Worcester Highflow 3.5 not firing up - HELP PLEASE

[Macktheknife]

I have a Worcester 3.5 Highflow which when calling for heat the boiler does not fire up. However when I manually open the motorised valve the boiler fires up and the radiators seem to heat up ok. When I then return the valve back to the normal closed position after a few minutes the boiler switches off - even though it is still calling for heat.

Any suggestions on a possible cause and remedy would be VERY much appreciated.

Many Thanks

Mack

 

[PEDANTICVINDICTIVEMAN]

Duh, if the motorised valve is getting power and not working guess what needs fixing.

 

[megawatt]

PVM has a way with words but is spot on

As the valve isn't opening the boiler is simply circulating primary water through the heat bank and as soon as the CH temp is reached (quite quickly in this state) the CH stat cuts off the gas.

Workaround until you get the valve changed (if you don't want to freeze) is to hold it in the open position using the open position "latch". This will be unlatched though if a demand for HW causes the heat bank temperature to drop below the HW stat setting (any reasonable draw off of HW). Best thing to do is to make sure all the family have had their showers/baths and then latch the valve open and set the HW stat to minimum.

If it's the actuator its a 5 minute job for the DIY'er, if the valve is seized though and requires changing its quite a big job and, unless you know what you're doing, I'd get someone in.

Hopefully it will be the actuator

Good luck