Pipe Stat

going by a stat this standard pipe clamps on 22mm or 28mm pipe hot water and held by springs, the problem with this type of stat is that it is time to start even when the pipe was hot enough for 10 minutes (is there a better type of pipe stat on / off switch earlier), I thought of an idea if you engage a temperature gauge which has a mechanical hand that moves for reading is in a sealed tube curves which is filled with a special liquid when the liquid is hot, the curved tube try to pinch it could it not be used in conjunction with a micro switch and be installed as a stat pipe, other people must have thought of this idea before me, if this type of pipe stat is on the market could you let me know.

Ambient temperature hose stats are normally mounted on primary solid fuel to prevent hot water from overheating.
These types of thermostats have been on the road for many years and have been rather successful.
Depending on where you place your stat and what it is used or can not be part of the reason why its not working to your satisfaction.
Always use a large amount of heat transfer compound on these statistics to make them work more accurately.

Can not you lag your pipes and wrap in a cloth behind / hardware on your stats, tooa