Circulating air through house

[stockdoct]

I have a 2-story home, brick, decent insulation but 100 years old .....with a Trane 120,000 BTU furnace which I'm rarely using since I had my new Lopi Freedom insert installed. The Freedom is inside the main living room's masonry fireplace (ground floor) and the family sleeps in 3 bedrooms upstairs. I have a digital thermometer in each of the rooms.

Traditionally, the upstairs bedrooms are about 5 degrees warmer than the living room (heat rises). With the Freedom insert now, the upstairs is cooler than the hot living room by about 10 degrees but I thought I could fix that by intermittantly turning on the furnace "blower" without the furnace generating heat --- there's a switch that turns the blower on easily. Well, it didn't work.

Now, when the living room w/Freedom insert is 75 degrees, the upstairs bedrooms are 65. And when I turn the furnace blower on, I can hear the furnace blower clearly and feel the cool air coming from all the vents, but after an hour there has been no change in the temperatures; the living room is still 75, the bedrooms still 65. In fact, after a one-hour trial this week, the living room temp INCREASED to 76, the upstairs dropped to 63, and I had to open the living room windows to cool off the ground floor.

Why would that happen? What ideas do you have that might lead to the furnace blower not equilibrating the temps throughout the house? I'm puzzled, and unfortuantely looking forward to some chilly nights upstairs this winter for me and the kids.

 

[karri0n]

I have this same problem, except that the temp difference is much greater. I have poor insulation and windows, and last year I could have the downstairs at ~80 degrees while the upstairs was ~55 or lower. Upstairs space heaters were a necessity, driving my electric bill astronomically high. This year I plan on caulking and plasticing all windows, and hoping for the best. I also have radiators rather than forced air furnace, so this solution is not available to me.

 

[fossil]

stockdoct - With a house that old, the central Trane heating unit is quite obviously a retrofit. The system has "return" ducts that take air from the living space to the central handling/conditioning unit, and "supply" ducts that send that air back into the living spaces. The ducts terminate (or originate, depending on how you want to think of it) at registers, which are the "grates" in your home where air is either entering or leaving the space in which they're installed. These registers can be few or many, and can be found in floors, walls, and ceilings...especially in a retrofit system in an old home. I imagine that in a retrofit installation in a home as old as yours, the system might be quite simple...even just one supply and one return, possibly. The ductwork may travel substantial distances in uninsulated spaces (attic or crawlspace/basement) between return register to the central unit and back to the supply register. The ductwork may not be very well insulated. Running that fan, expecting to take warm air from one place in the house and put it into another place in the house may be a losing game. What goes in may be nice warm air, while what comes out may be chilly. Learn your system. Turn on the fan, and go to every room with a sheet of paper, find all those registers and place the paper on them...you'll see immediately whether the register you've found is a supply (into the room), or a return (out of the room). This may help you figure out if trying to use the central system will help or hinder the distribution of warm air through your house. You can throttle or close most registers...just keep in mind that you need to maintain a rough balance between the total cross-sectional area of duct on the return and supply sides of the fan to keep it happy. Rick

 

[Elfin]

I run my furnace fan to help distrubute heat from the stove in the living room thru the house... but it doesn't move a whole lot of heat. I'd say we usually sit at least 10-15 degrees cooler in the rooms furthest from the stove, or behind closed doors, and I live in a moderate climate so it's pretty easy to hold those temps.

My house is old too, and we have just one furnace return which is about 30 ft away from the stove but thankfully in the same room. Somehow, the heat tends to trap near the stove, and this is where a strong fan can really help. It should be near the floor and pointed towards the stove... sounds crazy but after hearing this advice here on hearth.com I tried it and it really WORKS. We just ordered a new ceiling fan that can run in reverse (also supposedly helpful) and a powerful fan exclusively for the purpose of moving the heated air. I'm interested to see how much these two elements will help even out the temps in the house, as we should be moving warmer air right to the path of the furnace return.

 

[LLigetfa]

You have to pay attention to where the cold air returns are and block off the ones where it is cool. YOu should be able to block them off with paper.

Since warm air rises, it won't get sucked into the cold air return near the stove as long as there are open returns in colder spaces.

You also would want to close some of the warm air registers.

What I have is a dedicated blower that blows cold air onto the stove from the floor below. The warm air then gets positively displaced and migrates to the rest of the house. The chimney chase that goes through a room upstairs is vented top and bottom so it warms the space. Upstairs is still cooler but since the bedrooms are up there, that's the way we like it.