Another Truma Submersible Water Pump Thread

[JaneandIain]

Morning everyone, and sorry for starting yet another Truma Pump thread.

Our Truma submersible pump (connecting through an Ultraflow connection) has suddenly started blowing the 7.5A fuse (3 yesterday alone). common sense says it’s likely to be an issue with the pump, particularly as when we bought our van we were told we had to keep turning pump on and off on the main control panel, not allowing the Whale pressure switch to do its job. Obviously occasionally we have forgotten to turn it off and the pump has therefore kept running.

Having checked it yesterday, I have tried spinning the impeller at the bottom of the pump, and to my untrained brain it seems fairly stiff. I’m guessing it should spin quite freely?

Logic says to me it’s most likely a pump issue rather than a sudden fault in the electrics, so I’m figuring a replacement Whale pump might be the way to go.

 

[Paullus1959]

Yes, the impeller should spin freely.
I swapped the Truma Ultraflow for the Whale version a few years ago. I don't think the performance is significantly beter or worse than the Truma but where it is much better is in the flexibillity of the hose. The Truma is quite rigid which can cause problems on a sloping pitch where the water inlet is level or worse, below the level of the water barrel opening. The flexibillity of Whale on the other hand completely elliminates any such problem. I use a Colapz Fresh Water Mini when on a full-service pitch and It's a struggle to get the Truma pump to sit in it properly.
On the other hand, I now have two Truma pumps lying around, one used and the other brand new if you're looking to save some money.

 

[Hutch]

I agree with Paullus, your pumps impeller should spin easily, when one of my pumps siezed up, I replaced it with a whale pump with the Truma connector to the van, and yes it is much more flexible, My spare pump is still an old (10 years +) Truma, with foam wrapped around it for winter use.

 

[ProfJohnL]

I agree the symptom most likely points to a pump failure, but I think you should be also looking to resolve the possible cause of the pump failure, and your comment about having to turn the pump on and off, despite having a pressure switch strongly suggests there is an underlying problem to be resolved.

When you are occupying the caravan with a pressure switch, there should be no need to have to manually turn the pump on and off - That is the principal job of a pressure switch to do it for you automatically. You should turn the pump off when you run out of water or change the water barrel, and when travelling and leaving the van in storage, and it it is advisable to turn it off when you leave the caravan to visit local attractions etc, just in case the caravan develops a leak.

You need to investigate why the pressure switch does not seem to work. Just a few simple checks might hint at the reason.

With a full water barrel, does the pressure switch turn the pump off when all the taps (and drain valves) are closed? If not, then the pressure switch may need adjusting - see the manufacturers instructions.

If the pressure switch does turn the pump off, but even with all the taps closed every few minutes or less the pump turns on for a moment to restore pressure, then you have a leak. Check all pipe joints and fittings for any obvious signs of a leak and get it fixed, but also you can sometimes get a leak through the pressure switches' non return valve. You won't see any outward sign of this, as its allowing the upstream pressurised water to leak back to the water barrel through pump hose. - refurbish or replace the pressure switch.

Just a note about the momentary pump blips. If interval between 'blips' is only 20 minutes or more then that might be normal and due the hot water stored in the water heater contracting and reducing the internal pressure as it cools down.

A submersible water can use up to about 50W (about 4A) of power when pumping water. The pump is designed to use the water flowing through the pump to prevent it getting too hot. If the water flow is is too restricted ( for example if the pressure switch does not work) or if the pump is allowed to run dry, heat can build up in the motor and it may be enough to soften or distorts the plastic surrounding the motor and its shaft enough to allow water to get into the pump's motor which will certainly damage it and most likely destroy it quite quickly.

Provided there are no leaks in the system, and the water barrel is not allowed to run dry, a pressure switched water system is usually very reliable and practical solution.

You may wish to change your pressure switch manufacturer, in which case Whale is a well respected well proven alternative system.

 

[audiorob]

WhaleAdjustingyourpressureswitchb.pdf (whalepumps.com)
This might meet your need - I have a laminated copy in my van as the pressure sensor needs adjustment from time to time, especially if changing between battery and mains. Also been lent out on site a few times!

 

[Hutch]

The fuse in my Coachman for the water pump is a 10 amp fuse. Check to make sure your fuse is the correct rateing, but a stiff impeller leans towards the pump needing replacment. Borrow one from a nearby caravanner to check it out. Most folk are really helpfull.

 

[JaneandIain]

Wow, thanks for all the helpful replies

I agree the symptom most likely points to a pump failure, but I think you should be also looking to resolve the possible cause of the pump failure, and your comment about having to turn the pump on and off, despite having a pressure switch strongly suggests there is an underlying problem to be resolved.

When you are occupying the caravan with a pressure switch, there should be no need to have to manually turn the pump on and off - That is the principal job of a pressure switch to do it for you automatically. You should turn the pump off when you run out of water or change the water barrel, and when travelling and leaving the van in storage, and it it is advisable to turn it off when you leave the caravan to visit local attractions etc, just in case the caravan develops a leak.

You need to investigate why the pressure switch does not seem to work. Just a few simple checks might hint at the reason.

With a full water barrel, does the pressure switch turn the pump off when all the taps (and drain valves) are closed? If not, then the pressure switch may need adjusting - see the manufacturers instructions.

If the pressure switch does turn the pump off, but even with all the taps closed every few minutes or less the pump turns on for a moment to restore pressure, then you have a leak. Check all pipe joints and fittings for any obvious signs of a leak and get it fixed, but also you can sometimes get a leak through the pressure switches' non return valve. You won't see any outward sign of this, as its allowing the upstream pressurised water to leak back to the water barrel through pump hose. - refurbish or replace the pressure switch.

Just a note about the momentary pump blips. If interval between 'blips' is only 20 minutes or more then that might be normal and due the hot water stored in the water heater contracting and reducing the internal pressure as it cools down.

A submersible water can use up to about 50W (about 4A) of power when pumping water. The pump is designed to use the water flowing through the pump to prevent it getting too hot. If the water flow is is too restricted ( for example if the pressure switch does not work) or if the pump is allowed to run dry, heat can build up in the motor and it may be enough to soften or distorts the plastic surrounding the motor and its shaft enough to allow water to get into the pump's motor which will certainly damage it and most likely destroy it quite quickly.

Provided there are no leaks in the system, and the water barrel is not allowed to run dry, a pressure switched water system is usually very reliable and practical solution.

You may wish to change your pressure switch manufacturer, in which case Whale is a well respected well proven alternative system.

John, thanks for such a comprehensive reply. I tracked down the instructions for adjusting the pressure switch (it is a Whale switch fitted) and it looks like it had never been properly set up. I followed the instructions as linked to by Audiorob, and got into a situation where the pump turned off as you would expect in a pressure system. I get the feeling the dealer might simply have been rushing through the handover. Unfortunately the 7.5Amp fuse still trips, so I think it may well be time for a a replacement pump, probably a Whale.

WhaleAdjustingyourpressureswitchb.pdf (whalepumps.com)
This might meet your need - I have a laminated copy in my van as the pressure sensor needs adjustment from time to time, especially if changing between battery and mains. Also been lent out on site a few times!

Thanks AudioRob, I had tracked down those instructions and they seemed to get the pump set up as you would expect, however when running it still blows the fuse. Points at the moment towards a new pump initially

The fuse in my Coachman for the water pump is a 10 amp fuse. Check to make sure your fuse is the correct rateing, but a stiff impeller leans towards the pump needing replacment. Borrow one from a nearby caravanner to check it out. Most folk are really helpfull.

Thanks Hutch, unfortunately didn’t get the chance today to try someone else’s pump with a new fuse. The original fuse fitted is 7.5Amp; certainly Truma don’t make it easy to find the necessary fuse rating.

 

[Hutch]

Good luck, I went through three fuses before I believed in the fact that my pump was Condemmed to the bin. I keep the tubing and made up a bit of kit to blow the water out of the water system between winter outings.

 

[RogerL]

The pressure switches are voltage sensitive - when on site with EHU, it'll be fairly constant at about 13.8V but if you're off-grid with no EHU it's dependent on the state of charge in the battery, which varies from 12.0 to 12.8V, possibly lower when running other items - so it's best to adjust the switch when the battery isn't being charged and is on the low side.

 

[JaneandIain]

Thanks to all who answered this thread.

I've bought a new Whale submersible pump with Truma connection, fitted a 5 amp fuse (as specified by Whale), adjusted the pressure switch, and all seems good now.

The Truma pump that kept blowing fuses will be consigned to the bin. Only thing I would say is that the Truma cover for the Aquaroll seems much better quality than the Whale version, but that's a minor thing given we now have a working pump.

 

[ProfJohnL]

The pressure switches are voltage sensitive - when on site with EHU, it'll be fairly constant at about 13.8V but if you're off-grid with no EHU it's dependent on the state of charge in the battery, which varies from 12.0 to 12.8V, possibly lower when running other items - so it's best to adjust the switch when the battery isn't being charged and is on the low side.

Strictly speaking it's the pump that is voltage sensitive not the pressure switch. As the supply voltage reduces the pressure the pump can achieve also reduces, and it takes slightly longer to raise its pressure when the outlet taps are closed.

But I do agree with your strategy to set the trip point of the pressure switch.