I've got a Drayton Tempus One timer controlling my combi and want to bridge it with a thermostat so I can leave the timer turned off during the warmer months whilst maintaining the ability to turn on the CH if the temp drops below a certain point at night. Purchased a Danfoss RET-MD and wired its switched contacts across the timer's switched contacts, but the control voltage to the boiler drops to around 190VAC. Even with the timer out of the circuit altogether the control voltage is low. The wiring diagram for the Danfoss stat indicates that the switched contacts are isolated but something is drawing down the control voltage.
Any ideas where I'm going wrong? tia!
- cal