Fresh water pump ‘pulsing’

[OllieGBR]

Afternoon all
I’ve replace my water pump and had a small leak so after stripping out all the electrics [again] as my pipes were not quite pushed home meaning a panicked switch off, strip out and mop up!
Now I’m testing the pressure before I connect every thing back up.
The water pump is pulsing. The old one never did this.
I don’t believe I have any leaks, I have paper towels on the joints.
Is there a sensitivity setting - perhaps this grub screw in the picture? However in the manual there’s a big ‘no no’ on making any adjustment there.

 

[DXX]

I would normally think a pulsing pump would be due to a lack of an accumulator but it looks like you have a large water heater / calorifier in the system.
You say no external leak but could you have a leak back to the tank?
Here’s a youtube video from the Fiamma site showing how to change the valve seat seal. Maybe there is damage or debris across this rubber valve?

 

[DXX]

Looks like a pressure regulating valve on your water heater (red hose connected), are you sure the heater regulating valve is not set lower than the pump discharge pressure?
I’m not sure if you have a accumulator (with a diaphragm) in the system, if not it will only require a very small amount of water passing to drop the water pressure and trigger the pump operation.
EDIT: according to the Fiamma site you should have an accumulator installed with this pump. If you don‘t it’s almost certainly why it is pulsing.

 

[OllieGBR]

I have the accumulator installed. It has a valve on the top, perhaps it requires some 'back' pressure?

 

[DXX]

I have the accumulator installed. It has a valve on the top, perhaps it requires some 'back' pressure?

Normally an accumulator would come pre-charged with nitrogen or air, is it new?

 

[OllieGBR]

Normally an accumulator would come pre-charged with nitrogen or air, is it new?

No, it was already fitted. I have replaced the pump as the last one blew the fuse and never restarted.
I'm trying to find instructions on the accumulator.

Thanks for your help!
Ollie.

 

[DXX]

No, it was already fitted. I have replaced the pump as the last one blew the fuse and never restarted.
I'm trying to find instructions on the accumulator.

Thanks for your help!
Ollie.

Normally the gas / air connection will accept a bicycle pump, air will be fine on this accumulator, especially if it has a plastic body.
If you want to know if the accumulator diaphragm has failed just depress the gas / air valve, if water comes out it’s failed. If gas / air comes out it’s good but you’ll need to re-charge it with a pump and gauge to the manufacturers specification. Note that it’s a small accumulator you’ll need to be quick disconnecting the bicycle pump or you’ll loose pressure.

 

[OllieGBR]

Normally the gas / air connection will accept a bicycle pump, air will be fine on this accumulator, especially if it has a plastic body.
If you want to know if the accumulator diaphragm has failed just depress the gas / air valve, if water comes out it’s failed. If gas / air comes out it’s good but you’ll need to re-charge it with a pump and gauge to the manufacturers specification. Note that it’s a small accumulator you’ll need to be quick disconnecting the bicycle pump or you’ll loose pressure.

Thanks, just found the pressure setting;

• Pre-charged pressure is 19 psi

 

[OllieGBR]

The pressure was 45psi
I reduced this to 19 psi - thought that was it.

Nope - back to the drawing board.

 

[DXX]

The pressure was 45psi
I reduced this to 19 psi - thought that was it.

Nope - back to the drawing board.

You should check the accumulator pressure with zero water pressure.

 

[OllieGBR]

You should check the accumulator pressure with zero water pressure.

I'll give that a go tomorrow - good idea.

 

[DXX]

I'll give that a go tomorrow - good idea.

Any progress?

 

[OllieGBR]

The van is with the dealers having the door re-sprayed, so I didn't manage to test the no pressure scenario.

I spoke with a plumbing friend who said the best way to allow for sensitive switches is the use of a non-return check valve. After some research I found a few on caravan suppliers websites and ordered one. It will be here for the weekend.