Ravenheat 84et dead loss

[DrLecter]

My Ravenheat combi stopped working a fortnight ago. Using the fault finding guide I have attempted to diagnose and fix, but with no joy
The boiler does not work for HW or CH. I have changed the following in the same sequence; CH & HW sensors, main summer/winter switch, timer, main circuit board, low water pressure switch.
When switching boiler on the light on the front comes on. When selecting 'On' the timer relay clicks and testing continuity across terminals 3&5 it's ok. But still no voltage to pump and no movement of relays on main circuit?!

From reading through the fault finding flow chart in the boiler manual regardless of other faults the boiler pump should at least run?

I am wondering if the replacement circuit board could be faulty? It was an exchange board rather than brand new. But I'm sure it would have been tested.

 

[picasso]

Have you tested the overheat stat ?

 

[DrLecter]

Hi, yes I have tested and have continuity between terminals 1 & P1

 

[picasso]

Check to see if you have 240vac between pump live and earth.

 

[DrLecter]

No voltage between pump live and earth.

 

[dax1gasman]

Hi,
have you checked continuity across your low water pressure switch.
3 wires black,brown and blue.
low water pressure trips boiler off, expect continuity across Black and brown.
Sufficient water pressure continuity across black and Bue.

 

[picasso]

Recheck all the connections you have made to the board and dax beat me to the low pressure switch

 

[DrLecter]

There is continuity across black and brown but no continuity across black and blue! This is a new switch so not sure why this is happening. Is it possible to short the black and blue to trick boiler and see if pump runs? Or is there any reason other than a faulty switch (as pressure gauge is reading 1.2 bar) that low pressure switch not operating correctly?

 

[DrLecter]

I removed low pressure switch and found opening in port to be completely gummed up. Screwed a self tapper into blockage and pulled it out with pliers. Switch back in and continuity between blue and black. Jobs a good un thanks to your diagnostic help! Heating back on. I bet the weather warms up now!

 

[dax1gasman]

yeah you can trick it by linking them-Black and blue.

Just to add im only using the wiring diagram and it shows the switch rest position ie no water between black and brown, from what you said that would indicate no water in boiler.

 

[Agile]

With all those parts you bought ( including a dodgy repaired PCB ) I would have expected it would have been far quicker and probably cheaper to have called a boiler engineer!

Or perhaps you prefer to live in the cold without hot water for two weeks!

Tony

 

[dax1gasman]

have you mixed ble and brown up??

 

[picasso]

( including a dodgy repaired PCB )

Got any proof its dodgy or is it just your opinion ?