lots and lots of options, from the Honeywell DT90e, but I'd suggest you consider a programmable stat since you are going this far. These will take care of both the temps and timings, so' they'll run yer hoosie.

Honeywell T6360 (English - 4 pages) User manual Honeywell T6360 (English - 4 pages)

You can use a wireless thermostat with a combi and they frequently are. For example in a new installation, or with one that already has an existing wireless thermostat. The wired receiver can be connected at any convenient point, usually next to the boiler, and then the thermostat can be positioned in the best location without the need to run a new cable out to it. Although not good practice, you could use the earth wire as the switched live but you should put red sleeving or insulating tape round both ends to show it is not an earth wire. Don't forget to change both ends of the wires! It's a straight swap, the diagrams you posted show that the terminals of the old and new thermostats have exactly the same function number for number [1 is live, 2 is neutral, 3 is switched live]

That does sound like a faulty 'stat all right, tho' I guess other things could cause similar symptoms (tho' not sure what!) With its compact and unobtrusive design, the Honeywell T6360 thermostat blends seamlessly into any room decor. It is built to last, with quality materials ensuring durability and reliability over time.

Honeywell Home 1-Channel Wired Mechanical Room Thermostat Honeywell Home 1-Channel Wired Mechanical Room Thermostat

if so, it becomes more complicated. This is really for systems where there isn't an existing wired thermostat and the thermostat installation is from scratch. So to answer your question, if you do have the Wiser with the control box, the best way forward would probably be to exchange it for the wired version.I suspect the thermostat isn't correctly calibrated at the moment as I seem to need to turn it right up to the top for the heating to come on. As this needs looking at I was thinking of replacing at the same time with a digital thermostat. Thanks everyone, super helpful as I can't say this is a subject matter I know anything about! Hmm perhaps a prog stat might be a little bit of overkill then as do all my programming on the boiler at the moment and that all seems to be working fine. I would like to lower the temperature that the thermostat is set to turn on the heating, but having removed the front cover, it isn't obvious how to do this.