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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Vaillant Ecotec-Honeywell T6360 PCB 2A fuse blows https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1381771723 Message started by CD on Oct 14^th, 2013, 6:28pm

Title: Vaillant Ecotec-Honeywell T6360 PCB 2A fuse blows
Post by CD on Oct 14^th, 2013, 6:28pm

Vaillant Ecotec Pro PCB 2A slow fuse keeps blowing when I connect the Room Stat.
The Room Stat is the Honeywell T6360B.
I followed the info on 1 of your previous forums saying that
boiler terms go to stat terms
3 1
4 3
5 2
But I've blown 4 fuses and I think the last 1 fried the board because now nothing works.
Before I at least had hot water.
I've tried 3 different stats including the old one and all the same.
Even wired the old 1 back in place & that blew out.
Any ideas would be greatly appreciated...

Title: Re: Vaillant Ecotec-Honeywell T6360 PCB 2A fuse blows
Post by Lectrician on Oct 14^th, 2013, 6:46pm

Trapped wire in the wall back box?

Did the fuse only start blowing AFTER you swapped the stat? Not before?

I don't have the diagrams to hand to check the terminals. Will look later.

Have you blown the fuse in the wall isolator (FCU) for the boiler, or plug top possibly? After one fuse blown, you should have looked for issues.....not gone on to blow four! Lets hope te PCB is OK.....

Title: Re: Vaillant Ecotec-Honeywell T6360 PCB 2A fuse blows
Post by Lectrician on Oct 14^th, 2013, 7:37pm

The Room Stat has connections for:

1 - LIVE IN
2 - NEUTRAL IN
3 - LIVE OUT (to fire boiler)

The boiler (by my manual):

3 - LIVE OUT
4 - LIVE IN (to fire)
5 - NEUTRAL OUT

So, what you describe in your post is correct.

However.

When I google the manual for the PRO model, Vaillants site doesnt show a 3, 4, 5 - It shows an L, N, Lr (Lr being the return to fire). 3, 4, 5 are for internal boiler wiring.

Have you a photo of your connections in the boiler?

Title: Re: Vaillant Ecotec-Honeywell T6360 PCB 2A fuse blows
Post by thescruff on Apr 1^st, 2015, 10:01pm

3-4-5 is fine as the OP has posted and suggests the problem is elsewhere.

5 is a spare neutral goes to 2 for the stat anticipator