Problem With Mitsubishi Water Pump

[dsfbrit]

I have just looked at that schematic and realise what the 'check valve' is. I have taken that apart quite a few times to pour in water and have cleaned it several times. I did not know why I was doing it, I just copied what the guy did with the old pump 7 years ago when the house was built and had to pour water in to fill up the pipe back to the water tank. The spring was thrown away as being unnecessary. I read somewhere on TV(?) this was 'normal' practise for reasons I cannot recall.

I will give it another clean anyway.

By the way, when I installed this new pump 2 years ago, I also had problems with the pipe in the tank - in fact lots of problems. When I changed the pipe in the tank, it was ME that did not fit the footer valve. I found the old damaged pipe that I replaced and now realise there was indeed a footer valve fitted which I did not notice. When I repaired the water system two years ago, it was one day before I had friends coming from the UK to stay for a month -and suddenly I had no water

So I replaced everything I could, including the pump, as I had just 6 hours to fix it!!!

Thanks again for all your help.

David

edit: the reason that two years ago the pipes were all broken in and around the tank, was due to the inlet cutoff valve into the tank failing (the ball cock), and then the inlet water had kept flowing and the water had overflowed the tank. The tank gradually emptied of water and flooded outside the tank and turned the tank into a 'boat' that floated higher and higher inside the concrete casing that houses the metal tank as the water level outside the tank was rising, pushing the concrete cover up, denting the tank and making a mess of everything. The old pump burnt out... what a mess just one day before friends came to stay!!! So when I repaired this it was done in a hurry for sure and no wonder I did not notice the footer valve!!!

Edited September 23, 2010 by dsfbrit

[T_Dog]

Congrats as well on getting it fixed, and its been fun to read your updates.

We just noticed a problem with our rental house. About 300-400 liters of water is leaking every day somewhere under the house. We have the option of using public water or stored water that is then pumped. The pump will run every 4 minutes all night long so we switched over to public water. Since there are teak floors and concrete below that, it will be an expensive fix. We are moving in four months so hopefully the leak will stay minor until then! There's a problem you don't want! Cheers again on the fix.

[dsfbrit]

Thanks for your help T-Dog. Its been interesting solving this problem.

I wish I could offer you some advice in return. My problem was minor by comparison.

Out of interest how does using the public water help, is the leak from the stored tank water???

Good luck with it...

Edited September 23, 2010 by dsfbrit

[Pib]

I have just looked at that schematic and realise what the 'check valve' is. I have taken that apart quite a few times to pour in water and have cleaned it several times. I did not know why I was doing it, I just copied what the guy did with the old pump 7 years ago when the house was built and had to pour water in to fill up the pipe back to the water tank. The spring was thrown away as being unnecessary. I read somewhere on TV(?) this was 'normal' practise for reasons I cannot recall.

When the spring was thrown away that killed / deactivated the check valve. Basically it no longer worked and assuming the plastic/rubber seal was left in it was no more than a loose object being bounced around in the pump intake manifold. The pump manufacturers wouldn't build the check valves into the pumps unless they served a purposed/prevented certain problems; otherwise, they would just be wasting money on adding in addiitional/unneeded parts.

[Pib]

Here's a picture of the kind of pipe check valve I've been mentioning. Basically they are a just a piece of pipe (usually brass) about two inches long threaded on both ends with a spring & wafer (or ball) on the inside. In attached picture the spring & wafer are shown on the outside. They come in varying pipes sizes. They allow water flow in one direction only/prevents back-flow. Usually, if a store has them they will be within arm's reach of the footer valves. My local Lotus store even has them (next to the footer valves).

[T_Dog]

Thanks for your help T-Dog. Its been interesting solving this problem.

I wish I could offer you some advice in return. My problem was minor by comparison.

Out of interest how does using the public water help, is the leak from the stored tank water???

Good luck with it...

The public system has about half the pressure of our pump and tank. That minimizes the loss and saves on electricity as well. Both supplies travel through the same leaky pipe to the house proper after the selection valves. I keep looking for wet floor or wetness near the walls, but so far nothing. The meter keeps creeping though! This is something I am going to keep in mind as we start construction in a few months.

[Pib]

One final picture taken from the Mitsubishi pump booklet/instructions and I'm out of here. Notice the valves shown in the picture/diagram. The first large value on the left is probably the water meter cutoff valve/a main cutoff valve; the other smaller valves could either be small cutoff valves, or check valves that allow water flow in one direction only....I expect they are check valves. Like to prevent the high pressure of the pump output from pumping water back into the lower pressure water main line, or the water main line from trying to force water back through the pump into the tank when the pump is off. This way, you have both the water main line and your pump feeding water to your house without either one interfering/being fed back into by the other. And you can see the footer valve at the bottom of the underground tank.

[dsfbrit]

Thanks Pib, its interesting just how many configurations you can have for something the 'uninitiated' would think is something so simple. I may fit a pressure valve somewhere in the system over the next weeks if I see one somewhere.

Thanks again for your help...

David

[dsfbrit]

Thanks for your help T-Dog. Its been interesting solving this problem.

I wish I could offer you some advice in return. My problem was minor by comparison.

Out of interest how does using the public water help, is the leak from the stored tank water???

Good luck with it...

The public system has about half the pressure of our pump and tank. That minimizes the loss and saves on electricity as well. Both supplies travel through the same leaky pipe to the house proper after the selection valves. I keep looking for wet floor or wetness near the walls, but so far nothing. The meter keeps creeping though! This is something I am going to keep in mind as we start construction in a few months.

Ok I get it - a good plan - hope it works out. Better to experience these problems now so you can ensure they dont happen on your new house. Good Luck with it...

David

[Pib]

Also, keep in mind your pump worked fine before/without the footer valve, and assuming you don't have any check valves, the pump also worked fine without the check valves. So, what changed/failed to cause the current problem? As we talked before, you "first" may want to try adjusting the pressure switch even if you can't find a pressure gauge right now. It's easy and quick to do...beat digging up pipe, unhooking/reconnecting pipe, etc.

Turn the pressure switch screw a quarter or half turn, run the water again, and see what happens. On my WP-255 pump, turning the screw counter clockwise lowered pressure and turning in clock wise raised pressure. You see that the switch spring is compressed more (raising the pressure cut off and cut off pressure points).... when turning the screw clockwise and when turning counter clockwise the spring pressure is reduced (lowering the cutoff/cut on pressure points). This adjustments changes "both" the cut off and cut on points at the same time by the same pressure amount; I don't think you can change just the cut on pressure "or" just the cut off pressure point, as that is physically designed into the switch. Just be sure to remember the screw starting point, how many turns in which directions in case the adjustment does not help the situation.

Even without a pressure gauge, you'll be able to visually know from the speed/volume of water coming from a water tap whether the direction you turned the screw raised on lower the pressure points. On my WP-255 it took approx 2 full turns of the screw to lower the pressure cut on and cut off points from 50 and 60 psi (way too high for this pump...mal-adjusted at the factory or by the installer), respectively, to 30 and 40 psi, which is the stated design specs for my pump. As mentioned earlier, your pump has little lower stated design specs/pressures.

Attached/below are the specs for Mitsubishi pumps...don't worry whether your pump part number ends with a Q3, Q2, Q1, or just plain old Q, as the differences are very minor and are usually just minor changes in the external physical shape (kinda like how Toyota Fortuners come out every year with only minor changes). Good luck.

Just an update to my pressure switch adjustment post above. Where I mentioned I didn't think you could adjust the cut-on or cut-off pressures "individually," well, I've discovered you can adjust both individually/separately.

Adjusting the screw on top of the spring adjusts the cut on "and" cut off pressure points, but it's primary purpose is to adjust the cut on pressure (i.e, the low end pressure) . But if you adjust the screw to where the cut on pressure is 2 psi lower (just for example) it will also lower the cut off pressure (high end pressure) by 2 psi.

Now, to change the cut off pressure you need to adjust the other small screw secured by a small nut on the mid part of the pressure switch...it's only about an inch from the other adjustment. Before I thought this screw and its securing nut was just to hold a bumper pad in place for a part of the switch to bump against when switching. Well, this is true, but by adjusting this screw it raises the bumper pad up or down a little which affects the cut off pressure. Loosen the small nut slightly holding the screw, make a half turn or so of the screw, recheck with the pressure gauge with the water running very slowly, and you will see a cut off pressure change. By adjusting both screws you can set both the cut on and cut off pressures. You'll need to go back and forth a few times to get both pressures just right, but it very easy to do. Or, I guess said anoher way regarding the two adjustments, the screw on the top of the spring seems to adjust "overall/both" cut on and cut off pressures, and the other screw seems to have more of an affect on the "range" between where the cut on and cut off pressures occur. Using a pressure gauge in making the adjustments you be able to easily see how the two adjustments affect/interface with other. JUST BE SURE TO MAKE THESE ADJUSTMENTS USING A PRESSURE GAUGE; DON'T MAKE THE ADJUSTMENTS BASED ON HOW THE WATER FLOW/PRESSURE JUST KINDA SOUNDS/FEELS TO YOU....USE A PRESSURE GAUGE TO MAKE THE ADJUSTMENTS TO PUMP MANUFACTURER SPECIFICATIONS.

After the final pressure adjustments are made, secure the two screws/nut by tighting the nut on the one adjustment and putting some finger nail polish on both screws/nut to keep them from vibrating loose. I have now set my WP-255 to exactly 2.1 bar (30 psi) and 2.8 bar (40 psi) per the pump design specifications. Some of the other WP series pumps have slightly different pressure settings. I could have set the cut on and cut off pressure points to a smaller pressure variation like 2.4 bar and 2.8 bar, respectively, which I did do briefly try, but the pump just seemed to be doing too much kicking on and off trying to maintain this smaller pressure range.

As mentioned earlier the pressure switch had either come mal-adjusted from the factory or mal-adjusted by the installer two years ago (i.e., pump pressure set way to high/pump trying to work beyond its capability, which was causing my pump problems).

[Naam]

"Adjusting the screw on top of the spring adjusts the cut on "and" cut off pressure points, but it's primary purpose is to adjust the cut on pressure (i.e, the low end pressure) . But if you adjust the screw to where the cut on pressure is 2 psi lower (just for example) it will also lower the cut off pressure (high end pressure) by 2 psi."

not in my case Pib. i have two Mitsubishi pumps each 400Watt (don't know the model number). both were set, when installed cut off @ 40 psi, one pump cut in @ 35 psi and the other one @ 32 psi. one of them had recently a leaking pressure switch which i had to replace. cursing and sweating i tried to change the factory settings of the new pressure switch which was set @ 28/32. i managed to change the cut off @ 40 to match the other pump but i could not manage to raise the cut in. had a the plumber here who installed the pumps 4 years ago but even he couldn't do the job.

as we have a separate tank for each pump we have to switch off every alternate week the "stronger" pump to empty both tanks evenly

p.s. besides the toy tanks of the Mitsubishis i installed a separate big pressure tank and i am thinking of triggering both pumps simultaneously by one pressure switch mounted on the tank. do you see any negative implications?

Edited September 27, 2010 by Naam

[Pib]

Since you say you have a Mitsubishi 400 watt pump with tank I'm assuming you are talking about the WP-405 model, whose pressure switch is suppose to be set to 2.4 bar/35 psi/cuts on and 2.8 bar/40 psi/cuts off. Now the new pressure switch you got which was set at 28 / 32 psi (1.9 / 2.2 bar) was definitely set wrong for your Mitsubishi pump (maybe for any Mitsubishi pump) and would cause that pump to cycle on and off quite a lot. See Atch 1 spec sheet for various Mitsubishi pressure switch on/off settings.

Maybe the WP-405 pump pressure switch is constructed differently than my WP 255 pressure switch. But when I look at these switches on the various Mitsubishi WP models in the stores the switches are all shaped the same, either in a gray or black plastic casing, and different on/off pressure settings stamped on the top of the switch cover. Does your switch look like mine in Atch 2, where it's shown with the cover off. The Philip's head screw on the very top is the adjustment that will raise and lower both the cut on and cut off pressures, and the slotted screw head with nut lower down on the picture is the one that will adjust the range/differential between the cut on/cut off pressures.

The only thing I can think of regarding your two tank question with the pressure switch controlled by only one of the tanks is the air pressure differential that will develop over time between the two tanks as the air is lost/ absorbed in one tank a little faster than the other. This might cause some pushing back and forth of water between the tanks as the tanks balance pressure between each other during during pump cut off. And I guess you could actually lose all air pressure in one tank over time while the other tank has air pressure on top which might cause some strange water flow issues. I don't have any experience in a two tank setup, so I'm really just guessing. Good luck and Cheers.

[Naam]

"Does your switch look like mine in Atch 2, where it's shown with the cover off."

it looks like yours but it's a generic and not a Mitsubishi part. the store had no matching switch and delivery from BKK would have taken a week (i was told).

edit: looking at the magnified picture of your pressure switch i have to amend that my switch does not look like yours and neither does the broken switch which is a genuine Mitsubishi part.

Edited September 28, 2010 by Naam

[Naam]

"The only thing I can think of regarding your two tank question with the pressure switch controlled by only one of the tanks is the air pressure differential that will develop over time between the two tanks as the air is lost/ absorbed in one tank a little faster than the other. This might cause some pushing back and forth of water between the tanks as the tanks balance pressure between each other during during pump cut off."

that problem is avoided with a check-valve at each pump outlet.

[Naam]

thanks a lot Pib!

[Pormax]

I too have a problem with my water system.

First of all I will descibe my setup. I have a Lucky Star Deep Well pump which originally ran water to the house and garden. However was insufficient power to heat water for showers so I added which pumps a 1000 litre tank which sits on a 1 metre high stand this leaves 80cm drop to my Mitsubishi WD255Q3 water pump inlet. I have a valve on the pipe leading up to the tank inlet and also have a valve between the tank and the mitsubishi pump.

The Lucky Star Deep Well pump works well and is continuously on when water is running either into the tank or when watering the garden. Every morning we open the valve on the inlet to the tank then once full, close again.the Deep well pump still used for the gardening and I have a valve which I close to prevent water going into the pipes feeding the house (one storey)

I have two proplems. Firstly like reported before my pump goes on and of about every second. Secondly on a number of occassions recently the Mitsubishi pump has stopped working altogether. Luckily I also have a valve where I can divert water from the well pump to the house, so when this first happened I did just that after closing the valve from the Mitsubishe pump outlet. Later I decided to try and investigate if there was a power problem. Could not find one so plugged the pump back in and it worked again. Other times this has happened usually when somone is taking a long shower,I just close the valve on the mitsubishi outlet and open the diversion valve from the well pump so I still have water goung to the house. I wait 10-15 minutes and all ok again. To me this sounds like the pump is overheating and cutting out. Correct or not?

So 2 questions. How can I stop this cutting out/over heating problem? Second as to how to stop the continuous pumping every second.

I have tried to resolve the problem with the pump going on and off every second. I have drained the Mitsubishi pump and then refilled it with water. No change. Have tried adjusting the pressure switch but can either only to get it to stay constantly on when water is running or pulsating every second. I don't think that the problem is the water tank as this inadvertently ran dry not so long ago when we forgot to refill one morning. After we refilled the tank the same problem was there.

Now I am not at all technically knowledgeable so simple/instructions advice required. Do not have or even know what a water pressure meter looks like.

[Pib]

Regarding the Mitsubishi pump and how you drained it: turn off power to the pump, cut off the water inlet and outlet to the pump, then remove the plug at the bottom of the tank until empty, replace that plug, turn the water inlets/outlets back on and the power back on....after about 30 seconds the pump should shut off. This is how to remove the waterlogged condition of the tank..

Now the pump should run for approx 5 seconds and then turn off for approx 5 seconds with one tap fully open. However, if the tank was waterlogged then something caused it to get waterlogged (like maybe a bad air charger valve) so the waterlogged condition will come back within a few days to a few weeks...and you'll be back to quick on-off cycling of the pump about every second. And when it's cyling so quickly it causes motor overheating and a thermal device in the pump motor trips...this thermal device then resets itself after approx 15 minutes as the pump motor cools off...and of course will trip again when overheating again.

If a waterlogged pump tank is not the problem you need to ensure the pump is indeed getting enough water because if it's not getting enough water to its inlet it going to run a lot/cycle very frequently in trying to suck in enough water....kinda like a person who is not getting enough air in that they will try to breathe quicker.

[Crossy]

Something people sometimes miss, is that the tank should contain AIR (not water)!

[Pib]

Yeap, without air which gets compressed inside the tank/on top of the water and acts as a spring (stored energy source) to push down on the water when the pump motor turns off, the pump has no choice but to turn right back on to keep the pressure up.

[Pib]

Below is a cut and paste from a web site that I think gives a good summary of how a water pump pressure tank works...how "air" in the tank is compressed to to create an energy spring so to speak. If that air leaks off/is not kept at a certain charge, then that energy spring is loss since water is a liquid and can't be compressed. For the Mitsubitshi type pumps/tanks there is no rubber diaphragm in the tank to keep the water and air separated to prevent the air from being slowly absorbed into the water; therefore an air charger/balance/control valve is used to add just a little air on each pump cycle to keep the air charge correct which creates that energy spring at the correct level.

Also, when draining the water from the tank be sure to let it completely drain out which then allows air to rush into the tank...air that will be compressed to its initial pressure level when you put the drain plug back in and start up the pump. And "if" the water pump's air charger/balance/control valve is working properly that valve will keep the air charge at the correct level; if it ain't working properly (like maybe the rubber diaphram within the valve is ruptured) then it can't add that small charge of replacement air on each pump cycle to replace that little bit of air which is naturally absorbed into the water at the water and air boundary.

Summary: all water in a water pressure tank is bad...a.k.a., a waterlogged tank...can cause the pump to quickly cycle...run most of the time...overheat; the proper balance of water and air in the tank is good....that air spring is doing the pressure work while the pump is off/resting/cooling off.

In a closed, automatic water system a pressure tank is used to store water and maintain system pressure between specified limits (such as 30 to 50 PSI). As the water level in the tank rises, tank air is compressed in the upper part of the tank until the upper pressure limit is reached (i.e., 50 PSI). At this "cut-out" point a pressure switch opens the electrical circuit to the motor and the pump stops. The compressed air in the tank acts like a spring pushing down on the water to create system pressure. When a valve is opened in the water system, the air pressure in the upper part of the tank forces water to flow out of the tank and into the system. As the water is drawn from the tank, the air occupies a larger space and the pressure drops until the lower limit is reached (i.e., 30 PSI), At this cut-in point the pressure switch closes the electrical circuit to the motor and the pump starts. A cycle is thereby completed.

[ruebenpiatt]

I also am having issues with my WP155Q3 - came home to find it running and over heating and no water out of the tap!! I pump from a well and have had no problems for 2 1/2 yrs. Found the tank dry ,so I primed it and got water flowing to the house ... But when you turn off the tap the pump cont. to run and Will not shut off!! A pressure valve issue??

I can press the spring under the round cap and it stops but as soon as I release it - she running again!!

Any help would be Great!! Can not find the book that came with it as far as trouble shooting issues.

We use it all the time as the village water is on and off so often, we found it best just to use the well.

[Pib]

Since you say you got water flowing to the house it sounds like it's pumping OK. But since it don't turn off when you turn the tap off the pump continues that sound like it either is still trying to reach it's pump cut-off pressure which is only 1.9bar/28psi on this model, OR the electrical pressure switch you refer to is defective.

When you say you got it pump water again...did the tap water pressure seem the same as below....when it was working normally? If it felt lower than before then maybe you have a water supply/suction issue....that is the pump ain't getting enough water to it and it just keeps trying to reach the cut-off pressure of 1.9bar/28psi.

Or the pump could indeed be reaching its cutoff pressure but a defective pressure switch keeps it running. That happened to my WP255Q once in that the switch's electrical contacts began sticking together from years of contacts/arcing which occurs during each contact. Fortunately, I was home when this happenned...but the pump would just keep running....I expect it was pumping pressure much above 2.8bar/40psi cutoff pressure....maybe up around 60psi...but it just would not shut off. I tapped on the pressure switch and it stopped running...but after some more pump on and off cycles the contacts would freeze/stick together again. I took the switch cover off and the contacts looked pretty blackened/pitted....I just went and bought a new switch and it fixed the problem. I later took a closer look at the old switch and the contacts were indeed in bad shape from years of contacts/arcing/on-off.

But I would think if the contacts had welded themselves together which would keep the pump always running with power applied that just pressing the pressure spring as you mention would not unfreeze the contacts and it would have kept running anyway...but when you press the spring it does stop which means the contacts are not welded together---but they still could be sticking together when they make contact. This switch could still be bad...the contacts could still be sticking together and it's just your abnormal pressing of it spring breaks the contact, but resumes contact/sticking together as soon as you take away this abnormal situation.

I would first make double sure your pump is getting adeqaute water supply....if getting adequate supply then it sure sounds like it could be the pressure switch. You first might want to look at the contacts and try cleaning them...could be dirty/pitted contacts...or even bugs/ants have clogged things up in the switch---BUT BE SURE you have turned off power to the pump before cleaning the switch!

[brownknees]

Glad I have found all this "info"!I did not know about the comp air so tommorow morning I will set to and drain the pump and refill/My pressure switch though looks like it has a relay on top with contacts ,not sure if I can adjust or maybe I will not ned to!!?

[Phil Conners]

I recently installed a rain shower, but the pressure is kinda weak. The house is a bungalow (ground floor only), the tank is standard above-ground, and the pump a Mitsubishi WP-155Q3.

With only the shower running the pump runs for 4 seconds, then stops for 12 seconds, repeats. Is this normal? I was thinking, is there a way to adjust the pressure valve up to create higher pressure? Or would the pump overheat in that case?

I've already emptied the pressure tank for water, there was quite a bit in it. It came with the house, second hand, so I don't know the history of the pump, i.e. if any of the valves have been replaced in the past.

[Ackybang]

Hello Phil - you've inhereted a small well pump, which will 'pulse' quite naturally - you need a constant pressure pump to remedy this problem.

Having said that, it sounds like you're encountering some sort of restriction in the system, down the line from the pump, which means your pump is reaching critical pressure quickly, and then because of the restriction, is taking a while for the pressure to drop sufficiently for it to cycle again. In this case, if you could increase the pressure of the pump, it would cut out for even longer, probably. With appropriate guage pipe work, and a clean system, 12 seconds is too much, for sure.

These jobbies, once you fill the reservoir under the lid are self priming, and as far as I know you can't adjust the amount of atmospheres in the tank - they are pretty reliable, automatic pumps, with a set pressure rating.

If you installed the rainshower yourself, take the head off, and look for restrictive gaskets / filters that can be removed. If the pipe system is old, right upto and including the shower taps, it might have rust / calc / sediment build up before / in the tap(s), restricting the flow of water, which is quite common in old systems here, with the water quality.. Many taps have removable filters in them too, which will open up the flow rate considerably. If you're replacing old taps, make sure you turn on the pump after removing them, and flush out the system / crap before installing new. Same rule with adding new pipework - the plastic sawdust can reek havoc with taps / valves, and restrict your whole system.

Generally, your pump should be able to transmit water upto 12 meters without too much trouble, especially in a bungalow, I think they are rated for vertical flow. Take the shower head off, and open the system - is it still doing the same ? If it is, you need to clean out the system / taps. You might even have to replace the shower tap(s), if they are not servicable. If you're using an instantaneous heater, check any controlling flow / inlet / outlet valves / filters, and remove if necessary. Instantaneous water heaters can restrict water flow tremendously in showers..

Was it like that before ? Is it like that when you open other taps in / outside the house ? You'll have to work it out with process of elimination - but it sounds like your pump is actually okay, especially if you've emptied it, and then re-filled the top / primed it. Was there a lot of dirty sediment in the tank ? This might be your answer. A picture might help.

Good luck !

Edited May 20, 2013 by Ackybang

[pigeonjake]

sorry if im repeating anything someone else has writen,

ive got these pumps in our house, and i dont have a tank at all, they pump the water direct from our bore holes, at 12mts and the other one is 18mts,

we havnt had a problem at all,

jake

[lopburi3]

I recently installed a rain shower, but the pressure is kinda weak. The house is a bungalow (ground floor only), the tank is standard above-ground, and the pump a Mitsubishi WP-155Q3.

With only the shower running the pump runs for 4 seconds, then stops for 12 seconds, repeats. Is this normal? I was thinking, is there a way to adjust the pressure valve up to create higher pressure? Or would the pump overheat in that case?

I've already emptied the pressure tank for water, there was quite a bit in it. It came with the house, second hand, so I don't know the history of the pump, i.e. if any of the valves have been replaced in the past.

I don't have that type of shower but suspect it needs a high water flow but do check for restrictions first and compare with a full opened tap (how long pump pause) and you have a very small pump (we found the 405 models not up to task in two story house with normal point of use heaters). The relay can be adjusted but it is not easy and could get you zapped and not much improvement can be expected in high pressure but the low pressure cut on can be increased to make the flow stay near full pressure (but you did not mention that being a problem). Be very careful and read instructions for adjustment if you do try to change settings - normally they are lacquered tight so will not easily change and there is electric there if you do not cut power (but be sure hot lead is cut - not all switches are wired correctly). I would kill main house breaker to be sure if you do not have a test screwdriver.

[Phil Conners]

Thanks for all suggestions. I now timed the pump with a faucet just after it and with that the pump runs 7 sec on and 6 sec off. I guess I will have to remove the shower faucet and see if there is something stuck somewhere.

As mentioned the house is one floor only. Due to how the pipes were laid there is a quite long distance from the pump to the house, maybe about 50 meter, all horizontal though so would that make a big difference?

[Pib]

Phil,

You have a WP155 model (sets on top of small pressure tank) which has a pump turn on pressure setting of 1.3bar (19psi) and pump turn off pressure of 1.9 bar (28psi), which results in an "average" pressure of approx. 24psi as the pump cycles from off to on. However, you really shouldn't notice this pressure variation unless maybe shooting water from a hose in a jet stream pattern and you'll see the max distance the water will shoot will vary a little as the pump cycles. Don't try messing with the pressure switch as the switch settings are set to maximize the design of the pump. Messing with the pressure switch to where it would make the pump run continuously would just cause problems like overheating and would just make the psi run at around the 28psi level until the pump shuts down for overheating if you ran the pump continuously for 30 minutes or so. Plus, if the pump don't cycle enough (turn on and off) the air control valve won't work properly causing the pressure tank to become water logged after a few weeks. The air control valve maintains the proper amount of air added to the pressure tank that creates/maintains a compressed air spring/cushion on top of the water in the tank which allows water to continue to be pushed out when the pump is off.

Now, if you switched to constant pressure model of the same pump wattage (i.e., the 155 watts) like a EP155, which also has upper and lower pressure limits of 19psi and 28psi (more to ensure a min or max pressure is not breached) but its design will maintain a much less varying pressure due to the flow control device built-in. However, the "average" pressure of the WP155 will be very similar to the constant pressure of the EP155, but the EP155 will continuously to maintain this more even pressure. So just switching to a constant pressure model is not going to fix your problem because your WP155 is giving an average pressure very similar to the EP155 constant pressure. Now, higher wattage pumps in the various WP and EP/CP models do give higher pressures, but the highest pressure in the Mitsubitshi WP/EP/CP lineup (and other similar type pumps) is approx. 2.8bar (40psi). I use a WP255 which uses pressure settings of 2.1bar (30psi) pump on and 2.8bar (40psi) pump off for an average pressure of 35. My shower upstairs is plenty strong even when another tap is running wide open somewhere in the house.

Also, your pump switching on and off is normal for the type of pump design you have which uses a small pressure tank in the 10-20 liter ballpark...I expect your model is closer to the 10 liter size. Constant pressure pumps also usually have a very small screw-on pressure bottle of around 1 liter in size to help deal with small leaks to keep the pump from running "all" the time due to small leaks.

Since you say your pump runs 4 seconds and turns off 12 seconds that telling me you appear to have a restriction in the system...maybe there is a flow restrictor in your shower head. With one tap or the shower running wide open you pump should be cycling but probably closer to a 50/50 interval like approx. 4 seconds off and 4 seconds on, or 3 seconds on and 3 seconds off, etc. Since your current off cycle (12 sec) is 3 times as long as your off cycle (4 sec) that's telling me the pump is not needing to push out a lot of water...like it's only pushing water through a small diameter pipe, a restricted shower head, etc. During the time the pump is off, water is continuing to be push under pressure from that small pressure tank until the pressure drops to 19psi, the pump then turns back on to bring the pressure back up to 28psi, and then the pump turns off again....this cycling gives you that average pressure of 24psi.

Now, with above being said, you are not going to get a strong shower with a small wattage WP/EPCP155 since it only puts out a max of 28psi with a max head height of 12 meters. Starting at the next higher WP/EP/CP model of the 205 series is where the pressure increases to the 30-40psi range with a head height of 16 meters. But even getting a pump with a higher wattage/pressure output won't help much if you have a restriction in your system. Good luck.

[Pib]

Thanks for all suggestions. I now timed the pump with a faucet just after it and with that the pump runs 7 sec on and 6 sec off. I guess I will have to remove the shower faucet and see if there is something stuck somewhere.

As mentioned the house is one floor only. Due to how the pipes were laid there is a quite long distance from the pump to the house, maybe about 50 meter, all horizontal though so would that make a big difference?

Yes, even horizontal distance makes a difference due to friction and weight of the water. 50 meters is quite a distance for a small/low pressure pump. It's kinda like turning the water on at an outside tap and the water seems to rush out with good pressure and volume at the tap; but hook a 20 meter water hose to the tap and then the pressure/volume output at the end of the hose seems significantly less....well, it is due to water friction on the interior of the hose, weight of the water in the hose, etc.