I have a Bailey Ranger 550/6, 2008 model. Last week was our first proper trip away in the van and I became conscious of what seems a strange characteristic of the water system.
The van is fitted with a Truma submersible pump, a Whale inline pressure switch and a Whale surge damper. The pressure switch appears to work correctly (i.e. the pump comes on when the tap opens and turns off shortly after closing the tap). However, I have noticed a buzzing noise that appears to come from the pressure switch when there is anything other than full flow from the taps. (This is not the pump buzzing, as I can hear that sound separately).
For example, when I open the tap, the pump comes on (I can hear the normal whirr from the pump), but there is also a buzz from the pressure switch for a second or so until the tap is fully flowing. Likewise, when I close the tap, the pressure switch buzzes for 1-2 seconds as the pressure builds up, until finally there is a click and the pump turns off. The buzzing rises in pitch as the pressure rises before the switch shuts the pump off. Likewise, if I open the tap slightly so that there is limited flow, the pressure switch seems to buzz continuously.
Is there a fault with my pressure switch, or is this normal behaviour? I did try adjusting the pressure switch as per the instructions, but it didn't make any difference. My previous van had microswitches on the taps, so there was no pressure switch to worry about.
Another thought... could it be caused by air in the system? Maybe I should check the O-rings on the external pump connector.
I know I can replace the pressure switch, but I don't want to start pulling pipework apart without good reason.
Our last van was a GT60 2009 so will be the same system as yours, never buzzed. Sounds as though switch contacts are not completely switching off. Worth checking if your pump running light is still on or flickering.
Thanks birdman101. The buzzing stops when the pump switches off so it does sound like the microswitch is switching off properly. For some reason it buzzes just before the switch shuts off. But I will check what the pump light is doing before it shuts off. The van is currently in storage so I will have to take a barrel of water over to the van at some point to do some tests.
I think the buzzing may be caused by internal vibration of the pressure switch due to a defective rubber diaphragm or debris inside the inlet port. The best solution is to drain the water system, remove the wires (noting where they go), remove the jubilee clips from each end of the pressure switch then remove the pipes at either end (inlet and outlet). Undo the two securing screws that fixes it to the floor then strip the switch apart. Remove the inlet port which is fixed by the two screws to which there will be a rubber plunger on a centre shaft which is the diaphragm that pumps the water through. Remove the diaphragm and inspect it to see if the rubber has perished or if there is a tiny hole in it and also clean for any bits in the pressure switch and it may be a good idea to flush it through with a hose. The internal parts are not replaceable so any defective parts and the complete pressure switch will need to be replaced but if all looks well then re-assemble in reverse order, refill the system and then check to see if the buzzing has been eliminated. It's worth a try as I can't see any other reason why buzzing should occur when water is being delivered via the pressure switch or water system.
Thanks for the detailed reply, tango55. I'll certainly give that a go. If all else fails I'll try a replacement switch. I know my local dealer stocks them.
Hope you manage to get it fixed but please come back with a reply as to what the outcome is as it can be useful for anyone suffering the same symptoms.
OK, I visited the van and did some more investigations today.
In the end it turns out the buzzing is coming from the Truma non-return valve (attached to the back of the water inlet), not from the pressure switch as I originally thought. I removed the non-return valve to inspect it. I did find a piece of plastic debris inside, but after removing it the buzzing remained.
What seems to be happening is as follows. As soon as I turn off the tap, pressure builds up in the system. Before the pressure switch shuts the pump off (which takes 1-2 seconds), the Truma non-return valve starts to buzz. The buzzing stops when the pump stops. Could this be caused by a faulty valve?
Interestingly, I noticed the Truma non-return valve has a price label on it, which makes me suspect it might not be original.
Anyway, that's the story so far! Any thoughts appreciated.
Okay, here's a handy tip. Get a long screw driver, place the blade end on the non return valve and put your ear on the handle end. Get an assistant to operate the water taps and when the water shuts off listen for any buzzing through the screw driver and you can determine if this is the offending part or not. You can do the same with the pressure switch just to unsure that the vibration isn't travelling through the pipes back to the non return valve. That way you can confirm which part needs replacing.
Using this screw driver method is an old technique used by qualified mechanics to detect worn moving parts in the vehicle engine but is on old trick that works on most things that have internal working parts.
Quote: Originally posted by tango55 on 02/7/2015
Okay, here's a handy tip. Get a long screw driver, place the blade end on the non return valve and put your ear on the handle end. Get an assistant to operate the water taps and when the water shuts off listen for any buzzing through the screw driver and you can determine if this is the offending part or not. You can do the same with the pressure switch just to unsure that the vibration isn't travelling through the pipes back to the non return valve. That way you can confirm which part needs replacing.
Using this screw driver method is an old technique used by qualified mechanics to detect worn moving parts in the vehicle engine but is on old trick that works on most things that have internal working parts.
Great idea! I had thought of getting hold of a stethoscope, but the screwdriver idea sounds good. Thanks!
The buzzing was definitely coming from the non-return valve. I replaced the valve, but was surprised to find it didn't cure the problem. So then I removed and inspected the pressure switch, and saw that the inlet was in poor condition, contaminated with limescale and gunk. Rather than fiddling about dismantling it I just replaced it with a new one, and hey presto - no more buzzing.
I immediately noticed that the new pressure switch responded much more quickly than the old one. What I think was happening was that the old pressure switch was responding slowly and allowing back-pressure to gradually build up in the non-return valve, resulting in a buzzing noise as the valve closed. Exactly why the valve buzzed I'm not sure, but I guess the combination of a rubber diaphragm and a spring could exhibit this behaviour.
The pump now switches off almost immediately on turning off the cold tap, whereas it previously took 1-2 seconds to respond.
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Topic: Pressure switch buzzing? (Water system)
