Firefly needs help with plumbing!

Firefly625

Firefly625

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A cry for help to this superbly knowledgeable forum

The problem; Fresh water pump ran and ran when I first put boat back in the water this year, eventually stopped after it managed to prime itself but probably took 4 minutes? (seemed a long time anyway!) . Then we have an issue that whenever you run any of the taps on-board (hot or cold) pressure tails slowly off and after around 20 seconds its just a dribble. We have 2 Vetus fresh water tanks fitted and linked together. Water fresh and clear from tanks, and tastes absolutely fine (so rare for boat water!). We have 3 outlets, galley water tap, shower tap in heads and shower tap on bathing platform. Water pump is flojet 40psi 17 l/p/m rating.

Solutions I have tried to date;

1. Filled tanks (as they were just half full) to see if increased pressure of full tanks helped, no change

2. Checked in-line filters, a little bit of plastic swarf in filter which I cleared, but no change at all so obviously was not hindering flow.

3. Took water filler cap off to see if lack of pressure was due to vacuum effect, no change.

4. Checked throughout boat to see if any water escaping from any pipes, but no leak found.

5. Took the plunge and purchased brand new fresh water pump, 40psi 17 l/p/m pump (direct replacement for what is fitted)..... no sodding change..

Things I have noticed.
1. Some occasional air bubbles appearing in clear water pipe which feeds pump.... where is air getting in that pipe when tanks full?

2. New pump, although correct rating now seems to be over pressurizing calorifier and 3bar pressure relief valve now peeing out water whenever tap is operated and filling bilges! (nice... :mad: )

The other slight issue is space... my Hardy is a little tight on room so I cannot actually get to have a good dig round all the pipes etc they are just hidden away and the calorifier is just impossible to reach... but any suggestions really appreciated!
 
If you are using clear unreinforced pipe on the inlet side of the pump this could be collapsing when the pump starts, restricting flow. Depending on the extent of the distortion the pump would struggle to get up to pressure.
 
Salty John said:
If you are using clear unreinforced pipe on the inlet side of the pump this could be collapsing when the pump starts, restricting flow. Depending on the extent of the distortion the pump would struggle to get up to pressure.
Click to expand...

Salty John, Thanks for that, I like the idea, it is indeed unreinforced pipe so that could be the issue! Pretty easy to swap as well so will try that this weekend (unless anyone else comes up with any other ideas). Even if they do it could well be a issue adding to the overall problem so worth changing.
 
If access to the pump is OK, try connecting a length of hose to the output of the pump. Direct this overboard and see if the pump alone is OK. This should show you if the problem is before or after the pump.
 
Nothing much to add to excellent advice above. Sounds like limited flow to pump, which is why it tails off after 20sec, atwhich time the accumulator is exhausted

Ref the pressure relief valve on the h/w tank, there should be a screwdirver adjustment to alter the pressure at which the pressure switch turns off the pump. If you turn this down a bit it should be ok. Switch might be integral to the pump, rahter than separate component
 
jfm said:
Nothing much to add to excellent advice above. Sounds like limited flow to pump, which is why it tails off after 20sec, atwhich time the accumulator is exhausted

Ref the pressure relief valve on the h/w tank, there should be a screwdirver adjustment to alter the pressure at which the pressure switch turns off the pump. If you turn this down a bit it should be ok. Switch might be integral to the pump, rahter than separate component
Click to expand...

Thanks JFM, does sound like limited flow to pump, didn't seem that way when I took the connector off from the pump and got a good dousing of water, but then its not the initial pressure that's issue!!
Therefore these suggestions that have been made do make a load of sense.

The pressure relief valve is mounted on the far side of the calorifier & it looks like this;

AFX_9_40314_L.JPG


But I can only just reach the red knob with a par of grips, & it does not matter which way I try and turn the knob it has the same result it just spurts water at high pressure out the valve....
 
Does the system have a charcoal filter fitted, just a thought as no one else has mentioned it, might just be blocked up and ready to change, as its a hardy it might have one, good builders fit them standard.

Sounds to me like there is loads of pressure, have a close look at the inlet filter, presume its a curcular one you can see through and see the filter gauze, now these crack in cold weather and draw air in, also has the o ring been lost or displaced, as jfm said its probably drawing air if after a short pumping session.
 
volvopaul said:
Does the system have a charcoal filter fitted, just a thought as no one else has mentioned it, might just be blocked up and ready to change, as its a hardy it might have one, good builders fit them standard.

Sounds to me like there is loads of pressure, have a close look at the inlet filter, presume its a curcular one you can see through and see the filter gauze, now these crack in cold weather and draw air in, also has the o ring been lost or displaced, as jfm said its probably drawing air if after a short pumping session.
Click to expand...

Hi Paul, thanks for that input, you more than most know how tight my engine room is... I do not believe I have a charcoal filter, well I can't see one anyway... But I do indeed have the circular in line filter which I did take the top off and clean the metal gauze out. The thought that this might have a split or O ring fault is a possibility so I will have a closer inspection. Didn't see any water around the area but you never know....

My first job is to disconnect outgoing supply from pump and switch on to see if pressure drops like it does at the tap, if so I will replace the feed hose from tanks to pump with reinforced pipe as suggested, will also make sure all jubilee clamps etc all tight and no air getting in system, then try again.. will report back!

Thanks everyone for your very useful suggestions!
 
Firefly625 said:
Thanks JFM, does sound like limited flow to pump, didn't seem that way when I took the connector off from the pump and got a good dousing of water, but then its not the initial pressure that's issue!!
Therefore these suggestions that have been made do make a load of sense.

The pressure relief valve is mounted on the far side of the calorifier & it looks like this;

AFX_9_40314_L.JPG


But I can only just reach the red knob with a par of grips, & it does not matter which way I try and turn the knob it has the same result it just spurts water at high pressure out the valve....
Click to expand...

Firefly I don't think i explained that well. I meant adjust the pressure switch in/beside the water pump, not the red knob on the pressure relief valve
 
jfm said:
Firefly I don't think i explained that well. I meant adjust the pressure switch in/beside the water pump, not the red knob on the pressure relief valve
Click to expand...

Oh I see what you are saying, no you were clear the first time, I just had the pressure valve in the forefront of my thoughts! Thanks jfm, I will have a look!
 
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