Domestic fresh water pressure

T

toad

Well-Known Member
Joined
31 Jul 2001
Messages
753
Location
ESSEX ENGLAND
Visit site
I have a Shur Flow water pump supplying a galley sink and shower head through a calorifer, the pump has died and is not repairable. As I intend to launch next Saturday a direct replacement is required in the next week, a replacement from Amazon is about £55. Looking at the old pump it has a flow rate of 10.6 litres a min and a pressure of 30psi which seems a bit high to me as I often have to tighten up the pipe connections. I think the pressure is adjustable by the screw on the end or I can buy the next size down which is 7lh and 20psi. Can anyone confirm that the pump pressure is adjustable in this way and what pressure do others run there system at. I have done a search and the only post that I can find seems to suggest a pressure of 15psi.
Thanks
 
Those pumps seem to last ( me) 15 months only, I keep the old ones and have 4 now! And a separate pressure switch so one day.....

I have gone from 40psi ( fantastic shower, really needle like) thru 30 and now at 20 tho I have gone for a more robust unit this time and it is also significantly noisier. Sorry cant read the writing on it in situ. Goit a chamfered plastic motor end body, the others were all metal motors..
The pressure switches seem to fail/become erratic, **** design tho the first thing to check is that you have really good current flow( thick wires) to the pump..
 
toad said:
I have a Shur Flow water pump supplying a galley sink and shower head through a calorifer, the pump has died and is not repairable. As I intend to launch next Saturday a direct replacement is required in the next week, a replacement from Amazon is about £55. Looking at the old pump it has a flow rate of 10.6 litres a min and a pressure of 30psi which seems a bit high to me as I often have to tighten up the pipe connections. I think the pressure is adjustable by the screw on the end or I can buy the next size down which is 7lh and 20psi. Can anyone confirm that the pump pressure is adjustable in this way and what pressure do others run there system at. I have done a search and the only post that I can find seems to suggest a pressure of 15psi.
Thanks
Click to expand...

The manuals are available in the "Education Centre" tab on http://www.shurflo.com/marine-products/default.html
If the pump pressure is adjustable I'd expect the details to be in the manual
 
Hi Guys
slightly off topic (apologies Toad) but I had a problem gaining pressure in the pipes today.
Is the pressure made in the pipes or right through the system to the tank normally.
The boat is a recent purchase, and other things have taken up my sattentions..... but, the water pump gained pressure about 15 minutes after filling the tank, and I noticed water oozing from the rubber sealed lid of the tank during the pumping.

Eventually pressure was restored.... but are they usually plumbed the same or are there differences and what should i check pl's?
S.
 
Last edited:
mitiempo said:
The pressure is from the pump to the taps and through the calorifier if one is fitted. The tank is never pressurized.
Click to expand...


vyv_cox said:
Sounds like there is problem with the suction valve(s) of the pump. If you don't have a suction strainer it's a good idea to fit one as the suction valve problem can often be caused by debris drawn into it.
Click to expand...

Thanks guys, yes there is a calorifier and no filter. Will do a check and fit filter.

I've taken to not emptying the tanks totally in the winter, but adding salt to deter freezing and to help keep bacteria down..... a bad idea???
It does allow me to run the solution through taps and pumps and so i've not been concerned even if very cold.
It does mean that I have to rinse out the tank each spring but it does seem to keep them both (drinking/domestic) clean
S.
 
Last edited:
Scotty_Tradewind said:
Thanks guys, yes there is a calorifier and no filter. Will do a check and fit filter.

I've taken to not emptying the tanks totally in the winter, but adding salt to deter freezing and to help keep bacteria down..... a bad idea???
It does allow me to run the solution through taps and pumps and so i've not been concerned even if very cold.
It does mean that I have to rinse out the tank each spring but it does seem to keep them both (drinking/domestic) clean
S.
Click to expand...

First reaction is to say yes it is a bad idea

But if there are no components that will be harmed by prolonged contact with salt water and provided you have researched what concentration of salt is necessary to give protection against freezing perhaps there will be no problems.

A better idea however might be to use a non toxic propylene glycol based antifreeze solution, which should be readily available for protecting water systems in RVs ( motor caravans on this side of the Atlantic)
 
Thanks for all your replies, the screw on the end does not appear to adjust the pressure so I have bought a 20psi unit from the local caravan shop and fitted it this afternoon. There is no noticeable difference between the 30psi unit and the 20psi one in operation. The last one lasted 12 years so I hope I have better luck than Blueboatman.

Toad
 
vyv_cox said:
Sounds like there is problem with the suction valve(s) of the pump. If you don't have a suction strainer it's a good idea to fit one as the suction valve problem can often be caused by debris drawn into it.
Click to expand...

Loads of strainers on e bay-get the version with the free turning wing nuts rather than one which rotates to screw on-easier to get apart-remove pump.
Other comment is that these pumps have a bad habit of refusing to fire up if left a while-brush shorts across commutator which needs a quick spin to free it.
Other thing they can be a pain to prime for some reason.
I was just looking in my Towsure catalogue which stocks the whole range.
Hot and cold water-what next double glazing.
Mind you after a long hard day sailing nothing like jumping into the boiling hot shower courtesey of the calorifier.
 
Scotty_Tradewind said:
I have a spare pump and will change it to check it out.
Thanks for the tip ffiill on the strainers, any particular make/model you would recommend?
S.
Click to expand...
Just e bay shurflow pump filters-they all have a plastic bowl which removes conventional filter way.Some are female threaded one end such that the whole filter rotates as you screw it onto pump.Others have similar set up to tap union on domestic system/gas bottle regulator.
Other end usually a barb for plastic pipe or again you can get it with a thread.
Should not have to pay more than about £8 ish.
 
mitiempo said:
The pressure is from the pump to the taps and through the calorifier if one is fitted. The tank is never pressurized.
Click to expand...

Surprised by that statement. I thought most boats had an accumulator between pump and the pipework to taps. If you switch on a tap the accumulator depressurises as the taps flow until the pressure drops below a certain level and the pump goes on.

If the pump carries on for a little while after the tap goes off then the chances are that it is refilling and pressurising the accumulator. Otherwise the pump would be going on and off far too often when the taps weren't being used.
 
RupertW said:
Surprised by that statement. I thought most boats had an accumulator between pump and the pipework to taps. If you switch on a tap the accumulator depressurises as the taps flow until the pressure drops below a certain level and the pump goes on.

If the pump carries on for a little while after the tap goes off then the chances are that it is refilling and pressurising the accumulator. Otherwise the pump would be going on and off far too often when the taps weren't being used.
Click to expand...

That is true but an accumulator is not essential. My Sadler did not have one until i fitted it. The questioner said the tank was being pressurised, no mention of an accumulator.
 
vyv_cox said:
That is true but an accumulator is not essential. My Sadler did not have one until i fitted it. The questioner said the tank was being pressurised, no mention of an accumulator.
Click to expand...


Ah, I have found in the darkest deepest corners of my expansive bilges, an accumulator.... detached with pipes hanging and seemingly bypassed from the system.

The plot thickens!

Going down to the boat again 2moro, so if I detect more i'll report back
S.
 
You must log in or register to reply here.

Share this page

Top