Central heating pressure dropping
I really hate to say this, but your suspected problem is probably way beyond the capabilities of a DIYer. If you are still having problems, it may be time to call in a pro. I have not seen any good answers to this kind of question here on the Stack. I don't think we really have a HVAC expert here.  Bite the bullet, find a really competent tech with the right diagnostic tools to find and fix your problem. What you are losing in comfort, fuel effiency , and potential fuel costs might be more than the bill from a proper repair. You may have an equipment malfunction and only putting off the inevitable.