A high efficiency furnace should draw air from the same pressure zone ! Meaning the inlet air pipe and the exhaust air pipe should be in close proximity to one another allowing equal pressure changes. Both pipes should always be installed on the same side of the house as well. Whomever said you are allowed to to draw intake air from the basement is just looking to make some easy money on nuisance pressure sensor trips....
Hi, Mod mid-efficiency furnace haad fresh air insulated dampered intake duct for combustion. In this case intake can be inside the basement. Our local code allows this.
Nonsense. Many furnaces can be installed using either outside combustion air or inside. It's permitted per the manufacturer's installation instructions. In most cases it makes more sense to use outside air, especially if the furnace is located in a heated space, because if inside air is used, the makeup cold air will be drawn in to the structure from outside through leakage.
Yep. Not only that, but some of the earlier high efficiency furnaces didn't even have an air intake pipe. I had an Amana, probably from the
90s, that had a standard open burner arrangement just like the furnaces from the 70s. I just drew air from the room where it was installed. The exhaust on the Amana, was the standard PVC out the side wall of the house.
Not that it matters at this point, as this is a revival of an old post, but the install manual for the furnace would have the answer as to how it can be installed. My Rheem, it could installed either with outside air or using air from within.
Same thing here. My two Heil furnaces never required outside air, the first running for 22 years, The current one running for 10 years. No nuisance trips or other issues.
Luxaire, installed 1994. No nussiance trips.
- . Christopher A. Young learn more about Jesus .
CAN BE does not mean SHOULD BE.
Using outside air for combustion is more efficient. You are using air that you paid to heat and sending it up the flue. Sounds to me the contractor for the OP is just lazy.
The difference in heat may not be that great. One factor is where the furnace is located, ie is it in the heated space, an unheated basement, garage, attic, etc. Even assuming worse case, it's not clear to me how much difference it makes. Yes heated air is used for combustion. But the alternative, bringing in cold outside air, just means less heat is generated in the furnace. You're getting more heat of a furnace with 60F air going into it than with 20F air.
I know relatively new, circa 2007, expensive houses built here that have furnaces in unfinished basements that use the basement air.
Hi, Any how, today's new houses are so air tight we have to bring in controlled outside fresh air into the house.
Maybe so, somewhere. But I've yet to see a new house that was so airtight that it needed it around here, NJ.
Hi, In cold climate up here every new house going up has provision for fresh air intake. My house was built in 1994 per R2000 specs. If it doesn't bring in fresh air, it may cause indoor CO problem. Summer or winter, we seldom open windows.
Hi, Ever done an energy audit to see how air tight your house is?
Where is this CO problem supposed to come from?
My 1957-built home in the Chicago suburbs still has the original Lennox for ced air funace. It has a real chimney for the exhaust, and drew heated bas ement air for the input.
About 20 years ago I put in a 4" dryer duct type of air input from the outs ide to a 4" hole I cut in the side panel of the furnace. It is pretty much sealed off on the other sides, so now the outside air is probably 90% of t he combustion air the furnace uses. I also filled in the gas nozzle orific e and then drilled it back out at about 1/2 the cross section area, so that the flame in the furnace is much smaller (about 50%). That reduced the he at available, but I had previously checked and the furnace never had to run full-time even at below zero temperatures, so I felt comfortable in making the change. I did have to rebalance the air-gas mixture shutter to get a clean blue flame, but it was well within the adjustmment range provided. G as consumption is down noticably without any change in comfort level, and t he slight drafts we used to get around the weatherstripped doors to the out side has been elminated.
Not really, Tony. My house was built in early 1950s and not especially tight even with my updates to windows, doors, insulation, etc. Very small square footage so the heating and cooling costs are pretty modest, and I never ask for especially cool or especially warm temperatures either. A couple grand a year pays for all my heating and cooling, hot water heating, and other gas appliance use.
forced air funace. It has a real chimney for the exhaust, and drew heat ed basement air for the input.
outside to a 4" hole I cut in the side panel of the furnace. It is prett y much sealed off on the other sides, so now the outside air is probably
90% of the combustion air the furnace uses. I also filled in the gas noz zle orifice and then drilled it back out at about 1/2 the cross section a rea, so that the flame in the furnace is much smaller (about 50%). That reduced the heat available, but I had previously checked and the furnace never had to run full-time even at below zero temperatures, so I felt com fortable in making the change. I did have to rebalance the air-gas mixtu re shutter to get a clean blue flame, but it was well within the adjustmm ent range provided. Gas consumption is down noticably without any change in comfort level, and the slight drafts we used to get around the weathe rstripped doors to the outside has been elminated. Lengthening the burner cycle by down-sizing the orifice probably helped a lot. On newer furnaces, the heat exchangers have a very narrow efficiency band, which is much more inefficient on either side of the peak heat transfer BTU input. If you downsized the orifice on one of these furnaces, I would doubt anywhere near as much of a benefit in operating cost, since then your longer longer burner cycle would occur at a far less efficient operating point for either the burner or especially the heat exchanger. Your method worked great for older furnaces, which also were notoriously over sized.
About 1320Sq ft plus 600 sq ft basement - heated with gas - never over $750 for heat and hot water - in central Ontario (where it was
-36C over the weekend)
A lot of new homes are also GROSSLY oversized in the furnace department. My furnace is a dual stage, and I've locked it down to the low output. Smallest furnace I could buy, other than a "trailer" unit, and it has never run more than 9 hours in a 24 hour period - so it is still oversized.
Mine is also oversized, running about 65% of the time for the fan and maybe 50% of the time for the burner in -5 degree F outdoor temperature. Original house has a 160K BTU/hr furnace (circa 1952). I replaced it with a
75K and subsequently updated windows, doors, insulation. A 50K unit would suffice albeit marginally at these unusually low outdoor temperatures.Have something to add? Share your thoughts — no account required.
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