Water pump. Acceptable flow rate?

[Bro]

Present water pump playing up (not cutting out as ought).  It's a Par-Max 3 which delivers 3.5gpm and cost of same spec. replacement is about 3 times that of same make pump delivering 2.4gpm. My question is, what pump flow rate do you guys find acceptable, ie. is 2.4gpm generally sufficient to get decent shower flow?

[Tony Brooks]

That will depend upon your shower head. 2.4 gpm may be fine with an economy head and I suspect it will be OK on an ordinary one. it may not be on one of the "rain storm" heads.

 

I note that you do not give the cut out pressures. make sure the new pump cut out pressure is very simmilar to the old one.

 

The lower output one will be less likely to cycle when a tap is open.

[Jen-in-Wellies]

Worth putting a bucket in your shower and seeing how much water your shower uses per minute. If it is significantly less than the pump capacity, then derating the next one should be OK. Another consideration is operating pressure of the pump as Tony said. Generally, the higher the pressure and the higher the flow rate, then the more they cost.

If the only problem with the current pump is the cut out not working right, then a better solution could be installing a separate pressure switch and bypassing the one on the pump. The pump fitted ones have a reputation for unreliability, though I've not had a problem with any myself. If living aboard, then pumps are a consumable. Around 4 years on average I've found.

 

Jen

[Bro]

10 minutes ago, Jen-in-Wellies said:

Worth putting a bucket in your shower and seeing how much water your shower uses per minute. If it is significantly less than the pump capacity, then derating the next one should be OK. Another consideration is operating pressure of the pump as Tony said. Generally, the higher the pressure and the higher the flow rate, then the more they cost.

If the only problem with the current pump is the cut out not working right, then a better solution could be installing a separate pressure switch and bypassing the one on the pump. The pump fitted ones have a reputation for unreliability, though I've not had a problem with any myself. If living aboard, then pumps are a consumable. Around 4 years on average I've found.

 

Jen

Excellent response Jen.  Particularly like idea of separate pressure switch as nothing wrong with pump itself. Shall be grateful for any advice on suitable pressure switch.

[Bro]

29 minutes ago, Tony Brooks said:

That will depend upon your shower head. 2.4 gpm may be fine with an economy head and I suspect it will be OK on an ordinary one. it may not be on one of the "rain storm" heads.

 

I note that you do not give the cut out pressures. make sure the new pump cut out pressure is very simmilar to the old one.

 

The lower output one will be less likely to cycle when a tap is open.

Thanks Tony. Cut out pressure would be same for both (25psi).

[Tony Brooks]

Square D if you can find one, probably Ebay I am afraid.

 

Fully adjustable for both cut in and cut out pressures.

Edited June 8, 2018 by Tony Brooks

[Bro]

15 minutes ago, Tony Brooks said:

Square D if you can find one, probably Ebay I am afraid.

 

Fully adjustable for both cut in and cut out pressures.

Great! I'll get searching.  Present pump cuts in at 15psi and cuts out at 25psi.

[adrianh]

Square D switch probably from Italy supplier on Ebay is your best option. You will need to tee into your pipework and connect to the pressure switch with a small bore pipe as the switches are 3/8 or 1/4 bsp female thread. A spiral pig tail connection with 6mm pipe reduces the chance of the switch pulsing on off close to the set pressure.

[Bro]

On 08/06/2018 at 18:25, Tony Brooks said:

Square D if you can find one, probably Ebay I am afraid.

 

Fully adjustable for both cut in and cut out pressures.

Thanks Tony.  Square D seem to be rated for A.C. voltage not 12DC.  Important do you think?

[rusty69]

13 minutes ago, Bro said:

Thanks Tony.  Square D seem to be rated for A.C. voltage not 12DC.  Important do you think?

My ebay square d clone has been running fine for years from 12v supply. 

[Sea Dog]

For comparison purposes,  the Par Max 2.9 works fine for me with a standard B&Q type shower head.  Remember that a replacement shower head is considerably cheaper than the difference in price of a bigger pump.

[Bro]

47 minutes ago, rusty69 said:

My ebay square d clone has been running fine for years from 12v supply. 

Would this be the boyo?:-

https://www.ebay.co.uk/itm/Well-Water-Pump-Parts-Double-pole-Adjustable-Pressure-Control-Switch-/173216249078?_trksid=p2349526.m4383.l4275.c10

[rusty69]

21 minutes ago, Bro said:

Would this be the boyo?:-

https://www.ebay.co.uk/itm/Well-Water-Pump-Parts-Double-pole-Adjustable-Pressure-Control-Switch-/173216249078?_trksid=p2349526.m4383.l4275.c10

I think this is the one i bought 

 

https://m.ebay.co.uk/itm/SquareD-Water-Pressure-Switch-4-6-bar-2-pole-PS6SQD/153045240318?hash=item23a23509fe:g:uFYAAOSwFJBZXK0N

[Bro]

18 minutes ago, rusty69 said:

I think this is the one i bought 

 

https://m.ebay.co.uk/itm/SquareD-Water-Pressure-Switch-4-6-bar-2-pole-PS6SQD/153045240318?hash=item23a23509fe:g:uFYAAOSwFJBZXK0N

Thanks Rusty.

[Tony Brooks]

1 hour ago, Bro said:

Thanks Tony.  Square D seem to be rated for A.C. voltage not 12DC.  Important do you think?

Technically, yes it matters because when the contacts break under load the AC turns itself off within 100th of a second so self extinguishing any arcs. The switches we ha don the hire fleet had a permanent magnet to draw the arc away and thus extinguish it. However a number fell out and it seemed to make not a jot of difference. I would try for DC (of any voltage larger than 12) but if its not economically possible get the largest Amp rating. Remember they are double pole switches so you can parallel the contacts to reduce the current on each set or keep one set as a spare.

 

Anyway you now have a link to a 12V one

[mrsmelly]

On 08/06/2018 at 17:44, Bro said:

Present water pump playing up (not cutting out as ought).  It's a Par-Max 3 which delivers 3.5gpm and cost of same spec. replacement is about 3 times that of same make pump delivering 2.4gpm. My question is, what pump flow rate do you guys find acceptable, ie. is 2.4gpm generally sufficient to get decent shower flow?

I replaced with a par max 1 a third of the price and does the job just as well.

[rusty69]

8 minutes ago, mrsmelly said:

I replaced with a par max 1 a third of the price and does the job just as well.

Wot is a parmax 1? Mine is a parmax 2.9

[mrsmelly]

4 minutes ago, rusty69 said:

Wot is a parmax 1? Mine is a parmax 2.9

Same thing. Bottom of range.

[MtB]

Although the basic Parmax 2.9 has the same spec as the other common pump, the ShureFlo Water King, I've replaced two Water Kings recently with Parmax 2.9 and mildly regretted it as shower performance seems to have reduced. Flow rate from the galley sink tap seems a little lower too.

 

I've not done any comparative measurements so this might be my imagination, and the Parmax works perfectly well, just not quite as well as the equally cheap Water King if shower performance is important to the OP. 

 

The Water King has a problem though, it has a reputation for only lasting two or three years before beginning to leak. This I why I replaced one of them. 

[Sea Dog]

2 hours ago, Mike the Boilerman said:

Although the basic Parmax 2.9 has the same spec as the other common pump, the ShureFlo Water King, I've replaced two Water Kings recently with Parmax 2.9 and mildly regretted it as shower performance seems to have reduced. Flow rate from the galley sink tap seems a little lower too.

 

I've not done any comparative measurements so this might be my imagination, and the Parmax works perfectly well, just not quite as well as the equally cheap Water King if shower performance is important to the OP. 

 

The Water King has a problem though, it has a reputation for only lasting two or three years before beginning to leak. This I why I replaced one of them. 

Funnily enough, I replaced 2008 Par Max 2.9 a year or two ago with a new one and also noticed a small drop in performance. Still fine, but not as fine as it was previously.  They don't make 'em like that used to!

[Bro]

Thank you gentlemen for advice given.

Accordingly I bought Square D switch, fitted in place of the faulty pump integral switch, set cut out to approx 30psi and now everything tickety-boo!  Cost, ............. change out of £30.

New par-max 4 (suggested replacement for no longer available 3) is around the £150 mark, I believe.

Result!

 

[MtB]

On 01/07/2018 at 13:01, Sea Dog said:

Funnily enough, I replaced 2008 Par Max 2.9 a year or two ago with a new one and also noticed a small drop in performance. Still fine, but not as fine as it was previously.  They don't make 'em like that used to!

 

Interesting. The 2.9 and the 3.5 look identical to me despite one costing twice the price of the other. The cynic in me suspects the only difference is the setting on the pressure switch.

14 hours ago, Bro said:

Thank you gentlemen for advice given.

Accordingly I bought Square D switch, fitted in place of the faulty pump integral switch, set cut out to approx 30psi and now everything tickety-boo!  Cost, ............. change out of £30.

New par-max 4 (suggested replacement for no longer available 3) is around the £150 mark, I believe.

Result!

 

 

Thanks for the update, much appreciated. 

[Sea Dog]

3 hours ago, Mike the Boilerman said:

Interesting. The 2.9 and the 3.5 look identical to me despite one costing twice the price of the other. The cynic in me suspects the only difference is the setting on the pressure switch.

Oh heck, does that mean I am going to be emptying my "shed" and crawling under the well deck shortly then?

[Bro]

On 14/07/2018 at 11:00, Mike the Boilerman said:

 

Interesting. The 2.9 and the 3.5 look identical to me despite one costing twice the price of the other. The cynic in me suspects the only difference is the setting on the pressure switch.

 

Thanks for the update, much appreciated. 

A little more information for those who may be interested:-

Square D  switch used is model 9013FSG2J20.  I unscrewed the pressure setting nut 3 full turns which, I am told, reduces the cut out pressure from 40psi to approx. 30psi.