Cold as ice and/or burning up for your love

June 28, 2012 2:51 PM

I have a 1700 square ft. house. I have an air conditioner/heating system that is set up to operate with the whole house as one zone. I have one room that is out of proportion to the rest of the of the rooms in the house (much larger, much higher ceiling) that is always hotter in the summer and colder in the winter. So I'm thinking the solution is for that room to be separated into a second zone. How?

Is this by any chance a job that we can accomplish ourselves? Is it possible with the existing AC/heater? Does it require a pro? I have literally no idea where to even start with this process....so hope me please?

posted by BlahLaLa to home & garden (14 answers total)

I believe another zone requires another A/C unit. That's how it works in my family's large and weirdly-shaped house: 5 zones and they all have their own A/C units.

Think about it--zone A is hot, so it needs the A/C. But there are ducts from the same unit going to both zones A and B, so how can you only cool zone A without cooling zone B, too? Unless you manually went around closing the vents.

Our heater/boiler is two zones on one unit, and our plumber says every winter when we have problems that that's the reason, because the two different thermostats are competing for when the unit should go on and off.
posted by thebazilist at 2:56 PM on June 28, 2012

One idea is to get a separate unit just for that part of the house. One idea is a ductless air conditioner/heater, like this Mitsubishi item.

These are common in Asia and decently efficient.
posted by Ruthless Bunny at 3:03 PM on June 28, 2012

Yeah, zones are traditionally per unit. The ductwork for Zone A is blocked off from Zone B, each zone has its own unit. You would need a professional for that.

You might consider a ductless split air conditioner in the big room to assist rather than going to significantly more expense to zone a single room.
posted by Lyn Never at 3:03 PM on June 28, 2012

My parents' house has a flow control in the main duct branch between upstairs and downstairs. Maybe you could look around for something similar? If you don't have anything like that, it's hard to imagine a simpler solution than a window A/C unit and a space heater in that room. They are not very efficient, but it would fix the problem instantly. Plus the window AC units are pleasant to stand next to when you come inside from an extremely hot day :)
posted by scose at 3:04 PM on June 28, 2012 [1 favorite]

You could try closing or blocking the air output vents in other parts of the house to force more conditioned air into the uncomfortable room. Also, fans can help - maybe put in a ceiling fan?
posted by exogenous at 3:04 PM on June 28, 2012 [1 favorite]

I would say get a window unit in the summer and a nice space heater for the winter. Both can be unsightly (the space heater less so) but it would be a heck of a lot cheaper than getting a second A/C unit like thebazilist mentioned. We had to do that for our upstairs bedroom.
posted by Quincy at 3:05 PM on June 28, 2012

You could try closing or blocking the air output vents in other parts of the house to force more conditioned air into the uncomfortable room.

This is exactly what I did to balance cooling and heating between my (tall, wide, open) first floor and my (very cozy) second floor. In the summer, all but one downstairs vent is closed with all the upstairs ones open. In the winter, it's the opposite. Thermostat is on the first floor. I had to experiment a bit to find a good balance.

It may not work for you—depends on where your vents and thermostat are. But it's easy and costs nothing if it works, so worth a try?
posted by DrJohnEvans at 3:15 PM on June 28, 2012 [1 favorite]

New panel, thermostat(s) and possibly some wiring from the panel to the room. If your current AC can blast the whole house as it is, power consumption and time aside, likely it's just controller stuff, so maybe a little bit of pro depending on your skills.
posted by rhizome at 3:32 PM on June 28, 2012

In commercial HVAC systems, there are thermostat-controlled dampers between the main ducts and the branches, giving you some degree of control over the temperature in the area served by the branch. Something like that might be possible in your house, depending on the duct layout, although I've never seen it in a home myself.

A ductless split system would probably be the way I'd go (and in fact I'm thinking about getting one for the master bedroom in my house, so I can close the door at night and just air condition it without chilling the rest of the house during the height of summer). They are about $3-5K installed, a bit more if you want it to have heat pump capability as well, which seems like a nice feature.

Depending on how old your main air conditioner is, a split system may be more efficient than messing around with the central air.
posted by Kadin2048 at 3:59 PM on June 28, 2012

Also here is pretty much the same question on diy.stackexchange, with some good answers.
posted by Kadin2048 at 4:02 PM on June 28, 2012

Like DrJohnEvans, we had success in partially closing ducts to smaller rooms. We also found that leaving the blower set to "on" rather than "auto" kept a more consistent temperature and saved us energy in the long run.
posted by advicepig at 5:10 PM on June 28, 2012

You might also want to do a quick check of your duct work it might need some taping and sealing.
posted by bitdamaged at 6:13 PM on June 28, 2012

We just went through this same deal, to regulate the temperature in baby's room, as it was colder than the rest of the house. We have an HVAC tech in the family. He fiddled with the dampers in the attic and got it adjusted. Also: he recommended against closing off vents. The air circulates to the closed vent and back and causes undue stress/energy cost on the system.
posted by litnerd at 6:22 AM on June 29, 2012

Do you have a ceiling fan in that room? It should help.
Also, we have a cathedral ceiling family room. To keep it toasty in the winter (Canada) we installed a small gas stove. With the ceiling fan it's perfect.

Summer is little problem, as the floor (where we humanoids dwell) is cool. I did adjust the AC flow (by both closing vents in the rooms and the valves on the ducts in the basement) to drive all the cold air upstairs.
posted by mbarryf at 6:26 AM on June 29, 2012