immersion stat

You can get things a bit like TRVs, which instead of measuring room temperature, measure hot water cylinder temperature and close off the coil when it's up to temperature. (I presume this is an indirect system?) I'm not sure what the right name for this is, so I'm struggling to find it on google.

Danfoss seem to call them Temperature Controllers.

There are versions with variable maximum temperature up to 60 or 90 degrees.

The AVTB are a combined sensor an valve, the also have sensors that can control separate valves if that suits better.

The original ones were "silitron" valves or something similar... - however you can do the same with a two port motorised valve and a cylinder stat.

However I am not usre if that is permitted if the Rayburn is a solid fuel one with gravity (thromo syphon) circulation?

Erm, surely if the water is getting so hot, it cannot be doing much good to the heating element either. I'd have thought attempting to stop it getting so hot was a safer approach. Brian

No neither do I but they work much like the ones in some older cars to stop the radiator boiling over etc. Brian

Heating elements in kettles get to 100 centigrade, those in irons and cookers over 200, doesn't seem to harm them.

They are around. I fitted two immersions into a thermal store last year and each had provision for two stats. They were fitted with one normal adjustable stat scaled up to 70 ish and the other also adjustable but with a reset button for the over-temperature protection and wired in series.

It is obviously cheaper for the industry to use a single item if it will fulfil both roles though.

I also bought a couple of high range stats - standard fitting but for more industrial applications that were scaled up to 120.

Contact me directly if you want details of the source of those.

Bob

Very much hotter when covered in scale.

Actually, that's the element outer casing - the element itself will be well over 100C, as it's packed in magnesium oxide insulation.

Even if permitted you really don't want to have anything able to close the the gravity loop from a solid fuel boiler and a gravity loop is what it should be as well, not pumped. Unless that pump is a "load controller" set up to allow gravity circulation if the pump isn't running.