Draining and refilling combi system

[Phil2003]

I'm about to replace the flow switch (aka differential pressure switch?) on my 15-yr-old Vaillant combi boiler.

I'm no plumber but I think I can manage it okay.

The snag is that the plumbers' merchant supplying the switch says I'll have to drain the system before fitting the switch and refill it afterwards.

I've no idea how to drain and refill.

Can anyone help?

 

[corgiman]

my advice is dont do it get a professional in as changing them can be a bit of a wotsit

NOT A DIY JOB in my opinion

 

[Phil2003]

A bit of a wotsit in what way?

There are 3 small bolts holding it in position, and two slim water pipes with push fittings supplying the flow - that's all.

It doesn't look difficult.

Am I missing something?

 

[corgiman]

D'OH thought you meant the diverter valve
not a bad job
Still would suggest getting a chap in though
if you really want to do it here you go

TURN OFF THE FLOW AND RETUN PIPES FROM THE BOILER (unmissable they are the bigger pipes there have built in valves)

TURN OFF THE COLD WATER SUPPLY PIPE (Precautiony measure)

OPEN A HOT TAP (to drain off water supply)

GET A SMALL HOSE AND ATTACH IT TO DRAIN OFF LOCATED ON FLOW ISOLATING VALVE

OPEN DRIAN OFF UNTIL NO WATER IS PRESENT

TO FILL CARRY OUT ABOVE IN REVERSE

and remember that if you are not 100% confident in doing the job save yourself some time and money in the long term and call VAILLANT service solutions they offer and brilliant service for not much money