Replies

1. 
   ponytl | Mar 22, 2006 03:20am | #1

   if what you are speaking of is what i have in an office building...  i have a boiler and a chiller...  for the offices (spaces in the building) there are ducted air handlers... in each they have 2 coils  one for hot water from the boiler and one for cold from the chiller.. each has a low voltage valve for the hot & a valve for the cold... the thermosat controls the flow of water thru the coil via the valves... air blows thru the coils either heated or cooled... they refer to this as a 4 pipe system  as the the water recirculates... basicly 2  systems... so heat and cool can be on at the same time in the building... pretty simple system

   p

2. 
   mike585 | Mar 22, 2006 03:37am | #2

   With a furnace you burn gas or oil and the air is circulated around the furnace heat exchanger where it picks up heat.

   With the coil and boiler setup you pump water that is heated by a boiler through a coil in the hot air duct. The coil heats the blown air and the air comes to the space through registers.

   Both are still forced air systems. Most people prefer the baseboard radiators because it's nice, even heat.

   Does this help?

3. 
   RadiantRich | Mar 22, 2006 02:35pm | #3

   One advantage to the hydronic method is simple zoning. You can place several hot water coils throughout the house and each one is controlled by a thermostat and a zone valve. Then since you have a boiler there, you could do radiant heat in some areas to temper the floor, and heat your domestic hot water with it too.

   You can zone with traditional forced air using dampers in the ductwork but extra considerations need to be made to maintain adequate airflow.