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takinatrip

  • Posts: 72
Burnt out pressure switch
« on: December 16, 2013, 07:29:41 pm »
Ive got a shurflo 100 psi pump and in 12 months Ive burned out 2 pressure switches. Ive adjusted the cut off so it doesnt cycle when under load I cant think what else could do it? Ive taken the switch apart so I can see whats inside and the little contacts in the switch have burned out and even melted the spade connector sleeve.
Any ideas  ???
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Clever Forum Name

  • Posts: 5942
Re: Burnt out pressure switch
« Reply #1 on: December 16, 2013, 07:44:17 pm »
Are you using a controller ?
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takinatrip

  • Posts: 72
Re: Burnt out pressure switch
« Reply #2 on: December 16, 2013, 07:49:44 pm »
No just a tap on the pole to control flow.
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Clever Forum Name

  • Posts: 5942
Re: Burnt out pressure switch
« Reply #3 on: December 16, 2013, 07:55:19 pm »
What about the wires for the pump. Have you used decent wires (amp rating) and decent connections?

Sounds like wiring is getting hot? or like you say not switching off....
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Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #4 on: December 16, 2013, 08:20:23 pm »
12vdc is a very aggressive on switch contacts. Every time the pump switches off and on a flash will occur as the contacts make and break.

I doubt it has anything to do with faulty connectors etc.

This was the reason why we went for a controller 8 years ago as the Shurflo (and others) don't tollerate the on and off application very well. Although you have adjusted the pressure higher to reduce cycling you have created another problem. The higher the pressure before the pressure switch cuts out, the higher the amps the motor is drawing which creates a greater flash across the points.

You could get a cheap 40 amp 12 v relay and use the pumps pressure switch to activate it. The relay will draw very little current from the pressure switch which should make it last for years. Relays are cheap and will be much easier to replace as and when it should fail.

http://www.ebay.co.uk/itm/5-PIN-12V-40A-Automotive-Changeover-RELAY-including-WIRING-LOOM-/400292899718?pt=UK_Cars_Parts_Vehicles_Terminals_Cabling_ET&hash=item5d3350eb86#ht_4825wt_1161

This should work although you will still have to replace the microswitch on your pump. These microswitches are available for a couple of £'s from Maplin.


In the power tool trade, 12v machines could be wired so the positive wire went straight into the motor (red) and the switch was on the negative wire (black). The disadvantage is that the motor is 'live' but the windings in the armature do reduce the flash across the points of the switch.

I would still wire in a relay though.
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takinatrip

  • Posts: 72
Re: Burnt out pressure switch
« Reply #5 on: December 17, 2013, 09:04:07 am »
Thanks for the info guess Ill have to look into adding a relay or something to prolong the life of the switch.
Never had it happen before. I took the micro switch out of the pressure switch assembly and as you say you
could see it had flashed and almost destroyed the contacts.
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Ian Sheppard

  • Posts: 1217
Re: Burnt out pressure switch
« Reply #6 on: December 17, 2013, 09:49:29 am »
Have to Agree with Spruce and he is spot on. with the pump running flat out as you are with no form of control there is a very high inductive load (stored energy) across the pressure switch combine this with the high pressure plus heat the pump motor creates in the system and as the pump stops on the pressure switch this load has to go somewhere. So it arcs across the switch or Flash to use Spruces term this arc is what is burning out the switch.

It is surprising how high the pressure can be I did a comparison earlier this year. This article covers it. http://www.thehub360.com/spring-pressure-comparison.html

You will also find that by controlling the pump the pump draws less current from the battery.
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H20cleaning

  • Posts: 2098
Re: Burnt out pressure switch
« Reply #7 on: December 17, 2013, 10:48:08 am »
Go to maplins there only £2.50  :o £5.00 a year is cheap lol
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Peter Fogwill

  • Posts: 1415
Re: Burnt out pressure switch
« Reply #8 on: December 17, 2013, 01:46:24 pm »
Likewise I would recommend you use a relay as they are much more heavy duty than the pump switch, and much more easy to change over.  The relay instead of the pump switch it taking the heat. There is a wiring diagram on the window-tools forum.
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DG Cleaning

  • Posts: 1726
Re: Burnt out pressure switch
« Reply #9 on: December 17, 2013, 04:19:26 pm »
I must disagree my second hand shurflo has yet to burn out any contactors in 18 months.
I sometimes turn the flow down a bit with my tap and I can hear the pump turning on and off.
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Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #10 on: December 17, 2013, 07:51:24 pm »
Quote from: Peter Fogwill on December 17, 2013, 01:46:24 pm
Likewise I would recommend you use a relay as they are much more heavy duty than the pump switch, and much more easy to change over.  The relay instead of the pump switch it taking the heat. There is a wiring diagram on the window-tools forum.

Hi Peter,

The wiring diagram sticky seems to have gone.
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Success is 1% inspiration, 98% perspiration and 2% attention to detail!

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Peter Fogwill

  • Posts: 1415
Re: Burnt out pressure switch
« Reply #11 on: December 17, 2013, 08:06:38 pm »
It's in the FAQ page.
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Peter Fogwill

  • Posts: 1415
Re: Burnt out pressure switch
« Reply #12 on: December 17, 2013, 08:08:58 pm »
Quote from: DG Cleaning on December 17, 2013, 04:19:26 pm
I must disagree my second hand shurflo has yet to burn out any contactors in 18 months.
I sometimes turn the flow down a bit with my tap and I can hear the pump turning on and off.

What do you disagree with?
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Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #13 on: December 17, 2013, 08:11:36 pm »
Quote from: DG Cleaning on December 17, 2013, 04:19:26 pm
I must disagree my second hand shurflo has yet to burn out any contactors in 18 months.
I sometimes turn the flow down a bit with my tap and I can hear the pump turning on and off.

The original Shurflo pumps we had were 65psi rather than 100psi. Cycling would be greater on these units than on the current 100psi pumps.

Although I recommended a relay if this is how you operate, I personally would never not have a controller again. I love a fast flow for rinsing, but I find I waste water with too higher a flow rate with the washing and scrubbing phase even using the controller.

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Success is 1% inspiration, 98% perspiration and 2% attention to detail!

The older I get, the better I was ;)

Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #14 on: December 17, 2013, 08:13:02 pm »
Quote from: Peter Fogwill on December 17, 2013, 08:06:38 pm
It's in the FAQ page.

Cheers. I was looking for it last night whilst doing this reply. One of the links to it didn't work either.
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Success is 1% inspiration, 98% perspiration and 2% attention to detail!

The older I get, the better I was ;)

Peter Fogwill

  • Posts: 1415
Re: Burnt out pressure switch
« Reply #15 on: December 17, 2013, 08:27:55 pm »
Just had a look and it's still there.

Anyone wondering about the relay from Maplins the product code is N02AW

Peter

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Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #16 on: December 17, 2013, 08:49:29 pm »
Quote from: Peter Fogwill on December 17, 2013, 08:27:55 pm
Just had a look and it's still there.

Anyone wondering about the relay from Maplins the product code is N02AW

Peter



Got it. Thanks
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Success is 1% inspiration, 98% perspiration and 2% attention to detail!

The older I get, the better I was ;)

Clever Forum Name

  • Posts: 5942
Re: Burnt out pressure switch
« Reply #17 on: December 17, 2013, 08:51:25 pm »
While we are here. What's the number for the switch from maplins please  :-*
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Spruce

  • Posts: 8364
Re: Burnt out pressure switch
« Reply #18 on: December 17, 2013, 09:04:37 pm »
Quote from: Pure H20 Services on December 17, 2013, 08:51:25 pm
While we are here. What's the number for the switch from maplins please  :-*

GW71N
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Success is 1% inspiration, 98% perspiration and 2% attention to detail!

The older I get, the better I was ;)

DG Cleaning

  • Posts: 1726
Re: Burnt out pressure switch
« Reply #19 on: December 17, 2013, 09:06:42 pm »
Quote from: Spruce on December 17, 2013, 08:11:36 pm
Quote from: DG Cleaning on December 17, 2013, 04:19:26 pm
I must disagree my second hand shurflo has yet to burn out any contactors in 18 months.
I sometimes turn the flow down a bit with my tap and I can hear the pump turning on and off.

The original Shurflo pumps we had were 65psi rather than 100psi. Cycling would be greater on these units than on the current 100psi pumps.

Although I recommended a relay if this is how you operate, I personally would never not have a controller again. I love a fast flow for rinsing, but I find I waste water with too higher a flow rate with the washing and scrubbing phase even using the controller.



Tbh honest water usage isn't an issue for me if it was I would use a controller.
I've never managed to empty my 400L tank yet on a full day.
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