Water pump 'hammers' after use

Nemos Dad

Free Member
Posts
42
Likes
13
The water pump in our Rimor 'hammers' after the taps have been switched off. It bangs repeatedly for several seconds each time - seems worse on the hot water. Occasionally it goes on for so long that the main control unit decides to shut the pump off. I believe this may be something to due with system pressure or even air in the system? Can anyone help with a solution please? It is a Fiamma 10 litre/min pump, which is fairly new and works OK in terms of water flow, but just has this annoying hammering. Cheers.
 
Bleed it

Well follow some instructions from somewhere, and bleed the system through all hot and cold outlets starting with the shortest first.........steve Bristol
 
Bleed the system is the first thing, Does it happen with all the taps? If it doesn't try each one individually, possible it could be a faulty microswitch, I had this on a caravan

Channa
 
Hi ya,
If water flow is ok,
Are you sure it not just the Expansion Vessel maybe vibrating on something, or something Loose up against it !.
 
Thanks for the replies. It is the same on all taps, but I thought it is a sealed system which cannot be bled, but I'll do some research to see if there's a way....
 
Water pump 'hammers' after use.

Water hammer in a domestic system is often due to unsupported pipes the flowing water has mass and momentum and sets up a short oscillation of the pipework when its free flow is suddenly stopped, best I can suggest is check for similar pipe movement in your van, or a reason for a pressure wave oscillation in the water column within your pipework, compressible air in the system is as you suggest a possible likely cause. Alternatively do you have you a Fiamma Aqua 8 fitted in the system ? try altering its air pressure slightly.

Rgrds,

Rob H.
 
air pocket in the system somewhere, put the pump on by opening every tap in turn, both hot and cold settings you might find it spitting a load of air out on one of them. usually caused when draining down the system and then refilling. High spot on the pipework allows the air to go to that point.
 
It will no doubt be a pressurised system so look for the pressure switch on the outlet of the pump and if it is adjustable turn the pressure setting down a fraction (so the pump wont have to try have to try so hard to generate the pressure to operate the switch).
Dave
 
It sounds like you have a pressurised system with a pressure switch,not the micro switch system.

If you have a good water supply at the taps and the pump does not switch off when you turn the tap off then you will probably have to adjust the water pressure switch.
 
Still hammers, but only on hot....

Spent some time in the van today attempting to get rid of the hammering. The pump itself seems OK - good flow of water, especially if cold only, then switches itself off fairly quickly. The problem is with the hot water. No matter which tap I use, the hot water system is very noisy (although no 'spluttering' of water) then when I turn the tap off, the pump hammers for around 5-10 seconds. Sometimes this goes on for so long that the pump cuts out and I have to re-set it at the main control unit (off then on again). The pump is a Fiamma Aqua8 , which I don't think has any adjustment. I was wondering if it is worth fitting the Fiamma A20 Expansion tank - if so, should this be fitted in the main feed from the water tank, or in one of the hot water pipes, as this seems to be where the problem is.

Does anyone have any experience of these expansion tanks? They look fairly easy to fit, and only around £25.
 
dr dave said:
It will no doubt be a pressurised system so look for the pressure switch on the outlet of the pump and if it is adjustable turn the pressure setting down a fraction (so the pump wont have to try have to try so hard to generate the pressure to operate the switch).
Dave
Click to expand...

wakk44 said:
It sounds like you have a pressurised system with a pressure switch,not the micro switch system.
If you have a good water supply at the taps and the pump does not switch off when you turn the tap off then you will probably have to adjust the water pressure switch.
Click to expand...

I tend to agree with these posts the hot water taking longer to stop the pump as there's more water to compress I've a separate pressure switch which does this and just needs occasional adjustment
 
witzend said:
I tend to agree with these posts the hot water taking longer to stop the pump as there's more water to compress I've a separate pressure switch which does this and just needs occasional adjustment
Click to expand...

Thanks Witzend. That certainly makes sense, as there will be much more water in the hot 'side' of the system - only what is in the pipes on the cold 'side'. Trouble is, I have no idea if there is a pressure switch? Does not seem to be one on the Aqua 8 pump, and no mention is made in the instructions. Also cannot see anything else obvious within the system. Anybody know?
 
Cheers Rog - looks like it might be the small grub screw on the front face of the switch that alters the pressure (although the instructions say not to touch this!) I will give it a very careful tweak and see what occurs.....
 
Any positive displacement pump needs an expansion vessel of some kind, otherwise the few cycles of the pump creatingthe pressure to switch it off may well cause water hammer. A small lone should do the trick but a larger one is often used to reduce the pump cycling, on my last boat I had a 2litre one which greatly reduced the number of times the pump operated though sometimes it ran for longer topping up the depleted expansion vessel.
 
Nemos Dad said:
Cheers Rog - looks like it might be the small grub screw on the front face of the switch that alters the pressure (although the instructions say not to touch this!) I will give it a very careful tweak and see what occurs.....
Click to expand...


..... or you could try replacing the pressure switch with this kit.
01203B02

shown on the Fiamma website as costing 14 euros. (cheaper than a new pump) and not that difficult to fit.
 
The hammer effect is a result of a pressure wave resonance, so adjusting the pressure may make the noise less, though it will not remove the base problem of trying to compress the in-compressible till the magic cut out pressure is reached. Fitting an expansion vessel allows the cut off pressure to be reached with an air buffer to handle the pressure impulses from the pump. In reality an expansion vessel of some kind should always be present in a positive displacement pump system
 
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top