Keith Brown Posted January 10, 2016 Share Posted January 10, 2016 Hello, I would appreciate some guidance please. I have just replaced a Shurflo water pump in my 2002 Swift Gazelle as the original had packed up. Fitted it all OK and pump started when isolating switch put on. However, pump did not stop when the Truma water heater was full and just kept pumping water, which meant water was being forced out of the overflow pipe on the water heater. Only solution is to switch pump off via isolating switch. No taps switched on, no leaks detectable. Checked all wiring was as per old pump and all correct. I am now out of ideas, so please help Link to comment Share on other sites More sharing options...
Ninian Posted January 10, 2016 Share Posted January 10, 2016 Hi. It's possible that if you haven't pressurised the whole system that the switch within the pump will not activate. Link to comment Share on other sites More sharing options...
Robbo Posted January 10, 2016 Share Posted January 10, 2016 If it's pumping continuously, have you checked that the dump valve is closed? Link to comment Share on other sites More sharing options...
Tracker Posted January 10, 2016 Share Posted January 10, 2016 Is there a pressure regulating adjustment on the pump that maybe needs to be reduced as from what you say it sounds as if the pump is maybe sending water into the system at too high a pressure? What does the water pressure feel like when you open the tap? Is it similar to what it used to be or is it much higher? Link to comment Share on other sites More sharing options...
Brambles Posted January 10, 2016 Share Posted January 10, 2016 Robbo - 2016-01-10 2:31 PM If it's pumping continuously, have you checked that the dump valve is closed? I shall vote for this suggestion. Link to comment Share on other sites More sharing options...
Algernon Posted January 10, 2016 Share Posted January 10, 2016 The problem is not the pump What has happens is the non return valve on the truma boiler over flow has popped out. This can happen when there is a sudden pressure drop. The NRV is in the elbow probably red in colour. You can get them online. Leisurespares etc They cost about a fiver, get two and keep one as a spare! Algernon Link to comment Share on other sites More sharing options...
Algernon Posted January 10, 2016 Share Posted January 10, 2016 Here you go This is what you need. Bit dearer than thought, but it won't break the bank. https://www.leisureshopdirect.com/electric/caravan-gas-water-heater/boilers-and-heaters/truma-boat-boiler-bm10-and-bm14-and-spare-parts/elbow-fitting-for-hot-water-outlet-truma-boilers I am assuming you have a Truma C boiler of course? Algernon Link to comment Share on other sites More sharing options...
Keith Brown Posted January 11, 2016 Author Share Posted January 11, 2016 Algernon et al, Thanks for all the suggestions. You are correct about a Truma boiler as well. I will get the part you suggest and fit it at the weekend. I did wonder about that myself, but there doesn't seem to be anything to the valve, but hey ho! Roll on the weekend when I can get it fitted. I will update post with, hopefully, a success story! :-D Thanks again everyone. Keith Brown Link to comment Share on other sites More sharing options...
Tracker Posted January 11, 2016 Share Posted January 11, 2016 If I replace a part and a problem arises that did not previously exist the first things I check are the things that I have done. On that basis, if the boiler overflow/outlet/dump valve was not overflowing with the old pump why does it do so with the new pump? Link to comment Share on other sites More sharing options...
tonyishuk Posted January 11, 2016 Share Posted January 11, 2016 Ninian - 2016-01-10 2:09 PM Hi. It's possible that if you haven't pressurised the whole system that the switch within the pump will not activate. Could it be that some versions of the pump do not have pressure switches ? Rgds Link to comment Share on other sites More sharing options...
Algernon Posted January 12, 2016 Share Posted January 12, 2016 The elbow, which is situated outside at the top of the tank, contains an integrated vent valve which is totally different from the dump valve. The valve allows the air to escape from the top of the tank If you take the elbow off and you can blow through both ways out through the narrow end then the valve has popped out. It is very tiny. The cause can be a sudden pressure drop on the cold side of the system ie undoing a fitting when there is pressure in the line. It can also happen when filling. The best way to fill the system is to keep the taps open and make sure all the air is expelled and that the water is running through the hot and cold taps. In Keith’s case I don’t know why it has happened but if there is water coming from the elbow and running down the PVC vent tube then it definitely needs replacing. I am no expert but just sharing my experience. Algernon Link to comment Share on other sites More sharing options...
Brambles Posted January 12, 2016 Share Posted January 12, 2016 The valve is actually to let air in, not out, for when you drain the tank. Link to comment Share on other sites More sharing options...
Algernon Posted January 12, 2016 Share Posted January 12, 2016 There you are I said I wasn't an expert Thank you for correcting me, now it make sense? Algernon Link to comment Share on other sites More sharing options...
Rayjsj Posted January 12, 2016 Share Posted January 12, 2016 Let us know if you fix it OK Keith. Link to comment Share on other sites More sharing options...
Brambles Posted January 12, 2016 Share Posted January 12, 2016 Algernon - 2016-01-12 1:09 PM There you are I said I wasn't an expert Thank you for correcting me, now it make sense? Algernon ... but rest of what you said makes sense and only a mute point I made as still does not affect the fact it is likely to be faulty. Apparently the later designed elbows are supposed to be better and the valve guts cannot fall out. edit - Although I think a possibility is the valve sticks a bit and when the vacuum forms in the tank and the valve suddenly releases the air rush blasts the valve out of the fitting. Always open taps when draining system. Link to comment Share on other sites More sharing options...
Algernon Posted January 12, 2016 Share Posted January 12, 2016 Thanks I noticed that the design had changed by the moulding of the vent pipe was at a 90 degree angle from the original. It happend to us while out in the sticks, because stupidly, I undid one of the pipes while it was still under pressure. It took me a while to sort out why water was coming out the vent pipe when I reconnected everything. I wrongly thought it was just an elbow. To overcome the problem in the short term I folded over the vent pipe and cable tied the whole thing to the the elbow. I kept the pump isolated when not in use. Then got is sorted until we got back home by buying a new one. Algernon Link to comment Share on other sites More sharing options...
Robbo Posted January 12, 2016 Share Posted January 12, 2016 This old post may be of interest even though it was for a Truma Combi 4: http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Truma-combi-4/30043/ I must admit, I always thought the hot water oulet from the boiler unit incorporated a pressure relief valve. I now know it is an air vent valve (thanks Brambles). According to Truma, any excess pressure in the system is equalised at the dump valve. I heard somewhere that grit can sometimes get into the inner workings of the vent valve, preventing it from closing properly. Perhaps compressed air or pressure washing might dislodge any debris. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 13, 2016 Share Posted January 13, 2016 A ‘breather-valve’ has been fitted to the hot-water outlet of Truma combination air/water heaters since the original C-3400/C-6000 models began to be marketed in 1994, and the same valve has been fitted to Truma “Ultrastore” boilers. The original valve (comprising a T-piece with the breather-tube rising vertically) appears to have been changed to the present horizontal breather-tube design when the Truma “Combi” range was introduced in 2007. Breather-valve failures are far from rare (GOOGLE on “Truma breather valve") and reports usually seem to involve water pouring through the breather-tube and, when the valve is removed for inspection, nothing is found inside the valve to inhibit the water flow. Example of this can be found here: http://www.caravantalk.co.uk/community/topic/61119-truma-ultrastore-water-coming-out-of-the-breather-pipe/ http://forums.outandaboutlive.co.uk/forums/Motorhomes/Hints-and-Tips/Truma-Ultrastore-Water-Heater/18007/ When a breather-valve fails completely I’ve yet to read of anyone finding the valve’s internals when an inspection is made. There’s no doubt (as Brambles mentions) that when the heater’s water reservoir is drained without a hot-water tap being opened the weight of water in the reservoir will induce a ‘drag’ on the breather-valve to cause it to open and let air enter the reservoir. I’m a mite doubtful though that this drag would be sufficient to pull the valve’s internals into the water reservoir, or that the pressure of air passing through the valve would drive the internals out. But I’m comfortable with the theory, and it would explain why valve internals aren't found if they are ending up inside the water reservoir. Link to comment Share on other sites More sharing options...
Keith Brown Posted January 16, 2016 Author Share Posted January 16, 2016 Hello all. Just a quick post to say that I replaced the valve on the Truma boiler and Bob's your uncle, the problem is solved. Quite why the valve should fail at the same time as the pump is beyond me as it appears to be a double failure, unless the new pump generated just that little extra bit of pressure and mucked up the valves internal? However, one very happy motorhomer again :-D It was truly awful being away for the weekend and having to rely on water from jerry cans with hot water via the kettle only. Reminded me too much of camping years ago. Thanks again all, keep up the excellent work! Keith Brown Link to comment Share on other sites More sharing options...
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