Sealed heating system
Posted by Dave on November 07, 2002 at 06:17:48:
Six years ago I had a central heading system fitted and I am puzzled about exactly what type of system I have and the suitabiity for my house. The system is sealed - there is no separate water tank and the hot water cylinder is an Indirect type. However the hot cyclinder does have a vent pipe to my domestic cold water tank, unlike completely sealed systems. There is a cold water supply to the heating system fitted with a gate valve on the flow pipe into the hot water cylinder. Ordinarily this valve is off but the plumber who fitted the system said that we should open this valve to let more water into the system if the pressure ever drops out of the green zone on the pressure guage on the boiler. The boiler is a Vaillant Thermocompact VC GB 242 E. I live in a hard water area and have to top up the system about every 6 to 9 months. When I do this, opening the valve for 10 seconds is usually enough to get the pressure back to the middle of the green zone. Recently I have set out to learn about plumbing and now know enough to have some concerns about introducing fresh water into a system in a hard water area. I am also puzzled as to why I have to top the system up as if it is sealed, this should not be necessary. Any comments or advice would be very much

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