"Changed for same as previous one had lasted for 20+ years and had finally stopped turning boiler on (a resistor had burnt out) easy to swap just had to take front control panel off, but as my rear bracket was cracked (where it is wired up to) I changed that as Well just swapped the wires like for like, no drilling extra holes even after all these years it is exactly the same. A bit more expensive than others on market but due to the reliability of previous one decided to stick with the same."
"Fitted as a replacement for exactly the same unit that must have been about 20 years old. The battery had gone in the old unit otherwise it was working fine. It appears very expensive compared to the competition and has a basic set of features. Having said that it works well, is relatively easy to use compared with some of the others and is no more difficult to install although in this case it was a straight plug in replacement."
"This timer has been around for quite a while now, to the extent that some of the original versions are now reaching the end of their (long) useful lives and giving up!
I've just replaced an 'old' ST699 like with like for a customer to keep down the cost of the change-over.
No messing with wiring - the back-plate on the current version is still the same as when the original was released more years ago that I care to remember (or indeed, can remember!) so just the timer box needed to be swapped.
The ST699 is now looking dated and is overpriced for such a basic 24 hour timer, but as with all things Honeywell it is robust and will last and last and last.
The ST699 will cope with both fully pumped systems or gravity feed hot water and pumped heating.
Some of you might want the benefits of 7 day timing, in which case you need to upgrade to the ST799."
"Expensive and unreliable. However, it is very simple for the end user to operate and straight forward to install. I only ever buy one to replace one of the many I find not working properly on an almost weekly basis."