Hi, When putting away my christmas decorations I noticed that the attic was full of condensation and the feed and expansion tank had very hot water in it. My heating had been on for about 2 hours at the time. Also there is no lid on the tank or insulation .Should there be?

Also there is no lid on the tank or insulation .Should there be?

Is this an actual expansion tank for the boiler?
No lid on an expansion tank Explain "lid"
A boiler expansion tank needs to be closed so it can pressurize when the boiler heats up so the hot water in the boiler has room to expand and maintain its basic boilers pressure. If this is that expansion tank it needs to be closed and pressurized by the boiler. Obviously if there is hot water in a cold environment condensation will occur and that metal area needs very well insulated. My next concern is the moisture in the attic. If the insul gets 5% of moisture in it its now lost 95% of its insulation "R" value.
Is this steam heat that you have?

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Is this an actual expansion tank for the boiler?
No lid on an expansion tank Explain "lid"
A boiler expansion tank needs to be closed so it can pressurize when the boiler heats up so the hot water in the boiler has room to expand and mantain its basic boilers pressure. If this is that expansion tank it needs to be closed and pressurized by the boiler. Obviously if there is hot water in a cold environment condensation will occur and that metal area needs very well insulated. My next concern is the moisture in the attic. If the insul gets 5% of moisture in it its now lost 95% of its insulation "R" value.
Is this steam heat that you have?

Signed 21 Boat

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Hi, sorry for not being clear I don't know much about these things. The tank is a small plastic tank in the attic which I have been told is for the central heating. It is the highest tank in the house. When the attic had condensation in it the small tank was steaming and when I felt the water it was nearly too hot to touch. As far as I know the heating system was put in the house about 15 years ago, if that helps

You have a open system. Not very popular in the USA. Years ago they were used in the USA and they were especially seen in northern areas like New York.

It is the simplest kind of hot water system and called the "open" system. In this arrangement, the increase in volume due to the expansion of the heated water is taken up by an expansion tank located above the highest point in the system, usually in the attic. This tank is open, with an overflow pipe at the top, so that if the tank becomes too full of water, it will flow out through the pipe and not over the side of the tank to the attic floor.

In these type of systems there can be high humidity in the attic space. If you have concerns I recommend you contact a local heating company for a ON Site inspection to be sure it is operating properly.