07-11-2016, 03:33 PM
The flow temperature sensor will be an NTC thermistor - do these go wrong with age?
On that boiler, it ought be a decent one. Accurately knowing the flow temperature is an essential part of the "Weather Compensation" scheme that Viessmann do. In warmer times, the flow temperature can get as low as 30C, so it would have to maintain its accuracy down at those levels.
At the risk of stating the obvious, IR thermometers under-read from copper. A layer of black insulating tape is all you need to get an accurate reading. But certainly, I'd expect 30C to result in pipes that are warm to the touch compared to the adjacent gas pipe...
But having said all that, it's entirely possible that they cheaped out when doing the control electronics for that boiler, given that the 100 model was a cut-down UK special.
Anyway, it's easy enough to check, as the installation guide gives a chart of temperature vs resistance for the sensor (see attachment).
On that boiler, it ought be a decent one. Accurately knowing the flow temperature is an essential part of the "Weather Compensation" scheme that Viessmann do. In warmer times, the flow temperature can get as low as 30C, so it would have to maintain its accuracy down at those levels.
At the risk of stating the obvious, IR thermometers under-read from copper. A layer of black insulating tape is all you need to get an accurate reading. But certainly, I'd expect 30C to result in pipes that are warm to the touch compared to the adjacent gas pipe...
But having said all that, it's entirely possible that they cheaped out when doing the control electronics for that boiler, given that the 100 model was a cut-down UK special.
Anyway, it's easy enough to check, as the installation guide gives a chart of temperature vs resistance for the sensor (see attachment).
