New water pump for 2-story townhouse -- what to look for?

[ozyjon]

Hitachi WM P350GX

[sandyf]

The OP says his current pump doesn't provide adequate pressure to the upstairs. Could be the 155W just doesn't have the head required. IE: can maybe "fix" the waterlogged issue but still need more head. 250W is usually good for 2nd floor. I would go with constant pressure type for a new one.

I would agree. I have the same pump as the OP but I have a bungalow. I get adequate shower performance but doubt if it would work upstairs.

My sister in law has a 255 pump and that has far greater pressure.

[wpcoe]

Thanks again to all who have contributed. I've re-read and it seems to be the general consensus that the pump can be easily restored to its previous glory, probably just by draining water from the pressure tank, but maybe also by replacing a diaphragm or seal of some sort. I've posted a request in the Hua Hin forum section to see if I can find someone quickly and easily to do it for me.

If it works, this will be a stop-gap measure until the end of the year when I decide where I want to live long-term. Whichever place I choose, I'll probably replace the pump with a larger one to get better upstairs water pressure. The status quo (i.e. downstairs showers) is tolerable, but would be "nice" to fix.

Before this thread, I thought I'd be looking for some "psi" type of pressure spec to determine the best capacity for the upstairs, but it appears that pumps are generally chosen by their wattage?

I would go with constant pressure type for a new one.

I noticed constant-pressure pumps at HomePro for about the same price. How do they work? What are the pros/cons?

[sandyf]

Before this thread, I thought I'd be looking for some "psi" type of pressure spec to determine the best capacity for the upstairs, but it appears that pumps are generally chosen by their wattage?

You are perfectly correct, only it is not quoted as 'psi' but as 'kPa'. The pressure switch settings for a 150 pump are 140/180, for a 200 pump 200/260 and for 250 and above 220/280.

The first figure is the pressure that the pump will switch on at, and then off at the second figure. As you can see there is quite a big difference between a 150 pump and a 200 pump, small difference between the 200 and 250 and no difference between a 250 and a 300.

[sandyf]

PSI is not a SI unit and should be best avoided.

Many of us were brought up on imperial units and even if you learned to become a bi-unit person its not easy to leave behind.

Pounds per square inch is a lot more real than kilos per square centimetre.

[sandyf]

PSI is not a SI unit and should be best avoided.

Many of us were brought up on imperial units and even if you learned to become a bi-unit person its not easy to leave behind.

Pounds per square inch is a lot more real than kilos per square centimetre.

Calculations in SI are much easier.

Specific weight from water is weight/volume, so Kg/L

It is easy to see that ten meters water column is equal to 1 bar.

Or when I see a water tank, I can without needing a calculater estimate (not guess) the capacity from that tank. And also calculate the weight when filled with water.

But I grew up with this. It is not without reason that SI is used in science.....

SI are not units in their own right, the SI designation only means they are an internationally recognised unit.

Grams,litres and metres are metric units and ounces,pints and feet are imperial units. Imperial units are just as valid as metric units and many of my generation will talk imperial until they are 6 feet under.

Up until the time the UK decided to go metric, imperial units were taught, now it is metric and in due course all Brits will be metric speaking, although I think milk and beer will remain imperial. Not sure where the Americans are heading with their units.

[bankruatsteve]

Screw metric and Imperial. American standards should be international. There's 4 quarts to a gallon, and pints and cups for drinking, 16 ounces to a pound and you can divide by a dozen to get something - now I forget.

[DavoTheGun]

What in the name of @@@@@ are you idiots on about, the OP was talking about His f@@@ing pump, no wonder I hate .TV. ! full of <deleted> ! and no doubt this will be deleted !

[bankruatsteve]

What in the name of @@@@@ are you idiots on about, the OP was talking about His f@@@ing pump, no wonder I hate .TV. ! full of <deleted> ! and no doubt this will be deleted !

Full of rage for what? Are you annoyed that no one applauded your brilliant suggestion? If you hate TV, you know how to fix that.

[Pib]

Here's a photo of the pump with its white top cover removed and sitting beside it:

Soi-80-water-pump.jpg

The label says:

Hitachi

EX Series

WT-P

155 EX

Japan

Is there an easy remedy for "water clogging"? I googled "water clogging" and didn't see anything that seemed relevant to a runaway water pump. If I can ease another six months or so out of the pump, that would be nice.

Tomorrow I'm going to be at the local mall which has a HomePro and I'll try to remember to see if they have a 250W Hitachi and/or a 255W Mitsubishi, and how much they cost.

Another symptom is a drastic increase in the random cycles of the pump. Previously it would turn on for maybe one cycle every couple hours (? not sure, because never timed it, but it wasn't very frequent) and I attributed that to some small leak somewhere in the plumbing slowly bleeding off the pressure. Since the monthly water bill is only B47 and my electric bills have been modest, I didn't really care. Now, it seems to be doing a cycle about every 35 seconds. Based on KhunBENQ's subtle "Worry!" I've been turning off the pump when I know I won't need water for a while.

[edited to add:] With the help of a Google search and Google Translate, this appears to be the specs for my current pump:

Hitachi-ST-P-155EX-pump.gif

(PS to Mods: I intended to put this in the DIY forum section, not Electrical. Can you move it, please, unless you think it should stay here. Thanks)

Your problem description sounds like a water logged pressure tank....that is, the tank the pump/manifold assembly is setting on. When the tank becomes waterlogged there is very little to no air in the tank...basically it 100% full of water and that is "not" a good thing. Normally the top 1/3 to 1/2 of the tank will contain air that gets compressed when the pump motor runs until it reaches the cut off pressure and the pump turns off. The water in the tank compresses the air.

The compressed air stores energy like a compressed spring. When you initially start using water the energy in the stored spring (the compressed air) pushes the water out under pressure...the pump does not have to turn on until the pressure drops to the cut-on pressure, sucks water in, as water refills the tanks it compresses the air again until the pressure reaches the cut off pressure and the pump turns off. Basically the compressed air is like a spring on the top of the water.

This type of tank does not have a rubber/metal diaphragm/bladder to keep the water and air separated, therefore, the air will get naturally absorbed into the water over a X-days to maybe 2 weeks unless replenished. A device called an air charger/air balance valve injects a small amount of air into the tank each time the pump turns on to replenish the small amount naturally absorbed into the water. On your pump it's probably a square looking thing mounted directly on the manifold assembly and may have a hose coming out going back into the manifold assembly or it may not have the hose as it connects internally...see below snapshot for a Hitachi pump manual to give you a general idea. I think from blowing up your picture I do see the valve type where the small black hose feeds from the air charger valve via a small hose into the water intake area. On Mitsubishi pump of similar designed it's a 6 side shaped valve that screws into the top of the tank with a small hose running out the top to the manifold intake...see Hamselv2's #22 post and for the Hitachi pump below snapshot from a manaul. Regardless of exact location/shape the purposes is to inject a small amount of air on each pump on cycle to replace/keep balanced the air (energy spring) in the pressure tank.

Hitachi Air Control/Air Charger Valve

Mitsubitshi Air Control Valve

I have Mitsubishi pump and my air balance valve went bad several years...a pin hole size rupture in the rubber diaphragm contained within the valve which prevented it from replenishing air into the pressure tank. Until I replace that valve my pump would act just like yours...turn on with slightest use of water, the shower would pulsate, etc. Even a small leaks somewhere...like a commode bowl slight leak or a leaky faucet can cause the pump to turn on frequently because you no longer have that compressed air energy spring to push the water out...instead the pump will turn on.

You can easily confirm it a waterlogged tank by turning off power to the pump, turn off water input and output to the pump, completely drain the water from the pressure tank (there is a drain plug at the bottom) so air can get into the tank through that drain hole. Repeat completely drain of water until air can get in. Then put the drain plug back in, turn on the water inlet/outlet valves, and apply power. It should run about 30 seconds before refilling/repressurizing and then turn off automatically. Now turn on one tap partially to see if the pump works/cycles normally...that is runs for say approx 3-5 seconds and then turns off 3-5 seconds. Also maybe check your shower to see if the pulsating is gone.

If all is well now that confirms your pressure tank got waterlogged (all water, no or very little air) The pump should continue to work OK for a few days to maybe a week or so, but during that period you see it slowly revert back to the same problem "if the air control valve" is not replenishing the air. A new air charger/control valve costs around Bt750.

[wpcoe]

I finally got out in the mid-day heat to further evaluate the project. As I understand it, I basically need to turn off/unplug the pump, close the water supply to/from the pump, drain the water via a drain hole, reverse steps.

There is no shut-off valve on the output side of the pump:

Can I proceed with no shut-off valve on the output side? Is the worse case scenario that all the water in the pipes in the house will also drain out via the drain hole? Or, ... ?

Secondly, which of these is the "drain hole"?

If it's B, do I just unscrew the grey plastic piece in the middle? (Optional bonus question: what is behind A?)

[wpcoe]

Too late to edit my previous post, but this supercedes it:

I found a shut-off valve on the output side of the pump farther up the water line (the plumber who did this has nothing on Rube Goldberg...) so I turned it off, turned off the inlet valve and removed the grey plastic plug on "B". Took longer than I thought to drain the water, probably 6 or 7 minutes. But, when it stopped draining, I replaced the grey plastic piece, plugged in and turned on the pump.

I think it's better now, but not sure it's ideal. If I turn on the kitchen faucet, the pump engages 5 seconds, goes off 10 seconds. If I also turn on the bathroom faucet, i.e. two faucets on full blast, the pump engages for 20 seconds and is only off for 4 seconds before re-engaging. Seems to me that's working a little harder than it should, but at least it's not the non-stop galloping that seems like would wear the pump out if left that way. Later this evening I will try to take a shower upstairs to see if the overall pressure is better.

Better than before, and maybe good enough to make it through to the end of the year. <fingers crossed>

Thanks to all for the patient and explicit advice above.

PS: Wonder how many p.s.i. it's producing. LOL!

[khunPer]

Compared to my pumps, B is the drain – you can use a the shaft of a screwdriver to turn the it out. Release the pressure of the water through a normal water tap, before you open the drain. You may also need to open at the top, to get air in and all water out of the pump tant. If you make sure all water taps in the house are closed, you may not drain the water from pipes.

[sandyf]

I realise that there is probably little you can do but if you ever have any work done on the pump then you should try and do something about the outlet pipework. I can see from the photos that the outlet has been reduced from the 1 inch to what looks like half inch very close to the pump. It has also been done with too many elbows. Every elbow and reduction puts a restriction on the flow and reduces performance at the outlets. The pipework between the pump and the outlets should be as straight as possible and as large as possible.

You mentioned a shut off valve on the outlet, that must be on the half inch pipe. That is not doing you any favours as the diameter in a half inch valve is less than a half inch pipe.

Something to think about and I appreciate it is not straightforward when not your own home.

Good luck.

[Pib]

Too late to edit my previous post, but this supercedes it:

I found a shut-off valve on the output side of the pump farther up the water line (the plumber who did this has nothing on Rube Goldberg...) so I turned it off, turned off the inlet valve and removed the grey plastic plug on "B". Took longer than I thought to drain the water, probably 6 or 7 minutes. But, when it stopped draining, I replaced the grey plastic piece, plugged in and turned on the pump.

I think it's better now, but not sure it's ideal. If I turn on the kitchen faucet, the pump engages 5 seconds, goes off 10 seconds. If I also turn on the bathroom faucet, i.e. two faucets on full blast, the pump engages for 20 seconds and is only off for 4 seconds before re-engaging. Seems to me that's working a little harder than it should, but at least it's not the non-stop galloping that seems like would wear the pump out if left that way. Later this evening I will try to take a shower upstairs to see if the overall pressure is better.

Better than before, and maybe good enough to make it through to the end of the year. <fingers crossed>

Thanks to all for the patient and explicit advice above.

PS: Wonder how many p.s.i. it's producing. LOL!

The on/off cycle is correct...it's working normally now that the pressure tank is no longer waterlogged. Now you just need to figure out why it got waterlogged--probably due to a defective air charger valve. Until this is fixed it will revert back to it's old ways within a few days to maybe two weeks as the air in the pressure gets naturally absorbed into the water.

You might want to check and make sure the small pencil diameter hose leading from the air charge valve to the intake is not clogged...if it's clogged then air can't get from the air charger valve into the input water stream that ends up in the tank. Take it easy in removing the hose/the two plastic nuts...when screwing back on the plastic nuts just tighten them finger tight and then around an additional half turn with a wrench. The nuts do not have to be very tight to prevent any air or water leak due to the low pressure at the hose point. You can also should be able to easily disassemble the air charger valve if desired...they are super simple on the inside...look very closely at the rubber diaphragm as that is about the only thing that can fail other than maybe dirty checkballs...look very closely for a rupture which could be very small.

[wpcoe]

Unless a sudden burst of motivation infuses me, with my highly lazy nature I will wait to see how long this "fix" lasts. Once it starts galloping away again, I'll revisit your post, Pib, and give it a go.

[sandyf]

PS: Wonder how many p.s.i. it's producing. LOL!

Ha!

It should be around 2 bar when switch off.

There are conversion tables avaible to convert this to PSI!!

Arjen.

The pump the OP is using will switch off at 180kPa which is about 26 psi.

I have the same pump and had to change the pressure switch recently.