PerfectPrime TC41/T2, 4-Channel K-Type Digital Thermometer Thermocouple Sensor -200~1372°C/2501°F, 20 x 4 Data Log Storage Function (2 Pipe Clamp)

This thermometer seemed to be the best value when I looked through the various options at Amazon. A range of thermocouples are provided, and this is a flexible product that is easy to use. The item was despatched from Hong Kong but reached me in an incredible four days, having passed through Belgium and France before arriving at my home in England.

Update :I have no idea whether pipe clamp thermocouples need several uses to 'bed in', however, the readings are now closer to those from the bare wire thermocouples (1.5-2.0C lower, rather than ~7C lower). That puts them into more of an acceptable range of accuracy and I will use them for a more extended period to see whether they improve further.Original review :I bought the Perfect Prime digital thermometer to test the pipe temperatures at various locations around my home heating system. The pipe clamp thermocouples looked particularly useful, for obvious reasons.It soon became obvious that something wasn't right. Using only the two supplied pipe clamp thermocouples on the flow and return pipes, at the boiler connections, the Perfect Prime display unit was giving different readings compared to the digital temperature gauge on my Vaillant boiler.I did two tests :- Placed one of the 'bare wire' thermocouples in a kettle of boiling water. The digital unit displayed a temperature of 100.8C. This indicated that these thermocouples result in an accurate reading.- fixed a 'base wire' thermocouple on to the flow pipe, as well as one of the pipe clamp thermocouples, while the boiler was in heating mode (burner was firing). I waited for the displayed temperatures to stabilise and saw that two different temperatures were displayed. Bare wire = 64.2C; clamp = 56.6C. The pipe clamp thermocouple was reading 7.6C/11.8% lower than the bare wire unit. Ridiculous !!There is nothing in the User Manual relating to calibrating any of the thermocouples/clamps so I assume that they are all intended to be used 'out of the box'.Overall the unit is reasonably well made but, for me, the potentially most useful components (the pipe clamp thermocouples) are precisely what ruins the ease of use and accuracy of the unit.Digital thermometers with twin 'base wire' thermocouples are available for less than 1/3 of the price of the Perfect Prime kit, and that's certainly what I'd had I known what I know now.

Perfect for balancing your central heating radiators.