Hi I wonder if anyone can help. We have a truma crystal water pump with filter. More often than not we have a problem where water pours out of the inlet where the pump connects. I have tried new O rings and another pump and the problem is the same. It works sometimes and others not. I think it is air in the system but cant work out why with the taps open it does not clear. Can anyone give any ideas on how to help? Onsite with no water at the moment. Thanks
A leak at the water pump housing can be caused by several reasons. The first is a defective 'O' ring which you have already replaced but also make sure there is no debris in the hole where it seals too. Also, it could be one of the two securing clips that is not tensioning properly and sometimes have to be replaced. However, if the clips behind the housing have worn then a new housing will be required which comes complete with new clips anyway plus it incorporates a non return valve for the cold water supply. If you have a filter then remove it and see if that stops the leak because if the filter hasn't been changed recently then it could be partially blocked causing back pressure. Another reason for back pressure is if the hot water tank non return valve is defective which is the black plastic spigot directly behind the drain plug (bottom right looking at the hot water tank inside) but a good sign to note that this is not performing is if it takes a lot longer for the water pump to re-pressurise after turning off a hot tap in comparison to a cold water tap.
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Thanks for the reply. A neighbouring caravaner kindly lent me his pump to test. It worked so one new pump later problem solved. Weird that the O ring did not resolve it.
can I suggest that the O rings you fit MUST be the correct ones . I found that the diameter of the rubber on the ones bought from a caravan spares shop specifically for the pump differed from the ones bought from a DIY shop
In your first post you said that you had tried new 'O' rings and another pump and the problem is the same so I can't understand why the pump is now okay.
Is the flow rate the same as your existing pump?
If it has slower flow rate then this may explain the reason why because a higher rate pump may still get back pressure due to the fact that it can't deliver the water fast enough into the system.
I had the same problem a few weeks ago and had to use my 'Reich' spare pump which has a slower flow rate than my 'Whale' pump. I replaced both the water inlet and hot water tank non return valve and solved the problem.
Tango. Your i think your theory is correct. I had a high flow pump and an old slow flow pump. The slow flow was brittle and broke. Hence i replaced with the high flow. The new one is standard
What you need to do is try the two pumps independently and see if the higher rate pump leaks in comparison to the slower one. The reason why I think the pumps are now a higher flow rate is because the slower feed rate pumps produced a weak flow at the shower head and because extra pressure is required (to balance the heat with hot and cold water) they re-designed the pump respectively to meet the modern standards.
When you try each pump also try the shower and see what the water flow is like and I bet there is a difference. If the leak at the housing can be eliminated it will be better still.
I found that the pump with the slower one feed was acceptable but struggling to feed the hot so was difficult to balance the heat due to this reason. When I tried the higher rate pump I got back pressure but the shower was better. This told me that something was either worn or blocked and due to the fact that my caravan was manufactured in 1999 much of the water supply equipment is standard and exhausted. I knew this because the water inlet housing had 'Carver Compact' on the flip cover which the company doesn't exist anymore and replaced by replica parts by Truma so I knew that the cold water non return valve (directly behind the inlet where the cold water pipe connects to) was outdated and not working effectively. I replaced the inlet water housing which now has 'Truma' on it so should last another 15 years at least. Whilst changing that I also replaced the pressure switch (kept the old one as spare) and hot water non return valve which was most likely the offending part. However, since replacing with new parts the water system is like new again with no back pressure and a satisfactory water flow on both the hot and cold with the 'Whale' high rate flow pump.
Hi Tango, just wanted to say thanks for your advise. I have the van out this weekend so will try this. i already know that the high flow pump still leaks but the premium pump does not. i have the Truma housing so my prime suspect is the hot water non return so i will replace this first. (if i can find it)
The location of the hot water non-return valve (looking on the inside) is at the bottom right of the hot water tank (directly behind the drain plug).
The non-return valve costs less than a tenner but if you do decide to replace it you will need the right tools for the job. The hexagon on the non-return valve is 20mm. which you will need either a long socket (to go over the spigot part) or a combination spanner as a ring spanner is likely to slip off. Because the valve is quite close to the tank side, you are restricted for room so I initially tried a 20mm. box spanner with 'T' bar but that slipped off because the plastic non-return valve is really tight and I mean TIGHT. The best solution (if it won't come undone) is to snap the spigot off with a chisel which then leaves the old thread behind in side the hole which will have to be removed by the use of a junior hacksaw blade and cut under the top (12-o-clock) down to the thread and along the bottom (6-o-clock) so basically the stud is split into two. Undo the external drain plug and use a long FLAT screwdriver (not cross-head) about 6 inches long and probe it into the the hole against the old stud. A slight tap with the hammer should dislodge the two halves of old stud to the inside of the caravan. The problem then is that there is old hardened sealant left inside the thread so with the hole being steel and the valve being plastic it will just chew up the new thread so it's best to clean the threaded hole out with a 16mm. x 2mm. pitch hand tap (best to use is a second tap and not a plug tap) but you won't be able to use a tap wrench because of the restricted access so an open ended spanner will have to be used to turn the square drive on the end of the tap. Finally, apply some PTFE tape around the thread (but I also used a pipe sealing agent too called 'Boss White' to make sure it didn't leak) and tighten the new valve up with the new rubber 'O' ring in place by using the long 20mm. socket. Re-fit the hot water pipe to the new non-return valve and test for any leaks.