I've been running my furnace blower 24-7 for the past few years. I find it keeps the house temperature more even, especially in the summer. Now that winter is here, I'm wondering if it's still makes sense.
The boys have moved out and the girls are away at college most of the winter. I have turned off the heat ducts to their rooms and keep the doors closed.
We keep the living areas at about 68 and the master bedroom a bit cooler by closing the heat ducts slightly.
I just went into the boys' room and it's 62. That got me wondering. The cold air returns in the 2 unheated rooms are still open. Am I wasting more energy than the evenness is worth by drawing the colder return air from the unheated rooms, recirculating it with the 24-7 blower thus causing the furnace to come on more often?
I wonder if I should build covers for the cold air returns in the 2 unheated bedrooms and block them or maybe even stop running the fan 24-7 since I'm only really concerned with the temperature on the first floor.
The only problem you may have is the same problem the elderly mother of a late friend of mine had while she was still alive. When my friend died me and the guys adopted his elderly mother and helped her when she called and she was having a problem with her heat cutting off. The old woman would get cold so she ran the thermostat pretty high. She had closed of her son's room and register along with another room she wasn't using. Her heat kept shutting down due to overheating of the combustion chamber in the furnace. Closing the registers kept the airflow through the furnace too low thus it would overheat and the high limit would shut down the whole thing. There might be a way to disable some of the burners if you wind up with the same sort of problem. You may be able to find out the minimum required airflow through your furnace for it to operate properly by contacting the manufacturer. ^_^
Yes, that can be a problem if you shut off too much of the airflow. It all depends on the relative size of the ducts/registers you leave open and those you close.
As for running the blower 24/7, I think in most cases that's a losing proposition. We;ve had that discussion here before and there are some strong believers. But here is my thinking. A lot depends on where those ducts are routed. In homes more than a couple decades old, here in the USA, it's common to have ducts run from the basement to second story through exterior walls. Those ducts at best have what, an inch of crushed up insulation, if that? Not good when it's 20F outside or if it's summer, in full sun and it;s 90F out.
How about duct runs in the basement? If it's a finished basement that is kept heated, then it probably doesn't matter. But if it's an unheated, unfinished basement, all you're doing is pumping 70F air around the loop, allowing it to lose heat in the basement, in any exterior wall runs, etc.
And in my experience it's uneeded and doesnt' do anything usefull. My house is well balanced in winter. In summer, like in most houses, the upstairs is warmer, but even when I let the blower circulate constantly, it made no measurable difference. If you have a balance problem in the winter, it would seem better to me to try to address that directly, by adjusting registers, dampers, etc.
And then there is the issue of how much energy it uses. If you have one of the new ECM type blowers, they are a lot more efficient. But I think some of the claimed savings is partly marketing hype. They claim a lot of savings when running it 24/7 compared to a conventional blower. I buy that. BUT, I have one and when you have it set to constant fan, the fan speed is about half what it is during AC mode, ie half of what it is with that conventional blower on an older system. So, you're not moving the same amount of air either. And that could be one reason why in my case leaving it on did nothing to improve the upstairs vs downstairs. Still, as I said, I do believe that they use signiicanly less electricity overall.
Hi, One reason I use wireless thermostat. I put it in a occupied room. My kids also left their nest and there are empty rooms in the house. If blower is running 24/7, it should be at much slower speed.
But, my vote would be to just cover the cold air returns in the 2 unheated rooms with aluminum foil and duct tape for now. The reason is, as you suggested, that you don't want the cold air returning to the heater to cause it to cycle on and off more often. The only returns to the heater should be coming from the heated space.
Keeping some air movement through the unheated rooms may be worth-while just to keep humidity even and prevent the room getting "stale" . We have 2 rooms that have been left "unheated" as well - just one now since our oldest daughter is back from Burundi. Keep the temperature about as above.
It is a two stage furnace, but the only variability of the fan is either high or low speed, automatically selected by the furnace. When running 24-7 it runs at the lower speed, unless the furnace goes into high heat mode.
That furnace will LIKELY be running 1/6 HP constant and 1/3 or 1/2 HP on full. Quite possibly, if it kicks onto high only when on high heat, it runs 1/3HP and 1/2. AC induction motors are relatively in-efficient - not an issue when in heating mode because all the "wasted" heat produced by the low efficiency just reduces the amount of fuel required. DC brushless fans are a LOT more efficient - and the constant speed operation on the variable speed units runs closer to
1/12 or 1/16 HP. My old furnace ran 1/6 HP constant, and 1/3 hp whenever the heat or A/C was running. - but it was a retrofitted 30 year old furnace (originally single speed - I put the 2 speed fan on to reduce the power consumption on constant run.)
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.