Posts Tagged ‘HVAC’

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DIY HVAC zoning

2011/06/17

Last December (just in time for the “perfect storm” of energy credits…) we had a new heat-pump installed to replace the old gas furnace.  Additional work was done to run ducts to my office upstairs.  The plan was to make the upstairs actually workable during the summer, rather than having the window unit chill the office overnight, then lose the battle at 2 or 3pm and effectively end my productive work day.  So far the system has worked nicely, though the actual compressor has been a persistent noise problem (which Carrier is slowly working on).

The problem is, there really is no such thing as “balance” in a straight ducted system like this.  If the heat is on at any point, the duct to upstairs has to be completely closed off in order to not boil me alive, since there’s plenty of existing heat-producing equipment on my desk.  If it switches to cooling mode, I have to open the duct lest the ambient temperature ooze through the roof and equally boil me alive.  To help this later situation the installation included a duct-assist fan for the upstairs registers, which has to be turned on in many cases to get enough cold air (which is heavy and doesn’t want to go upstairs) where it needs to be.

Unfortunately, the assumption that there would be enough air return “falling” down the stairs hasn’t turned out to be true, which means I’m likely going to have to look into adding return registers and figuring out how to route a duct alongside the supply to the basement.  That’ll mean disassembly of the supply duct because it was positioned in the middle of the available space….

All of this is of course a preamble to the real topic (as per the, um, topic line) of this post, which is my plans to turn this into a zoned system.  The actual meat is after the break…. Read the rest of this entry ?

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