Radiators need constant bleeding

[andymarshalluk]

My central heating is very noisy which is a result of the radiators requiring constant beeding. The puzzle here is trying to understand why this only effects two radiators throughout the entire house. There are 6 rads upstairs and 7 downstairs. The two affected are one upstairs on the landing and one downstairs in the hall way. Once bled the system is great for about week then we start again with noise and having to bleed these two same rads. Its a \\\"Bleeding Nuisance\\\", please help!

 

[KermitTheFrog]

I'm no expert, but my plumber told me that air tends to always collect at the same points in the system (perhaps the hightest part) which would make sense. So even if the air isn't getting in there, it could be collecting there.

Count your self lucky - I can't get rid of the banging at all, no matter how much I bleed the radiators!

 

[stevesey]

Count your self lucky - I can't get rid of the banging at all, no matter how much I bleed the radiators!

Air is often a symptom of banging/noise not the cause. Bleeding won't help fix the cause.

 

[gas4you]

My central heating is very noisy which is a result of the radiators requiring constant beeding. The puzzle here is trying to understand why this only effects two radiators throughout the entire house. There are 6 rads upstairs and 7 downstairs. The two affected are one upstairs on the landing and one downstairs in the hall way. Once bled the system is great for about week then we start again with noise and having to bleed these two same rads. Its a \\\"Bleeding Nuisance\\\", please help!

Have you a sealed system or open vent (expansion tank in loft?) If it is open vent you must have air being drawn in from somewhere. Are you bleeding the system when it is turned off and cold as it should be? Have you checked to see if the system is pumping over when in operation? (water coming out of vent pipe over expansion tank) if this is the case then you will constantly be drawing in fresh aerated water. What is the condition of the water in your system? If very black, rusty or like sludge/treacle then this could be Hydrogen gas being given off as a by product of the corrosion taking place. When you bleed the upstairs one do you get water out?

 

[andymarshalluk]

Many thanks for the reply, the system is an open system,the water is black when I bleed off. I have not tried bleeding the system when it is cold, this i will try. How do I get rid of the black water throughout the system? I have heard of flushing agents, furnox etc but do I need to be aware of any limitations with my boiler rads etc. Do flushes harm the system and can I use an inhibitor?

 

[gas4you]

Unfortunately when the water is very black the only real answer is to employ somebody to powerflush your system and make sure the header tank is cleaned out in the loft at the same time. There are various makes of system cleanser on the market the most common ones made by Sentinel & Fernox. It is after the system has been cleansed that you would add the inhibitor when filling the system for the last time.

I would suggest calling in a local CORGI to examine the system to find out if there is an underlying cause behind the black sludge build up and constatnt air problems