Honeywell 3 port manual lever

4 Apr 2008
Reaction score
United Kingdom
Hi I have just plumbed/wired a 3 port valve y plan system with st9400c programmer and wireless stat.

With the hw and ch off on the programmer, moving the manual lever on the valve all the way seems to run the pump. Is this correct?

Sponsored Links
just noticed when the programmer switches off the ch, the pump seems to keep running at a slow speed! I have double checked the wiring.

When i switch off at the fcu and back on again the valve returns to orriginal position and the pump stops.

Must be a dodgy programmer microswitch?

looking at the reference guide for the 3 port valve, when the last position was ch, the orange wire will have 100v on it, which connects to the boiler and pump live.

Pump should not be running with 100v, but I can feel the pump vibrating slightly!

going to check the voltage on orange wire now
Sponsored Links
well I can't get 100v out of orange wire! only get 240v when ch or hw is on.

when hw is called for the programmer is sending 240v to the on wire and 178v to the off wire!

new programmer needed methinks.

closer inspection it seems the valve is vibrating/humming, not the pump!

can't be good for the valve lol

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local