The W-B Greenstar 29HE installation manual shows a "Y-S wiring module" with a connection called "DV" or "Boiler/pump demand" but doesn't explain what this does. Am I right in thinking that it's an input to enable the boiler to fire only when the pump is running?
The FAQ mentions outside weather compensation but I can't find any details on the web, can anyone enlighten me about this?
Can anyone suggest a cheap basic 3 channel programmer?