Is Zoning System right for me

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Old 10-09-14, 06:43 AM
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Is Zoning System right for me

I have a 3000 sq ft split level house with an upper floor extension, so there are a total of 4 levels (2 full floors and 2 half floors) that need to be heated and cooled. There are two gas forced hot air furnaces in the attic that provide both heat and A/C. The 1st zone provides heat to the upper floor (3 bedrooms and a bathroom) and to the next half floor (2 small bedrooms and a bathroom) The thermostat for this zone is on the upper level. The 2nd furnace provides heat to the main floor(living room/kitchen/family room and dining room) and the lower half floor (kids play room and office). The thermostat for this zone is on the main floor.
The problem I'm having with this system is the 2 half floors on each zone are a lot colder than the full floor on the same zone. So, for example when the heat kicks on for the upstairs zone, the upper 3 bedrooms are fine, but the lower two bedrooms on that zone are about 10 deg cooler. The heat shuts off when the thermostat, which is upstairs, is satisfied so the lower 2 bedrooms never get to desired temperature. We have similar problem with the 1st floor zone (kids play room and office are always cooler). We tried balancing ducts and even tried a wireless thermostat so we could control zone from the lower bedroom - when we did this once the lower bedrooms got to temperature the upstairs was about 10 deg warmer.

I'm not sure if my problem is that the ducting is inadequate for the colder rooms, or that there is no returns installed on the lower floors, or just that my house is problematic with the multiple levels.

I've met with a couple of HVAC contractors to try to address this situation. One suggested installing a mini-split unit in each of the 4 colder rooms (2 bedrooms and kids play area and the office). This sounded like it would solve our problem but would cost around $10k.

Another suggested adding baseboard heat to the 4 colder rooms. for this we'd need to add a boiler and I'm not sure of the cost.

Another suggested adding a zoning system to the furnace controlling the bedrooms so I'd have one zone for the 3 upper bedrooms and the other for the 2 lower bedrooms. They would install two thermostats, one for upper bedrooms and one for lower bedroom, and a bypass damper for when one of the zones is not calling for air. This sounds good and it would cost me $3k to have it installed for just the furnace controlling the bedrooms. I've heard other HVAC contractors say that don't like zoning systems - they never work right and they can damage your equipment. I think my situation, with the different levels on each zone, make sense for a zoning system. What do you think?
 
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Old 10-09-14, 06:13 PM
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I have never seen a zoned warm air system work well. How is the cooling? You might be able to add a little bit of electric baseboard to help in the colder areas if the A/C does well.
 
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Old 10-10-14, 02:59 PM
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There's not as much difference between rooms with the cooling as we have with the heat. It's not great but tolerable. I'm not too interested in baseboard as it is not efficient.

How much should a mini split system cost me? I would need one 36000 btu unit outside and 4 inside units?
 
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Old 10-10-14, 03:52 PM
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There's not as much difference between rooms with the cooling as we have with the heat
My guess is that your ductwork and vents are in the ceiling or the upper parts of the wall. That's a great combo for A/C but miserable for heat.

I have a hot air system that I added A/C to. All the ducts are down low. The heat works great but the A/C in the upper rooms is poor.

The problem now is trying to get large returns where they are needed.
 
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Old 10-10-14, 04:32 PM
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For the cost of a 4 zone mini-split, you could use the electric baseboard for a LONG time.
 
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Old 02-12-15, 05:11 PM
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I went with the zoning system and its been working great for about 3 months so far!
 
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Old 02-12-15, 05:15 PM
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Zoning is actually a band-aid for poor duct design and balancing.

The same goes for adding baseboards or mini-splits. No one has any interest in solving problems; they just go for the expensive and energy intensive band-aids.
 
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Old 02-12-15, 06:06 PM
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Glad to hear the zoning system is working well for you.

Zoning is actually a band-aid for poor duct design and balancing.
I agree but once the house is built it's extremely hard to make any real changes.
 
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Old 02-12-15, 06:50 PM
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Good to hear you are happy with the system to date but zoned warm air systems tend to be very hard on equipment becuse of the usual differences in zone size. I wish you well in the long term. Please check back in from time to time with updates.
 
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Old 02-13-15, 02:15 PM
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Two stage or modulating equipment is needed for proper zoning.
 
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