What to do about a cold room?
Hello everybody, this is my first post here. I did read the rules and look for a FAQ, I think I understand that questions from homeowners are welcome so long as they aren't DIY things.
I'm asking what can be done about a particularly cold room in our home. This is our third winter in this house. The first winter we just used it for storage, the second winter we turned it into a nursery but our newborns slept with us in the master bedroom. This year our twin daughters (now 16 months) are sleeping there and the cold really bothers me. We have a space heater in the room, but it seems like there should be a better way.
The room feels significantly colder than the rest of the house. Based on its position, it is probably the longest duct run from the furnace of any room. The room only has one vent (almost all other rooms have two vents). The room is also north facing, so doesn't get much sun warming. It is partially above the garage, so the floor (insulated) is partially above unheated space, and two and a half of the walls are exterior facing.
Are there any reasonable things that a HVAC contractor could do to try to warm up this room? Are there things I could check myself that would help in giving advice?
I'm not happy with having a space heater in this room once the girls grow out of their cribs and move into toddler beds.
Thanks in advance for any suggestions. If you have questions, I'll do my best to answer.
if the duct to this room is accessible then you may be able to enlarge this duct or add another supply if there is no accessability to the duct work then your limited to what you can do...possibly installing a ductless mini-split system,or a ptac(like you see at economy hotels....
You have a common issue with having a room that has more exposure then others in the house. It is also not the easiest situation to fix.
My guess is that the room is not colder at certain times, such as during the day when the sun is out. Also, is the room warmer during the cooling season? If so, then you need to have supplemental heat installed (or just keep the space heaters.)
If you have a larger duct or more ducting run to the space and the conditions are only during certain times of the day, you will be over compensating for the conditions of the room at other times.
Try the "rob Peter to pay Paul" method of closing one regester off in the warmest rooms that have more then one regester to see if the air will be forced into the cold room.
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what is the square footage of room and is it a standard 4x10 floor or ceiling register,nevertheless i would suggest the same as others upsize duct or add another register.
Originally Posted by DanYoung
Is there a return air in this room? If not then make sure the door stays open so that the air can move freely.
Also the system is controlled by the thermostat. It dosn't care what the temperature is in that room and shuts the system off when it is satisified. You may try shutting down the registers that most effect the thermostat a little to make the system run longer to heat this room. I would not close them completely. It could take some trial and air to get it close that way.
The other thing you may try is running the fan all the time to keep the air moving through the house.
How old and what type of system do you have? If its old then you may try replacing it with a 2 stage system which would run on low speed most of the time and have longer run times.
Its a good Life!
You need to verify the amount of air going to the room compared to what a heat loss calculation says you need before changing the ducts. I just checked a house with a similar problem and the air flow to the room was fine but there was significant air infiltration from the eaves to under the floor. Most builders do not do a good job of air sealing the rim/band joist area and the under floor and the insulation is not in good contact with the floor allowing an air bypass. A blower door test with an infrared camera may help in the diagnosis. If this is the case the best way to improve is to use a spray foam insulation under the room in the floor joist cavities. This will give you both insulation and an air barrier in one product. If you find that the airflow to the room is less than required and infiltration is not a problem then duct improvements will be needed.
If you don't test, it's just a guess.
P.S. Find the problem, fix it, and get rid of the space heater.
I dont like using them but you could try an inline booster fan in the duct and put turning vanes right before the branch of that take off on the trunk to capture the air and force it into the room.
I had a problem room like this recently, turned out to be very little insulation in the attic over this room.
You can do it; call in a professional, the safety factor is an issue in itself.
Originally Posted by mbarson
"Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great." -- Mark Twain
For starters I would not reccomend shutting off any registers thru the house to accomodate for low air flow in another area. There is a good possibility that the duct work is undersized and if you have a heat pump this could cause some mechanical failures. I agree with Mbarson have someone do a load on the room fix all possible infiltration leaks, then adjust air flow accordingly.There are numerous ways to approach your problem(s) like repairing, upsizing or adding supplies and returns.There is a chance you could create another problem as ROBO stated "over compensation". In this case you could add a damper system with a thermostat to shut this area down when needed, similar to a zone but will not control the system just the dampers.But make sure the remaining duct will handle the system without problems. My advise is to get a contractor to do the above and I second getting rid of space heaters in a bedroom especially with children in the room!
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Unless a duct system is perfectly designed and installed it will require dampers where the branch duct leaves the trunk. This is the only way to control the air flow through the system as air is lazy and will find the easiest way out of the duct. That often means the branches and registers closest to the blower get more air and the ones the farthest the least amount of air.
If your trunk is visible, look to see if you have manual damper levers and if not they can normally be added. Then, as others have advised, have a load calculation done that will determine the heating and cooling needs of each room and the required amount of air flow to deliver the heating and cooling. Doing a blower door test is a good idea too.
With the information from the load calc effort, have a pro evaluate the duct system and determine if there is sufficient supply and return air. Often return air is undersized which chokes the amount of air on the supply side. Adding more return air volume is often necessary. The final step is to have the duct system balanced where the air flow to each room is measure (using equipment for doing that, not holding a hand in front of a register) and adjusted using the dampers to deliver the proportional volume of air.
This should all be part of the original installation and commissioning of a comfort system, but all too often is skipped.
When I purchased my home a couple of years ago I found that my second floor system was not maintaining even temps with there being 8 - 10 degree differences between bedrooms in summer and winter. I had the return air duct increased in size (one central return in main hall went from 14" to 18"), added dampers to each branch duct, and the air flow balanced. Each room is now within .20 degrees of the others.
Thanks for all the great answers so far. I think there are some things I should measure and check before doing anything else, but here is information I probably should have added in the first place.
There is good access to the return and supply ductwork in the basement, but once the duct turns and heads into the first floor it is all inside walls and floors from there. The bedroom in question is on the second floor. I haven't identified yet which of the ducts in the basement leads to the bedroom, but I don't think that matters (although I did see one duct joint that didn't look well sealed, I need to climb on my ladder and see if air is escaping). There are also some ducts that are dented, but the HVAC company that originally installed them told me the dents weren't big enough to effect air flow.
The house is new construction built in 2005. We are the first owners, but had nothing to do with the construction or options (it was built for another buyer, and the deal fell through). I wish I had seen it built so I knew where the ducts run, but unfortunately I don't. The builder made a big deal about how well the house is sealed, and claims builds to some local voluntary standards that are pretty high.
I haven't tried yet closing registers in other rooms to see if I could force air to the cold room. It is certainly worth a try (but not an ideal fix). The bedroom in question is 11' x 11', and has one floor register. I haven't measured it yet, but 4x10 seems about right. Return air from the room flows through a "vent" (don't know if that is the technical word) above the door and into the hallway, where it is picked up by a central return duct.
We don't usually run the fan 24/7, but there is a timer built into the system that circulates air regularly regardless of whether there is a call for heat or cool. That brings up another question (how efficient is it to circulate with a 6" undamped outside air duct), but that is a topic for another post.
I've looked very carefully at the trunk and all the basement ductwork. There are no dampers that I can see whatsover.
I like the idea of doing a blower door test with infrared camera. When we had the home inspected, we found a small part of the living space ceiling (about 10' by 10') that was uninsulated. It was an easy mistake for the insulation guys to make, because that space was only accessed through a separate access door in the garage. Regardless, I've had my doubts about the insulation since then. When we had them come in to fix that mistake, I paid extra to have a bunch of extra insulation blown in above the garage around the base of this bedroom, but it didn't help noticably.
Uhm, maybe I should have said this to begin with. Our system has one stage of heat and one stage of cool. Heat comes from a natural gas furnace, and cooling comes from an air conditioner. No heat pumps.
I wasn't familar with "mini-split" or "ptac" before this message. If I understand, they are both basically in-wall heaters.
Finally, I like the idea of a booster fan, it seems straightforward, but I take it there is something wrong with that approach?
I'm not sure what to do next (other than call in a contractor). I really don't want to start tearing up walls for new ductwork, so that leaves:
- Have the infrared test done to look for leaks or underinsulation.
- Play with the registers in other rooms.
- Check that possibly leaking joint I saw last night.
- Get a booster installed.
I don't like these as much, since it doesn't really "fix" the problem so much as mask it.
- Install an in-wall heater (ptac, mini-split)
- Keep using space heaters
Thanks for all the advise!
Where are you located? There might be someone on this board close to you that could help.