Thread: Hitachi water pump - help please

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

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.

Also check for leaking pipes

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

Ben, I wouldn't spend time worrying about the pump I would concentrate on finding where your left thumb went.

clean yer fingernails..

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Gonna try Thetty's suggestion. Breakfast first, though.

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

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

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.

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

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.

Looks like it is going to be a Grundfos.