PRIMATIC SYSTEM

My domestic hot water and central heating system is nearly 5 years old. When I bleed the radiators the water is brown and one particular radiator needs frequent (every 2 months) bleeding. I feel therefore that the system needs to be descaled. The hot water cistern is a TRIBUNE PREMIER 100 litre Model TP180B and has a bewildering array of pipes and valves attached to it. There is no cold water tank in the loft, just a central heating make up tank. Above the hot water cistern is a vessel of 18 litre capacity manufactured by ZILMET. The arrangement is different to that which I am familiar. I notice on the label of the descalant fluid bottle that it should not be used in a PRIMATIC system. How can I tell if my system is a Primatic?

MOD

moved as posted in wrong forum

from your description it sounds as though you have an unvented cylinder

so it wont be primatic

Agree with kev on the unvented front.

The brown water sounds like corrosion and should be checked out pronto, does the air smell like rotten eggs when you vent the rads

Many thanks for your advice. The water seems to be brown from a gunge coating the walls of the header tank in the loft. I can not smell hydrogen sulphide wheen I vent a radiator.
GGL