Air lock in water system

[Curly]

Drained the system for fresh water, refilled and cannot remove the air lock.

When taps on individually or all on the pump takes about 10 seconds to kick in and then when turned off takes 15-20 seconds to stop and it runs on with a gurgling sound as if air is still in system/pump. Turning taps on and off repeatedly and refilling tanks to no avail. Also the dump pipe under the van for the winter overflow makes a non stop hissing sound when the water/taps are on, any ideas most welcome and a Christmas card promise for the correct result.

 

>:-( >:-(

[tonyishuk]

My observations FWTWorth. Noone has replied so:

 

Curly - 2008-08-28 7:59 AM

 

Drained the system for fresh water, refilled and cannot remove the air lock.

When taps on individually or all on the pump takes about 10 seconds to kick in

[/Quote]

Would seem normal to me, as pressure is falling in the pipe work and water coming from taps until pressure switch kicks in.

 

and then when turned off takes 15-20 seconds to stop and it runs on with a gurgling sound as if air is still in system/pump.

[/Quote]

Partly normal, pressure building in system, reverse of above.

 

Turning taps on and off repeatedly and refilling tanks to no avail. Also the dump pipe under the van for the winter overflow makes a non stop hissing sound when the water/taps are on, any ideas most welcome and a Christmas card promise for the correct result.

(

 

Q. Is water coming from the taps ?

Q. Is water and air coming from the taps.

Q. Is your Loo tank connected to the main tank or does it have a header tank ?

 

I have a water system which sometimes is a problem and I do the following and it seems to work for me.

 

Tank three quarter full.

Turn off all taps.

Turn on bathroom cold tap, wait until water comes through with minimum air.

Test the Loo Flush, (I have no header tank) until no air in flush water.

Then run Kitchen cold water tap until minimum air.

Try Loo again.

Turn Off All taps and return to bathroom.

Open Hot tap and run, this takes some time because the hot water cylinder has to fill, expelling air and fill with water and is definately a water air mix for some time.

When the flow is stabilised with minimum air. close.

Repeat with kitchen hot water tap.

May have to repeat the above, tap by tap for a while.

Finaly I check the external shower tap both in full hot and cold positions.

 

Works for me ;-)

Rgds

[Derek Uzzell]

I think I'll hold fire until Tony's first two questions are answered, but my initial thought is that there's a fault with the water-pump as, once the water-system has been filled and the air expelled, the pump's reaction to a tap being opened fully should be almost immediate. Similarly, once all the taps have been shut (after water has been drawn off) the pump should shut off very rapidly. 10 seconds and 15-20 seconds respectively sounds much too long to be right.

 

Presumably the motorhome is still a Rapido 9-Series?

[Curly]

Hello thanks for replies, Yes loo connected to main tank, water and air from taps for a short while then when only 1 tap open the pressure is low, not the usaul flow volume and when another tap opened then both are redused to a trickle, if shower is opened virtually nothing.

Checked diaphram cannot see and damage to it but the pump continues to make noise and seems to struggle to keep up with demand when reconnected.

Have sourced new pump from various suppliers and the cheapest and most helpful was from Chandlery World. They cannot figure out what is wrong but do not think it is the pump, will try and source a diaphram for me before I may need a new pump.

 

>:-( >:-(

[Brambles]

"Also the dump pipe under the van for the winter overflow makes a non stop hissing sound when the water/taps are on"

 

I think I would check out this dunp valve as source of problem. I think you may have dirt trapped in it and it is sucking air in.

Jon.

[Derek Uzzell]

Curly:

 

Assuming you've still got your Rapido 9-Series, then its water system includes a Truma C-Series 'Combi' heater and a pressure-sensitive diaphragm water-pump (probably made by SHURflo).

 

Most motorhome water systems comprise a fairly large-capacity hot-water boiler (12 litres for a Truma C-Series), plus several metres of narrow-bore hose connecting water-tank, water-pump, boiler and water-outlets (eg. taps, shower(s), toilet) together. After this type of water-system has been drained down, bringing it back into service SHOULD be straightforward. This is the technique I use:

 

1. Make sure all water drain-valves and water-outlets are properly closed.

2. Fill fresh-water tank.

3. Turn one HOT water-outlet to its fully-open position. (I normally start with the shower hot-water control as, in my Hobby's case it's furthest away from the water-pump, and I place the shower-head in a small bucket to avoid splashing.)

4. Switch on water-pump at motorhome's 12V control panel.

5. Leave water-pump running until water runs smoothly from open water-outlet. This process will take several minutes and, once complete, will indicate that the water-boiler has completely filled with water.

6. Turn off outlet and wait until water-pump has re-pressurised the system and has shut itself down.

7. Treat remaining water-outlets similarly. Turn each outlet fully on, wait until water runs from it smoothly, turn outlet off - move on to next outlet. When water runs smoothly from all outlets, all air will have been expelled from the system.

8. Switch off water-pump at motorhome's 12V control panel.

 

Your problem appears to be primarily a 'low pressure' one, where the water-pump can't deliver an adequate supply of water to the outlets. This implies an obstruction, or massive air- or water-leak, somewhere in the system, or a fault with the pump itself.

 

If there's an obstruction 'upstream' of the water-pump (ie. between the pump and the water pick-up point in the fresh-water tank - say a kinked water-hose, or a blocked filter at the pick-up point or at the water-pump's inlet), then I'd expect the pump to keep running indefinitely from the moment it is switched on with a water-outlet open. If there's an air-leak, then the air/water mixture will spurt out violently when a water-outlet is opened. In the unlikely event that the pump has become completely disconnected from its water supply (eg. the water pick-up hose in the fresh-water tank has fallen off), then it should be very obvious that the pump is just sucking in air.

 

If there's a blockage 'downstream' of the water-pump (ie. between the pump and the water-outlets - say a kink in the water-hose close to the water-pump), this might explain the delay in the pump starting up, but I wouldn't then expect the pump to run on for 15-20 seconds after the taps have been turned off. If there's a major leak downstream of the water-pump - through an open/faulty drain- or vent-valve or due to a split hose or connection - this should be very apparent visually. A minor leak will cause a pressure-sensitive pump to run intermittently for a few seconds when water-outlets are all turned off, but that's not what's happening here.

 

I'm uncomfortable with the statement that the hissing noise you mention is coming from the heater's safety/drain valve. It's more likely the noise is from the under-floor outlet of the vent-valve that's fitted towards the top of the Truma heater's side-wall. If the safety/drain valve were not sealing properly and water were being pumped through the hose connected to the valve, it's hard to understand why water isn't spurting (or a least dripping very noticeably) from the drain-valve's under-floor outlet.

 

For the safety/drain valve to protect the water-boiler from frost it needs to be installed between the boiler and water-pump. In this position the valve will be on the high-pressure side of the pump and, if it's not properly closed, will certainly allow water out - but it's difficult to see how it can possibly let in air when the pump is operating normally. (See "Water Worries" letter on page 212 of MMM September 212).

 

(Perhaps Rapido has fitted a supplementary drain-valve on the 'suction side' of the system between water-tank and water-pump. If this were the case, one might anticipate such a valve would hiss if it were not sealing properly and the water-pump was running, and you'd also get air entering the water system. However, a valve in that position a) wouldn't protect the heater from frost and b) would almost certainly be manually operated.)

 

Without the opportunity to examine your motorhome and see what's actually happening, it's going to be pot-luck whether any remote diagnosis will really help. If there's sufficient 12V power to drive the water pump, water can reach the pump unobstructed, with no air-leaks, and there's no obstruction or leakage between water-pump and water-outlets, then the system should function correctly.

 

The fault apparently has occurred suddenly and the water-pump seems to be behaving peculiarly. The symptoms present certain contradictions, but I still think the pump is the prime suspect. You've clearly been able to remove it from the motorhome, so bench-testing should be relatively straightforward.

 

If your water-pump is indeed made by SHURflo, then there seem to be two main service kits for respectively the pump-head or motor, plus three 'sub-kits' for discrete elements of the pump-head. If the pump is getting on in years, it may be financially wiser to replace the complete pump rather than just bits of it - at least then you'd get a 2-year warranty. I've looked through SHURflo's troubleshooting list, but there's nothing that immediately springs out as the definitive answer to your problem.

 

Hopefully replacing the pump's diaphragm will fix the fault. Otherwise you are going to have to start from Square One and check methodically through the system or get someone with the necessary experience to have a look at it. It's quite likely something (or even some things!) simple that's causing the problem, but, should the pump turn out not to be the culprit, it may be a beggar to correct if Rapido has made significant elements of the water system (heater, hoses, etc.) seriously inaccessible.

[Curly]

Hello Derek thanks for the detailed analysis/report, I may have identified the problem but first how do you know I have a Rapido 9 series? are you

the person I met in Slovenia on my way to Croatia/Montenegro and you were making your way to Poland? and if so I apologise that I did not recognise who you are.

Now what I did was to bench test the pump and all is OK, I then replaced the pump but connected a pipe from inlet directly into the main tank and there was a marked improvement not as it was but a lot better and the overrun of the pump was reduced to 4-5 seconds AND the hissing noise had disappeared, this I had mistaken for the dump pipe but was in fact from the normal drain valve for emptying the tank and when I got under the van there is a little drip from the same pipe indicating that it is not shutting off completely. So I am hoping that this is where the air is being sucked in from, now to get at the drain tap is fairly easy but to remove it is something else.

 

[Derek Uzzell]

Curly:

 

I just looked through some of your earlier postings until I found the Rapido reference...

[Curly]

Eurekaaaaa.

Job done, stripped down the outlet tap for emptying tank and as the internal washer is unique to this tap I had no replacement in my goody box so I reversed the washer and hey presto we back in business and the pump is much quieter and shuts off in 3 seconds.

 

(lol) :-> (lol) :->

[Brambles]

Mu earlier post.

 

"Also the dump pipe under the van for the winter overflow makes a non stop hissing sound when the water/taps are on"

 

I think I would check out this dump valve as source of problem. I think you may have dirt trapped in it and it is sucking air in.

Jon.

 

 

...I shall expect a Xmas card!!

[Curly]

Hi Brambles not quite right it was not the "dump" pipe which is for emptying the water heater against frost damage it was the drain valve tap for emptying the fresh water tank, the washer was slightly malformed hence the reason for inverting it and replaceing it BUT as you were close I will wish you a Merry Xmas during my Christmas meal. Thanks to all for your help and advice.

 

(lol) (lol)