Boliermate 2000 replacing store sensor

What is involved in repalcing the store sensor (GT149) on a Boilermate 2000? Does the system need to be drained? Is it a job for a heating engineer or could I have a go?

I assume it is this sensor, sometimes when I turn up the thermostat in the hall the heating doesn't come on and it can take 10/15 minutes before it fires up. Also sometime the heating won't turn off when I turn the thermostat down.

I noticed yesterday when I had the panel off the Boilermate when it wouln't turn off, Store_T1 was showing oEr (Sensor error) and flashed 99 (degrees) briefly.

The top sensor is easy to replace. No need to drain the boiler. Turn off the mains water, drain the pipes, unscrew it and put the new one in. I had to replace the top sensor when my hot water was fluctuating and hot water pump was making low grunting noise.

The other sensor can be replaced without draining if you are prepared to get wet a bit. Cool the boiler first and quickly replace the sensor. Or go through draining process and at the same time add inhibitor when you refil the tank.

Hi the store sensor fits in a pocket in the tank so is not in the water system. Generally they come out OK but the odd time they can stick a bit. Please note these sensors are not thermistors they are active devices so have +5v supply to them so please ensure you wire them in correctly. Hope this helps.