Fused Spur Blows when Heating Switched On !! Water Works OK

[alx]

Hi,

After a bit of advise.. On Sunday the Boiler blew.

Boiler is an Ideal Classic FF350
Programmer is a Danfoss TP715
Junction unit is a Danfoss WB12

Water had been on, and running fine. Switched the heating on, and 10mins later there was an electrical bang from the kitchen where the boiler is mounted. This has blown the relay on the PCB for the fan, (new PCB arriving today). The PCB neon was not illuminating, so there was obviously no power reaching the boiler. A test with a multimeter confirmed this.

However, and this is what is confusing me, the boiler is not wired directly into the switched 3amp spur below it. The spur feeds the programmer, this then runs up the back wall of the kitchen, I assume to the junction box in the airing cupboard upstairs. The supply then returns and the boiler is connected using a terminal block to this ?

There is no power on this supply, feeding the boiler. There is power on the switched spur and the programmer is powering up fine.

There is no continuity on the live from the spur to the feed originally used for the boiler.

Why is the boiler not just connected directly to the switched spur ? (like the installation guide suggests) ?

What is stopping the live supply which was originally feeding the boiler ?

Any help would be appreciated as we are without heat and water at the moment !

(just to add - I have wired the boiler up to a 3pin plug directly and it powered up the board and ran for a short time).

 

[alx]

There is continuity between the (HW on) feed on the programmer and the original live feed to the boiler..

How can I test the valves, pumps and stats in the airing cupboard ?

I can't find a live in the junction box ?

 

[D_Hailsham]

There is continuity between the (HW on) feed on the programmer and the original live feed to the boiler

Are you saying that the permanent live to the boiler is only live when the HW is on at the programmer? If so, the boiler is wrongly wired. A permanent live has to be live all the time, irrespective of what is turned on at the programmer.

How can I test the valves, pumps and stats in the airing cupboard ?

I can't find a live in the junction box ?

You need to find the live before you can test the devices.

This will be easy if you can visually identify the wires from the programmer to the airing cupboard. The wiring centre may have the terminals labelled, which should help.

If you have a mid-position valve, the programmer HW ON should connect directly to the HW cylinder thermostat common terminal.

If you have two 2-port zone valves, the grey wire should be connected to a permanent live and the brown wire to the relevant thermostat Call terminal.

 

[gas4you]

Classic FF350 only has one live to it. Switched.

Sounds like the microswitch in the ch zone valve head has broken, or in the 3 port valve head.

 

[alx]

Hi,

There is no live out the back of the programmer.. So I have a new one on it's way.. Hopefully be here today or tomorrow !

I will update the thread when it arrives, but have fingers crossed..

 

[gas4you]

Where are you getting the live from? Off the internet

 

[alx]

Yeah, got a new live on it's way..

 

[alx]

Right then..

New board and programmer. The hot water is no working as it should.

However if you turn the heating on, the fuse in the spur blows.

I am suspect of the mid position valve. Just need to know how to test it?

Any help, greatly appreciated !!

 

[alx]

Good day today..

Fitted the new programmer. Hot water works fine. Switched the Heating on - Fuse blew. Tested the Mid Position valve - cant find any faults with it, however once removed and circuit bridged the heating and pump are working perfectly. So new Actuator required.

Finally getting sorted. Thanks for all the advise. Should be fully sorted early next week, but at least we now have hot water. (we don't need the heating at this time of year anyhow).

 

[alx]

thought I was onto a winner with this, but finally fitted the new actuator today and it is exactly the same as before ?

Hot water is working fine, but if you turn the heating on, the fuse blows.

Seems really strange as it ran fine when we by-passed the valve, but with a new one fitted, it won't work..

Any ideas welcome !!!

Thanks..

 

[JohnD]

Hot water is working fine, but if you turn the heating on, the fuse blows.

I know nothing, but is there a short in the circulation pump? When you put heating on (and room stat calls for heat) it switches on the pump

presumably you are working with a wiring diagram from the Programmer company (I am just a householder, but the Drayton and Honeywell ones I have seen seem to be identical, subject to age and model of programmer)

you might do better to use a multimeter to check what is happening, rather than keep blowing fuses.

 

[alx]

I have disconnected the pump, and the fuse still blew..

I have chased around with a multimeter and can find no faults..

I suppose there is a possibility that I have bought a duff actuator, but I would imagine this is unlikely (it was new and sealed) !

I must be missing something, but I can't think what.. .

 

[seco services]

checked the room stat ?

 

[alx]

Edit;

I checked the resistance across the terminals and it it varied as the temp was moved. I am not sure how best to test it with a multimeter..

Pretty sure I tested the cables for breaks from the room stat to the terminal box and all seemed ok.

 

[seco services]

i would try bridging it out heating live straight to the white of the valve