Hot Water but No Central Heating

[keithmdw]

Again, a little unrelated, but I have learned a lot here so I thought I'd ask to widen my knowledge.

On my system there are two sliders on the programmer - one for CH and one for DHW.

In for instance, I slide the CH slider to ON (or the timer puts it on), what happens netx? I assume it waits for the thermostat demand heating? And then what, is that the point at which the 3-port valve comes into play and opens and requests the boiler to fire?

 

[MANDATE]

Putting the CH slider across supplies power to the room stat and if it's set high enough then the room stat supplies power to the motor on the 3 port valve. This will move the valve in two stages, firstly to mid point where it drops one power supply and picks up another which is used in the second stage. During this second stage a microswitch is also activated which allows the power to operate boiler/pump. (This was assuming the valve was at the HW positon when you put CH slider across, but it could have already been at CH position, it which case the boiler/pump would have the power without the valve moving). So you're right.

 

[keithmdw]

Thank you.

I am learning a lot. This all meant nothing to me before this problem, but I know understand a lot more about how everything works. Could never attempt to work on it myself (for that I will let an expert take over) but at least I know what I am talking about.