have an old boiler in my house that needs to be replaced it currently heats the hot water and blows hot air for heat so most of the ductwork for forced is in place would it be more cost effective to replace with baseboard hot water and hot water for the tap or should i go with a conventional hot air furnace and a seperate on demand water heater ??
Having lived in both air and water I can't say their is a big difference. Since you are all ready set up for forced air how could hot water be cheaper ? Hot water takes more to heat the pipes but stays warmer longer. Forced air has the dust bunnies but is a drier heat so warms much faster but last less. You are going to get a cast iron boiler I hope, a much longer life. I did get my steel boiler re-tubed much cheaper,it failed in 7 years, but lasted 14 + as I sold the house.
In my experience hot water heat (hydronic) is easily the most comfortable (second only to in-floor radiant heat). The radiators, whether the older cast iron or newer baseboard, radiate heat as well as circulate, thus more comfortable and fewer cold areas. Radiant heat presents less of a problem with heat gathering at the ceiling (thus the reason radiant heat was used in the old cathedrals). Negatives are: The initial installation expense may be more; inability to have central air conditioning; more difficult for the homeowner to extend the system. Forced air (known as scorched air by many pros) tends to hit you with cool air on start-up, can be noisy, often feels as though the room cools down faster, will send much of the heat to the ceiling as warm air rises, and presents more of a potential problem with carbon monoxide if the furnace heat exchanger fails. Positives include: Usually less expensive to install initially; easier for a homeowner to extend the system; can be used for a central air conditioning system.
