Lobster wrote:

wrote:
Lobster wrote:

wrote:

Wondering if anyone could help with the above. I have a sealed
central heating system(as far as i know) with a combi 80
potterton boiler.

I want to drain system and clean with fernox then add inhibitor.
I know how to fill it back up i'm just unsure how to drain it.
I've had plumbers in before who have drained it in a matter of
seconds.
There should be drain cocks at the lowest point(s) of the system
(something like this:
http://www.screwfix.com/app/sfd/cat/...3349&ts=21170).
Connect a hosepipe to the output and open the valve at the end.
You'll need to open the bleed valves on the radiators (starting
with upstairs!) to release the vacuum formed inside the system to
allow the water to flow out.

I'll go and have a look for the valve. Would it actually be inside
the boiler? As I've said plumbers have drained system before and they
seem to have front cover off at the time and do not connect any hose
etc. Unless I have a hose on there already.

There may well be a draining point within the boiler, however that
shouldn't be the only place. Unless your boiler is mounted at floor
level(!), if you drain from there you will leave everything below the
drain point (ie, the whole downstairs heating system, if the boiler's
downstairs) full of water. Hence the need for drain cocks at the lowest
point on the system (may even be built into the lockshield valves at the
ends of the radiators. If there's more than one 'low point' (eg if the
ground floor's solid and each if your downstairs radiators is fed from a
'loops' of pipe dropped down from the first floor, then each such 'loop'
should have a drain point.

That being said, it's unfortunately very commonplace for these to be
left off the system altogether by the cheapskate/idle heating engineer
who installed the system, so don't be too surprised if you can't find
it/them! If you can't, then you basically have to gradually undo a
coupling at a radiator valve, and collect the water which comes out -
takes a long time and may well be messy. Do you really need to do it?
And then you fit a drain cock before refilling....!

I certainly can't see how plumbers can have actually drained the system
before from your description - what task were they doing at the time?

David

No I don't really need to do it but I'd like to give it a flush and put
in inhibitor. Plumbers were in fixing leaky radiators both upstairs
and downstairs I think and I'm 99.9% positive they drained from inside
boiler(should've asked them when they were in). I can get under the
floor but they definitely didn't go under there to drain it down.

Boiler is on wall in kitchen at height of wall cupboards in the floor
cupboard beneath boiler I have the filling loop. I've took front cover
off boiler and can't see anything that looks like screwfix picture
link. I'm doing up kitchen at the moment and will be replacing old rad
which I'll be able to manage. So I was intending putting in fernox
flush while fitting new rad but then I've still got the problem that
this will need drained and then flushed a couple of times before adding
inhibitor.


Cheers