Very nice presentation, I made a video very similar for Allen a while back, but I have to say that I disagree with how your showing people how to test the thermistor, by using the displayed temperature on the front of the boiler and checking it against the resistance reading will always read the correct reading, purely and simply because the temperature which is being displayed on the front of the boiler is coming from the thermistor your testing so of course it’s going to be right. You have to use temperature clamps to ascertain the actual temperature and not rely on the display and the. Check the resistance against your temperature clamps. Other than that your videos are very good for the new guys.
Have I missed something? The "Naughty Corner" - I've listened to what you said at the start, and IMO can't find anything wrong with it. NTC - Increase temp = decrease in resistance and vice versa, so decreasing the temp = increasing the resistance, same thing. So @ 0 deg C = 33.6K Ohms, @ 30 deg C = 8.035K Ohms. (chart). As the temp moves either up or down it has the opposite effect on resistance. So as I see it, because the thermistor is a temperature sensitive device, it is best to describe it in terms of temp and not resistance. What did I miss? Thanks.
There are a number of issues you could get with a faulty thermistor, for example if the thermistor was reading too low a temperature because it was failing the boiler would fire up in frost protection mode.
Hi Smartchip, In my opinion the new 800/600 range of Combi boilers are the best Baxi have produced, obviously I am slightly bias because I worked for them for over 20 years.
With my full respect to your colleagues from viva he mentioned thermistor used for temperature, and flow also, as I know thermistor not used for flow measuring. Please let me know if I am wrong . Thanks
Hi Kamal, thanks for your feedback, some boilers which have a thermistor fitted to both the flow and return, will use the difference in temperature between them to detect the pump is running. When the boiler is at rest both thermistors will be about the same resistance, then as the pump comes on and the boiler fires the flow temperature will rise quicker than the return temperature.
Hi Jon, It's a Fluke 3000FC, the reason I got that is because of the Fluke Connect App so I can show the readings to camera when we do the videos, for training students I use the Fluke 114 as its easy to use and robust.