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Home Improvement--General/central air - hydronic system


Hi Steve,

I am currently in the middle of a home construction/remodeling project.  (adding a second story to an existing ranch).  I am looking at central air.  My heating system is new (1 year old) and is a gas fired boiler with hot water baseboard.  Instead of a central air unit, my contractor is recommending a heat exchanger to my existing boiler for hot and cold air.  What are the plusses and minusses for this set up?  I am concerned about the ducts and space.  

Most importantly, is this hydronic air system as reliable as baseboard and central air separate?   And price wise which is more afforadable- hydronic air with ducts or keep existing boiler and replace the baseboard?

Thanks for any insight,


You are looking at multiple variables and quite a few different cost scenarios here.  If your HVAC contractor is trustworthy they should be able to provide you with cost comparison figures for any proposed system(s).

My quick take, possibly the least costly, is to add a zone to the boiler and continue using the baseboard heat in the addition, keeping the existing baseboards on the first level.  This assumes that your boiler has adequate capacity to heat another floor level.  

Assuming you have a basement, and assuming that your upstairs is not finished, install an air handler/A-C coil in the basement with an outside compressor.  Duct the basement and feed the first floor rooms with branches from there.  Extend the trunk all the way to the new attic (through a finished chaseway) and feed the upstairs rooms through the second floor ceiling.  Use insulated duct in the attic.

This is just my first take based on your description.  Let me know if you have any other questions.  


Home Improvement--General

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Steve Major (Owner - Major Design Group)


I can answer any questions regarding the design and execution of home improvement and remodeling. This includes trade-specific questions (how-to) in all major building trades: framing, foundations, site prep, electrical, HVAC, plumbing, water treatment, interior finishing, trim & cabinetwork, exterior finishing, roofing, siding. PLEASE indicate your state or region, so I can provide the best possible answer. PLEASE provide photos whenever possible.


30 years experience in home improvement design and construction, all hands-on, including the construction of dozens of single-family homes and hundreds of remodeling projects in the northeastern US.

Author: "Architectural Woodwork - Details for Construction" published by Van Nostrand Reinhold (now Wiley).

BS -- Cornell University

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