Re-Calibrating Water Tank (1 Viewer)

Oct 25, 2015
456
283
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Funster No
39,750
MH
Bailey 79-4t
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Since 2016
Hi Guys. Anybody any ideas on how to recalibrate water tank sensor. Right nuisance as sensors are making water pump kick in for a couple of turns every 10 secs!! Also after filling completely and then just one bowl of water the level shows at 85%. Clearly not right
 

Jim

Ringleader
Jul 19, 2007
36,191
128,630
Sutton on Sea, UK
Funster No
1
MH
Adria Panel Van.
Exp
Since 1988
I doubt it is the sensor that it making your pump kick in, rather that will be a leak or your low point water drains are open or your water heater dump valve is open.
 

mike mcglynn

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Jan 6, 2008
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Hi,Targetpaster I would check out all your plumbing connections as you may have slight leak, before fiddling with sensor.

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Purple2
Oct 25, 2015
456
283
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Bailey 79-4t
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Since 2016
Thanks for all your tips so far. Checked everywhere, no leaks. Def a problem because when I mentioned the 10 sec thing you can literally set your watch with it! M\H only 4 months old so back to dealer on way home for a bit of a gripe as my Alde 3020 has a problem as well.
 
D

Deleted member 29692

Deleted User
The 10 second thing is the pump keeping your system pressurised so it's definitely losing pressure somewhere. Could be something to do with the boiler, it could be a very slow weep or drip from a tap or a joint somewhere, it could be lots of things but there will be water escaping somewhere.

Your other point, about the display of the tank water level not being accurate. That's a well known issue - the sensors are never accurate. There's pretty much nothing you can do about it, even if you replaced the sensor there's nothing to say it would be any better. You need to use the level shown on the display as a very rough guide, not expect it to be gospel truth.

We can have about three showers after ours is warning and beeping that it's empty (y)

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Feb 9, 2008
4,086
5,902
SW Scotland
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1,453
MH
LP Coachbuilt
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Since 2008 after caravanning for 20 years
You've a little leak. Turn the tank sensor off, it is impossible for them to work accurately.
 

scotjimland

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Jul 25, 2007
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it is impossible for them to work accurately.

depends on type of sensor..

the rod system as fitted to Hymers are reliable and accurate .. nothing to go wrong.. a just four s/s rods that work by conduction..
level indication.. zero 25% 50% 75% 100% .. same on waste tank.

the ones with a float and variable resistor are less reliable..
 
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Purple2
Oct 25, 2015
456
283
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Funster No
39,750
MH
Bailey 79-4t
Exp
Since 2016
Did all that. Van is so new we've not even used our shower yet! As I say thanks for all the tips which will be very useful in future but I think the sale of goods act may well kick in at the moment. Wanted to try a few fixes myself but 'higher authority' got the hump and said "back to dealer"

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D

Deleted member 29692

Deleted User
Just a thought on the pump. Have you filled the system, both hot and cold sides, properly - i.e. made sure water is flowing steadily from all the taps and the shower from both the hot and cold taps?

If there's any air in the system gradually working it's way out that could also explain the pressure dropping.
 
Aug 6, 2013
11,941
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27,352
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I'd go for a leaky valve on the pump or, if part of the pump, the pressure switch. The pressure in the system drops as water is forced back to the tank.
 
Feb 9, 2008
4,086
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Look at the shape of your tank. Most are rather convoluted to fit around and over chassis rails. The type of sensor used on vans can only work, accurately, if the tank is of regular cross-section. Besides, as you get to know your van you get an idea of how much water you use and how often to top up. My gauge reads empty most of the time as there is never more than 30 ltrs. in it, the waste rarely reads more than 1/4.

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Sep 23, 2013
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I'd go for a leaky valve on the pump or, if part of the pump, the pressure switch. The pressure in the system drops as water is forced back to the tank.
I'm with Tony. If you can't find any leaks (& they can be difficult to find - could be an underfloor junction somewhere :(), then the likely culprit is the non-return valve allowing water to flow back into the tank. This is usually part of the pump, or a separate item right next to the pump.

If you tell us the make & model, someone may know what is fitted.

On some systems, the water pressure is adjustable & if set too high, it can 'hunt' in the way you describe. I had a similar problem on an Abbey caravan, but that would be a 30 year old system if it was still on the road today. Cured it by dropping the pressure a bit.
 
D

Deleted member 29692

Deleted User
depends on type of sensor..

the rod system as fitted to Hymers are reliable and accurate .. nothing to go wrong.. a just four s/s rods that work by conduction..
level indication.. zero 25% 50% 75% 100% .. same on waste tank.

the ones with a float and variable resistor are less reliable..

So if you have say 85% left does it tell you that you have 100% or 75%?

To me that's no more accurate than any of the others.
 

scotjimland

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Jul 25, 2007
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Timberland
To me that's no more accurate than any of the others.

It is a digital instrument.. not analog .. it shows steps.. not exact level.. correct, it doesn't show small incremental steps.. but it doesn't need to..

Repeatability of a level instrument ( any measuring instrument ) is more important than an exact measurement to the nth degree ..

If you need or want exact level display you would need to employ a different type of instrument.. for example.. an ultrasonic level transmitter.. but for purpose of knowing how much water you have left this would be an expensive solution.. and simply overkill

Rod level measurement and control is widely used in the food, chemical and petrochemical industry as it is

a) relatively cheap
b) reliable
c) cheap and simple to maintain
e) easy to calibrate
f) is consistent with a standard, rule, or model, ie. accurate

bottom line.. it works, a perfect example of the KISS principal

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D

Deleted member 29692

Deleted User
It is a digital instrument.. not analog .. it shows steps.. not exact level.. correct, it doesn't show small incremental steps.. but it doesn't need to..

Repeatability of a level instrument ( any measuring instrument ) is more important than an exact measurement to the nth degree ..

If you need or want exact level display you would need to employ a different type of instrument.. for example.. an ultrasonic level transmitter.. but for purpose of knowing how much water you have left this would be an expensive solution.. and simply overkill

Rod level measurement and control is widely used in the food, chemical and petrochemical industry as it is

a) relatively cheap
b) reliable
c) cheap and simple to maintain
e) easy to calibrate
f) is consistent with a standard, rule, or model, ie. accurate

I'm sure you're right. My point was that it's only approximately accurate the same as the other type fitted in other motorhomes is only approximately accurate.
 

pappajohn

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Aug 26, 2007
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On some systems, the water pressure is adjustable & if set too high, it can 'hunt' in the way you describe. I had a similar problem on an Abbey caravan, but that would be a 30 year old system if it was still on the road today. Cured it by dropping the pressure a bit.
Sorry to say, the pressure is not adjustable, its pre-set at the factory and is defined by the pumps combined cylinder volume, piston stroke and the motors power.
What is adjustable is the cut off pressure which relies on the back pressure in the pipes and pump once the flow is stopped.
By adjusting the screw the pump can be made to switch off with a lower or higher STATIC pressure.
Too low and the pump may not work at all because of the pipework and taps resistance to allow water to flow freely.....too high and the pump will never get to the pressure needed to activate the microswitch and the pump will run continuously.
 

scotjimland

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Jul 25, 2007
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I'm sure you're right. My point was that it's only approximately accurate the same as the other type fitted in other motorhomes is only approximately accurate.

other types fitted such as floats with variable resistors are cheap and notoriously unreliable.. the ones most often complained about being inaccurate or simply useless..they tell lies.. not fit for purpose..

rod level is reliable and does the job required.. ie let's you know when to fill up...

If it shows say 50% I know I have less than 75% but more than 50% .. so no need to fill .. just yet

when it shows 0% I have less than 25% left .. .. time to fill up.. that's all you need to know..

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Sep 23, 2013
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By adjusting the screw the pump can be made to switch off with a lower or higher STATIC pressure.
Indeed. That's why I said water pressure rather than pump pressure.

... and of course there is also the possibility that at a slightly lower water pressure the non-return valve won't leak back. But if the pump is coming on every 10 seconds I suspect that's being over-optimistic.
 

pappajohn

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Aug 26, 2007
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Indeed. That's why I said water pressure rather than pump pressure.

... and of course there is also the possibility that at a slightly lower water pressure the non-return valve won't leak back. But if the pump is coming on every 10 seconds I suspect that's being over-optimistic.
My apologies, I assumed you meant to pump water at a higher or lower volume and pressure.
Its a common mistake some people make thinking that adjusting the screw to raise the pressure will make it flow like a fire hose.
 

pappajohn

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Aug 26, 2007
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I find when water stops flowing you have an empty tank....fairly reliable method and far more accurate than a guage.
My RV fresh and grey tanks always showed full grey and 25% fresh....no matter what was actually in the tanks.
But with a fresh capacity of 70 GALLONS and a grey of 40 GALLONS it never bothered me.

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scousebird

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Apr 18, 2012
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We had a problem with our Bailey tank & pressure sensor. Took it back to the dealers, turned out the sensor didn't reach the bottom of the tank so they replaced that and re calibrated. Works perfectly now.
 
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Purple2
Oct 25, 2015
456
283
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Funster No
39,750
MH
Bailey 79-4t
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Since 2016
Bit of a discussion going on there then and to be perfectly frank most of it was in Martian! We all bring different things to the party and unfortunately my 'speciality' is not the plumbing system on a brand new M\H which has gone slightly belly up on our second ever trip out. For the time being I think Webb's will be getting a visit shortly and much obliged for recent entries which I will have to research when I have a few hours spare.
 

Melvin

Free Member
Jan 22, 2016
230
182
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Coach built
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Don't get too dispondent , I'm having similar issues with mine and its booked in with the dealer to be sorted. From the feedback I received its not a big job .
By the way ,I take it that new MH is Peugeot based , did you know there is a manufacturers recall on it . Once again not a big problem , took mine in yesterday and the job was done in 40 mins .

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Purple2
Oct 25, 2015
456
283
Devizes
Funster No
39,750
MH
Bailey 79-4t
Exp
Since 2016
So I visited my dealer and they told me that the likely problem is faulty diaphragm in water dump valve. Anyway, booked in for that and dodgy ALDE control panel. Thermostat temp shown on panel always too high so never gets low enough for comfortable 'tick over' heating in M/H. Can use offset option but it's new so I'm not going to just 'make do'
 
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Purple2
Oct 25, 2015
456
283
Devizes
Funster No
39,750
MH
Bailey 79-4t
Exp
Since 2016
So kind. E mail is shenleybob@aol.com that is probably a better 'medium'
Goes in next Sat but may be useful for future.
Thanks

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