Central heating refill... panic!

[bobe70]

I decided to drain my CH system and fill the header tank with F5 in the hope of clearing some of the crap that would have built up over the years on an old, neglected system.

I followed the instructions from this site for the drain down.

Opened all rad valves
Shut off the supply to the header tank
Attached hose and drained outside
Open bleed valves

The system wasn't draining all radiators, a number of them I had to go and drain individually. I can't explain why, but I put it down to the system being old and having varuous extensions and modifications over the years that may have effected this?!

When pretty much all water was drained I poured the F5 into the header tank, which was empty.

Then,

Closed all bleed valves
de isolated the supply to the header tank

I have now been waiting for the system to refill for an hour and the downstairs rads aren't full.

How long should this take to refill (a fairly large house)? I am starting to panic a little and think that I have done something wrong.

 

[Whitespirit66]

Possible on an old, dirty system that the cold feed is blocked. Put a magnet on the feed pipe from ch F&E tank where it tees into the main pipework. If the magnet sticks, it's blocked with magnetite. Another reason could be if there was lots of crud in F&E tank that got sucked into system during drain down.

Also, what motorised valves have you got? Always best to latch these in 'manual' position during draining and refill. Often overlooked.

 

[bobe70]

What is the F&E tank? Im kind of learning this as I go...

I can only find one motorised valve, this is set to manual.

Rightly or wrongly (prob very wrongly!) I switched the CH on after about an hour. The boiler kicked in abd the pump is working. Lots of air movement now and getting loads of air out of the rads, but they are still not full.

I tested a drain valve on one rad and it has certainly been filling and the water coming out is very brown, perhaps due to the F5.

 

[Burnerman]

There could well be air locks too.....it may help to back fill the system, with a hose on that drain cock.
John
Edit...the F/E (flow/expansion) is the small tank you poured the solution into.
J.

 

[MrTherm]

--> *Then, Closed all bleed valves*

....yes, then open one bleed valve and wait until water shows, then same with each rad.

 

[bobe70]

There is certainly a lot of air movement, but when I bleed the rads I am just getting massss of air, no water.

If I so fill the system what do I need to be wary of? Can I cause damage/flooding?

 

[MrTherm]

If you are getting air released at the bleed valve then water will surely follow. If as you say there are various extensions you may have to wait a while.

Once filled and fully vented it will be as it was initially - no leaks or floods.

Water showing at every rad and vent point followed by header tank filled will show system has settled. There may be surge sounds when pump first runs but should clear.

Other vent points include, pump, boiler, any auto vents or similar.

 

[bobe70]

Well its finally refilled!

Took me about 7 hours of chasing air around the system, but its finally there.

switching the pump on and off every 30mins seemed to get things moving.

So is it possible that a system can take that long to fill, or am I likely to have an underlying problem?

Im certainly not looking forward to draining the system again next week to empty the F5!

 

[Whitespirit66]

So is it possible that a system can take that long to fill, or am I likely to have an underlying problem?

Did you try the magnet on the cold feed tee? May poss be partially blocked, which certainly won't help matters.

 

[bobe70]

Not yet, am purchasing a magnet on Saturday!