A newly retrofitted house will have reduced heat loss and will need a smaller heating and cooling system than before the retrofit. This means that any fuel-fired heating equipment is now oversized - a condition that can cause larger temperature fluctuations and inefficient short cycling, especially for mid-efficiency furnaces and boilers. High-efficiency furnaces and boilers are less affected efficiency-wise, but temperature fluctuations will still affect comfort for occupants, and the equipment will suffer more wear and tear.

When a mid-efficiency furnace or boiler operates less often, the chimney can get colder between firings, increasing the potential for down drafting and possible condensation and damage to the chimney. If your retrofit measures are extensive and you are concerned about this, have the system checked by a qualified heating-system technician.

A persistent problem for almost all new, existing and renovated homes is the need to have the heat distribution system balanced. Undersized ductwork, leaking ducts, inadequate or poorly placed return air grilles and ducts can mean occupant discomfort and higher heating bills. Improved insulation and air sealing may make some previously hard-to-heat rooms easier to heat, while others may overheat.

Simple rebalancing of the system by either adjusting the dampers in a ducted system or adjusting valves in a hot water system may help. Otherwise, find a competent contractor to upgrade or balance your system. Be warned, duct cleaning alone will not resolve balancing issues and generally has little effect on the HVAC system and indoor air quality.

If you have a central air conditioner that uses the same ductwork, it may have to be reset for the cooling season. Note the settings that were used for heat distribution as well as those for cooling so you can re-set the system yourself for each season.