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Installing a higher pressure fresh water pump


blackrose

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On 02/04/2023 at 13:30, Bobbybass said:

I installed a higher power water pump.....and suddenly I had water gushing from leaks all over the place....☹️

 

That hasn't happened in my case. Touch wood!

20 hours ago, BEngo said:

A stand alone pressure switch will enable the cut in and cut out pressures to be set individually.  Often, the problem can then be cured without raising the cut off pressure to risky levels.

 

N

 

Well I'd have tried that but the instructions on the switch I bought are too technical for me. I just needed to know where to connect the cables, etc, in simple English. I don't do too badly for a non-tradesperson but these switches aren't supplied with instructions designed for the average DIYer. 

 

I've set my hot water expansion tank to 42psi and the PRV on my calorifier isn't leaking. If I manage to work out how to fit and set the pressure switch in future I'll see if I can reduce the cut out pressure as you suggest.

Edited by blackrose
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5 hours ago, blackrose said:

Well I've ended up fitting the higher pressure pump without the Square D pressure switch because I don't understand how to fit it or set it.

 

Anyway the higher pressure pump (which has same flow rate as the old pump) has sorted the problem and the Morco now runs without cutting out. So it seems that it's water pressure as well as flow that are the defining factors when it comes to running these Morco heaters.

 

Obviously as Tony says, pressure is related to flow, but as I understand it pump specs for the flow rate are given as if there was no pipework resistance, so I think the old pump the wasn't achieving its flow rate and the new higher pressure pump is allowing a better flow rate even though it's rated the same as the old pump.

 

Last paragraph.

 

The telling bit was when you said that the gas cut out before the pump cut in. The pump stopped with the burner still burning, so until that point the flow rate was more than enough - otherwise it would not have reached the cut-out pressure. The pump did not cut in when the boiler needed it to, pump off = no flow, so I don't see it can be a flow rate problem.

 

 

That is like no Square D switch I have seen, but then I am well out of date. However, such switches are usually double pole, so my guess is that 1 & 2 are for one pole of the switch and 3 & 4 for the other. You can use one pole and keep the other as a spare or simply parallel them.

 

I think PH is the adjustment for cut out and PB for cut in, but that is from the relative positions and should not be taken as fact.

 

 

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9 hours ago, blackrose said:

 

Looking at this switch I'm not really sure which terminal connections I should be using?

 

Also I assume the two holes at the top in my second picture are for cable glands which I won't bother with, but what's the threaded female connector at the bottom for? It looks like a connection for the water supply?

 

The instructions supplied with the switch are far from clear.

 

IMG_20230527_123142.jpg

 

IMG_20230527_123211.jpg

 

As for setting the thing.... Some instructions in plain English would have helped. I thought these pressure switches were supposed to be easy to fit?

 

IMG_20230527_124446.jpg

That certainly doesn't look like my square d switch. I'm pretty sure my one came with no instructions. However, everything apart from which adjustment was which was fairly obvious. I think I had to resort to you tube for the cut in/out adjustment. 

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11 hours ago, rusty69 said:

That certainly doesn't look like my square d switch. I'm pretty sure my one came with no instructions. However, everything apart from which adjustment was which was fairly obvious. I think I had to resort to you tube for the cut in/out adjustment. 

 

F@ck knows what I've bought then! I'm sure someone on the forum posted a linked to it but it was so long ago I can't remember. 

 

Anyway the pump works fine without an external pressure switch. The Jabsco that I've just removed was 13 years old and never needed an external switch. It was still working fine when I swapped it for the new higher pressure one yesterday so hopefully the new one will be just as good. I'm just keeping the old one as a spare.

 

Apparently those pump micro-switches aren't difficult to replace, so I'm not entirely convinced for the need of external switches anyway.

Edited by blackrose
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Just now, blackrose said:

 

F@ck knows what I've bought then! I'm sure someone on the forum posted a linked to it but it was so long ago I can't remember. 

 

Anyway the pump works fine without an external pressure switch. The Jabsco that I've just removed was 13 years old and never needed an external switch. It was still working fine when I swapped it for the new one yesterday so hopefully the new one will be just as good. I'm just keeping the old one as a spare.

Our pumps only last 4-5 years before the switch fails. It's usually at this stage I snip the internal pump microswitch connection and connect in the square d to give a bit of extra time before it starts leaking. 

 

So, whatever you are doing that makes your pump last that long, please can you tell me what it is. 

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17 minutes ago, rusty69 said:

 

So, whatever you are doing that makes your pump last that long, please can you tell me what it is. 

 

Buy a decent pump to start with? 🤣

 

This is the switch I have. Does anyone know if it would work in case I do need it in future? Mine is the XMP but it doesn't have the external knob shown in the diagram.

 

IMG_20230528_091540.jpg

Edited by blackrose
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Female metal connector is water supply.  Beware the thread may be NPT  not BSP.

Black things are cable glands.

 Electrical connectors.  Depends which version you have, I think.  Mine is a 4 terminal version and the two sides are independent.  I would expect yours to be either 1 and 3 or 3 and 5 in the positive line to the pump  As it is now the right pair will show continuity on a multi meter.

 

N

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22 minutes ago, blackrose said:

 

Buy a decent pump to start with? 🤣

 

This is the switch I have. Does anyone know if it would work in case I do need it in future? Mine is the XMP but it doesn't have the external knob shown in the diagram.

 

IMG_20230528_091540.jpgpan widget

What pump do you use? I think ours is a jabsco parmax 2.9 or 3.0

 

Eta. Forget that. I see it is in your original post 

Edited by rusty69
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14 hours ago, Tony Brooks said:

However, such switches are usually double pole, so my guess is that 1 & 2 are for one pole of the switch and 3 & 4 for the other. You can use one pole and keep the other as a spare or simply parallel them.

 

16 minutes ago, BEngo said:

Electrical connectors.  Depends which version you have, I think.  Mine is a 4 terminal version and the two sides are independent.  I would expect yours to be either 1 and 3 or 3 and 5 in the positive line to the pump 

From the instructions (top right of image) it looks pretty clear to me that this is a 3 pole switch, and you can connect using terminals 1 and 2, or 3 and 4, or 5 and 6.

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