Boiler won't run properly. No hot water. Oil Burner

[confuscius]

I have a problem I need to fix so please help. The boiler is an HRM Wallstar burning 28 second RBO. It runs the heating using a room thermostat and Grundfos Selectric circulating pump in the airing cupboard upstairs and a Honeywell Three way motorised valve controlling water for heating/ gravity hot water. It has a water cylinder upstairs with a Honeywell T70 cylinder thermostat strapped on the side. The timer unit downstairs is a Potterton EP3002. I discovered the boiler had turned itself off and operated the EP3002 on/off slide and when I turned them both back on again the boiler fired and ran for about an hour then turned itself off again. When I turned the heating and water slides off again and then turned the heating on the boiler ran constantly and the house got boiling hot and ignored the room stat. Only turning the on-boiler dial down cooled it down and obviously there was no hot water. I bought a new EP3002 and swapped the new front over (but not the new backplate) and this did not fix it. I changed the powerhead of the three way valve fitting a 4000-3916-003 replacement powerhead but not the valve itself. The boiler fired and ran for a couple of hours but I checked the 3 way valve and found it was operating constantly back and forward. I noticed the cylinder was now hot. I opened the box containing the wiring centre and ,with the power to the EP3002 turned off , there was still power flowing through the single orange wire aswell as the single white wire. I thus decided the cylinder stat was faulty and replaced it with a Honeywell T55 set at 60 degrees C. The valve has stopped constantly operating back and forwards. The boiler turned on and ran but kept turning off and then reigniting. The boiler now fires, runs for a while but then shuts down the orange light. Turning the water slide off on the EP allows the boiler to run and heat the house. Nothing has been changed before the problems began although I moved/disturbed the EP 3002 which is not fixed to the wall but resting on top of the boiler to get to an aerial wire behind it. This morning I found that the boiler had again turned itself off. When I turned the room stat up it fired the boiler. The room stat clicks ok. I had left the hot water slide position at off. I don't know whether it is my imagination but it seems to be ok until it gets up to temperature andthen things start to turn off. Any help would be greatly appreciated.

 

[grib]

Exellent decription of your system (except for the gravity hot water bit as wallstars only have two pipes and you have a diverter valve so it is clearly pumped.... but now I'm just being pedantic).... Not so sure what the original problem was except the boiler was turned off (why did you notice this..no heating, no hot water, what was the symptoms ?)

Before getting too far into this problem can you confirm that when you changed the valve head you ABSOLUTELY got all the wires back in exactly the right place?

If you follow this link and check the wiring diagram for the Y Plan you should be able to check through that you have re wired it correctly. http://content.honeywell.com/uk/homes/systems.htm... There would also have been a diagram in the box with the valve head if you still have it.

 

[oilman]

From the mention of the aerial, it seems you have a wireless controller. If this is the case, you could be getting interfered with.

 

[confuscius]

Hi Gents and thanks for the swift replies. Firstly my apologies to Oilman for misleading you but the aerial relates to the TV mounted nearby. The Programmer is hardwired. With regard to the wiring of the valve I believe I have just copied the old wiring into the wiring centre wire for wire. Having reread the wiring diagram mention is made of adding an additional link in between the grey wire and, from memory the hot water connection. This I have yet to do. I had thought it was just a question of old for new. I hope this fixes things and will come back to you but any comments in the meantime most welcome. Thanks Grib and Oilman.

 

[confuscius]

Hi gents, You were right about the wiring. Having swapped over "C" and "1" on the cylinder stat and running a wire between the grey wire and the HW ON position on the EP3002 the system works again. I basically took the whole wiring system to bits and reassembled it using the wiring diagram supplied with the powerhead. Success! Thanks for your help.

 

[WDIK]

the grey wire as you descrbe is usually associated with the orange, in that when the valve is in the on position grey to orange is the micro switch proving the valve has moved to the on position
in other words makes a circuit between orange and grey