Are you referring to the pressure in your boiler? If so the pressure should rise when the C.H is on and drop back when it is off.
If your boiler is empty of water or your C.H has developed an air lock in the piping, the pressure will be nil, your boiler will not work, you will have no C.H or hot water and your boiler will alert you of this by sounding a continuous alarm.
Why not have your boiler checked out by a competent heating engineer who should be able to advise you of any problems and rectify them for you before you go to the expense of ripping up your floor?
Sam's nan
April 2010
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