Mitsubishi pump fast-cycling

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tamada
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Mitsubishi pump fast-cycling

Post by tamada » December 30, 2022, 8:50 am

WP-305 pump is about three years old. A couple of weeks back the outlet water pressure was low so I suspected the outlet filter needed changing. Found the pump was running continuously with symptoms of either low or no inlet supply or a lost prime. Turned off, let it cool down and drained the pressure tank as well. Refilled, primed but it wouldn't turn off and sounded like it was still cavitating. Found the seal on the screw top on the inlet side was perished so replaced that. Fired up again and it ran up until cavitation stopped, steady outlet pressure with no air. However, I had to rap on the case of the pressure switch to get it to 'auto' turn off.

Now have adequate outlet pressure but cycling very fast. I think the pressure switch may need replacing.

Any insight or advice?

Ta
tam


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Re: Mitsubishi pump fast-cycling

Post by Drunk Monkey » December 30, 2022, 10:03 am

Did you not search for the Mitsu service n repair center location in Udon prior to your purchase Tam ??? tut tut tut [-X

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Re: Mitsubishi pump fast-cycling

Post by Khun Paul » December 30, 2022, 5:01 pm

I have noy ever had Mitsubishi Pumps, a couple fo times found sneaky bugs had made a nest inside the Pressure switch, removed same cleaned it up , no problem. also the electronic swich the same , bunged up. Managed to buy a NEW electronic switch and a New pressure switch as a just in case .
Everytime over the years replaced a worn Pump, removed all the external additions, ( switch/pressure switch, external hoses ) . Keep as spares.

Plus have found over the years constant running mainly due to low pressure input, as it is pumping air and what Water it can get .

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 30, 2022, 10:20 pm

Although they're sealed units, I will drain it again and remove both the pressure switch and inlet pressure diaphragm, clean, check and replace. I did change the latter on the previous pump, maybe five years ago but can't recall the actual fault it fixed. I really should write stuff down.

Thanks KP. Happy New Year.
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Re: Mitsubishi pump fast-cycling

Post by Potamoi » December 31, 2022, 12:30 am

Sounds like the pressure switch to me. Not sure if that one has low and high adjustments but doubt it does on a consumer model. It can also be the accumulator tank if the bladder is leaking internally to cause the fast cycling.
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Re: Mitsubishi pump fast-cycling

Post by Colin1a1 » December 31, 2022, 4:00 am

This is a very simple pump. It doesn’t have a diaphragm in the tank, and relies on an air pocket trapped in the top of the tank as a damper. If by cycling You mean switching on and off then it sounds like the pressure switch has had it. It’s probably full of crap. Don’t take the pressure switch apart as You will not be able to put it back together. It was assembled by a machine and not fat fingers. I get my pump parts from Steve at Udon Hardware. Your best bet is probably to give him a call. PS He speaks very good English which is helpful.

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 6:21 am

Thanks Colin, there is a small diaphragm inside the hexagon-shaped housing on the top side which I replaced on a previous pump. However, it does point towards the pressure switch being the problem this time. I know they are not supposed to be tampered with. Went through a bit of pain 15 years ago when the well-meaning but useless brother-in-law thought he could.

I get my pump parts from the pump emporium on the south side of Phosi, before the roundabout, where the owner's daughter speaks good English while commenting on my excellent Thai language skills and good looks.
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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 6:31 am

Potamoi wrote:
December 31, 2022, 12:30 am
Sounds like the pressure switch to me. Not sure if that one has low and high adjustments but doubt it does on a consumer model. It can also be the accumulator tank if the bladder is leaking internally to cause the fast cycling.
They have "do not open" and "do not adjust" signage but as others have mentioned, they get crud in them. Easy to open and the screw adjustment is just begging to be tweaked which B-i-L found irresistible. Had me chasing my tail before he mentioned he'd had a go at adjusting it!

I hope the pump shop is open today: I could do with being charmed by a comely local lass. I do have a complete spare pump (rebuilt and tested the original one) but it's buried in the "other" shed.
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Re: Mitsubishi pump fast-cycling

Post by Khun Paul » December 31, 2022, 8:56 am

tamada wrote:
December 31, 2022, 6:31 am
Potamoi wrote:
December 31, 2022, 12:30 am
Sounds like the pressure switch to me. Not sure if that one has low and high adjustments but doubt it does on a consumer model. It can also be the accumulator tank if the bladder is leaking internally to cause the fast cycling.
They have "do not open" and "do not adjust" signage but as others have mentioned, they get crud in them. Easy to open and the screw adjustment is just begging to be tweaked which B-i-L found irresistible. Had me chasing my tail before he mentioned he'd had a go at adjusting it!

I hope the pump shop is open today: I could do with being charmed by a comely local lass. I do have a complete spare pump (rebuilt and tested the original one) but it's buried in the "other" shed.

Any probs contact me i may hav the bit you require

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 9:08 am

Khun Paul wrote:
December 31, 2022, 8:56 am
tamada wrote:
December 31, 2022, 6:31 am
Potamoi wrote:
December 31, 2022, 12:30 am
Sounds like the pressure switch to me. Not sure if that one has low and high adjustments but doubt it does on a consumer model. It can also be the accumulator tank if the bladder is leaking internally to cause the fast cycling.
They have "do not open" and "do not adjust" signage but as others have mentioned, they get crud in them. Easy to open and the screw adjustment is just begging to be tweaked which B-i-L found irresistible. Had me chasing my tail before he mentioned he'd had a go at adjusting it!

I hope the pump shop is open today: I could do with being charmed by a comely local lass. I do have a complete spare pump (rebuilt and tested the original one) but it's buried in the "other" shed.

Any probs contact me i may hav the bit you require
Cheers KP, I'll holler if I come unstuck.

For info, here's the topside diaphragm bit that I mentioned earlier. The Google translator calls it 'air charger'. When I dismantled the old one, the rubber (neoprene?) diaphragm inside had hair line cracks. From Colin's earlier comment, since this also screws onto the top of the tank, it must be what maintains the air bubble inside the tank.
.
wp305_air-charger.jpg
aka called 'flying saucer'
.
PS: If I do, can you charm me on my language skills and good looks too?
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Re: Mitsubishi pump fast-cycling

Post by Khun Paul » December 31, 2022, 10:20 am

I have over the years found that the Pressure switch is normally the pone that causes problems, however as with MANY THINGS here constant checking of connections can highlight some minor errors and upon tightening up solves the problem .
In my box of tricks I have THREE pressure switches and TWO aforementioned described ( one brand new ) !!!!!!!!!!!

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 12:21 pm

Update: fitted new pressure switch. Same problem.
Removed the air charger, disassembled, cleaned, inspected, reassembled, reinstalled. Same problem.

Wiped it dry and checked for seeps, pinholes, etc.. Nada.

Still bags of pressure and when the taps are closed, it holds pressure (no cycling). Just fast cycles under any amount of taps running.

OK, it's beer o'clock.
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Re: Mitsubishi pump fast-cycling

Post by colt1911 » December 31, 2022, 12:59 pm

Tam likely the preasure tank is water logged. Tried to attach a link for you but using pH..... utube has a repair process but you can get a new tank on Lazada cheap. Regards

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 1:29 pm

colt1911 wrote:
December 31, 2022, 12:59 pm
Tam likely the preasure tank is water logged. Tried to attach a link for you but using pH..... utube has a repair process but you can get a new tank on Lazada cheap. Regards
The original, fifteen year old pump tank rusted out and I replaced it with a lazada generic. All good, kept as a spare. This pump with the problem may be only three or four years old.

Waterlogged? I did completely drain the tank on my first troubleshooting exercise but that was with the old pressure switch. I will redrain again and see if that improves things. But I'll do that next year.
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Re: Mitsubishi pump fast-cycling

Post by Khun Paul » December 31, 2022, 2:29 pm

One assumes you have stripped down the impellor and checked to see if any impediment inside it. Apart from the pressure switch problem . I reierate whenever I have had a problem it has been water pressure ( not enough water being the problem ) .
I am sure you have checked thoroughly the outflow from your tank, but it cannot be ignored. Mitsubishi pumps in fact most of them are simple machinery, in/out and a mechanical device in-between pumping it. Nothing complicated so if still problems could be external , fast running normally it is hunting for pressure ( water ). Just a thought!!!!!!

That is why I installed more than one tank , does not take a lot to bung up the flow .

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Re: Mitsubishi pump fast-cycling

Post by tamada » December 31, 2022, 10:32 pm

It's baffling KP. Nothing has changed on the supply side or outlet side. The initial problem appeared to be a loss of inlet pressure leaving the motor running continuously with low output pressure.

There's bags of outlet pressure so doubt the impeller has issues.. I have pulled another pump apart to replace the seals on the impeller housing and there's not much in there to cause problems.

It primes ok so there's sufficient inflow and the dual tanks are full. If that was impaired and from previous experience, it would "hunt" continually. But in their simplicity, these pumps do operate on functioning interdependencies and from experience, it could be in those "feedback" loops.

If anything, it seems to be overpressured so following the "waterlogged" hint from earlier, I'll drain it again as I had only done that with the suspect, original pressure switch but didn't repeat the exercise after I replaced it.

I'll start from scratch with the purge, drain, refill, prime business next year!
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Re: Mitsubishi pump fast-cycling

Post by pf-flyer » January 1, 2023, 5:01 am

Have you checked out the air charger?
I replace the air charger on my Hitachi water pump every time I tear it down for my semiannual cleaning. Mitsubishi water pumps have an air charger also.
Note: I had a fast-cycling problem several years ago that was caused by a cartridge sediment filter on the output side of the pump that needed replacing.
"Life is like a tube of toothpaste. Outward pressure brings out the inward contents."

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Re: Mitsubishi pump fast-cycling

Post by pf-flyer » January 1, 2023, 5:05 am

[quote=pf-flyer post_id=665773 time=1672524085 user_id=4566]
Have you checked out the air charger?
I replace the air charger on my Hitachi water pump every time I tear it down for my semiannual cleaning. Mitsubishi water pumps have an air charger also.
Note: I had a fast-cycling problem several years ago that was caused by a cartridge sediment filter on the output side of the pump that needed replacing.
[/quote]

I apologize. I did not notice the previous posting about the Air Charger.
"Life is like a tube of toothpaste. Outward pressure brings out the inward contents."

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Re: Mitsubishi pump fast-cycling

Post by tamada » January 1, 2023, 8:11 am

Up at the crack of sparrow fart, loaded the BB gun and scared off the sparrows planning a raid on Yai's veggie patch...thence to work.

Turned off power and the water inlet and purged the system pressure before opening up the inlet prime cap and draining the tank.

Replaced the outlet filter (was a new only a few days before the original outage and not overly contaminated) and opened the water inlet, restored power and primed. Purged air in the outlet side and opened the water outlet.

Now functioning/cycling normally.

I think the initial drain, purge and prime had been done with the dodgy pressure switch still in place and I should have done it again after I had replaced it. This procedural error caused the tank to be overpressured.
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Re: Mitsubishi pump fast-cycling

Post by glalt » January 1, 2023, 11:15 am

These household water pumps have a small water tank and do cycle pretty often. I bought an extra tank with a bladder. It is called a reverse osmosis storage tank. I no longer have to drain the small tank on the pump. That extra tank is about three times bigger than the pump tank. For some reason the pump tank would lose the air cushion and would have to be drained to prevent the pump from cycling far too often.

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