Reduced voltage to Boiler from controls.

[oldstinker]

Hello all. Need some advise on where to look next. I have been called to a Vaillant Ecomax Pro 28e that will not fire up when demanded. o fault codes on boiler.
When demanded the pump will only run sometimes. The 3 port valve was switching but now intermittantly. Even with the pump running the boiler still refuses to fire.
Voltage to the boiler measured at the wiring centre beneath is only 120V and should be 240. Talked to Honeywell but got interrupted. 240V at orange wire and sill 240V when grey & white are attached to permanent live.
I a planning to replace the 3 port valve but am I missing anything or on the wrong track.

Cheers

Stinker

 

[cider]

Think your talking about non combi. Has it ever worked correctly? How far along the controlls does voltage change? if its after 3 port this could be where the fault lies as it uses 110 to hold valve in mid position in which case fault may not occur when valve de-energised (hw demand only). The boiler should have permanent feed, and controlls wired out of switch loop is this 240?

 

[oldstinker]

Cider , yes M8 it is a system boiler. There is only 120V at permanent live to boiler as measured at terminal 1 & 4 beneath the Boiler which I cannot understand.
I am going back today to investigate and will call Honeywell for more advise. Will post results later.

Cheers

 

[D_Hailsham]

There is only 120V at permanent live to boiler as measured at terminal 1 & 4 beneath the Boiler

Where is the supply to the boiler coming from? As it is the permanent supply, it should be coming directly from the mains (via the wiring centre) and not via the valve, programmer etc.

 

[kablamar]

What are you using to measure voltage? Are you measuring between live and neutral or live and earth.

The reading your getting may be a loose neutral or high resistance joint. You should check all connections in the junction box.

 

[Chipchidster]

Cider , yes M8 it is a system boiler. There is only 120V at permanent live to boiler as measured at terminal 1 & 4 beneath the Boiler which I cannot understand.
I am going back today to investigate and will call Honeywell for more advise. Will post results later.

Cheers

Did you ever get anywhere with this? My boiler is doing similar and my regular heating engineer is stumped

 

[ianmcd]

You have just Hi-jacked 12 year old post, it is against site rules for a very good reason, if you want the correct advice start a fresh post