Hitachi WM-P750GX Water Pump overheating (code C3)

[Guitar God]

I've had the pump for a year and never even had to take the cover off except to reset it if the water tank had ran dry but now in the past few days it's shut off with a code C3 (overheating) for no obvious reason.

There's nothing blocking any of the vents, no leaves or dust in, on or around the pump, circuit board enclosure, sensors etc. The cover is on the correct direction, it's only 34C during the day, it worked fine in the full sun when it was 40 last summer. I have it set to constant pressure and on High pressure but that's the same as it's been since day one. Water temp in the tanks is lower than the highest it been and still worked fine.

I can't think of anything that's changed. The only thing that was done recently was replacing the resin in the sediment filter but that's pushed through by the well pump and this one pumps from the tanks to the house.

Any ideas why a pump would start overheating after working fine for a year? (Other than a year warranty. actually I think one has a 5 year warranty, so that's probably not it.)

Here's an English manual for the P400GX/P750GX pump attached in case you have this pump but no EN manual for yours.

Hitachi WM-P400_750GX_En.pdf

[CGW]

I have 2 of these pumps and they have been running fine for three years now! (tempting fate?) Have you tried changing the mode out of high pressure and running pump with the cover off?

[IMHO]

Does it run for a period of time before it shows the overtemp error, or is it persistent?

If the former, how long is it running before is shuts off, and does the runtime vary based on how fast it's running? (i.e. low flow rate vs. high flow rate)?

If the error is permanent, maybe it just needs a reset?

You say you've had it for a year... maybe you've had it a little less than that, and it's just the angle of the sun right now?

I have had the controller on the smaller 400W version die after ~2 years, which cost 4,000 Baht to replace out of warranty. my 750W one has been going strong for over 4 years though.

Edited March 6, 2016 by IMHO

[Utley]

The small black pressure tank probably has some water in it. Shut the pump and the water intake off. Unscrew the pressure tank at its base and shake out any water. DO NOT remove the little screw at the top as you will release the tank's pressurized nitrogen.

[Guitar God]

It would run for 10-20 hours between errors. There's really not much sun directly on it so I don't think that's it. I don't want to run it without the cover and get water or dust on the control board.

I set the pressure to low and put it in normal mode ( had been on high and constant pressure)

I unscrewed the air tank but didn't notice much water that came out.

It's running without errors now. I'll try going back to the old settings when I'm back.

[Guitar God]

So, I finally had a technician from Hitachi come out, take off the impeller cover and found all the vanes had broken off due to sand that had gotten in there when the guys who redrilled our well bypassed my Mazuma sediment filter after they they turned the pump back on.

It took a month to order the part which turned into 6-8 weeks and in the meantime I put in a Hatichi WM-450GX pump, less capacity and pressure but the same as the original.
The meager water pressure upstairs was even less with the 450 but it worked without any errors for close to two months.

I swapped out the 450 for the repaired 750 and after a week or so it started overheating with a code E3 again.

I took off the impeller cover, both the intake and output tubes to the pump, checked the one-way valve on the input, the tank with the diaphram, didn't see any problems.

I thought there might be a leak in the outdoor plumbing so I put a shutoff valve on the pipe that goes to all the taps outside. No leaking toilets or leaks in the house plumbing and I only hear the pump running when a tap in open.

I'm at a loss why it would be overheating all the time. I've heard they shut off if the water is over 45 C and if your tank is in the sun, the water could get too hot. If that's the case, it should have also happened with the 450. The pump is always quite hot when it shuts down with the E3 error so it's not just a faulty overtemp sensor.

Any ideas why the 450 ran two months without an error and the 750 overheats and turns off once a week or so?

[MJCM]

I know it’s an old topic, but I am having the same issue with a brand new Hitachi Inverter WMP-400XV, which is the newer version of the WMP-400GX.

 

Went to the toilet at 5am and water wasn’t flowing, so went outside and pump was in Error (C3) (Overheating). I had to reset it a couple ofvtimes before it started to work again. Water is very cold and also the weather is reasonably cold as we have lots of rain storms the last couple of days.

 

i also checked for leaks in the plumbing but none, the funny thing is that is pump is the replacement for the WMP-400GX as it had sprung a leak, which was fixed by an installation team, but it started leaking approx in the same area a day later.? So we bought a replacement ?

 

not very happy to say the least with the shop that sold me both pumps, will take my business elsewhere in the future.

Edited May 5, 2018 by MJCM

[MJCM]

Update:

 

Fair to the shop where we bought the pumps, they are willing to send a team from the Manufacturer to deal with our problems.

 

So kudos to them

Edited May 8, 2018 by MJCM