Horstmann C27 - heating keeps tripping fuse

[alphabeta]

Hi all,
I am having issues with my Horstmann C27 which keeps blowing the 5 amp consumer fuse. Used to have the Horstmann C17 before and had been working for a few years. One day when I used the Boost button it tripped the 5 amp fuse and screen went blank. Replaced the fuse but it kept blowing the fuse. Sometimes would go for 5 minutes, sometimes 10 minutes, sometimes half an hour, radiators heat up then at a random time the fuse would blow. Sometimes can have it come on for an hour and go off at a specified time without tripping but the next time I use it, it trips.

Thought it was the control panel so changed from C17 to C27. C27 is tripping fuse out as well. Attached is a simplified version of the way i have the back panel wired at the moment. Does it look right to you? Do I need to add other connections?

I know the C27 is a dual channel device for Hot Water and Central Heating but I only need the Central Heating side working.

My dad knows a bit about electrics and has separated the heating system onto it's own circuit but still tripping as I say.

Anyone any ideas as to why it might be tripping? Possibly a break in the wiring somewhere? What would be the cheapest way to get this fixed? Use a remote timer panel?

 

[AndyPRK]

I would think it unlikely for the timer itself to blow the fuse , but something on the heating system.

Disconnect pin 4 and run for half an hour + and see if fuse ok.

 

[Iggifer]

I would be leaning towards a motorised valve head going/gone faulty. Or the actual valve body itself sticking.

What boiler type/ heating system do you have? S-Plan/Y-Plan/Combi etc

 

[alphabeta]

Think it's Y Plan.

 

[alphabeta]

Boiler is Warmflow 50/70 and fully pumped system.

 

[Taylortwocities]

Try Andy's advice first. That will at least disconnect the live feed to the mid position valve. If it doesnt blow the fuse then it may be the valve, the pump or the boiler itself.
Work your way round the Y plan wiring diagram bit at a time and you should beable to locate what is causing the problem.

If you don't understand any of the above words, then you'll need someone who knows their way round domestic water systems wiring.

 

[alphabeta]

Have disconnected cable from 4 and left hanging. boiler doesn't come on. I presume this is meant to happen? Will post again after half an hour. In theory is just the pump running then?

Where would be the best place to look for the value? Hotpress cupboard?

 

[AndyPRK]

that is correct. It isn't meant to work.

The pump shouldn't run unless you father connected that upto the plug ?

Yes look in the hot press cupboard


Value will be similar to this
http://www.ebay.co.uk/itm/GENUINE-H...490249?hash=item3ab8150c09:g:evYAAOSwnipWVitA

 

[Taylortwocities]

Have you even looked at a Y Plan circuit diagram?

As you can see, if you disconnect at 4, then it basically disables everything forward of that point. So of course the boiler and pump wont run!
I suggest you next reconnect at 4 and isolate the pump and boiler at 8 and see what happens.

But this all supposes a lot of things
like, do you actually have a Y Plan? and is it wired in a standard way? or do you have an S Plan, or a C or a W…etc

 

[Taylortwocities]

WTF is a "hotpress" cupboard?

 

[AndyPRK]

WTF is a "hotpress" cupboard?

What the Irish call an airing cupboard

 

[alphabeta]

Taylor, I see you have 'With every mistake, we must surely be learning' as a comment on your post yet your throwing out insults when people ask questions. And I had attached a basic diagram of the wiring panel for the Horstmann C27 to run the boiler so I was taking it to be channel 4 to disconnect from it, not the diagram you provided.

For the others who would like to make a positive comment and who are interested, the Control Panel ran for half an hour without tripping when I had disconnected Live from the channel 4.

 

[AndyPRK]

As expected, the timer itself is unlikely to cause the fuse to blow.

The main components left are:
Boiler
Pump
Valve
Thermostat

Your best bet is to get an electrican with an insulation tester to fault find.

or disconnect some of the components.
What did you dad move ?

 

[alphabeta]

It had been on the same circuit as some of my lights but there was a free 5amp 'channel' on the consumer board unit so he moved the boiler controls onto that and kept the lights on the other circuit.

 

[flameport]

Used to have the Horstmann C17 before and had been working for a few years.

C17 is single channel, so you do not have a Y plan system.
Does the boiler even heat the hot water at all, or is it just for central heating?