Water pump keeps running even after pressure switch turns off

[lost in isaan]

I recently built DIY water filtering system. I have two water pumps: mitsubishi water pump that pumps from rainwater tanks and hitachi for well water.

The thing i'm curious about is why does mitsubishi pump keep pumping even after i hear the pressure switch click off? It runs couple of mins and stops at around 4 bars. I thought the issue was with pressure switch, so i got one that switches off at 1.9 bar. Previous one switched off at 2.8 bar, but that did not change anything.

 

My hitachi pump switches off at 1.8 bar and works like it should.

 

Not a critical problem as the pipes should be able to handle the pressure, but in a long run more potential leaks and i don't really need that much pressure.

 

Any ideas or suggestions are welcome.

 

Pictures of my DIY system:

 

Edited July 27, 2023 by lost in isaan

[In the jungle]

The Mitsubushi pump like yours has two switches. 

 

It has a pressure switch and a flow switch.  The flow switch has encapsulated electronic components and is immediately before the pump outlet.

 

The pressure switch is adjustable although the manufacturer tells you not to touch it. 

 

Nothing you can service on the flow switch.

 

 

[lost in isaan]

12 minutes ago, In the jungle said:

The Mitsubushi pump like yours has two switches. 

 

It has a pressure switch and a flow switch.  The flow switch has encapsulated electronic components and is immediately before the pump outlet.

 

The pressure switch is adjustable although the manufacturer tells you not to touch it. 

 

Nothing you can service on the flow switch.

 

 

That explains it, thank you

[ExpatOilWorker]

That is a very nice and neat setup.

Do you pre-strain ur rainwater?

What type and how many microns are your filters?

What is the purpose of the greenish tank in the corner?

[wildpuppet72]

Beautiful setup looks so clean to the eye

[lost in isaan]

7 hours ago, ExpatOilWorker said:

That is a very nice and neat setup.

Do you pre-strain ur rainwater?

What type and how many microns are your filters?

What is the purpose of the greenish tank in the corner?

Thank you.

I use "first flush" system for rainwater and 100-mesh small filter before the pump.

On the wall i have 5 filters: small easily cleanable 100-mesh filter, 5-micron sediment filter, carbon filter, resin filter and lastly UV filter.

 

The greenish tank is a 100-litre pressure tank.

 

I don't intend to drink the water, it's just a simple and inexpensive way to make it more clean ????

Edited July 28, 2023 by lost in isaan

[ExpatOilWorker]

5 hours ago, lost in isaan said:

Thank you.

I use "first flush" system for rainwater and 100-mesh small filter before the pump.

On the wall i have 5 filters: small easily cleanable 100-mesh filter, 5-micron sediment filter, carbon filter, resin filter and lastly UV filter.

 

The greenish tank is a 100-litre pressure tank.

 

I don't intend to drink the water, it's just a simple and inexpensive way to make it more clean ????

Beautiful workmanship, well done. Nice little side glass for level and I like you have many unions for future maintenance. 

How many m3 of rainwater have you so far run through ur filtration train?

I use about 200 m3 of rainwater a year and found that 10 micron plug up too fast.

I pre-strain at 300 micron to avoid larger organic material foul the tank.

For level, I went electronic with a 0-0.3 bar 4-20 mA pressure transducer. It is accurate down to 10 l.

 

[The Theory]

On 7/28/2023 at 9:29 AM, lost in isaan said:

lastly UV filter.

I would use an UV filter (about 7 watts each) in each water storage tank.
I have plan to hang them in my water tanks rather than in the middle of fast flow water pipes. And they just need to be on part time by a timer. Perhaps 3 or 4 times a day for an hour or 2. 

[sometimewoodworker]

2 hours ago, The Theory said:

I would use an UV filter (about 7 watts each) in each water storage tank.

There is no point in adding a UV filter.

 

You may decide to add a UVC light and if you do you need proper UV transparent waterproof fittings for them

[Thaifish]

On 7/27/2023 at 8:42 PM, lost in isaan said:

I thought the issue was with pressure switch, so i got one that switches off at 1.9 bar.

Try bleeding air out of the highest point. Air can mess with the pressure switch big time. There should be an air bleed valve to do this.

Edited July 29, 2023 by Thaifish

[The Theory]

2 hours ago, sometimewoodworker said:

There is no point in adding a UV filter.

You are absolutely right ????

2 hours ago, sometimewoodworker said:

you need proper UV transparent waterproof fittings for them

They are waterproof, built for this purpose.