Conventional boiler cylinder ACL HTS2 not working?

[Skylark NW]

I heard a public info ad recently saying that if the hot water is too hot to bear when washing hands, the thermostat is set too high.

This applies to me, despite my ACL HTS2 thermostat being turned fully counterclockwise. I'm assuming a problem with the thermostat, installed 1987. Is this a common fault? Would exercising the temp control screw make any difference? To be honest, the water temperature has been "too hot" for many years but I've taken no action.

A quick search shows the HTS2 to be obsolete. Is an HTS3 fully interchangeable?

I'd appreciate the knowledge and experience of the forum. Many thanks in advance.

 

[oldbuffer]

1. Its unlikely that the "ad" was referring to the cylinder thermostat. This needs to be set to around 60 degrees to avoid the proliferation of legionella bacteria. It's possible to heat the water to, say, 40 degrees, then once a week heat it to 60. OK if done automatically, but very easy to forget if manual.
2. The trend is to fit a Thermostatic Mixing Valve (TMV) to the hot supply of outlets. This limits the temperature at the outlet, generally to around 38 - 40 degrees by mixing cold into the hot. Fitting a TMV is obligatory in hospitals and nursing homes.
3. Turning the thermostat down will only make a difference once the water has cooled below the level you want, and is then heated up again. The thermostat will then shut off the heat source when the new, lower, temperature is reached.
4. The HTS2 is probably still working. Worth trying per 3. above before replacing.
5. The HTS3 can replace the HTS2. The HTS2 I believe came pre-wired, the HTS3 doesn't. Provided you know how to isolate the electrics, you should be able to fit it yourself. Do remember that these have mains voltage on them, and its best to turn off the power to the whole property at the consumer unit or units. If you can't do that, don't touch it.
6. The Drayton Controls web site will have a wiring table.

 

[oilhead]

60oC at 1/3rd the way up the cylinder can result in much higher temperatures at the top take off from the cylinder.
Any cylinder stat will be compatible but they are all quite coarse in there settings.