George Collings Posted December 30, 2011 Share Posted December 30, 2011 Having stripped and more importantly restored the odd shurflo pump to working order. Here are my thoughts. The pump is basically a three chamber wobbling plate operated diaphragm device with a one way valve in each chamber. As long as the flexible valves are in good order with no debris trapped to prevent a good seating if the motor runs the pump works. I have never tried blowing air through one in either direction but would expect flow to occur from inlet to outlet but not in the opposite direction. Poor performance is usually attributable to age hardening of the flexible valves particularly in very cold weather. I have reservations about the reliabilityof flushing water from the system with compressed air. I base this on my observation of how water sticks to the inside of the tranparent hose I use to fill my fresh water tank. Obviously after use, to inhibit biological growth it is desirable to as much water water as possibe out of the hose. Even after swinging a couple of meters of pipe around my head as fast as possible to sling the water out there is still a lot stuck to the hose as globules. I fear that despite bowing out with compressed air the same thing happens inside a water system and that eventually the globules will drain and collect in pockets where frost can still cause damage. For the last dozen or so years I have relied on a simple drain down with all taps left open followed by a longish drive to shake the drops down and then the taps left open for a week or two to assist drying out. Just once I forgot to drain down the flexible shower hose but the only damage was the frost pushed the O ring sealed connector apart at the mixer. The resultant leak showed the moment I turned the pump on after refilling and squeezing the parts together was effective. Happy New Year Link to comment Share on other sites More sharing options...
Derek Uzzell Posted December 31, 2011 Author Share Posted December 31, 2011 George Collings - 2011-12-30 10:51 PM Having stripped and more importantly restored the odd shurflo pump to working order. Here are my thoughts. The pump is basically a three chamber wobbling plate operated diaphragm device with a one way valve in each chamber. As long as the flexible valves are in good order with no debris trapped to prevent a good seating if the motor runs the pump works. I have never tried blowing air through one in either direction but would expect flow to occur from inlet to outlet but not in the opposite direction. Poor performance is usually attributable to age hardening of the flexible valves particularly in very cold weather. I have reservations about the reliabilityof flushing water from the system with compressed air. I base this on my observation of how water sticks to the inside of the tranparent hose I use to fill my fresh water tank. Obviously after use, to inhibit biological growth it is desirable to as much water water as possibe out of the hose. Even after swinging a couple of meters of pipe around my head as fast as possible to sling the water out there is still a lot stuck to the hose as globules. I fear that despite bowing out with compressed air the same thing happens inside a water system and that eventually the globules will drain and collect in pockets where frost can still cause damage. For the last dozen or so years I have relied on a simple drain down with all taps left open followed by a longish drive to shake the drops down and then the taps left open for a week or two to assist drying out. Just once I forgot to drain down the flexible shower hose but the only damage was the frost pushed the O ring sealed connector apart at the mixer. The resultant leak showed the moment I turned the pump on after refilling and squeezing the parts together was effective. Happy New Year In the past I've drained down my motorhome's water system in the time-honoured manner and also blown back through the taps and shower-head. The latter procedure is tricky with my Hobby as the tap/shower-head design doesn't lend itself to using a connector/hose as Brambles describes. Having false teeth also complicates the tap-blowing job and I've never attempted to purge 'by mouth' the water-hose that leads from the Hobby's water-pump to the toilet bowl. Until last year I had never had frost-related water-system problems but, when I revived the Hobby from hibernation in March 2011, when I switched on the water-pump to refill the system one of the X-FIX manifolds began to leak badly. Fortunately this manifold was close to the pump (so the leak was immediately evident) and fairly accessible. X-FIX manifolds are modular, with one module snapping into another and with module-to-module sealing via an O-ring. However, when I pushed the displaced module back into position it detached itself as soon as the pump was restarted. As will be apparent from the webpage I referred to above, X-FIX fittings have fixing lugs top and bottom and, in the case of this particular manifold Hobby had only bothered to put a screw in the upper fixing lug. If there had been a screw in the lower fixing lug (which there is now!) the modules could not have come apart: on the other hand, if the modules had not come apart the frozen water inside might have physically damaged the X-FIX fitting. I've got similar reservations regarding how completely a motorhome's water system can be purged using compressed air. Nevertheless, after having drained down the Hobby as usual in November this year, following this up some time later using my 'gizmo' to blow air through the water hoses, a good deal of water did emerge from the water outlets during the purging exercise. I'm not greatly concerned about water globules collecting in pockets in low level flexible hose runs as I believe the hoses should be able to cope with that water expanding should it freeze. But I really don't want water globules collecting and draining back into the X-FIX fittings as I'm not confident those fittings can handle frozen-water expansion. As I said in an earlier posting, the gizmo thingie cost nothing and its once-a-year use involves no alteration/surgery to the Hobby's water system. Using the Floë procedure of repeatedly pressurising the 'closed' water system to 15psi and then opening a water outlet (tap, toilet-bowl valve or the connection at the water-pump's outlet) definitely does expel more water from the system than a simple drain-down. I'm sure it won't have got all the water out, but, if it's got enough out to avoid frost damage, then that's good enough for me. The alternative would be to pump 'potable' antifreeze into the system, but I'm reluctant to do that as long as I can be reasonably confident that compressed-air purging will provide sufficient protection against frost damage. Link to comment Share on other sites More sharing options...
Rayjsj Posted January 2, 2012 Share Posted January 2, 2012 graham - 2011-12-28 5:08 PM We had the same cycling every 5 minutes occurence a couple of years ago. It started very suddenly and we could find no leaks anywhere. Then I realised it had started when I put something under the seat where the little yellow dump valve was sited. I checked and all looked ok but a packet of loo roll was just resting on the lever. Moved it off and all was fine. You can open the valve by pushing it down and it must have just cracked it open. When we got home I made up a little cover to stop it happening again. Graham, What yellow 'dump valve' under the seat ? I have looked but can't locate it, It is an 'Eberspacher' Combitronic you have is it ? (as i have in my Starburst/Starlet II). I have arrived back home now, and intend to try and solve the problem rather than just switching off the pump. Ray ;-) ps. my Pump is a 'Posiflo' 3000-151-2201. 12v 7litre. evidently British Made, and spares still available, wonders will never cease (i hope !). Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 3, 2012 Author Share Posted January 3, 2012 Rayjsj - 2012-01-02 7:21 PM graham - 2011-12-28 5:08 PM We had the same cycling every 5 minutes occurence a couple of years ago. It started very suddenly and we could find no leaks anywhere. Then I realised it had started when I put something under the seat where the little yellow dump valve was sited. I checked and all looked ok but a packet of loo roll was just resting on the lever. Moved it off and all was fine. You can open the valve by pushing it down and it must have just cracked it open. When we got home I made up a little cover to stop it happening again. Graham, What yellow 'dump valve' under the seat ? I have looked but can't locate it, It is an 'Eberspacher' Combitronic you have is it ? (as i have in my Starburst/Starlet II). I have arrived back home now, and intend to try and solve the problem rather than just switching off the pump. Ray ;-) ps. my Pump is a 'Posiflo' 3000-151-2201. 12v 7litre. evidently British Made, and spares still available, wonders will never cease (i hope !). Although Graham now has an Autocruise motorhome, I believe he was referring to his previous vehicle - an Auto-Sleepers Nuevo - when warning about the underseat 'dump valve'. The yellow colour suggests this will have been the standard Truma manual drain-valve and I think Graham was issuing a general warning (ie. "Make sure you haven't put something on top of a drain-valve lever") rather than a warning specific to your make/model of motorhome. I think you've only got a couple of choices regarding what's causing the cycling every 5-10 minutes. 1. A leak 'downstream' of the water pump. This will inevitably cause water to emerge somewhere. I note that you've checked the water connections inside the vehicle, but have you checked for water emerging underneath the motorhome, just in case (as Graham highlighted) the leak is through a drain- or bleed-valve? 2. The water pump. It's now over 6 years old and its internals may be worn or slightly damaged (if, say, grit had got in). But, before considering repair/replacement, you might try adjusting the pump's pressure-switch as described in the files on the Posiflo website: http://www.posiflo.info/ I don't how expensive Posiflo service kits are, but a brand-new Posiflo pump very similar to yours retails in the £60-£80 range. Repairs to Posiflo pumps are claimed to be easy. (It's perhaps worth saying that a SHURflo equivalent pump should be a bit cheaper.) An earlier Posiflo-related thread: http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=21595&posts=13 Link to comment Share on other sites More sharing options...
Rayjsj Posted January 3, 2012 Share Posted January 3, 2012 Derek, Thanks for the Link, i have now Downloaded the PDF files from Posiflo,and have part no's etc., also after reading the other thread on the subject from 'Nuevoboy', I realise that I also have another possible cause of the 'Phantom Cycling Pump' In the System, we have a 'general ecology' Filter and tap assy., it's not leaking,as i said I have checked for leaks, but was wondering if the cycling is the 'Pumps' way of telling me that the Filter needs changing ? I have a new filter to fit ( at a Cost !!!) . And will do so before I start trying to adjust the Pressure screw on the pump, I will also check the water connection to the Underfloor 'Hydronic' unit, as All of the 'Jubilee type clips' in the van required tightening so far. So probably that does too. I'll let you know if and when the problem is fixed. Thanks again. Ray Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 3, 2012 Author Share Posted January 3, 2012 Rayjsj - 2012-01-03 2:54 PM ...In the System, we have a 'general ecology' Filter and tap assy., it's not leaking,as i said I have checked for leaks, but was wondering if the cycling is the 'Pumps' way of telling me that the Filter needs changing?... I suggest you try the pressure-switch adjustment first and, if that is ineffective, then you can swap the filiter if you so wish. I can't see the filter on your water purifier contributing to your water-pump's 'phantom cycling', so (as long is doesn't actually NEED changing) you might as well leave the present filter in place. Beware of over-tightening the jubilee-clips. If the joint isn't leaking, then all additional clip-tightening will do is compress the hose and put extra pressure on the (usually) plastic fitting on to which the hose is attached. Link to comment Share on other sites More sharing options...
Rayjsj Posted January 9, 2012 Share Posted January 9, 2012 Derek, I have found the cause of the 'Phantom Pump Chatter', The two connections to the Calorfier (insulated/heated water tank) are controlled by 'Pressure relief valves' , the lower one is piped into the cold water supply but still monitors boiler pressure, the outlet is under the van, THIS is dripping ! so the Pump is doing it's job correctly,re-pressurising the system to make up for the faulty valve slowly draining the water out of the Calorfier. It had me going at first as the cold Inlet is at the lowest point of the tank and the Hot outlet at the top (of course !!) and BOTH have relief valves in them. 'Belt and Braces' ?? I have ordered a relacement from E-Bay @ £5.99, from the markings on the item it is an exact match , 3 bar and upto 160 degrees working temp. anyway, a job for when it arrives. hopefully that will be the end of the 'Chatter'. Thanks for the input. ;-) Ray Link to comment Share on other sites More sharing options...
JamesFrance Posted January 9, 2012 Share Posted January 9, 2012 Ray do you have a link to this item on Ebay? because I have the same problem with a calorifier on a boat and it is dripping into the bilge so we have had to blank off the hot supply. I cannot find this item from usual boat suppliers and the calorifier is made in Italy. Link to comment Share on other sites More sharing options...
Rayjsj Posted January 9, 2012 Share Posted January 9, 2012 James, Of course ; http://www.ebay.co.uk/itm/120799930656?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 don't know if it is OK for your boiler, but it looks OK for mine. and cheaper than an Eberspacher Dealer or a Yacht Chandlers. Ray Link to comment Share on other sites More sharing options...
JamesFrance Posted January 10, 2012 Share Posted January 10, 2012 Thanks Ray, it is different unfortunately and I don.t see the one on the other pages there either. Link to comment Share on other sites More sharing options...
Rayjsj Posted February 9, 2012 Share Posted February 9, 2012 2005 Autocruise Starlet II (Starburst) I finally got around to fixing the water leak in my system (Pump chattering every 10 minutes or so). I replaced the faulty 'Bypass pressure valve' attached to the 'Calorfier' in the Eberspacher Combitronic system. In doing so i learned a bit more about the system, the 'header tank' under the seat alongside the Calorfier contains 'Anti-Freeze' which is pumped around the Calorfier tank 'water jacket' as well as around the eberspacher diesel heater, I tried working over the side of the seat framework, but after bruising my ribs, I worked out that the Tank (calorfier) would have to come completely out to be worked on properly , I was glad I did, the Fittings were very hard to remove, and would have been impossible 'in situ'. The old pressure valve had a rubber core, which had perished, jamming the valve slightly open, hence the leak. The new one has a much more robust 'hard plastic' core(EPDM), which hopefully will last a lot longer. We'll see. Ray The new Valve : http://www.ebay.co.uk/itm/120799930656?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 It was only £5.99 a couple of weeks ago. A 3 bar one is required. ;-) Link to comment Share on other sites More sharing options...
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