(central-heating) air in system

[brabus]

Hi,My parents live in a bungallow, and recently had a new(C/H) system installed,a few rads were blocked so had system power flushed and result ok but still have one cold rad!
My main problem is that I can bleed system 4 England every other day,air air and more air,and next day rads banging, Knocking , water rushing around,more bleeding (Where is this air coming from)???
Ime aware of Gases being released re sludge in system causing this prob maybe, but this has been going on it seems too long now
Its a vented system
9 in no rads
Grundfos (red) pump
System also heats a hot water copper tank 4 hot taps
Boiler is a Baxi installed 4 months ago
Seriously Flushed & inhibiter added
Above enquiry is probably (a how longs a piece of string Question),and could Have one of a hundred causes,
But if Anyone has any ideas Wow how handy that would be !!
Take care you lot
Alon (DEVON)

 

[gas4you]

Sounds like the system could bepumping over or sucking in at the expansion tank in the loft. You need to go up there with a jam jar full of water, put this over the vent pipe, get someone to turn on the system and see if any water is sucked up the vent.

Pumping over will be obvious if it is doing this.

 

[Agile]

The obvious question is what do the installers say about this?

When replacing the boiler they should have identified any problems with the existing system. Thats indicated by considerable sludge.

Its really their responsibility to sort it out at no extra charge!

Did they notify CORGI and complete the benchmark certificate?

Tony

 

[brabus]

thanks both of you
I sat looking @ the pump/pipe work today and to me it has 2 B the tank /vent pipe taking back air,
but wanted some one else 2 come up with same diagnosis
Will now check as you say to do

and if this turns out 2 be the problem will indeed get installer back good and quick
THANK YOU BOTH ONCE AGAIN
ALON ( DEVON )

 

[Softus]

Its really their responsibility to sort it out at no extra charge!

Only in your easily beleaguered opinion. The reality is that it might not be their responsibility, but if the power flush didn't achieve what they said it would then clearly there's a case for getting them back.

Mind you, some people consider that power flushing is primarily a show for the customer.

 

[brabus]

hi,
Re my previous entry , and your replies what would cause pumping over or sucking in (probably as obvious as it sounds no doubt) but why does it happen ?
Alon (Devon)

 

[gas4you]

Incorrect configuration of pipe work and/or positioning of ch pump, or a blockage in a pipe.

 

[mlb3c]

Mind you, some people consider that power flushing is primarily a show for the customer.

now now softus kev is wetting himself here

 

[brabus]

Have just been up to (C/H Tank) with said Glass Jar to check suck/over pump as suggested!
Results were,
bled system before start and tank level dropped by 60 mm, then put full (1/2 ltr) jar on vent,flashed up boiler and pipe sucked all but 1 inch of water from jar,
Shut off blr,water in jar returned to full,did cycle 8 times vent sucks /blows same each time the same,
I would have thought if I had a Problem the vent would have drank the water and called 4 a Top up
How do results sound to you ok or not ,
Take Care
Yours Alon (Devon)

 

[Onetap]

Have just been up to (C/H Tank) with said Glass Jar to check suck/over pump as suggested!
Results were,
bled system before start and tank level dropped by 60 mm, then put full (1/2 ltr) jar on vent,flashed up boiler and pipe sucked all but 1 inch of water from jar,
Shut off blr,water in jar returned to full,did cycle 8 times vent sucks /blows same each time the same,
I would have thought if I had a Problem the vent would have drank the water and called 4 a Top up
How do results sound to you ok or not ,
(Devon)

Not OK.

The fact that you need to bleed it incessantly and that you needed to have it powerflushed both indicate the same problem.

The system volume (pipework, boiler, radiators, etc) is fixed, so when it sucks water or air down the open vent, an equal volume of water is displaced into the open vent tank. The oxygen in the air sucked in dissolves and corrodes the radiators, filling the system with black sludge.

Probably the original configuration was cold feed (CF), pump, boiler, open vent (OV).

This was OK for cast iron solid fuel boilers with huge waterways; there was a negligible pressure difference across the boiler, so the height of the water column in the cold feed was the same as that in the open vent, so there was no flow through or into the feed and expansion (F&E) tank.

It's not OK for higher efficiency modern boilers, which have narrow waterways and so a big presure difference.

Check the arrangement fo the CF and OV.

 

[brabus]

sorry not conversant with terminlogy re (CF & OV)

Alon

 

[Onetap]

sorry not conversant with terminlogy re (CF & OV)

Alon

Ooops, see above now.

 

[Agile]

Incorrect configuration of pipe work and/or positioning of ch pump, or a blockage in a pipe.

In spite of what Softus thinks, its the installers responsibility to identify any faults in the system and correct them when they fit a new boiler.

It would be fixed in about 35 minutes by converting to a combined feed and vant.

Tony

 

[Softus]

In spite of what Softus thinks, its the installers responsibility to identify any faults in the system and correct them when they fit a new boiler.

Where is this responsibility defined? Is it, like a great many things, only in your head?

 

[megawatt]

I have to agree with Softus in this instance Tony.

The installer cannot be held responsible for the entire installation simply when a boiler is changed as there are many aspects of it which are unknown ... Quality of hidden plumbing etc.

You are not responsible if, the day after you leave the property post boiler comissioning, the house is flooded due to a previously badly fitted compression fitting popping off ... Though I can understand why the customer may think that you are