3 port motorised valve wiring question.

[Burger]

If you decide to try different wiring combinations in your connector box make sure your programmer is independently fused with a 3amp fuse! I incorrectly wired a replacement three way valve and fried mine because it had a 13amp fuse.

Oops! You live and learn

 

[SJB060685]

If you decide to try different wiring combinations in your connector box make sure your programmer is independently fused with a 3amp fuse! I incorrectly wired a replacement three way valve and fried mine because it had a 13amp fuse.

Am I reading this right. You accidentally wired up a new three port wrong (it happens to all of us) and because there was a 13amp fuse you fried the programmer before fuse blew? That I understand but there should only ever be one fuse on these systems (apart from any that might be in boiler), have I read that wrong?

 

[Wbjimmy]

Yes. Thats exactly what I did. There is one isolating fused switch in my airing cupboard which protects the control box, programmer, 3 way valve and cylinder thermostat. I inadvertently wired up a replacement 3 port valve wrongly and because the isolating switch had been wrongly fused with a 13amp instead of 3amp fuse it burnt out the programmer! So I ended replacing the programmer - as well as the fuse!

 

[SJB060685]

Ah I see. Yes I’m fully aware of how a fuse protects the system and components, however I initially read your comment as you had two switched fused spur lives into the heating circuit. As you know this is a no lol. Was on a job once and the heating circuit had two lives to it through two switched fused spurs, we didn’t realise, isolated the first then got a shock when taking out some of the wiring. Never again lol