Make the Probe

Fig. 1

The easiest way to make the probe is to insert a cable
(preferably a silicone cable) in a nipple that fits your boiler. The casting can be hard silicone rubber or reinforced epoxy that can withstand over 100 degrees. See Figures 2 and 4.

Another way is to fit a teflon tube into a bush with a brass shaft. See Figures 1, 2 and 3. The fitting must be tough. (The teflon expands in heat and moisture which makes it dense)

Fig. 2

Fig. 3

Fig. 4

Tips & Ideas

Sometimes it can be difficult to fit the probe because of too few boiler bushes in the boiler. One way is through the water gauge upper nipple. See Figures 1 and 2.

Another way is to enter a blanking plug. See Figures 3 and 4.

fig 1

fig 2

fig 3