Best location for a forced air furnace
OK, I’m having a minor difference of opinion with someone on furnace placement and thought I’d turn it loose here and see what the consensus thinks:
Assuming a ranch style house with a 32×49 footprint. Forced air nat. gas furnace./central air unit. Ductwork in crawl with cold air return in attic.
My thought is that the best place to put the furnace would be as close to center of the house as possible. Therefore limiting the distance that the heat has to be transferred and giving me a better chance at heating each room equally.
The person I’m having the difference of the opinion with says that the center of the house is the worst place to put it and that the best would be to put it on one end and pump the heat alllllll the way across the house.
What is your opinion?
jt8
“Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree.” — Dr. Martin Luther King, Jr.
Replies
My opinion is that it really doesn't matter as long as it is correctly installed.
My first frivolous thought is to put it near the chimney.
Another consideration with a lot of older houses that have somewhat questionable insulation and draft/infiltration control is to place it neareer the north end, so that the frist locations supplied get hotter air - they will be losing more heat and need it. The old timers heere have a saying, "you can't drive heat north, but you can let it settle south"
I know this does not apply to a well thought out, tight insulated modern house though.
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My first frivolous thought is to put it near the chimney.
I agree... if the house has a chimney.
The conversation started in relation to my project house. A starter-level ranch house that I've taken down to the studs. There is NO chimney. The new furnace will be 90% or better efficient so that it will just use a PVC for exhaust. Within reason, I can pretty much pick where I want the furnace.
Since the original floorplan did not have a back door, I zapped a couple back-to-back closets to create a compact utility room (approx 7.5x13). Space enough for furnace, water heater, breaker box, w/d, and maybe a couple feet to hang coats. The utility room also allows a back door to be added. I think it is a good use of space and puts the furnace in a very good location (within a couple feet of the center of the house).
Meanwhile this dude, who claims to be an HVAC specialist (but ain't gonna do the HVAC in MY house!) keeps sqawking about, "oh the center of the house is the worst place for a furnace." "You can't put a furnace near BR's." "The end of the house is the best place to put it." He has even suggested putting it in the GARAGE... whereupon I'd have about 4" vertical space to squeeze enough duct to feed 49' across the house.
I guess I'm just inclined to tell him to shut the He11 up, but wanted to make sure the bast ard wasn't correct ;)
jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
I'll go with your instinct on whether he is a bag of BS or not. The only reasoning I can think of why a furnace cannot be placed near bedrooms is that it will make a small amt more noise there. I certainly would not want it on the other side of the wall where my headboard of the bed stands. But in general, it can be dealt with. In mobile homes I have lived in, the furnace unit is generally located off the hall near the bathroom/laundry and between a couple of bedrooms. I was aware of when it came on, but not when sleeping. ( Of course, once I get to sleep, you can light up a jet engine under my pillow and only have a 5o/50 chance of waking me up, LOL)
Some extra soundboard and insulation could help with sound there. Seems like a utility room oughta have the denser fire-rock gypsum instead of 1/2" SR anyway
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There may be a slight advantage to having the furnace near the outside when placed on a wood floor, since there will be a little less vibration transmitted through the floor. But placing it near a center beam or post would work about as well.
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He has even suggested putting it in the GARAGE
Every new clone mcmansion out here in PNW for the last 10 years or so has the furnace inthe garage, maxmizes profit margins of builders is only thing I can figure. Think that if indoors here there is an extra $120+ earthquake shutoff for NG valve required.
Another opinion on where to put the furnace is "in the scrap yard"
Brother renovating house for office space needed new heat and maximum space. (Spfld IL, similar climate to you?) .
Scrapped the furnace (literally, it was old coal gravity converted to gas in the 50's) and put a packaged heat pump OUTSIDE! Added insulation to the cabinet outside. Spfld is muni power so elec is only 4.8 cents kW-hr, while gas is dear (over $1/therm).
Got a $450 rebate for installing 4T HP, net DIY total install costs including electrical feed <$1.5 K. 90% NG furnace would have been at least $600 DIY. Payback for HP even in central IL works out to less than 4 years for the rates there.
Yeah, CWLP is awesome. Probably the lowest rates in the state, especially after everyone jacks their rates come January. And they have some good incentives like you mentioned. If it was within CWLP-land, I would have been tempted to go for an all electric house.
Unfortunately, the project house is a few miles away. In the land of twice the rates and no incentives.
Every new clone mcmansion out here in PNW for the last 10 years or so has the furnace inthe garage, maxmizes profit margins of builders is only thing I can figure. Think that if indoors here there is an extra $120+ earthquake shutoff for NG valve required.
Hmm... the ones I can remember seeing are like Mom's house. While the access doors are in the garage, the furnace itself sits in the house. So in her case, she has crawlspace (ergo room for ductwork) underneath the furance but goes into the garage to change the filters.jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
>>>>>>>The person I'm having the difference of the opinion with says that the center of the house is the worst place to put it and that the best would be to put it on one end and pump the heat alllllll the way across the house.
Who is this person and what's his/her interest? The HVAC guy that want's to put the furnace near the door to the crawl space?
"Let's go to Memphis in the meantime, baby" - John Hiatt.
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Who is this person and what's his/her interest? The HVAC guy that want's to put the furnace near the door to the crawl space?
Friend of a friend who is an "HVAC specialist" and has supposedly installed many, many residential, commercial, etc, HVAC systems, but... only does it as a side job. I have an aversion to people who act like know-it-alls. You could work in a field full-time for 40 years and not know everything about it, so don't try to act like you do just from having worked in it "on the side" for 10-15 years.
This is the same dude who recommends putting a 99 cent filter in because the expensive filters will "overwork the furnace fan and shorten the life of the furnace."
I think he is full of sh1t, but am no HVAC person, so don't feel I'm on firm enough ground to tell him to shut his trap. As it is, I just try to ignore him, but as he is a friend of a friend, I tend to run into his opinion more than I care to.
jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
Edited 10/31/2006 11:41 pm by JohnT8
Not really enough info...I do my installs as close to center as possible with a Tee fitting and balancing damper off the discharge. But, like Piffin said, I also look for the chimney. I would also consider the location of the condenser. I am with you tho', center always seemed to work for me.
We generally define "best" as what makes the best use of the avaible space and produce the best performance, both of which don't necessarily equate to least expensive.
The farther the air has to move the larger the ducts are and the more expensive it is. That's the only downside to having to travel farther the way I see it.
I'll argue for putting it in unused space, such as attics or crawlspace over a closet or the garage anyday, unless it's a very spacious house with a dedicated furnace/utility room.
Beer was created so carpenters wouldn't rule the world.
OK, so if Joe HO comes to you and says, "either the center of the house or on the end will work fine." Which one would you pick?jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
OK, so if Joe HO comes to you and says, "either the center of the house or on the end will work fine." Which one would you pick?
That depends. Noise, exhaust, space, ease of access, and a final factor I'll simply call neat-o-ness. Using a hidden space that would never get used otherwise is often full of neat-o. Often the furnace is put where it's easy for the installer or GC, not where it makes the most sense for the actual end user.
Beer was created so carpenters wouldn't rule the world.
You have to consider access to chimney/flue for a conventional furnace, and the availability of a reasonable flue route to a sidewall for a condensing furnace. Also, consider how ductwork with be routed with regard to major obstructions such as a center beam, major drain lines, etc.
I hope he didn't size the system based on his gut experience.