Hi there.
I have “Y Plan” central heating and hot water system.
I have a very basic timer that allows me to turn each of the systems on/off a couple of times a day.
I leave the central heating system constantly on and control the heating with an electronic thermostat, which gives me a lot more flexibility as to when to come on.
However, the hot water is the issue - I want to have more control over this and would like to replace the timer with a relay (Zigbee), so that I can heat the watertank via HomeAssistant.
I have a few initial queries:
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Are there any relays with their own “failsafe” built in? I.e. that will automatically turn off if they have been on for a certain time? What I am concerned about is that if the hot water is on and my HA system crashes, I might be left with the hot water tank being constantly heated all day, when I am out.
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Are there any ways to somehow test the heat of the water inside the tank, so that I can have the hot water come on earlier if necessary?
At the moment, we have the hot water timer to come on at about 5.30 am, so we know that by 7am, we shall have enough water for a bath.
However, if someone used all the hot water from the night before (for example, lots of washing up and a bath before the bed), there is still not quite enough hot water and it could have done with coming on at 5.00 am instead.
I would say that I recently bought one of these:
to control my extractor fan.
It is working brilliantly but I am hesitant to use it with my hot water because of the lack of redundancy.
Any pointers/advice would be very much appreciated.