How do I use/program 2 CH controllers?

[MrCheese]

I've moved into an old house with a Trianco Contractor oil powered boiler. Connected to that is a Danfoss SET2e.

In the hall is a Honeywell CM67.

There is an electric hot water immersion heater upstairs in the airing cupboard.

I'm not sure how I should use the Danfoss & the Honeywell together - lets say I want the heating to come on every day at 7am and switch off at 7pm, I can program that on the Honeywell. Do I just need to program the Danfoss to be on at the same times.

If I set the Danfoss to be on all the time and the Honeywell to switch on/off at different points in the day, will I be wasting lots of oil having the boiler on when the main timer is off?

Any help or pointers would be greatly appreciated as I've only seen systems with one controller before.

 

[TicklyT]

The Danfoss is a programmer, controlling the on / off times for your system.

The Honeywell is nominally a thermostat, controlling the temperature the house will be heated to.

.......but.......

Modern programmable thermostats have taken over many of the functions of the programmer, controlling both time and temperature.

So it depends on how the system has been wired up, and how the heating system is piped.

Some systems were piped up with gravity hot water and pumped heating. For this, the timer controlled the boiler,and the thermostat controlled the pump. The final hot water temperature is controlled by the internal boiler thermostat.

Other systems are piped up with automatic valve(s). On these systems, the controls, along with a cylinder thermostat, operate the valve(s), and switches in the valve heads control the pump and boiler.

The programmer may be set up to have overall control of the on/off times for the heating, and may be the only time control for water heating.

Or the programmable thermostat may be set up to control both time and temperature for heating, leaving the programmer to control the hot water heating only.

Even with both timers on, the boiler should only run if there is a call for heat from either heating or hot water system.

 

[simond]

Providing the system is a modern fully pumped type, I would suggest you leave the Danfoss programmer CH section set to 'ON 24hrs' and use the CM67 to control all heating requirements.

The Danfoss then becomes just a HW timer.

 

[D_Hailsham]

The Honeywell is nominally a thermostat, controlling the temperature the house will be heated to.

The CM67 is a programmable thermostat. It's the predecessor to the CM927.

The Set2e has the options for HW only or HW and CH, which suggests that you have an old system with pumped heating and gravity hot water.

Rewiring so you can use the Set2e for Hot Water and CM67 for heating will be tricky.

Do you have a motorized valve in the HW cylinder pipe and a thermostat on the side of the cylinder?