutes ago, aoneseller said:

So, I should turn srew#1 to the left more until I reach 1.3 cut on pressure? Just to get close to the pump's specifics. By the way the pump works good since I have adjusted. 

That screw will change both the cut on and cut off pressure, not just the cut on pressure. 

 

When you say the pump is working good, you really just mean it appears to be working OK since it pumping water although the pressure cut on/off points are incorrect and may damage the pump/wear out components sooner, etc.

 

Up to you if want to tinker some more....see if adjusting the screw can get you the pump's design pressures like shown in the spreadsheet earlier.   Maybe give in another 1 turn CCW which should lower the pressure points....your pressure gauge will tell you if that happens.

 

You sure someone didn't tinker with the pressure switch before in hopes of making it put out more pressure than it's designed for.  

[aoneseller]

I have adjusted screw#1 to the left around 1 and half turn. Which made me closer to the pump's design. However I noticed different numbers from the spreadsheet on the pressure switch. It is 1.4 on and 1.9 off. I've attached the photo. So my new readings are 1.4 on and 2.2 off? Check my short video. 

[Pib]

That's more than close enough.   But if you want to tinker some more and get it at 1.4 and 1.9 you will need to adjust the "span" screw adjustment.....that screw halfway down the switch secured by a nut. 

 

Make  half turn adjustment on the span screw (be sure to first loosen the nut holding the screw and then retighten the nut).  I can't remember now but I think a screw CW turn reduces the span...start with a 1/2 turn....if it don't reduce the span then turn it back to it original point and then initially turn a 1/2 turn CCW....see what happens. 

 

Once the span between the cut on and off points reduces you'll have to adjust the screw on top again which adjusts both cut on and off pressure.  It's a back-and-forth thing between the two adjustments until you get the span and pressures correct.   Just be sure to make small adjustments...like 1/4 or 1/2 turns as you are now close to 1.4 and 1.9 or 1.3 and 1.9....whichever you want to use.

 

The reason you are seeing a difference in numbers between the specs on the spreadsheet and the switch as small changes in specs occur over the years depending on the "exact" pump model number  OR the sw1itch has been replaced and a 1.4/1.9 switch was used instead of 1.3/1.9.   Like on my WP255 pump it specs are 2.1 and 2.8 bars and that was the specs on the original switch and a replacement switch about 6 years ago when I first had to change the switch.  But a few weeks ago when needing to change the switch again all I could quickly/easily find was a Mitsubitshi 2.2 and 2.8 switch which is fine.    But don't worry about a 0.1 bar difference....heck, the gauge you are using probably has that much accuracy error.

 

 

[aoneseller]

Once again, thank you Pib for the knowledge about adjusting the pressure switch. The evening cut off problem has completely gone since the adjustment. This morning I tried to adjust the span screw but I didn't have a very small size wrench and I couldn't make accurate adjustments with my pliers. But anyway I don't want to tinker it any more. Thanks. 

[EAT25]

Thank's for all you have been wrote to here.  These help me understand how pumps works, mine WP-205R, and I did solve the problem; on / off within  2-3 sec.