Sorry Paul, I did not know you had asked a question 5 days ago, I only just stumbled upon this question today (23rd Jan) purely by chance, I am still relatively new to these forums and didn't see any notification that you had asked a question.
What I did was by passed the faulty timer, but the problem becomes a little tricky as the timer acts like a junction box since mains is first wired to it from the mains fused spur, since the timer also requires mains power to drive the clock, and then from here the power feed is then taken to the boiler, Live is wired to the boiler at terminal marked L3, Neuteral is wired to the boiler at a terminal marked N, and the earths are connected to the boiler in the middle terminal with an earth symbol.
What type of timer your installation is using i have no idea, but the general principle is below:-
Then L2 is the boiler control wire, when you apply live to L2 via the Room Thermostate contacts, it will fire up the boiler in the CH mode, L1 is internally looped to L3 permanently at the boiler end, so when the plug is pushed into the boiler L1 can be Live at 230v!
I had to leave my faulty timer wired in as it was being used as a junction box come timer, so i did not de-commission it, otherwise you will need to re-alter the wiring, so essentially I traced the two contact wires from the Room Stat, back at the timer module, and wired one wire to Live terminal at the timer, the other contact wire I wired to another terminal on the timer which also leads a wire back to the boiler at terminal L2, leaving all other wires terminated as were,
In other words, one of the contact wires from the Room Stat was terminating at a certain post on the Timer, and one of the other contact wire from the Room Stat was wired at a terminal post that also leads away to L2 on the boiler, so leave the Room State contact wire on the timer where it is, and remove the other contact wire from the room state and wire it to Live.
So each time the room state contacts close, i.e. when you turn up the heat demand, the boiler would fire up, and when the room reaches the set temeperature the contacts would open and boiler would stop.
But remember to set sufficient flow temeperature from the boiler so as to allow radiators to warm up the rooms to the required temeperature or else if the boiler flow temeperature was set too low, then the rooms might not reach the set temeperature according to the room stat setting and the boiler could go on forever!
Mind you i prefer the later method at my own house, i use low flow temerature and allow the boiler to run 24/7 and it maintains a nice steady temeperature throughout the day and night instead of running it at flow temperature and allowing bthe room stat to control boiler heating cycling, so i set my room state to like 25degrees and since I run my boiler which is vaillant at 35 to 40 degrees flow temeprature and this maintains a steady 20 degrees throughout.
Occasionally if it gets very cold outside, i may have to increase the flow temeperature to say 50degrees, that more than componsate for cooler outside temperatures and the inside is still around 20 to 21 degrees. ( I used nearly 10,000Kwh between 7th October and 10th Jan and my gas bill came to £350.00 with constant 24/7 heating.) And my boiler is an old vaillant 221 and is 15 years old and still going strong.
What I did was by passed the faulty timer, but the problem becomes a little tricky as the timer acts like a junction box since mains is first wired to it from the mains fused spur, since the timer also requires mains power to drive the clock, and then from here the power feed is then taken to the boiler, Live is wired to the boiler at terminal marked L3, Neuteral is wired to the boiler at a terminal marked N, and the earths are connected to the boiler in the middle terminal with an earth symbol.
What type of timer your installation is using i have no idea, but the general principle is below:-
Then L2 is the boiler control wire, when you apply live to L2 via the Room Thermostate contacts, it will fire up the boiler in the CH mode, L1 is internally looped to L3 permanently at the boiler end, so when the plug is pushed into the boiler L1 can be Live at 230v!
I had to leave my faulty timer wired in as it was being used as a junction box come timer, so i did not de-commission it, otherwise you will need to re-alter the wiring, so essentially I traced the two contact wires from the Room Stat, back at the timer module, and wired one wire to Live terminal at the timer, the other contact wire I wired to another terminal on the timer which also leads a wire back to the boiler at terminal L2, leaving all other wires terminated as were,
In other words, one of the contact wires from the Room Stat was terminating at a certain post on the Timer, and one of the other contact wire from the Room Stat was wired at a terminal post that also leads away to L2 on the boiler, so leave the Room State contact wire on the timer where it is, and remove the other contact wire from the room state and wire it to Live.
So each time the room state contacts close, i.e. when you turn up the heat demand, the boiler would fire up, and when the room reaches the set temeperature the contacts would open and boiler would stop.
But remember to set sufficient flow temeperature from the boiler so as to allow radiators to warm up the rooms to the required temeperature or else if the boiler flow temeperature was set too low, then the rooms might not reach the set temeperature according to the room stat setting and the boiler could go on forever!
Mind you i prefer the later method at my own house, i use low flow temerature and allow the boiler to run 24/7 and it maintains a nice steady temeperature throughout the day and night instead of running it at flow temperature and allowing bthe room stat to control boiler heating cycling, so i set my room state to like 25degrees and since I run my boiler which is vaillant at 35 to 40 degrees flow temeprature and this maintains a steady 20 degrees throughout.
Occasionally if it gets very cold outside, i may have to increase the flow temeperature to say 50degrees, that more than componsate for cooler outside temperatures and the inside is still around 20 to 21 degrees. ( I used nearly 10,000Kwh between 7th October and 10th Jan and my gas bill came to £350.00 with constant 24/7 heating.) And my boiler is an old vaillant 221 and is 15 years old and still going strong.
