I agree with B , if you have a check valve or closed water system water in the tank will expand 1/23 what that means for every 23 gallons of cold water after heating you will have 24 gallons.
the old fashioned cast iron rads, where very efficient, they need just a water temp of 140 f to deliver heat , the thin line rads need a water temp of about 180 - 200 f to deliver the same amount of heat. I do not know how many service calls i have been on where some renovator installed new thin...
it is very important to open a window or two when using a fireplace. most houses have all matter of exhaust devices (dryers ,bathroom exhaust, kitchen hoods ect )but nothing coming in so the house has a negative pressure .
as electric motors get older the insulation starts to break down. most compressors are guaranteed for 5 years . Electric motors draw 10 times their normal current when starting . I assume this is a central unit of 3-5 ton ?
Be careful some municipalities will not allow this . I heard that one homeowner did this and the water Was sent to the street and then froze causing an accident that ended up in court.