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Community and Q&A

Small Duct High-Velocity Central Heating

Brian_Smart | Posted in Energy Efficiency and Durability on

We own an eclectic home that was built in 1973 in Boulder Colorado. From the front entry there are three levels going up. First, to a formal living room (1), then next to a family room, kitchen and formal dining room (2) and then next to the bedroom level with 4 bedrooms (3) with an attic above the third level. The entry level has the garage, a utility room (boiler, water heater), and a full bathroom. From the entry level you can also go down 1 level to a single room that was converted to a bedroom. The home has no AC and a boiler system for hot water base-board heat. Based upon the existing floor plan I really feel like we only have two choices for cooling either mini-split systems or a high velocity small duct system. I am thinking that we could leave the hot water heating system in place and just add cooling as an independent system. Because we are in Boulder with 300+ days of sun a year; would either of these systems be amenable to a solar system and a Generac power cell or Tesla power wall? We could locate the mechanical in the utility room or the non-conditioned attic. I am leaning toward the high velocity system, but there are clearly efficiency issues with small ducts.  Any thoughts would be helpful. The house has other eclectic issues I am planning to address, but let’s start with this. Thanks

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  1. user-5946022 | | #1

    Don't think whatever you meant to attach or reference came through properly

  2. davidsmartin | | #2

    Be aware that small duct high velocity systems can be very noisy.

  3. Expert Member
    Akos | | #3

    There is nothing wrong with a well designed and installed high velocity setup. Sometimes it is a better option for older houses as it can be installed with minimal interior work. All the piping and fittings do add up, the air handler is not cheap so not a budget option.

    One option you can look at SpacePak's Solstice extreme. This can run both your existing radiant heat and provide cooling in the summer. The system can only provide lower temperature water for heat in cold climate (less BTU output out of your existing rads), chances are you will also need to run the hydronic air coil in the winter time to supplement for heat.

    Not cheap though, but might be a simpler way to transition to electric heat.

    Strategically placed wall mount mini splits can work for cooling only, but you won't get much comfort in an older home with lots of rooms. Mini splits for heat and cooling can be made to work but with lots of rooms but it usually means a ducted unit. This is best to install during a major reno since you need to run a lot of ducts.

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