Domestic Water Pump

[Lastdraft]

The water pressure on my 31 ft boat is not good. I have taps/shower fwd and taps in the galley aft.  My question is , would a better more powerful pump be the answer to increasing the pressure, and if so, what would be the best pump to install ?  Any help / advice as always , appreciated. 

[OldBerkshireBoy]

Do you know what you have at the moment and possible age of it, also is the water constant or surging?

[marshman]

Probably more important do you have a accumulator cylinder? My guess is not but just replacing the pump may help but to guarantee a constant and realistic pressure you probably need an accumulator tank!

I guess someone else will come along with possibly the same conclusion and will be able to tell you more about them

[Regulo]

An accumulator tank will not increase the pressure achieved at the taps. It will reduce (or stop) cycling on and off by retaining a reserve of pressure in the system. The running pressure of the pump is your limiting factor in end pressure at the fittings.

[Smoggy]

If you fit a higher pressure pump make sure you check the PRV on the calorifier is up to the new pressure, you will probably need to replace that too with a 4bar PRV or the extra pressure will just pee out the side into the bilge.

If you have accumulator or expansion tank they will also need the air pressure adjusting accordingly or they will not work very well.

I upgraded my pump to a 45 psi and fitted a 4 bar PRV and it made a good difference, don't be surprised to find a few leaks first time you pressure it up though as it will have been checked at the lower pressure.

[Daddy Mouse]

Are you certain it's a pressure issue? For the pump to build up pressure you need sufficient flow. If the pump will only deliver the volume of water that comes out of the tap at 1psi that's as much pressure as the system will develop with the taps open. So it could be you need a higher volume pump not a higher pressure pump.

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[grendel]

it could be that you have an air leak into the system, that is dropping the pressure at the tap end.

[Regulo]

. . . . or a blocked, or semi-blocked, fresh water tank vent/overflow? If water comes out, air has to get in!

[MauriceMynah]

If the pump is the problem, What would be the effect of putting a second pump, (electrically switched not pressure switched) by the point of delivery and a non return valve?

[dnks34]

If a label is visible on your existing pump post a picture of it as knowing the specs could help provide you with clearer solution advice. 

[Regulo]

5 minutes ago, MauriceMynah said:

If the pump is the problem, What would be the effect of putting a second pump, (electrically switched not pressure switched) by the point of delivery and a non return valve?

By point of delivery, do you mean just prior to the taps/shower outlets, MM? Not much to be gained, the original pump won't be able to deliver enough water to the second pump's intake. Better to sort out the original problem, rather than introduce more potential trouble by addressing the symptoms.

[MauriceMynah]

7 minutes ago, Regulo said:

Better to sort out the original problem, rather than introduce more potential trouble by addressing the symptoms.

Killjoy

[Regulo]

"Potential trouble" is your middle name, I believe? 

[Lastdraft]

The water is not surging, it is a constant flow but a weak flow, I have to run around under the shower to get wet, if you know what I mean.

I have a few things to think about now, as always great comments and advice, greatly appreciated.  Thank you all. 

[Daddy Mouse]

Is the boat new to you? Has the flow changed or has it always been slow?
If you can let us know what the existing pump is, make model etc, what diameter the pipes are and how far the taps are away from it I will have a look at the pump curves for you and see what it should be delivering, and see if you need a different pump.

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[Lastdraft]

DM. The water pressure has always been weak. Unfortunately I am not down on the boat until next month and I have no idea what type of pump it is. 

I will take you up on your kind offer of help and send you a photo with details asap. 

Thank you 

[petersjoy]

As no one has mentioned it, if it's an old pump could it be the impellor is worn? that would show those symptoms.

[Smoggy]

I would assume it's a diaphram pump in which case the valves can get worn and crud under them letting some back and lose pressure, it should have a strainer before the pump that can get full of crud and restrict flow and easily cleaned.

If it's an impellor pump it's way outdated for it's use and needs replacing for a modern diaphram pump.

[MauriceMynah]

10 hours ago, Regulo said:

"Potential trouble" is your middle name, I believe? 

Just as a pedantic point, Potential trouble are my two middle names. :-)