Hi guys…newbie here, hope someone can help…my boiler appears to have a reoccurring fault and I’d like to know if I do a multimeter continuity test on the two contacts in the pic and not get a beep…does that mean it’s faulty…even when I adjust the potentiometer I don’t get a beep. If it’s working properly shouldn’t I get a beep at some point when I rotate the potentiometer? Thanks Mike

 

The two end contacts of a potentiometer have the full resistance track between them, so it is unlikely that a continuity test (which checks for low resistance) would show continuity and cause a beep.
If, however, the pot wiper is connected to one end contact (i.e the pot is wired as a rheostat), then the continuity test should work at one extreme setting of the wiper.
The above assumes that the board is not powered up during the test. Any continuity or resistance test will likely be corrupted if the board is powered up.
Do you have any reason to suspect the potentiometer is faulty?

 

Thanks Alec….much appreciated…the potentiometer is part of the front panel on my central heating boiler and it’s failed twice before and just done it again. I get a message saying OFF which, when the boiler is working, will happen if I turn the potentiometer fully anti-clockwise. However, when I turn it clockwise to full heating temp, the OFF sign goes off and the boiler runs. My engineer has changed this panel twice and I suspect will have to do it again. I’m thinking this is just a switch and if I link the two contacts together, thereby eliminating the switch, it will just stay on…I never adjust it, it’s always fully clockwise. what do think?

 

I’m thinking this is just a switch

You would need to verify that before risking shorting it out.

 

I have a pic of the control panel…it has OFF and MAX…so I’m guessing it’s a switch…when it’s working, I can hear a click as I turn the knob…I can’t hear any clicks now. This is one of the panels replaced…I have noticed that this happens following a power cut…not always but when it has stopped working it’s always following a power cut…would it have anything to do with the boiler powering up incorrectly…for example…should I ensure there is power and then switch the boiler on…because when there’s a power cut, it goes off and when the power returns it comes on again but directly, should it have power and then be switched on? I’m really at my wits end with this as you can see…but the fault definitely lies within this panel and this switch has been the only factor that has changed when the fault disappears….

 

I’ve done some more digging and come the conclusion it’s a rheostat and not a potentiometer….and the sort of device used to dim lighting as a dimmer switch…which can be bypassed…so if this keeps failing, I’m gonna short the contacts…but I’m also concerned that rheostats have very little in them to go wrong, just need cleaning, it’s not like they can break…or can the resistive material become so faulty it no longer functions as a conductor at all….the continuity test didn’t work regardless of where the wiper was….any thoughts anyone…