Fresh Water Gauge Stuck

[Tim McGann]

My fresh water gauge always reads 75%. Is there a float or similar that needs a jiggle? Perhaps a reset? Thanks for any advice.

 

[PP Bear]

Mine reads 25% after endless attempts at cleaning it, so guess it’s stuck If you have the type of tank that you can access from the top, then open it and have a look to see or feel, but, if like me, you have a low slung sealed tank then it’s cleaners I’m afraid.

 

[kev54]

Not found one yet that works properly!

 

[Two on Tour]

Not found one yet that works properly!

My Mopeka wireless Bluetooth sensors for both our fresh, grey and LPG are spot-on accurate.

 

[LesW]

My Mopeka wireless Bluetooth sensors for both our fresh, grey and LPG are spot-on accurate.

View attachment 820327

Were they easy to fit?

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

My fresh water gauge always reads 75%. Is there a float or similar that needs a jiggle? Perhaps a reset? Thanks for any advice.

My gauge sensor consists of five thin stainless rods. Two go down to the 25% level, with one each at the 50%, 75% and 100% levels. When the water bridges the rods, the electronics knows which rods are touching the water so it can display the level.

Sometimes the rods get covered with limescale, and need cleaning/descaling. Mine has worked fine for 10 years, but I recently had to replace it. The insulation between the rods at the top was failing and causing false readings. I had to cut the rods to the correct length, the same as the old ones. Not easy cutting stainless steel rod. I used a diamond disc and a Dremel drill.

You can test if that's the problem. One of the two longest rods will be the 'common' rod. When the resistance between that common rod and another rod drops to a low value, the gauge knows that water has reached that rod. It's not very sophisticated. If you short between the common rod and one of the other rods, you can make the gauge display whatever level you want for testing purposes. So you can tell if it's the sensor rods or the gauge electronics that is the problem.

Or you can take off the connector, and short between the common wire and the others to check that the gauge works properly.

 

[Two on Tour]

Were they easy to fit?

Yes, if you have underslung tanks.

 

[scotjimland]

My fresh water gauge always reads 75%. Is there a float or similar that needs a jiggle? Perhaps a reset? Thanks for any advice.

Not a float switch ..
Water tank levels are measured using probes on the wall of the tank at different heights, , generally at 25, 50, 75, 100% ..
When covered with water, they conduct a small current to the level sensor , thereby indicating the level on the gauge.

Overtime they become coated with limescale.. which is an insulator.. so they stop conducting when water covers them,

Cure.. descale the tank and water system, I suggest food grade citric acid, available from Amazon in a 1kg bag for about £4

Pumping it though the hot and cold water system will also descale the Truma boiler, and taps

White wine vinegar can also be used..

I wrote to Truma for advice about this and this was the reply:

Descaling the Truma water heater

The Truma website it will tell you to de-scale as follows: -

“For hygienic reasons you should decalcify the water container occasionally. Use special decalcification products from camping specialists or conventional vinegar essence or citric acid, for example.

Fill the decalcifying product in the recommended ratio into the appliance via the water system, allow it to work and then rinse the Combi heater thoroughly with fresh water”

following an email to Truma I received the following reply: -

“Please find below instructions for descaling the Truma water heater:
Dilute 2 litres of white wine vinegar into 10/12 litres of fresh water, introduce into your water system via your water inlet, (removing the filter if one is fitted for this process) open the taps to pull through to the heater and then leave the solution in the heater for 4 to 5 hours and then flush through with fresh water”.

I was also provided with the following additional advice concerning the use of Citric acid:
The ratio Truma recommend is 1 tablespoon of citric acid to 1 litre of water”.

Make up the solution of Citric Acid,
I used an 11lt watering can and poured the solution into the fresh tank, then pumped through all taps, hot and cold, including shower head, and toilet flush. ;eave for 4 or 5 hours.

Drain down and flush system with plenty of fresh water..


My preference is Citric Acid