Boiler problem after draining down system

[wilko690]

Hi, before i call in the engineers i wondered if someone here may know of something that i've overlooked.

I had a problem with a 3 way motorised valve not turning between the ports. i knew i could change the motor but as it had been in the system for quite a while i decided to change the complete unit. not a problem as i had done it many a couple of times in the past.

I drained down the hot water cylinder and rads, turned of the rising main and tied the expansion tank ball valve in the raised position, however I did not drain the boiler. The old valve had 5 wires including earth, the new unit only had 4 no earth. wired it as per old unit excluding earth.

went to fill system, then problem started. neither rads or cylinder would refill, expansion tank filled to capacity without filling rads. worked out must be a blockage, which i cured by blowing back through the vent pipe. Then found that pilot light on boiler had gone out, unable to relight.
Thought it must be something to do with the new unit and its wiring so I refitted the old unit. still no luck cant see a spark and don't know if gas is going to the pilot light. does this have a shutdown system if there is no water getting though??

The boiler is pretty old but has always worked well, I think its a Baxi 382

Any advice apart from getting a professional in, as I know that will be the next step, just thought there may be something I need to check

Thanks in advance

 

[Whitespirit66]

Check that you have bought the right type of motorised valve.

If your original had 5 wires, then it will be a mid position 3 port valve. 4 wires in your new one will probably mean that you have bought an ordinary 3 port valve.

 

[twgas]

no shut down system on this boiler other than thermocouple, igniter probably dead-try removing viewing window and light with match,

the new div valve is simply double insulated so doesnt need earth