Water pump 'surging'

[sprocker]

Hi All,

I have an ongoing niggle where the water pump is 'surging' on a couple of taps.

The mixer tap in the en-suite heads, and day heads shower, both have this 'surging'. I can hear the water pump speeding up and slowing down when those two units are used.

All other taps (galley, en-suite heads shower, day heads sink, swim platform shower) are all OK and seem to flow correctly.

Has anyone seen this before and/or does anyone have any ideas or thoughts on what could be causing it?

 

[5teve]

It's normally because the pump pumps more than can flow so pressure builds it cuts out then starts again as pressure drops etc etc. You could try adding an accumulator in line (I have one to fit.. job on the list to do) as they can deal with fluctuations in pressure better from what I read

 

[sprocker]

Ok that makes sense. I wonder if it could be the tail ends on the tap that is limiting the flow, it looks newly fitted.

I guess I could swap round the shower hoses too, to isolate that as a fault.

I'll also research the accumulator route.

 

[BruceK]

It might be worth checking if you have more than one pump if it is any one in particular. (I have separate pumps for cockpit and shower(hw)/ galley and head) the latter being found under the island berth! :ambivalence:

 

[jrudge]

If it is the boat in your Pic I would be very surprised if it does not already have one.

They work by having an inflated membrane that causes the pump to run on and pressurise the canister so that the flow is evened out and also very small ( very!) uses of water dont trigger the pump.

They are inflated by bike pump and occasionally do leak and need pumping up.

I would start by finding it ( usually very close to the pumps) and pumping it up.

 

[sprocker]

If it is the boat in your Pic I would be very surprised if it does not already have one.

They work by having an inflated membrane that causes the pump to run on and pressurise the canister so that the flow is evened out and also very small ( very!) uses of water dont trigger the pump.

They are inflated by bike pump and occasionally do leak and need pumping up.

I would start by finding it ( usually very close to the pumps) and pumping it up.

Thankyou for that, she is a new boat to me so I'm still finding my way around her, I will check around the pump area at the weekend and see if it does already have an accumulator.

 

[jrudge]

Thankyou for that, she is a new boat to me so I'm still finding my way around her, I will check around the pump area at the weekend and see if it does already have an accumulator.

They are usually red ( no idea why!) and probably 12 inches across and a similar height.

It is very likely to be very close to the pump.

What boat is it? Someone will be able to tell you exactly where it is once the boat is known.

The other possibility is that the filter before the pump maybe a little blocked causing it to decrease flow at high rates as the gunk gets on the filter. These are usually right next to the pump and simple to take to bits / clean.

 

[sprocker]

They are usually red ( no idea why!) and probably 12 inches across and a similar height.

It is very likely to be very close to the pump.

What boat is it? Someone will be able to tell you exactly where it is once the boat is known.

The other possibility is that the filter before the pump maybe a little blocked causing it to decrease flow at high rates as the gunk gets on the filter. These are usually right next to the pump and simple to take to bits / clean.

The boat is a Princess 40.

I guess a general clean of the filters whilst I am there would be a good idea anyway.

 

[Truro Ex Pat]

I was told that you can try a long length of pipe to reduce the pressure but the tank option is the best.

 

[JerryC]

On the P40 the accumulator is fitted just above the water pump, behind the port water tank, but it's not a very big one so it will not eliminate surging. Accumulators are known to fail. Regularly clean the tiny primary water filter fitted immediately before the water pump. My OEM filter broke very easily but Force 4 sold me a bigger and better one for a decent price. You probably have another large water filter cartridge fitted behind a wooden panel in the cupboard underneath the galley sinks. It filters the cold water to the galley to drinkable standard but slows the flow when it needs changing.

 

[sprocker]

Ok thankyou for all of your help so far gents. I will check and clean everything at the weekend. One thing I don't understand though is if it was a dirty filter near the pump, wouldn't that affect all outlets? I only have a problem with the en-suite taps and the day heads shower.

 

[JerryC]

If your selected outlet (eg both basin taps full on together, or shower on full blast) exceeds the pump's ability to supply enough flow, the pump will run continuously, ie not hunting. Anything less will cause the pump to hunt, as stated earlier. An accumulator at best will partially limit this but not eradicate it. As the water pump is so far back in the lazarette, I'm surprised the hunting noise is that audible in the fwd cabin heads. Sure you can hear it (just) but is it really a problem? Sorry no idea why some taps seem more noisy than others.

 

[sprocker]

Sure you can hear it (just) but is it really a problem?

It's not really a problem in the en-suite taps, it's more of a potential problem for the guest shower when that needs to be used, I wouldn't want one of the grandkids to get scalded etc.

I guess it's more down to me being an engineer and liking things to be 'right'.

 

[JerryC]

Re potential scalding in the day heads shower, I don't think thats a real threat but you could try it yourself under extreme conditions! I think the water pump pumps equal pressure to the hot and cold circuits. The hot water flow from the starboard engine to the calorifier when underway is limited by an inline thermostatic valve like on your CH radiators at home, so that can be turned down. Does your immersion heater have a control? Mine doesn't and I should replace it (I switch it off when the galley hot water gets too hot!) so as far as scalding is concerned that's your weak point, not the surging pump. All IMHO.