IComparer<T> child as a generic param could not be used in Sort

Got stuck trying to sort my List<> in C#.

I have an interface type with its implementation class:

public interface IRoom
{
    // ...
}

public class Room : IRoom
{
    // ...
}

And a base class for my comparers:

public abstract class RoomComparer : IComparer<IRoom>
{
    public RoomComparer()
    {
    }

    public abstract int Compare(IRoom x, IRoom y);
}

And two its children:

public class StandardMultipliedSquareMetersComparer : RoomComparer
{
    public StandardMultipliedSquareMetersComparer()
    {
    }

    public override int Compare(IRoom a, IRoom b)
    {
        // ...
    }
}

public class SquareMetersComparer : RoomComparer
{
    public SquareMetersComparer()
    {
    }

    public override int Compare(IRoom a, IRoom b)
    {
        // ...
    }
}

Now, here's where the problems begin: I got a generic class Hotel with a list of my Room instances:

public class Hotel<TRoom, TComparer> : IHotel, IEnumerable<TRoom> 
    where TRoom : IRoom 
    where TComparer : RoomComparer, new()
{
    public List<TRoom> Rooms;
    protected TComparer Comparer;

    public Hotel(TRoom[] rooms)
    {
        Rooms = new List<TRoom>();
        Rooms.AddRange(rooms);
        Comparer = new TComparer();
        Rooms.Sort(Comparer);
    }
}

And here's the trouble - I got two errors on the line Rooms.Sort(Comparer);:

Error CS1502: The best overloaded method match for `System.Collections.Generic.List.Sort(System.Collections.Generic.IComparer)' has some invalid arguments (CS1502)

Error CS1503: Argument #1' cannot convertTComparer' expression to type `System.Collections.Generic.IComparer' (CS1503)

I tried many different solutions, but no result. What's happening?

Note: using Mono 3.10.0 on Ubuntu