Y Plan problem

[Oracle]

Hi all,

Got called to look at a boiler swap out, plumber had simply swapped the existing boiler for a new on, and added a pump overrun cable from the boiler to the pump.

He never tested the correct operation of the old boiler first.

Basically the new boiler seems to work ok, but the heating system as a whole isn't.

It a standard Y plan - boiler, mid port valve, cylinder stat, room stat.

I've had a very quick look at the wiring and it seems fine??

If the H/W is on, the valve goes mid position (when it shouldn't operate) and starts clicking. The pump and boiler fire ok. If then CH is then activated too, the valve goes fully over (doesn't go mid).

If both HW and CH are then turned off, the valve stays where it is, with boiler and pump running.

I'm going back tomorrow and will check the wiring again, and go through the honeywell fault finding process.

Anyone got any ideas?

O.

 

[sparkytim]

Is 3 port valve sticking? cliking noise sounds suspicious

Have often found cylinder stat wired wrong way round i.e. n/o and n/c reversed.

Hve fun!

 

[PC Electrics]

Does sound like it might be th e3 port valve, it shouldn't make any funny clicking noises (busted gears inside?)

Check also that the pump over-run wire has been independantly connected to the pump live and not just to terminal 8 (ie to the orange wire as well), as this would back feed 240V into the boilers call-for-heat terminal.

 

[Oracle]

hi guys

Went back today. The value operates fine - its not sticking, no worn gears. The clicking is the motor deenergising and then reemergising around the midport position - hence its rocking and not stalled.

Basically the was the value at fault - a faulty switch inside. A new value solved it

Many thanks for your help.

O.