I'll try to be clear in a field of which I know little... I have a new pellet boiler feeding hot water into a puffer for radiators and hot tap water. A thermostat in the house requests water at given intervals for the radiators. Fine, when I go on holiday, I tell the thermostat to wake up the day before I get back. But in the meantime, the puffer has been cooling due to heat loss and the boiler has been keeping the puffer temperature up. I would like the whole system to shut down until I programme it to wake up. Now, the manufacturer tells me there is a wire bridge on the circuit board. Without it, the boiler stays off, so what I would like to do is put a timer in on this. It's just one wire: out of one connector into another. Are there any times for just one cable? All those I've seen are plug-in between a power source and the utility. Any ideas? Thanks!
You need a relay, which is a usually part of a timer - but you need a timer which has separate contacts for its power, and the relay contacts, rather than a plug-in type timer that combines those.
This is not an uncommon configuration, but shopping questions are off-topic so you'll have to find one yourself. I wlll make a general comment that "DIN" relays (designed for mounting on a "DIN Rail" as part of industrial control solutions) often appear to be the most reliable form of these, but there are other form factors available.
You could also use a "plug-in timer" connected to a separate relay, but that's more parts than you actually need.
Concern: If you turn off the system completely while you are away, what happens if the temperature drops below freezing? Could be rather messy, which is why most systems are simply set back to 50-55F or 10-12C rather than being turned off, at least in heating season.