QUESTION ABOUT SPARES!

[oilman]

CHeck your GSIUR. Basically you mustn't go altering any design unless you can show that your moodification is at least as safe as it was originally. SO you can change some fixings or summat but I wouldn't go changing the design of a safety related bit on a boiler.

Agreed. The stat I replaced was a phial in a pocket fitted across the diameter of the outlet pipe. Mounting a pipe stat on the same pipe was the nearest I could get to the original position. The boiler had been running on the hi-limit stat for months. I set the pipe stat to operate at 75, so even if the pump stopped it should reach operating point before the limit stat.

Sludge in this system was unlikely as I had just powerflushed it.

For safety requirement, you could use two stats in tandem, one a pipe stat, and the other fixed to the surface of the he.

However, I accept gas boilers are more of a legal minefield.