Air in system.

[Deleted member 15266]

After having air in system for a year and continuously bleeding three rads a heating engineer put a can of fernox leak sealer in the system which seemed to work great but today I notice one of the radiators had air in it again (upstairs). Should I get him back to put another can in? We have 12 radiators in total.

 

[fidom]

It would be better to find the leaks. Sometimes all it needs is a gland nut tightening on one of the radiator valves.

 

[Deleted member 15266]

He said there’s no obvious signs of a leak so it must be under the hard flooring downstairs which I really doubt as there is no smell of damp and the floor was up to fit a new kitchen and the sub floor was dry. There are some pipes in the airing cupboard which a magnet sticks imo indicating sludge but he said that would cause a problem like that and to ignore. We do have lots of heat and hot water.

 

[fixitflav]

After having air in system for a year and continuously bleeding three rads a heating engineer put a can of fernox leak sealer in the system which seemed to work great but today I notice one of the radiators had air in it again (upstairs). Should I get him back to put another can in? We have 12 radiators in total.

Is it air of hydrogen? Been discussed on this forum quite recently. If it's hydrogen, you need to get some inhibitor in there.

 

[Ltnman]

I have had this problem for years. No visible leaks just air and no gas as I can’t light it. No smells and no damp either. I have just renewed the boiler and the problem persist.

 

[fixitflav]

I have had this problem for years. No visible leaks just air and no gas as I can’t light it. No smells and no damp either. I have just renewed the boiler and the problem persist.

Worth doing a bright wire nail test to check for corrosion. Come back if you want details.

 

[Deleted member 15266]

Yes please. Never heard of it

 

[fixitflav]

Yes please. Never heard of it

Put some water from the system into a jam jar to about 1" deep. Put some tap water in another jar as a a check. Add 3-4 bright wire steel nails, and leave for a couple of weeks. If the water stays clear you're OK, if it goes brown you need inhibitor.

If you have a Magnaclean or similar it's ideal for taking the sample and for adding inhibitor, a bit more trouble otherwise, need to get it from a bleed screw or something.

 

[fixitflav]

Here's one I did on my system earlier this year. Tap water on the left!

 

[Deleted member 15266]

Ill give it a go