Central Heating Zone control?
Hi Fox,
I am starting to see a five zone central heating system here...
A master time clock killing the whole system during the night etc, each of the 5 zones having its own room thermostat controlling a zone valve (shutting that zone down when the room is warm enough but allowing the rest of the house heating to continue).
Even if this isn't your application it may help to visualise things?
My last post (titled Relay Logic) would cover this scenario perfectly. The live supply going to the master clock switch, through the switch (switched live) to all five thermostats. Each thermostat switching its own zone valve (all zone valve neutral leads then return to mains neutral).
If you really need relays then small ones are available that are reasonably quiet and are rated for 100,000 operations (that's 2.5 months at one operation a minute or 11 years at once an hour, all day, every day!).
If you really want TTL logic then the circuit is easy but the input 240v AC to 5v DC isolators on every input and 5v to 240v isolators on every output will complicate the building a lot as you are ruling out relays (the easiest form of isolator). :idea: Maybe small transformers & rectifiers could be used on the inputs?
PM me (button below) if I can email diagrams to you?