Bleeding system, 2 rads not bleeding

[Taffytim]

Im just a DIY'er but i wanted to remove my radiators on my new house tonight to strip the paper from behind them.

The system is all combi-boiler heated with no tanks left in the house. I noticed there were 2 system bleed points when i started. I put a hose to the first in the dining room and undid the tap and nothing more than a trickle was coming out, and nothing else happened.

I attached the hose to the 2nd bleed point in my hall and most of the system bled out after opening the bleed screws on the rads upstairs. The dining room and the living room radiators stayed full (I only have 3 rads downstairs), also the 2 pipes leading into the ceiling which both have t junctions when they rise also seemed full. These pipes dont pop out upstairs directly above the ceiling where the disperse so i presume they get routed in the floorboards.

After the rest of the house was drained from the hall i went back to the dining room and again couldnt get the drain to work (again it just trickled) so ended up having to remove a pipe from the living room rad and drain into a bowl. That drained the dinning room rads as well.

What was i missing? I thought the whole system should drain from 1 point? Where else could i look to let the air in from the top of this part of the stystem? When i was doing this part i had removed all upstairs rads apart from the bathroom one, but the bleed screw was open here and it seemed to be on the same leg a the rest of upstairs. I couldnt see any bleed point in the loft but i didnt remove any insulation to look deep.

Any suggestions appreciated as im going to reconnect the system tomorrow and will need to rebleed and remove when we paint.

 

[Best]

Firstly, "bleed points", as you call them I assume are drain points. Drains can have the rubber washer swollen or stuck or they can be blocked with dirt/corrosion especially on old systems.
As your system must be a sealed type, it will not just drain out when you open one end of a pipe - all that happens is the pressure will release, perhaps a bucket of water & then the rest of water will be locked in system unless a vent is opened elsewhere.
Do make sure you get corrosion inhibitor put into system when you go to refill it. Try to avoid removing rads or especially draining entire systems as expensive to replace quality inhibitor.

 

[Best]

I should have also mentioned some systems have motorised valves which need switched to full open manually when draining & refilling systems. Not doing so can cause system to not drain properly & air lock when refilling.

 

[Taffytim]

Urrgghh, living and learning . . . .


Yes drain points is what i meant, looks like i didnt need to announce i am a DIYer

1. If i do have motorised valves, are these in the boiler or in my floorboards? Is it too late if ive not activated them or can i switch them open during the refill?
2. what else should i have done to have drained the system as i thought opening upstairs bleed valves would sort out this problem? I dont understand the airlock that i experienced if all of the upstairs rads were off (unless there are motorised valves)
3. The C/H system was replaced in the house about 7 years ago but the decoration is much older and it needed the paper to be removed, what should i have done if this is a no no?
4. Corrosion inhibitor, not something i knew about. Thanks for the tip. How much do i need for a 3 bed semi, 3 rads downstairs, 4 rads upstairs?
5. How do i introduce it to the system?

 

[Kyle87]

Next time try just turning the rads off at the valves either side. Open the nuts and drain into a bucket or bowl. You'll only get about half a bucket full dependant on your rad size.

Then take rad off and you've done it without draining system.

My old man was a decorator and he used to do this all the time. It isn't difficult but you need to beware that your valves my die once you touch them and start leaking so unless you have the know how to change the valves also its better to leave alone or have a plumber on standby

 

[stevetheplumber]

the rads you cant drain are dropped from above so have to be drained seperately