noisy water system Carioca Ci 644

[jo scott]

Our Carioca Ci644 has a noise problem which concerns me.

 

When we open the taps, we get a thumping noise as the water draws through .

 

The noise actually worsens and continues for a good 5 seconds after the taps are closed. (hot or cold - thetfod cassette - - makes no difference)

 

I cant see that any of the pipes are comprimised, twisted, kinked or rubbing against anything so ideas dearly sought. I'm concerned that we are disturbing people nearby - though it is not as loud outside as in.

 

I presume it must be an air lock of some form ..but we drain the system after each trip, after a poisoned myself with brackish water last year.

 

JO

[Derek Uzzell]

Presumably your Carioca has a pressure-sensitive water-pump?

 

When you open a tap or flush the toilet, the pressure in the water pipework immediately drops. A pressure-sensitive pump reacts to this pressure-drop by beginning to operate to raise the pressure back to its original value. When a tap is closed, it is normal for the pump to continue operating for a few seconds until the original pressure within the water system is regained.

 

Pressure-sensitive pumps do produce noise, and some pumps produce a lot of noise. Check how your pump is mounted. It's possible that it's attached to something (like the fresh-water tank) that will amplify the noise it makes, or is screwed down too tightly. Try detaching the pump temporarily from its mounted position and running the system with the pump 'free' to see if that helps. If it's the pump itself that's making the racket, then the only real cure is to replace it. If the noise is due to 'hammering' within the water system, then fitting a surge-damping expansion-vessel may improve matters.

 

I shouldn't worry about disturbing people nearby - although the noise does travel it's most unlikely to cause offence and one would need to be an incredibly light sleeper to be woken by it.

[tonyishuk]

Derek has covered it in one.

 

I would only add that it pays to switch the pump off when travelling ( hoses under pressure and could leak / pump water out before you realise it)

 

Maybe at night, if the pump repressures the system. (Usually a slight leak on the non return valve)

 

Rgds

[Derek Uzzell]

tonyishuk - 2009-09-04 10:59 AM

 

(Usually a slight leak on the non return valve)

 

 

There's normally no non-return valve as such in a motorhome water system that includes a pressure-sensitive water-pump, as the pump itself prevents water flowing back to the fresh-water tank.

 

If the pump 'stutters' occasionally, this may indicate a minor leak in the water system. In my previous motorhome's case, a weld had failed on its Truma Combi heater's water jacket. The fault was tiny and only leaked when the water was hot, with evaporation getting rid of the water that came out. The water pump used to run for two or three cycles with long intervals between occurrences. Eventually the weld-failure worsened until a damp patch developed beneath the heater and a new water jacket had to be fitted.

 

Most pressure-sensitive pumps have an adjuster to alter sensitivity. If no water leak can be found and a pump continues to 'false switch', it may be possible to prevent this by using the adjuster.

 

Perhaps worth adding that, if a motorhome is fitted with a Truma Combi heater with a 'non-manual' safety/drain valve and pressure-sensitive pump, if the drain valve opens spontaneously and the pump happens to be switched on at the time, the fresh-water tank will be pumped dry. There are rare exceptions to this rule (eg. some Hobby models) where the pressure-sensitive pump is controlled by tap micro-switches.