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MT-TUA-17S-11-9240 not responding to input signal


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One of these controllers is suppose to start a pump to run a hot water feed circuit loop when a dip water pressure occurs when a tap opens. 

 

However nothing happens.

 

The sensor seems to react,  in that a electrical screw driver lights up when the tap is open.  But note the screwdriver is dimly lit all the time. 

 

The controller is set on Wu and 10 seconds.  What function does the top switch do? The data sheet says this is the 'time adjusting knob' but it seems to have no effect. 

 

Switching the unit to 'On' and the bottom led comes on and the pump runs. 

20190503_062048.jpg

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Reading the manual (https://www.europacomponents.com/pdfs/Relpol_Multi_Timer_Instructions_Final.pdf))  it seems that the range knob sets the general scale of the time. Yours is set to one minute in the photo. Then, I think, the top time knob sets the proportion of that to be used. Yours is set to 0.9 so 0.9 × 60 seconds = 54 seconds.

 

Why are there two pairs of wires at the top of the unit? I'd expect either just a single line/neutral pair (for the Wu setting) or line/neutral and control if using one of the settings which use that input.

 

59 minutes ago, readiescards said:

The sensor seems to react,  in that a electrical screw driver lights up when the tap is open.  But note the screwdriver is dimly lit all the time. 

 

Trying to measure something with one of those is likely to be pretty misleading (and very dangerous if you're ever tempted to rely on it for checking that a circuit is dead). Much better to use at least a multimeter. It doesn't have to be an expensive one but it'd be better if it's one with a “Cat” marking for at least some level of mains safety.

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I'd normally use a multimeter but do the installation location it would be a two man job.  However I'll try to recruit someone to get a proper reading.  Especially as I'm curious what a half lit screwdriver means. 

 

Thanks for explanation of the top knob. 

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1 hour ago, readiescards said:

Especially as I'm curious what a half lit screwdriver means. 

 

 

It's a reference to some of the pretty useless, and IMHO dangerous, voltage indicating screwdriver/probe things with a neon light inside.

 

They are very poor indicators as to whether a circuit is actually dead, as they will light up with a very small induced current.  Equally, they may not light on a live circuit if it so happens that the person holding the thing happens to have picked up enough of an induced field to lift their body potential within about 60 VAC of the mains supply.

 

The dangerous bit comes when people rely on these things to check whether a circuit is dead, as they can give a false indication.  In my view they should have been banned from sale to the general public years ago.

 

They can sometimes be useful if the person using the thing is connected to a known to be good earth, but even then I don't wholly trust the things. 

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1 hour ago, JSHarris said:

It's a reference to some of the pretty useless, and IMHO dangerous, voltage indicating screwdriver/probe things with a neon light inside

 

Right, but @readiescards is asking how to interpret that half-lit reading in the context of their circuit not working.

 

First thing I'd do is test the pump controller on its own in a known-good circuit. If it seemed to be working OK then the next hypothesis I'd look into is that the pressure sensor is leaking electric current somehow so the pump controller isn't ever properly off so doesn't trigger when it's switched on.

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19 hours ago, Ed Davies said:

First thing I'd do is test the pump controller on its own in a known-good circuit.

 

I've only proven this by turning the controller to 'ON' but yep good idea I'll have to wire in a manual switch.

19 hours ago, Ed Davies said:

next hypothesis I'd look into is that the pressure sensor is leaking electric current somehow so the pump controller isn't ever properly off so doesn't trigger when it's switched on.

Ah that makes a lot of sense. 

 

As this is issue is in our holiday cottage, (insert holiday cottage plug here: https://www.holidaycottages.co.uk/east-of-england/lincolnshire/the-stables-in-the-wolds) I have limited opportunity for testing.  June is next testing time.  Will report back then.

 

19 hours ago, Ed Davies said:

how to interpret that half-lit reading in the context of their circuit not working.

 

Yes I'm not  a fan of the screwdrivers at all but it was all I could use one handed (due to installation and time restrictions) and I'm very curious to know what a half-lit/dimmed lit screwdriver is tell me. (On a known live, in the same physical location it lights up correctly)

 

 

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Half- lit means leaking slightly. Neons begin to light at 90v or so IIRC.

 

Could be an internal fault keeping the "switch" partly on, eg a capacitor or diode; a neutral fault on the load not allowing it to take the natural leakage of the "switch" down low enough; or an induced voltage in the wire to the load caused by proximity to another.

Or any combination thereof.

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I’d be inclined to say to put a relay in between the switch and the ‘controller’ tbh, as this is the exact same switch that @PeterW and I fitted in @newhome‘s install ( which = “ tried and tested “ ). 

The relay will not change state with ‘ ghost voltage ‘ but it appears the controller clearly is responding to this sub manis voltage signal so IMO I think that would sort it. 

@readiescards,

Take the live trigger ( output ) wire from the flow switch and have it power the coil in a normal relay ( solid state may not be a good idea ) and have the relay convey the common ( the live into the flow switch ) to the pump controller unit. 

That should give a definitive on or off signal to the unit and resolve the issue.

In @newhome‘s it went;

switch > relay > pump and worked well, just yours has an electronic component downstream which clearly doesn’t like ghost voltage.   

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  • 1 month later...

The moons have aligned and I've been able to access the holiday whilst my son was around to turn the hot tap on!

The resistance of the flow switch was:

no flow - 24 m Ohms

flow - 33 k Ohms

 

I'm surprised at such a high resistance for the 'on' value.

20190614_180840.jpg

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presuming it's not an electronic switch of some kind (Hall or somesuch) I'd say your reed switch is failing. You could try "cleaning" the contacts by applying a higher-current load, or trying them in a DC circuit.

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