Large bedroom too warm despite AC

8 years ago

My husband and I have a largish house (about 3500 sq ft) with a ClimateMaster Tranquility 27 geothermal HVAC system. We're happy in general with the way this system heats and cools our home, but the one problem is the master bedroom - which is about 300 sq. ft with a cathedral ceiling and located on the opposite side of the house (on the main level) from the HVAC unit (located in the basement). In the summer, the bedroom is always much warmer than the rest of the house. It does face northwest, and it's a corner room - so the late afternoon sun hits it hard (though we have shades and curtains drawn). We need to turn the AC way down for the whole main level (it's a 2-zone system) just to get the bedroom moderately comfortable. Short of putting in a window unit, is there any way to supplement the AC for that one room? I would prefer not punching through the exterior walls of the house, for what it's worth. Any advice would be appreciated.

Featured Answer

ionized_gw

8 years ago

I am with hubby. I would not want a window-shaker in the bedroom if there is any other way. You have a premium system with the ground source heat pump. Running a window unit might cost more to operate than overcooling the rest of the house. A ceiling fan might be counterproductive. You might be better off letting hot air stratify near the ceiling.

High wall mount mini splits don't have to be on outside walls if you can find a way to deal with the condensate. I have 6 on interior walls and the seventh on the outside wall has its plumbing run in the stud space, not directly to the outside. You could also install a small AHU in the top of a closet or in adjacent space.

Before jumping into a mini split, do make sure that your system supply and return ducts to the MBr are operating properly. Modifications to your primo GSHP system probably makes more sense than adding. Larger ducts would do it if possible. In addition to that, let's paint with a big brush and see if another zone can be added. Ask around and get recommendations for excellent HVAC pros in your area and then get them in to look at it. On the other hand, a MSHP would be very easy to operate with a small back up generator. That room might be a nice oasis in times of power outage.

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Comments (8)

tigerdunes
8 years ago
Ductwork supply should be looked at...
jackfre
8 years ago
Perhaps a duct booster fan would help, after TD's suggestion is examined. You may find it almost impossible to get to the duct work to really see what is going on. Look at your attic/wall insulation. You might gain there. I'd be interested to see what the temp leaving the HP is and what is being delivered.

You can throw a lot of money at your duct analysis and repair, or perhaps it will be simple. An alternative, that does require drilling a hole in the wall, but will give you excellent comfort in the bedroom would be the addition of a 9000 btu mini-split. It will be a dedicated system, quiet, efficient and you will not have to run the geo so hard to be comfortable in 10% of the house. If you look at this, DO NOT put the condensing unit right outside the bedroom. You will get some humming noise out of the condensing unit.
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mike_home
8 years ago
Do you have a ceiling fan in the master bedroom? How many registers are in the room? What other rooms are being cooled by this zone?

Rooms with cathedral ceilings are difficult to keep cool. You probably don't have enough registers in the room and the placement may not be ideal. Have you tried closing some of the registers in the other rooms on this zone?
udarrell
8 years ago
I wish the ductless mini-splits were less expensive, they can effectively solve a lot of problems & are very efficient. They are used a lot in some other countries.
jackfre
8 years ago
Udarrell, when you consider that they drive their central system to cool less than 10% of their house I think the cost vs energy savings begins to tilt the balance in favor of the mshp. No figures to back that up, but it seems to make sense.
profsuzy
Original Author
8 years ago
Thanks all for your comments. Yes, we have a large ceiling fan - about 60" I believe - that we keep running. There are 2 vents in the room, placed on either side of the king-sized bed, near the exterior side wall. The main heating/cooling zone covers the ground floor of the house - which includes the kitchen, "great room", dining room, study, and the master bedroom (about 2300 sq ft). The second zone covers 3 upstairs bedrooms and bath - about 1200 square feet. We keep zone 2 set to around 80 unless we have guests stayin over, but we keep zone 1 set to between 76 and 78 during the day, but we turn it down to 72 at night just so we can cool down the master bedroom to around 76. I thought that even if we put a window unit in the master bedroom (an idea my husband doesn't like), we could let the rest of the ground floor go to 78 or so, and just cool down the bedroom. The exterior of the house is fiber cement and stone, which makes the idea of drilling through the exterior wall unattractive - but I may talk to an HVAC contractor about that possibility. I also think I'll close off some of the other vents as mike_home suggested. Thanks all.
randy427
8 years ago
Keep in mind that when you pump cool air into a room, for the sake of efficiency, the warm air has to leave. Where are the return air registers located? Do you leave the door open?