All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.

Hello

If its radiant heat in a concrete slab for it can take a while to heat the house once the house has cooled down. If you have open or base board heaters heating should be faster than that,

If there is air trapped in the radiators heating will be slower, thats easily fixed.

Tell me how long the system has been installed, and what type of radiators you have. We can go from there,

Thanks, it sounds like there is air trapped in the radiators. Thats a common situation.

Near the top of each Radiator is an air bleed valve.

I have been in the business for 51 years ... so far Ive always been able to figure these systems out

The problem is most likely caused by poor water circulation. That can have several causes, and will be evidenced by the Boiler not running full time when heat is being called for.

Tell me what the boiler water temperature is, and what temperature the radiators are when you run your hand from top to bottom on each radiator.

Tell me how many times the boiler goes on and off in an hour roughly..

I need the model number of the boiler.