Central Heating Radiator

[1234567billy]

ONE OF MY CENTRAL HEATING RADIATORS NEEDS CONSTANTLY BLED ,SOMETIMES DAILY. DOES NOT TAKE LONG TO BLEED BUT IF NOT BLED THE 2 RADS IN THE CONSERVATORY ARE LUKEWARM. IF IHAD NEW RAD PUT IN WOULD THIS SOLVE PROBLEM. WATER COLOUR COMING OUT OF RAD IS A BIT DIRTY LOOKING.
PS THE OTHER RADS IN THE HOUSE ARE PIPING HOT

[murraymints]

your system may need topping up with water so to avoid air locks..may need a flush ? Builder will be along soon with professional advice

[KARL]

It matters whether your system is "closed" or "open" - the latter will have a header tank at the highest point of your dwelling, for example in an attic space. If it is open then in all likelihood it is self-filling but you would need to check that the tank has some water in it. The description you give of your radiator water suggests that there may be considerable sludge in the system in which case the system should be drained and cleaned with an additive, drained and flushed and then refilled with an inhibitor additive. If the system is closed then as murraymints suggests, it may help to ensure that it is properly filled to adequate pressure but if it is closed and keeps ingesting air then that suggests a leak somewhere. It is difficult to provide conclusive analysis without some additional checks and observations and solutions would depend on the conclusions.

[1234567billy]

KARL AS FAR AS I AM AWARE IT IS AN OPEN SYSTEM. CANT UNDERSTAND IN MY IGNORANT MIND WHY/HOW A 2FT X 2FT RAD CAN CAUSE SO MUCH TROUBLE WHILE THE OTHER 8 RADS ARE VERY WARM. HOW DOES THE FLUSH WORK AND HOW LONG WOULD IT TAKE

[KARL]

The accumulation of air will happen at a point where the circulation transports it and according to the basic physics of your particular system. The cleaning and recharging of a heating system works like this:
You drain the system completely and for good measure refill it again the drain again after running it for say an hour. Remember to have all radiator inlet valves fully open - leave the valves at the other end unchanged as these are the ones that govern the balancing of your system. Then you refill the system having poured the cleaner into the tank at the start of filling. Follow the instructions for the cleaner but usually it is then a matter of getting the whole system (i.e. circulating water)up to temperature (basically 40 degrees or above). You then drain, refill and circulate for say an hour. Then you drain a final time and refill with the inhibitor added as you start filling just like the cleaner. Fernox do a good range of chemicals but others are available. The whole process from start of initial draining to fully back in operation can usually be achieved in a day but the speed of draining is what tends to govern things - systems (in the UK) are frequently built in a way that means this is a slow process (sometimes a couple of hours or more).

[The Builder]

Air is obviously being introduced to the system ... somewhere. The problem could be obviated by fitting an automatic bleed valve into the pipework.

The trouble is that this doesn't solve the problem of where the air is getting in. Faulty circulating pump washers could do this, but that's just one possibility. It really needs someone to investigate. There are many other possibilities.