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A question if I may before I dive in.
I have an old gravity fed CH system which thanks to members here in the past - works very well.
It has a Danfoss Randal 3060 programmer that has died.
I have the original installation docs for the programmer - and it shows 7 terminals plus the earth.
In the wiring diagram from Danfoss - terminals 3 and 5 are not used.

I took my cover off , and they are used , so this is the beginning of my problem.

I have traced all wires and have the following.

Room Stat
Frost stat
Hot water stat
Central heating pump
Hot water pump
Boiler
Power supply

Ive drawn a schematic to try and get my head around this , but when looking for compatible replacements for 2 channel controllers , that reference to 2 terminals is still missing in the various cross reference tables.

Ideally - I would like to know how to wire each of the 6 components into a controller please ?

Many thanks

Steve
 
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Room Stat
Frost stat
Hot water stat
Central heating pump
Hot water pump
Boiler
In the main smart devices do the job of room stat, and since it alternates between some eco and comfort setting no need for a frost stat. The problem is the "Hot water stat" it only does anything in summer, but the likes of Hive are designed not to use the hot water stat.

There are three basic diagrams, C-Plan_old2.jpg this was the norm for years, then we added the tank thermostat C-Plan_old.jpg and finally we added a motorised valve, C-Plan.jpg all C Plan means is it is thermo syphon, and smart thermostats have different ways to control it.

Hive has a separate supply to pump and boiler, and a software fix, Nest uses the fact it has volt free contacts C-Plan_basic_Nest.jpg I think this C-Plan_basic_Nest_tank_stat.jpg will likely work with Nest, however I feel Nest is a poor option as it has no option to work with TRV heads.

Many systems are like Hive, with terminals internally connected, I think the Nest second diagram will work, but I have not tried it, so crossing fingers I have made no errors.

So wait for a few more replies and see if they think my diagram wrong, I remember doing boolean logic, but a long time ago, so maybe I have made an error.
 

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