Hi Neil,
Thank you for the feedback, and I'm sorry that you have experienced some issues with our pressure switches.
The blowing of the trip can be caused by many factors, including the type of trip. Faulty wiring, moisture or switch failure could have been a possible cause. Too many switch cycles per minute would also cause premature failure due to burning of the contacts; this can also be caused by faulty or incorrect installation of the expansion vessel.
If you have any issues with the next pressure switch, please get in touch with us at: 01777 871100. My concern is your next switch will likely do the same if the failure cause is not rectified.
Mark - General Sales Manager