One of the rooms in my house resists my efforts to cool it. My suspicion is the amount of technology in it is creating more heat than was ever expected by whoever installed the HVAC system. (It’s my home office)
Trying to force more airflow through the room’s one ceiling register by closing most of the vents downstairs has really only caused whistling and hissing downstairs.
The room is 10x13x8 feet, fed with one 4" flexible duct. The ductwork is all in the attic, immediately above the room. AFAIK, the stuff has an R6 rating, so I was contemplating laying some extra batts over the ducts as an attic with a black roof gets well, unbearably hot in the summer.
To get more cool airflow into the room, would it be better to add another duct to the room, or upsize the existing one to 6"?
Insulation is good, but it won’t bring more airflow. With the ceiling vent wide open, the airflow is barely perceptible. The vents downstairs have so much flow that I don’t even have to reach up to them to feel the breeze.
if the room is better insulated then it doesn’t heat up so much then it might not need as much cooling.
is there a good exhaust path for air from the room for new air to come in? maybe a small fan into whatever exhaust path will help lower the back pressure in the room.
if conditions are suitable cool the room using outside air overnight.
Look at the cause of the heat first, consider replacing desktops with laptops or implementing power saving options, replace CRT monitors with LCD’s (including using laptops). Turn off things such as printers if you are not using them, set up wake on LAN or other such auto start options. Replace lighting fixtures with LED lighting (or CF if you must).
As stated above the sell booster fans for the vent system.
Leave the office door open
Increase airflow by installing vents from the room into the hall, perhaps put a fan here to make the room negative pressure (so sucking in more from the vent).
Have your a/c system ‘suck’ air from this hot room by having a return vent installed here.
Put a additional vent, hopefully from a different ‘line’
Shade the sun, install better windows including using plastic sheeting
I would tend to look at insulating the ductwork as the first option.
But I’d also want to confirm that there are no holes or gaps in the ductwork that might reduce air pressure and permit cool air to leak into the attic.
I have heard that even “simple” changes like widening ducts can have unintended side effects if they screw up the balance of air flow/pressure throughout the rest of the system.
And my last thought is that technology can create hot spots in the room’s air; sometimes a box fan or ceiling fan can solve some of the problem just by circulating the air better so that you don’t have a cold side and a warm side. (This experience is thanks to an old 8x8 office with two computers, four CRT monitors, two printers and misc networking gear, all on one wall.) But unless you’re running a server farm, it seems like a home office would only make an existing HVAC deficiency worse, rather than creating the problem.
Rebalancing the air supply could be as simple as looking for a diverter somewhere in the line. Some HVAC systems in two-level houses just have a vane built into the main trunk line that you can flip to send more air to the upper level in summer or more to the lower level in winter. I’d start at the main air handler unit and look for anything in the ductwork that looks like a lever.
It’s not like I have racks of servers in here - just one iMac, a laptop with two monitors, an LCD TV and IPTV box, and an inkjet all-in-one. Nothing outlandish, but also nothing that existed when the house was built.
But that’s no excuse. I’ve had even older homes whose air conditioning could keep a room cool housing a large tower PC with 19" CRT, a Laserjet 3 and a photocopier all cranking away in full deforestation mode.
CRT monitors - weren’t those the big heavy things? I haven’t had one of those for close to ten years. Yesterday, the room lights were off and I had a box fan in the doorway blowing into the hall. No appreciable difference.
Up in the attic, there are no dampers. Just two large trunks coming off the plenum. One goes down a chase to supply the downstairs vents and the other goes to a box made of duct board and all of the upstairs ducts come off of that. FWIW, I did find a reference that indicates a room of this size should be fed with a 6" duct, so the existing duct is undersized.
To call me an inexperienced amateur would be far more praise than I deserve. But I’ll suggest this anyway…
So you’ve told us about the air going IN to the room. Does it have any way to get OUT? Airflow is a two-part deal.
My home office gets pretty stuffy in the summer, but it is clear to me that it’s because the air can’t circulate, despite a four-foot wide doorway to the living room. I’d love to put in a vent, but it’s a rental, so fans are my only option.
Does this room have a window/windows? If so, some seriously heavy drapes (or solid foam insulation) will cut the heat flow through them way down. And if the sun shines through them you might want to consider putting something like aluminum foil on the insides of the window and then back that with some solid foam insulation. That sunlight packs a lot of heat.
I have a similar problem with my office. It has a South facing window, and plants, so I don’t want to close the window. I put a box fan on the floor at the doorway, blowing inward, which helps a lot, but still isn’t always enough. I’m considering installing a transom (a rectangular hole above the doorway), with fans mounted in it to blow air out.
Instead of crawling around in the attic, reducting, replacing junctions, and re-engineering the entire house, it might be easier all the way around to buy a small, 110v window AC.
When I was researching 110v window ACs, I learned that you don’t want anything smaller than 8000 BTU. The 5000 BTU size simply cannot handle the job.
Everyone else apparently read the same information, because the shelves were empty of 8000 BTU ACs, and 5000 BTU ACs were stacked to the rafters in the stores.
In your case, the 5000 BTU size may be just the boost you need. You might be able to pick one up fairly cheap.
~VOW
It’s a bit of a unsightly project but you could make the room smaller by installing partitions sealing off sections of the room that don’t need to be cooled.