Venus Lunar 550/4 Truma Water Pump , kitchen and bathroom sink ....

[Thomas Dixon]

Update: Pump running but pressure dropping & not cutting off (2017 Venus Lunar 550/4)

Thanks again for all the advice so far, it’s really helped.

I now have 12V going to the pump, and it’s priming properly, drawing water into the system. Water is coming through to both the kitchen and bathroom taps, hot and cold, so that part seems to be working.

Current status:

• 12V supply to the pump confirmed
• The pump is priming and drawing water
• Water reaching kitchen and bathroom taps (hot and cold)

Issues:

• Pressure starts strong but quickly drops to a trickle on all taps
• The external pump continues running and does not cut off when the taps are closed

Possible causes:

• Airlock in the system
• Pump is underpowered (non-Truma motor bought in Spain last year)
• Pressure switch not reaching cut-off
• Possible leak or pressure loss somewhere in the system

If anyone with a 2017 Venus Lunar 550/4 or similar setup has seen this before, I’d really appreciate any suggestions on what to check next.


End of UPDATE

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Hi all
Prepping for the summer trip and discovered an issue. I have a 2017 Venus Lunar 550/4 caravan, and I’m having an issue with the water system. The taps in both the kitchen and bathroom have stopped working completely.

So far, I’ve replaced the external Truma submersible pump, but there’s still no change—no water flow at all. I also found that the 10A fuse had blown, so I replaced that as well.

At the moment, I’m not hearing any noise from the pump—no spinning or pressure sounds—so it seems like it’s not getting any power.

Has anyone come across this before, or have any suggestions on what I should check next?

Thanks in advance.

 

[borderbilly]

is the pump switched on at the panel?

 

[audiorob]

Shortly after I had my van I had a similar problem. As a pressure system the pump only operates when water flows causing the pressure to drop and so activate the pump. So now a job I undertake regularly, and especially after winter lay-up is to unscrew the tap spout and clear out a sometimes amazing amount of debris blocking the filters. Could this be your issue?

 

[Thomas Dixon]

is the pump switched on at the panel?

Hi yes, it is switched on at the panel, the led goes green so I know the panel has power

 

[Thomas Dixon]

Shortly after I had my van I had a similar problem. As a pressure system the pump only operates when water flows causing the pressure to drop and so activate the pump. So now a job I undertake regularly, and especially after winter lay-up is to unscrew the tap spout and clear out a sometimes amazing amount of debris blocking the filters. Could this be your issue?

Great, thanks, I will give this a go and see if it has any effect

 

[Charlie56]

has the pressure switch stuck?

 

[Thomas Dixon]

has the pressure switch stuck?

Hi charlie56, I have no idea what the pressure switch is or how to check if its stuck ? Thanks

 

[Charlie56]

Hi, the pressure switch cuts the power to the pump when there is sufficient pressure in the system. I would measure the voltage at the switch first. If 12v is getting there but not to the pump it would suggest the pressure switch

 

[Thomas Dixon]

Hi, the pressure switch cuts the power to the pump when there is sufficient pressure in the system. I would measure the voltage at the switch first. If 12v is getting there but not to the pump it would suggest the pressure switch

Thanks for your suggestion, I will try to find the pressure switch , and check the voltage

 

[Thomas Dixon]

Thanks for your suggestion, I will try to find the pressure switch , and check the voltage

Shortly after I had my van I had a similar problem. As a pressure system the pump only operates when water flows causing the pressure to drop and so activate the pump. So now a job I undertake regularly, and especially after winter lay-up is to unscrew the tap spout and clear out a sometimes amazing amount of debris blocking the filters. Could this be your issue?

Thanks for your suggestion,
Update: Pump running but pressure dropping & not cutting off.

I now have 12V going to the pump, and it’s priming properly, drawing water into the system. Water is coming through to both the kitchen and bathroom taps, hot and cold, so that part seems to be working.

Current status:

• 12V supply to the pump confirmed
• The pump is priming and drawing water
• Water reaching kitchen and bathroom taps (hot and cold)

Issues:

• Pressure starts strong but quickly drops to a trickle on all taps
• The external pump continues running and does not cut off when the taps are closed

 

[Thomas Dixon]

Hi, the pressure switch cuts the power to the pump when there is sufficient pressure in the system. I would measure the voltage at the switch first. If 12v is getting there but not to the pump it would suggest the pressure switch

Thanks for your suggestion,

I now have 12V going to the pump, and it’s priming properly, drawing water into the system. Water is coming through to both the kitchen and bathroom taps, hot and cold, so that part seems to be working.

Current status:

• 12V supply to the pump confirmed
• The pump is priming and drawing water
• Water reaching kitchen and bathroom taps (hot and cold)

Issues:

• Pressure starts strong but quickly drops to a trickle on all taps
• The external pump continues running and does not cut off when the taps are closed

 

[IanB1485]

The reason the high initial flow is that with no water flowing ( just after a tap is switched off) the pressure in the system continues to rise until it trips the pressure switch ,which cuts off the pump. When a tap is opened, initally this higher pressure in the system coupled with the high volume of the pipework inc water heater reservoir gives a good flow and as this 'stored water under pressure is used, the flow reduces down to what the pump can achieve, it has a low flow /pressure characteristic and the lower flow is the maximum flow of the pump. Some people opt for the whale high flow pump which a better flow /pressure characteristic.
In the inlet fitting of the caravan is a built in -non-return valve ( simple little black disc of rubber) and if this 'weeps' back to the external pump then the pressure in the inboard pipework will fall causing the pump to restart .To check this, allow the system to reach pressure then remove the water pipe rom the pump) from the inlet fitting and watch if after an initial loss of water on disconnection , water then continues to trickle out. The disc can be cleaned from the outside with a cotton bud wiping around the inside of the inlet tube where th disc sits. another fault although rare is a pinhole in the pipe from the pump to its connector with inlet fitting. a whale pipe is a double pipe one with the electrical cables in and the other being the water pipe, A truma has a blue sleeve covering both the water pipes and electric cables. , so is more difficult to see. To check take the pump out of the aquaroll and place it in a bowl of water about 200mm deep thus exposing most of the pipe and with pump running see if there are any pinholes in the pipe. another fault is that the water heaters i.e Truma ultrastore Alde 3020 and Whale , have an air admittance valve on the hot water outlet . it's there to allow air back into the hot water tank when draining down, thus allowing a faster drain down. There's a little ball in the fitting which closes under pressure and opens when no pressure on . If the seat of the fitting gets debris on the fitting it can 'weep' , Look under the van near where the water heater is , there will be a short piece of clear plastic tubing sticking down and if wet or water dripping from it then thats the cause of the pump cycling.
Another fault can be the pressure switch is set too high so when running the pump only just manages to reach cut-off pressure and when it switches the slight drop in pressure cause the switch to restart the pump.
Please take photos of your set to help the members diagnose possible causes