Just moved into flat with gledhill systemate 2000 thermal store - which I don't understand and central heating is not my thing anyway. Hot water is ok, but no heat. Since the thermal store is sealed there doesn't seem much to check out. But the F&E tank that sits on top is nearly empty & water level is below top of lower pipe. Might this have something to do with it? Could it help to add water to tank & bleed radiators? All ideas appreciated as can't really afford to call out plumber. thanks