To Zone or Not to Zone? Need Your Opinion!

DCTepper · 05-10-2012, 10:58 AM

We are in the process of finishing the basement of our 3 year old West Michigan home, adding approximately 1,000 sq feet of finished living space. We will be using the basement as our primary entertainment/play space once it is finished. To give you some background information; the furnace we have is 60,000 BTU, the basement is a daylight with three 60x42 slide-by vinyl windows. The builder added 2¾in cellulose insulation to all concrete walls and I will be adding an additional layer of R13 to all exterior walls as well. I took some preliminary measurements and the basement is 6°F cooler than the upstairs (63°F vs 70°F) with daytime temps in the 60's and nightime temps in the 40's.

We received estimates from 5 local HVAC companies, which is likely more than most would normally do, but we wanted to get multiple opinions on whether it was necessary to zone or not given the added expense ($3,000 in addition to the $1,000 in standard ducting).

Given these variables, what are your thoughts? Should we spend the extra $3,000 and have it zoned, or is the additional insulation, lack of walkout exposure, etc enough to keep it warm? What temperature difference might I expect if we do not zone?

Doc Holliday · 05-10-2012, 05:06 PM

I'd install a mini split system just for the basement. Those 60,000 btu's were meant for original square footage, not an additonal 1000 sq. feet.

DCTepper · 05-10-2012, 05:14 PM

Quote:

Originally Posted by Doc Holliday

I'd install a mini split system just for the basement. Those 60,000 btu's were meant for original square footage, not an additonal 1000 sq. feet.

Mini split system?

Doc Holliday · 05-10-2012, 05:26 PM

Yup. It's a complete a/c system without any duct work. Perfect for additions. Many different brands with different options such as two or three indoor blowers (for individual areas of an additon) and remote controls all on one outside condensing unit. The indoor blower simply hangs on a wall.

Google 'mini split a/c'. Here's one.

Doc Holliday · 05-10-2012, 05:34 PM

They call it a mini split because it's exactly like your home's normal a/c, has an outside condenser and an indoor evaporator and blower with a copper refrigerant lineset inbetween, but only a much smaller version. And no duct work. They are design specific for your needs, smaller areas such as additions.

This is more or less what the outside would look like.

newtech · 05-10-2012, 06:14 PM

Quote:

Originally Posted by Doc Holliday

I'd install a mini split system just for the basement. Those 60,000 btu's were meant for original square footage, not an additonal 1000 sq. feet.

A mini split will not cover all the rooms as the pic shows.

newtech · 05-10-2012, 06:27 PM

Quote:

Originally Posted by DCTepper

We are in the process of finishing the basement of our 3 year old West Michigan home, adding approximately 1,000 sq feet of finished living space. We will be using the basement as our primary entertainment/play space once it is finished. To give you some background information; the furnace we have is 60,000 BTU, the basement is a daylight with three 60x42 slide-by vinyl windows. The builder added 2¾in cellulose insulation to all concrete walls and I will be adding an additional layer of R13 to all exterior walls as well. I took some preliminary measurements and the basement is 6°F cooler than the upstairs (63°F vs 70°F) with daytime temps in the 60's and nightime temps in the 40's.

We received estimates from 5 local HVAC companies, which is likely more than most would normally do, but we wanted to get multiple opinions on whether it was necessary to zone or not given the added expense ($3,000 in addition to the $1,000 in standard ducting).

Given these variables, what are your thoughts? Should we spend the extra $3,000 and have it zoned, or is the additional insulation, lack of walkout exposure, etc enough to keep it warm? What temperature difference might I expect if we do not zone?

I live on the east side of Mi. We have a finished basement that we are in 99% of the time. Added a few duct runs plus some cold air returns and the basement is warmer than the main floor in the winter.

No need for cooling in the summer. ( but I have to manually adjust the dampers )

If you want a fully automated system... Then a zone system would be the way to go...

**beenthere** · 05-10-2012, 07:28 PM

Zone it. then you can control the temp of it and your main floor without having to adjust dampers manually. So if you suddenly change your living habits, you don't have to pop ceiling tiles to make adjustments. or go to the mech room and make adjustments.

dougp23 · 05-10-2012, 07:54 PM

Zone it. For a reasonably small fee (3,000 dollars) you'll always be comfortable and able to adjust the temperature to your liking. When it comes to a project like what you did with your basement, do you really want to do it half baked and save $3K? The whole project is probably running you close to 15K? Spend the extra, you'll never regret it. (We zoned our finished basement).

Doc Holliday · 05-10-2012, 08:28 PM

I'm confused. If a heat load calculation determines that a structures is losing/gaining 60k btu's per hour and thus the correct size system is installed to replace those btu's per hour than how can 60 btu's be enough to cover a new and additional 1000 sq feet? Am I missing something? Isn't that more structure to lose/gain heat?

Doc Holliday · 05-10-2012, 08:37 PM

Quote:

Originally Posted by newtech

A mini split will not cover all the rooms as the pic shows.

A four blower 2 or 3, 3.5 or 4 ton minisplit wouldn't handle four rooms? Why do they make them them? I suspect a big enough one could cover a vast bit more than just the areas in questons.

http://www.younits.com/quad-zone-min...oms-c-271.html

http://www.energysavers.gov/your_hom.../mytopic=12630

http://www.ehow.com/how_5032897_size...nditioner.html

bbo · 05-10-2012, 09:35 PM

Quote:

Originally Posted by Doc Holliday

A four blower 2 or 3, 3.5 or 4 ton minisplit wouldn't handle four rooms? Why do they make them them? I suspect a big enough one could cover a vast bit more than just the areas in questons.

http://www.younits.com/quad-zone-min...oms-c-271.html

http://www.energysavers.gov/your_hom.../mytopic=12630

http://www.ehow.com/how_5032897_size...nditioner.html

the thought process is most likely dealing with closed doors, indirect line for all rooms, etc.

Doc Holliday · 05-10-2012, 09:47 PM

One in the game room, one in the bedroom and either one or two in the living room. If you absolutely had to then one in the bathroom but an exhaust fan to remove humidity after a shower and leaving the door partially open would sufffice.

Outside of the mini split, I'm still left wondering how a system designed to replace 60k btu's per hour for an original structure is now supposed to handle an additional 1000 sq feet..? Is it because the other stats would be off to the upstairs so all the air would be flowing to the down? What happens when all the stats are calling?

**beenthere** · 05-11-2012, 04:17 AM

Part of the original heat loss was to the unconditioned basement. When the basement is conditioned, the main floor's heat loss to it will no longer exist.
Guessing the duct work is in the basement also. So the duct work had a heat loss to the basement. So with the basement heated, there is no longer any heat loss associated with the duct work. So the heat load the furnace was handling for the first floor is reduced, and that heat can now be used fo the basement.

DCTepper · 05-11-2012, 08:22 AM

Quote:

Originally Posted by beenthere

Part of the original heat loss was to the unconditioned basement. When the basement is conditioned, the main floor's heat loss to it will no longer exist.
Guessing the duct work is in the basement also. So the duct work had a heat loss to the basement. So with the basement heated, there is no longer any heat loss associated with the duct work. So the heat load the furnace was handling for the first floor is reduced, and that heat can now be used fo the basement.

Sorry, I should have mentioned that there are currently NO runs in the basement, only the preliminary batting insulation on the walls. I agree, the 6°F difference will become closer to 3-4°F at most once the ducts are run and the R13 is installed against the exterior walls.

As far as the mini system, I am not concerned with cooling as much as I am heating in the winter.