Is this normal water pump operation ?

[how241]

Hello,  This is the first time I am living in a house and have a  Mitsubishi water pump and large blue water tank.  The water pump goes on almost every time I use some water.  Is this normal water pump operation ?

[bankruatsteve]

Yes.

[chickenslegs]

This is normal.

The only time to be concerned is if the pump is cycling off/on frequently, or if it stays on long after you close the tap/shower.

[Pib]

The large blue tank sounds like just a water storage tank....you are talking a big tank probably standing around 1.5 to 2 meters tall and 1 meter in diameter, right?

 

And yes the pump will turn on almost every time you use any significant amount of water.  The two most common types of water pump designs used by Mitsubishi  and other manufacturers in Thailand is one where the pump motor/manifold assembly sets on top of a small pressure tank (on left in image below)...and the other type is just a pump motor/manifold assembly with a small liter size pressure bottle (on right side of image below).  

 

Now when I say turn on everytime that assumes around a half liter of water is being drawn like flushing/refilling a commode, taking a show, washing dishes, washing clothes, etc.   And it could easily be less than a half liter if the pressure tank/bottle (not to be confused with you blue water storage tank) was a its low end of water pressure due to a slight amount of water being drawn off earlier like maybe a half glass of water.   The pressure tank/bottle is meant to minimize the pump needing to turn on for slight draws of water/small water leaks somewhere; instead the pressurized water stored in the pressure tank/bottle supplies the needed small amount of water.

 

 But if the pump turns on even with the slightest amount of water being drawn then you probably have a waterlogged pressure tank/bottle....but that's another story.

 

 

 

 

[VocalNeal]

^ If it comes on a few seconds after the tap is turned on and cycles on and off every few seconds that is normal. If the cycle on/off time is very short like once a second, it is not. If your pump is direct mounted on top of the tank like the left hand image above you may if you wish (after turning off the water from the tank) remove the plug shown and drain out the water in the tank . Then replace the plug and turn the water back on. This will increase the cycle time IF there was anything wrong in the first place.

[how241]

3 hours ago, Pib said:

The large blue tank sounds like just a water storage tank....you are talking a big tank probably standing around 1.5 to 2 meters tall and 1 meter in diameter, right?

 

And yes the pump will turn on almost every time you use any significant amount of water.  The two most common types of water pump designs used by Mitsubishi  and other manufacturers in Thailand is one where the pump motor/manifold assembly sets on top of a small pressure tank (on left in image below)...and the other type is just a pump motor/manifold assembly with a small liter size pressure bottle (on right side of image below).  

 

Now when I say turn on everytime that assumes around a half liter of water is being drawn like flushing/refilling a commode, taking a show, washing dishes, washing clothes, etc.   And it could easily be less than a half liter if the pressure tank/bottle (not to be confused with you blue water storage tank) was a its low end of water pressure due to a slight amount of water being drawn off earlier like maybe a half glass of water.   The pressure tank/bottle is meant to minimize the pump needing to turn on for slight draws of water/small water leaks somewhere; instead the pressurized water stored in the pressure tank/bottle supplies the needed small amount of water.

 

 But if the pump turns on even with the slightest amount of water being drawn then you probably have a waterlogged pressure tank/bottle....but that's another story.

 

 

 

 

Yes,  you are right about the size of the blue water tank...The pump sits next to the tank...For some reason,  the photos I took will not upload...Thanks for your help...

[Crossy]

10 hours ago, how241 said:

Yes,  you are right about the size of the blue water tank...The pump sits next to the tank...For some reason,  the photos I took will not upload...Thanks for your help...

Resize your photos to be less than 128kB and they should upload, there's a forum bug, it's being worked on.

[how241]

Thanks.  Now I know that it was not something that I did wrong in attempting to upload the photos..

[AhFarangJa]

My pump cut in even if I drew a cup of water. I used to think this was normal until I had an air lock in the system, ( the pump was constantly switching on and off without any water being used ). Then I backwashed the large filter, and suddenly the pump only cut in after about five seconds of turning the tap on, and the pressure from the tap was also increased. Learnt a lesson there, and now backwash all filters once a month. 

[jacko45k]

On 10/29/2017 at 3:29 PM, Pib said:

 

 

 The two most common types of water pump designs used by Mitsubishi  and other manufacturers in Thailand is one where the pump motor/manifold assembly sets on top of a small pressure tank (on left in image below)...and the other type is just a pump motor/manifold assembly with a small liter size pressure bottle (on right side of image below).  

 

 

 

Is there any difference between these two arrangements, in particular to how they are utilized? I was recently asked the question and thought not.

[sometimewoodworker]

1 hour ago, jacko45k said:

Is there any difference between these two arrangements, in particular to how they are utilized? I was recently asked the question and thought not.

Yes there is.

 

The smaller square one is a constant pressure version EP series and is recommended if you have an electrically heated shower as you will have virtually no variation in pressure when it's on so the shower will have a constant temperature.

[Pib]

1 hour ago, jacko45k said:

Is there any difference between these two arrangements, in particular to how they are utilized? I was recently asked the question and thought not.

One is a constant pressure type pump (the one not setting on top of it's pressure tank) where little pressure variation occurs when operating normally,   The pressure of the other type pump (the one setting on top of its pressure tank) does vary a little bit but that variation is so small you will probably never notice it when operating normally.

 

I say "when operating normally" for both types because when either develops a certain type of problem, like their pressure tank/bottle becoming waterlogged pressure variation can be very significant...kinda like pulsating pressure along with the pump running a lot more than it should.   

 

The constant pressure type is usually going to be more expensive to repair for certain problems because it has electronics/constant pressure value which are somewhat pricey to replace.  The other type does not really have any electronics (other than a low cost start capacitor) nor does it have a constant pressure valve.   The constant pressure pump is also going to be a little more expensive to initially buy.

 

I have the non-constant pressure type, a WP-255 (250 watt pump), which I have had for almost a decade now. It's particular pressure settings of pump turn on at 2.1bar/30psi and turn off at 2.8bar/40psi (this 2.1 to 2.8 bar pressure range setting is probably the mostly commonly used in Thailand by these types of pumps.   

 

Now you are probably thinking a 10psi variation is going to be easy to feel for day to day use like taking a shower, washing dishes, washing clothes, using the water hose to water the lawn, etc., but your thinking would be wrong since that pressure variation is buffered by the pump's pressure tank, size of the piping going into your home, etc.,,it makes it feel like you are always getting a 2.5 bar/35psi pressure.    You will feel "no pressure variation unless you really concentrate on trying to feel some pressure variation" when taking a shower even with water heaters....I know I sure don't....I have 6000W shower heaters. 

 

However, I will add a disclaimer here that you may feel a little pressure variation if you have smaller pump (like below 250 watts) because the smaller pump will most likely operate in a lower pressure output range....like from 1.3bar to 1.9bar...with these lower pressure/capacity pump you will feel a little pressure variation. 

 

 

[HHTel]

On 10/29/2017 at 3:29 PM, Pib said:

refilling a commode, taking a show,

 

[Dazinoz]

When I first moved to this rental about 6 months ago the pump was cutting in and out every few seconds. I throttled the suction valve to the pump and that stopped that problem but probably reduced the throughput of the pump.

 

Also I have seen inverter pumps available now. Any one had experience with these?

[portroyal]

The only pump which works a very long time is the Mitsu one

[HHTel]

I've had a Mitsu pump for 12 years and the only 'repair' that was necessary was a replacement pressure switch about a year ago.

[RayD]

Just to mention that you can get spares for the mitsubishi, you don't have to replace the whole thing. I replaced the cracked mushroom shaped thing that pumps air into the reservoir (causing a water logged tank) and also the capacitor in the motor that burned out when a faulty toilet made it run continously while I was out. So top tip, turn it off if you're away for any length of time.

[Pib]

24 minutes ago, RayD said:

Just to mention that you can get spares for the mitsubishi, you don't have to replace the whole thing. I replaced the cracked mushroom shaped thing that pumps air into the reservoir (causing a water logged tank) and also the capacitor in the motor that burned out when a faulty toilet made it run continously while I was out. So top tip, turn it off if you're away for any length of time.

Similar for me....for almost the decade I've had my Mitsubishi WP255 pump....the only two repairs needed have been replacing the mushroom/six sided thing (air balance/control valve) which failed around the 5 year point which caused a waterlogging condition and I replaced the pressure switch when the switch's electrical contacts would intermittently seize together causing the pump to not cut off when reaching the upper cut off pressure.   Both components easily and cheaply replaced by me.   The pump still has the original motor start capacitor but I have a spare on-hand ready to install when it does fail some day....another very low cost component.

 

[how241]

Thanks for all the replies and info...Mine is a lower/basic model pump.  It just sits by itself.  Judging  by what I have read here, it appears to be working OK....Thanks

[mikecha]

4 hours ago, Dazinoz said:

When I first moved to this rental about 6 months ago the pump was cutting in and out every few seconds. I throttled the suction valve to the pump and that stopped that problem but probably reduced the throughput of the pump.

 

Also I have seen inverter pumps available now. Any one had experience with these?

hi if you have a fill and draw at about 2000ltrs   then a filling inverter does save but if u have jusst on of it does not

 

inverters  are savers if run all day like airco inverters do pumping small quantaties do not

 

if u have a big pump a soft starter is worth while takes the peak out of the start electric draw

[sometimewoodworker]

20 hours ago, Pib said:

The constant pressure type is usually going to be more expensive to repair for certain problems because it has electronics/constant pressure value which are somewhat pricey to replace.  The other type does not really have any electronics (other than a low cost start capacitor) nor does it have a constant pressure valve.   The constant pressure pump is also going to be a little more expensive to initially buy.

In my experience there is usually no, to very little, difference in price between the two.

 

On my EP series I've had to replace the flow switch after several years (about 8) of use and it has all the electronics with it, as I recall it was not much over 1,000 Baht including EMS from the Bangkok head office. Anyone with moderate DIY skills could easily do it.

 

They also had an English speaking engineer who helped me accurately diagnose the failure mode, so I only got the part I needed. 

 

The accumulator is probably the only other part that may fail, I'm not sure of the cost but less than 2,000, possibly under 1,000.

[sandyf]

18 hours ago, Pib said:

Similar for me....for almost the decade I've had my Mitsubishi WP255 pump....the only two repairs needed have been replacing the mushroom/six sided thing (air balance/control valve) which failed around the 5 year point which caused a waterlogging condition and I replaced the pressure switch when the switch's electrical contacts would intermittently seize together causing the pump to not cut off when reaching the upper cut off pressure.   Both components easily and cheaply replaced by me.   The pump still has the original motor start capacitor but I have a spare on-hand ready to install when it does fail some day....another very low cost component.

 

I must have been unlucky. I have a smaller Mitsubishi and after about 2 years the studs welded to the tank corroded and started leaking. Had the tank replaced with a stainless steel one.

I also have a Hitachi, about 8 years old now. About a year ago the pressure switch on that started leaking and had to replace it. I suspect the pressure switches are common, the one I replaced was made by Yamada Electric.

 

[Pib]

When something goes wrong with your Mitsubishi pressure tank, like corrosion, I rack that up to "corrosive" water like talked about at this site. 

 

My Mitsubishi WP255 is almost a decade old and no corrosion appears on the outside and I've never had a leak caused by corrosion.  This pump is unprotected from the rain other than it's plastic cover that cover the motor....pump gets rained on whenever it rains...gets sprayed on by the water hose...etc.  Never had a leak.  The water main water is supposedly drinkable and that exactly what I and my family have been doing for the last decade, but all water that is consumed/cooked with goes through a small carbon filter I change once a year....two such filters in use...one on the frig and one at the kitchen sink.  Me and the family are still alive.   The water main water is not corrosive/hard water so my Mitsubishi pump tank is hanging in there real good.  I live in Bangkok.

 

However, drive about 35Km's due west to my MIL's village/home in Nakorn Pathom province where I installed a Mitsubishi WP85 for her, it developed a very small leak on the underside where the tank bottom plate is welded to the circular side...looks like it developed from the inside.  Problem occurred about 5 years into it's life.   I had that fixed for Bt100 by having it blazed.  And two of the tank's feet developed some pretty good corrosion probably due to this small tank leak that keep these two feet damp all the time.....wired brushed/sanded that corrosion off and repainted the tank with primer and enamel paint....looks like new.   The water in the MIL's village is corrosive and not drinkable....and also comes with fine dirt particles for free...barely good enough to bathe in.

 

 

[how241]

Lots of good info here.  Thanks for all the posts.

[KKr]

On 10/29/2017 at 5:26 PM, VocalNeal said:

^ If it comes on a few seconds after the tap is turned on and cycles on and off every few seconds that is normal. If the cycle on/off time is very short like once a second, it is not. If your pump is direct mounted on top of the tank like the left hand image above you may if you wish (after turning off the water from the tank) remove the plug shown and drain out the water in the tank . Then replace the plug and turn the water back on. This will increase the cycle time IF there was anything wrong in the first place.

or replace the spring inside the top black box that tends to break quickly (i.e. every few years) in certain models.