Forever bleeding upstairs rads - cold, hot, cold, hot.........

[Mrast]

Hi all,

Brought my house in the summer - 9 rad, 5 down 4 up.
Vaillant Turbomax Pro 24e Combi boiler

All radiators downstairs brand new (double panel) with brand new pipe work (15mm copper) All rads downstairs have new TRV's.

They all work fine - get nice and warm and never have any air in them.#

Upstairs is a different story.

4 single panel old radiators not replaced.
3 bedroom rads were taken off wall and flushed out of all black gunk and sludge.
Dont ask me why for some reason we never took the bathroom rad off to clean up!

Upstairs rads are fed by microbore (correct?) copper with 15mm tails from the rads.

Im constantly having to bleed the rads upstairs. Once bled they get warm and appear to work ok for 2 weeks or so then just stay cold or luke warm at best until bled again.

Bathroom rad always has masses of air out of her.
Small bedroom doesnt appear to have much pressure to force the air it does have out and when it gets to water it drips out rather than being pressured out.
Other 2 bedroom have a little air but not much.

All rads upstairs also have TRV on - new in 2 bedrooms and old existing in small bedroom and bathroom.

System has been drained down umpteen times throughout the summer as we were putting the new system in downstairs.

Boiler pressurises correctly (1.5bar when idle, just over 2 bar when running CH)

Also recently there is a loud bang that comes from a pipe somewhere when the cold water from the kitchen tap is turned off and also when the downstairs toilet is flushed.

Can anybody please help me get to the bottom of this - i am quite confident with most DIY so will try virtually anything you guys throw at me.

many thanks for your time in advance.

 

[GQuigley67]

seems like alot of radiators for that boiler, you may need to upgrade your boiler to a 28 or 30kw rated one.

 

[GQuigley67]

could also be a balancing problem, if when putting the new system in there were additional radiators added then it may be that the boiler will need to be upgraded.

As for the loud bang, could be a pipe which isnt bracketed properly and is banging off something when you call for water due to the pressure.

 

[Mrast]

seems like alot of radiators for that boiler, you may need to upgrade your boiler to a 28 or 30kw rated one.

Just been on rad manufacturers website and the BTU output of all my rads added up is approx 38000

Boiler spec sheet says

CH Heat output range 80/60 deg C
8.9-24 KW
30.400-81.900 BTU/h

But thats all foregin to me! **blushes**

 

[Mrast]

could also be a balancing problem, if when putting the new system in there were additional radiators added then it may be that the boiler will need to be upgraded.

As for the loud bang, could be a pipe which isnt bracketed properly and is banging off something when you call for water due to the pressure.

No extra rads were added to what was previous there (infact we lost 1)

Changes downstairs were

Liv room had 2 1600x600 single panel and now has 1 1400x600 double and a 600x 600 double
Kitchen had 1 1400x600 single and 1 800x 600 single (was 2 rooms before i kncoked through) now has 1x 1400 x 600 double
Utility had 1x 1000x600 single and now has a 900x600 double
Hall had 1x 800x600 single and now has a 800x600 double

 

[franky]

Just check by balancing the system first like GQuigley67 said. The amount of air your getting seems a lot there must be pockets of air being pushed though your system, but if the bathroom rad is the highest it will collect the most air

 

[GQuigley67]

since the pipework downstairs is 15mm and the microbore upstairs is 8mm or 10mm then the water will be taking the easiest route to circulate which will be the 15mm pipe as it is a larger diameter with less resistance, try turning down all of the lockshields on the downstairs radiators and see if that helps.

since the bathroom radiator wasnt flushed then it may be nitrogen gas due to corrosion that is gathering in your radiator you may need to put sludge remover in the system flush it then put inhibitor into the system, best way to put this into the system is if you have a towel rail and put it in at the air point on the top of the radiator