Need help with HVAC zoning between first floor and basement

6 years ago

For our new residential construction (New Albany OH), the builder specked out two systems.

One smaller Bryant system for upstairs (1200sqft).

One bigger system for 1st floor (3300 sqft) and basement about (1500 sqft) finished. The HVAC says that this configuration would work quite well, and keep things comfortable.

I inquired about zoning the basement separate with electronic dampers. This would apparently cost $3k more than the original $20k. I am trying to weigh the pros/cons of leaving the original plan as is Vs putting this electronic damper zoning. Is there any other alternatives?

I know I have given very limited information, but do you think it is a fair estimate to just put an extra panel, thermostat and dampers?

The HVAC guys are working on the house now, so this would be the time to make any changes if we want. Thank you

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Comments (4)

mike_home
6 years ago
If you are going to add zoning then it is best that the furnace have at a two stage or variable speed equipment. Do you know what the model numbers is for the Bryant furnace and AC are for the first floor?

The alternatives are manual dampers for the basement which have limits as to well they will work. It depends on how well you want to control the basement temperature.

Be aware that most HVAC contractors don't do a good job when it comes to zoning. It requires the right equipment and skill to do it properly.
PRO
Prime Ohio Real Estate
Original Author
6 years ago
I don't have the model information yet - I had asked about it, but have not received it.

From what I was told by HVAC contractor, the two systems are single stage, 92% Gas furnaces, and 14 SEER AC units.
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I had a similar situation identical to your planed build 2 months ago for an existing 1995 home. My first recommendation was a separate system. The second was a dual zone system, and reluctantly gave a third recommendation of just ducting the basement off the existing furnace. I agree with David Cary about a separate system for the basement for many of his reasons including my own I told the other guy about , like giving the basement it's own independent return system to reduce sound transmission to the upper levels and odors down stairs. not to mention the simplicity, convenience, and redundancy of a back up if one heater breaks down in the dead of winter at midnight. The unit for the upper floors can be smaller saving a few bucks on the furnace, which can be put into the cost of the second separate system for the basement. The similar house I mentioned was 2400 on two stories and a 1000 sq. ft basement where the owner also worked from home. I did a quick load calculation and determined his new (2017) furnace of 60K Btu's wouldn't carry the basement load and pushed the separate system or replace the existing with a 80 to 90K furnace, he didn't believe me and had a few other people out. They all said the 60K was to small, so he had it replaced with a 80K and duct work for the basement without zone control for $5600. He's still going to freeze his feet off down there this winter..... and won't even be able to kick himself for not taking my offer to put in a separate furnace with duct work for $3800.
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ionized_gw
6 years ago
This is a totally underground basement? The problem is that you will want significant heat in the winter, but not much cooling in the summer. Air flow changes are the only way to do the changeover. Manual dampers can do it, but will only do it well when you are consistently in heating or cooling mode. In times of flipping temperatures between heating and cooling, you will have to twist the dampers all the time. The other thing is that you have to maintain the right air flow for the main blower. That means that you have to bypass air flow back to the return if closing dampers and not opening others. The alternative is to "manually" change the blower speed.
mike_home
6 years ago
last modified: 6 years ago
Basements which are mostly underground have a small heat load. In the summer the basement can actually become too cool if you leave the vents open. When I installed my new system I didn't get a separate zone for the finished part of the basement. I didn't think it was needed but now I know better.

I would be concerned creating a zone for the 1500 sq ft basement with a single stage furnace. I am willing to bet the first floor system is over sized which further aggravates the problem. I suppose a contractor who is very good a zoning could do it correctly. But then again someone who understands the physics behind good zoning design would probably recommend upgrading to a variable speed 2-stage furnace.

Need help with HVAC zoning between first floor and basement

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mike_home

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Need help with HVAC zoning between first floor and basement

Comments (4)

mike_home

Prime Ohio Real EstateOriginal Author

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