Horstmann E7 Quartz

[DNW]

My Control is about 15 years old, in dark green colour, but seems to be in good working order, except - To save costs, I switch the Water Heater button from "Timed" to "Off" position so that it won't come on automatically over-night and use the Boost Timer during day time whenever I need some hot water. I thought it would be locked to "Off" position but of late the Water Heater (mechanically or manually controlled) strangely switches on itself and moves back from "Off" to "Timed" position so that I have a full tank of hot water in the morning unnecessarily. It does not happen every night but about once a week. Can anyone please help explaining why it would mechanically switch back to "Timed" position? You have to push hard up and down to operate the switch and I don't think it is worn. Also the Boost Timer does not seem to be moving as it stays at the same position. Once set, should it not be moving from "Start/Set" to "Stop" direction automatically?

 

[ericmark]

With a 40 gallon tank of hot water unless using the Irish Willis system time controls temperature of water, not amount of hot water, and it takes so long to cool, only normal reason for a timer is to take advantage of off peak rates.

The Willis system uses an immersion in a small tank alongside the main tank and heats from top down, but only found in Northan Island.

There are other reasons, have considered a timer my boiler has no tank thermostat so since the immersion does, for it to switch on once a week after the boiler has turned off could be a good anti legionnaires precaution, as long as run for long enough.

And this is the problem with any timer, except Willis system, you need to ensure any water heated exceeds 60ºC.