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  1. #1
    Whopping Member
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    Hitachi water pump - help please

    I have an automatic water pump (Hitachi GP Series WT-P 250GP) which pumps water from my tank to my taps when I turn them on. It's less than a year old, but recently, I have noticed it running when there are no water taps on in our house. It sound like the pump is trying to pump air and water instead of water.

    I checked the water tank first, and it's full of clean water, with no obstruction in the pipe which goes to the pump.

    I removed the plastic cover and unscrewed the cap on top (pictured with my fat finger pointing at it), and there was a hiss of escaping gas. I poured water in the hole - Mrs benbaaa said this was the thing to do - until it was full, then screwed the cap on again. This seemed to fix the problem for a while, but now I get the sound of water and air being pumped again. Any advice?

    This is my pump.


    This is the cap I unscrewed.


    Cheers,

    bb
    The sleep of reason brings forth monsters.

  2. #2
    Have you got any cheese Thetyim's Avatar
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    Switch the electric off
    Drain the pump reservoir
    Switch it back on

    This will reset the air volume in the reservoir to the correct level

  3. #3
    Thailand Expat
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    I disassembled the shut off mechanism on mine and found it jammed with green algae. I cleaned it with a tooth brush, and it worked for about 4 months, then it started running all the time because it was full of algae again. The Toshiba is a good pump, but the water here is filthy.

    Think of that the next time you brush your teeth.

  4. #4
    Thailand Expat jandajoy's Avatar
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    Benbaa, we had a similar thing happen. Went on for ages. We'd open the cap, as you did and fill it up and it'd be fine for a while then start over again.

    Then, to my shame the bloke next door came round and made a slight adjustment to a screw on the top of the pump under the cover. It'd been good for months now.

    Our pump is not a Hitachi, its some Chinese cheapo but you might have such an adjusting screw on yours. Just a thought.


    By the way, here's a manual from Hitachi

    http://www.hitachiconsumer.com.my/ho.../WT-P400GP.pdf
    Last edited by jandajoy; 27-05-2010 at 04:13 PM.

  5. #5
    FarangRed
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    Also check for leaking pipes

  6. #6
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    Have you contacted Driving Force, I heard that he's an exert on pumps.

  7. #7
    Have you got any cheese Thetyim's Avatar
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    Ben, I wouldn't spend time worrying about the pump I would concentrate on finding where your left thumb went.

  8. #8
    Days Work Done! Norton's Avatar
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    Is your tank is below ground?

    If so the check valve in the water pump may not be working properly, allowing water to run back into the tank leaving air in the impeller. Remove the plastic cap your fat finger is pointing at. You will see a plunger like plastic valve with a spring. Pull it out and check to see if the rubber gasket and where it seats is clean. Also, make sure the spring is functioning.
    Whenever you find yourself on the side of the majority, it is time to pause and reflect.

  9. #9
    Thailand Expat nedwalk's Avatar
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    clean yer fingernails..

  10. #10
    Whopping Member
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    Quote Originally Posted by Thetyim
    Switch the electric off
    Drain the pump reservoir
    Switch it back on
    Could you give a few details about draining the pump reservoir? Like where is it, what is it and how to drain it? Please.

    JJ thanks for the manual - I couldn't find one.

    Quote Originally Posted by Norton
    Is your tank is below ground?
    I'm not very technically minded, Norts, but I think my tank is the large aluminium thing full of water behind the pump in the first picture.

  11. #11
    Whopping Member
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    Quote Originally Posted by benbaaa
    JJ thanks for the manual - I couldn't find one.
    D'oh! That's not a manual. It doesn't tell you anything about routine maintenance or what to do if it goes wrong.

  12. #12
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by benbaaa
    I'm not very technically minded, Norts, but I think my tank is the large aluminium thing full of water behind the pump in the first picture.
    Should have noticed in the pic. My apologies. Above ground so not likely a check valve problem.

    Try this.
    Quote Originally Posted by Thetyim
    Switch the electric off Drain the pump reservoir Switch it back on This will reset the air volume in the reservoir to the correct level

    If it doesn't work, try this.

    Quote Originally Posted by FarangRed
    Also check for leaking pipes
    The pipes between your tank and the pump. Turn off the pump and see if any water is leaking. If you see water leak then when the pump is turned on the leaking bit will be sucking air into the pump.

  13. #13
    Thailand Expat jandajoy's Avatar
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    Quote Originally Posted by benbaaa
    D'oh! That's not a manual. It doesn't tell you anything about routine maintenance or what to do if it goes wrong.
    Shows you how it works though don't it.

    Try this;

    http://www.inspectapedia.com/water/W...termittent.htm
    Last edited by jandajoy; 28-05-2010 at 12:34 PM.

  14. #14
    Whopping Member
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    Quote Originally Posted by Norton
    Should have noticed in the pic. My apologies.
    You're so polite.

    Waiting for Thetty to get back to me about draining the pump reservoir, as I have a knack of really fokking things up when I try to work out how to do stuff myself.

    JJ, thanks for that link:

    Here are the more likely causes of the water pump coming on at odd times when you're not (aware of) running any water. You may want to investigate these possible causes roughly in the order they are listed below.
    1. Running Toilets: A toilet somewhere in the building is running - this can be VERY hard to spot - unless you are meticulous. I've tried wiping the toilet bowl interior to make it dry and then feeling it later for wetness above the water line, or watching the water in the toilet bowl for ripples, or placing a little septic dye or food coloring in the toilet tank to see if it appears in the bowl below, or, simplest, simply turning off all toilets at their supply valve to see if the pump cycling goes away. A leaky flush valve or a leaky fill valve in a toilet causes this problem.
    2. Leaky Plumbing Fixtures: A plumbing fixture such as a sink, tub, shower, or clothes washer is leaking slowly - dripping into the fixture (where you can see it) or worse, dripping into a hidden building cavity such as a wall or ceiling cavity (where water stains eventually show up below) or into a floor or crawl space (where you may not see the leak).
    3. Leaking Water Tanks: An air leak at the water pressure tank, above the water line in the tank, (or a water leak from the water pressure tank) can cause the tank to slowly lose air and the water pump to cycle on. This is possible with both traditional steel water tanks and with modern captive-air bladder type tanks (water is in a separate bladder inside the tank). Older water tanks which have an air volume control (which rarely work) are designed to automagically add air to the water tank as needed, so if the AVC is working and if there is a little air leak on the tank somewhere (often you can spot a rusty pinhole leak), this condition could continue for a while before being diagnosed.
    4. Leaky check valve or foot valve: A check valve at the pump or a foot valve in the well at the bottom of the water pipe could be failing and leaking, sending water backwards from the pressure tank, through the water pump, and back into the well. This can eventually lead to loss of prime and loss of all water supply as is discussed at our website.
    5. Leaks in well piping: A water leak in the well piping between the building and the well or even inside the well could also cause a back-flow of water from building to well and lead to pump cycling on and off.
    6. Defective Pressure Control Switch: A defective pump pressure control might, in theory cause this intermittent cycling but in more than 30 years of practice I've not found this to occur.
    To Fix Water Pump Intermittent Cycling

    To correct the problem of water pumps coming on when there is no apparent reason, we need to find which of the causes listed above is occurring. Remember that on occasion more than one fault could be present. Each of the possible causes listed above is also discussed as a diagnosis and repair topic at this website. Use the links at page left or the "Search Box" on any of our web pages to look for further advice.

    Pretty sure that 1 and 2 aren't what's causing it. The pump still runs when all the water taps are off and all supply valves are off. I guess there could be a leak underground or behind a wall, but there's no evidence, so how could I find out?


    3 is N/A 'cos it's not a pressurized water tank. Not sure I completely understand what 4 or 5 are all about. 6 sounds like your slight adjustment to a screw. After I've tried Thetty's suggestion, maybe I'll get the shop guy to come and have a look. As I said, it's less than a year since it was installed.

  15. #15
    Thailand Expat jandajoy's Avatar
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    Quote Originally Posted by benbaaa
    I'll get the shop guy to come and have a look. As I said, it's less than a year since it was installed.
    By far the best plan.

  16. #16
    Have you got any cheese Thetyim's Avatar
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    Quote Originally Posted by benbaaa
    Waiting for Thetty to get back to me about draining the pump reservoir
    Turn off the electric
    Shut the red gate valve water supply from the tank. I can see it in the photo above.
    Open a tap in the house to relieve water pressure.
    Remove a plug from the reservoir. I can't see the plug in the photo. It will probably be 90 degrees from the house supply pipe. (facing the water tank)
    Let the water drain out then reverse all the things you did above to get back to normal.

  17. #17
    Thailand Expat
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    Quote Originally Posted by benbaaa
    I'm not very technically minded, Norts, but I think my tank is the large aluminium thing full of water behind the pump in the first picture.
    it is probably stainless steel, but never mind

    and if it is less than a year old and they installed it, call them back to fix it

    even if they didnt install it

  18. #18
    Whopping Member
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    Gonna try Thetty's suggestion. Breakfast first, though.

  19. #19
    I am in Jail
    Butterfly's Avatar
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    could be the same problem I had, it was the "pressure valve" if I remember correctly, it was broken and would go into an endless cycle

    eventually the "small reservoir" started to melt because the water was too hot

  20. #20
    FarangRed
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    it should cut out there Butters, joking apart it's sometimes difficult to tell you whats wrong without seeing it, one thing that does happen is the foot valve at the bottom of the pipe in the well I'm afraid they dont last long and stick open causing the water to go back down in the well, just get the guy who installed it to take a look

  21. #21
    Member RamboII's Avatar
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    Is there a water pump sold in Thailand that is demonstratively better than the rest, as far as reliability? I need to replace the pump running my underground lawn sprinklers (4 zones with 4 sprinkler heads on each zone) and eventually the pump for my house (3 bathrooms and two kitchens). From what I've read, hitachi and Grundfos are both good pumps, with Grundfos being more reliable and more expensive. I need reliable because I am away from Thailand most of the time and need my grounds watered regularly.
    the other Marmite

  22. #22
    Elite Mumbler
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    Quote Originally Posted by Butterfly
    could be the same problem I had, it was the "pressure valve" if I remember correctly, it was broken and would go into an endless cycle eventually the "small reservoir" started to melt because the water was too hot
    I had the same problem and solution. Things get sticky in humid environments and the pressure valve won't release as easy as the day you bought it.

  23. #23
    I am in Jail
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    Quote Originally Posted by RamboII
    Is there a water pump sold in Thailand that is demonstratively better than the rest, as far as reliability?
    I have been told many times that HITACHI were crap, and they broke down quite easily, could be unfounded rumors though

    it seems that everyone is swearing with FUJIKA, a bit more expensive but should last longer

  24. #24
    Thailand Expat jandajoy's Avatar
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    Quote Originally Posted by Butterfly
    I have been told many times that HITACHI were crap, and they broke down quite easily, could be unfounded rumors though it seems that everyone is swearing with FUJIKA, a bit more expensive but should last longer


    Your English is hysterical.

  25. #25
    Member RamboII's Avatar
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    Looks like it is going to be a Grundfos.

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