This is what this house has: a gas heater, electric ingiter, fan (blower). This is what's happening: Natural gas is released, electric igniter lights gas (creates heat), blower is activated, heat is blown though venting system. Then, gas expulsion is stopped (thus ceasing HEAT), and fan continues to blow for...oh...30-45 seconds. When the burners stop burning, the fan continues to blow, and we get chilly (not cold) air through the venting system, somewhat defeating the purpose of creating heat. (the house does become warmer, by small increments)The FAN"S INTAKE comes from ducting leading to the roof, outside, fresh air circulation, NOT recycled air circulation. The heater does have it's own fresh air inlet/outlet, as it should.
Shouldn't the BLOWER'S INTAKE come from inside the area to be heated (creating real warmth) as opposed to getting cold air from outside? Why was this system built this way?
If I redirect the blower's intake to recycle the air, what risks am I running?
2006-11-21 08:25:06 · 5 answers · asked by Ryan 4 in Home & Garden ➔ Maintenance & Repairs
The blower's circulation intake should indeed come from inside the structure; to have it come from outside is seriously weird. For the blower to run for awhile after the gas shuts off is perfectly normal; there is a thermal switch in the plenum which turns the blower on when the plenum air gets warm, and shuts it off again when the plenum has cooled off. I would install at least one return air duct (and possibly two or three, depending on the dwelling configuration) to deliver air to the furnace; there should also be arrangements for filters to clean some of the crud out of the air. Do double-check where the furnace circulation intake air is coming from -- the roof is simply too screwy to believe.
2006-11-21 08:37:02 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Being an HVAC tech, I think you might be mis-describing what is going on and/or confusing nomenclature. Let me take a stab at trying to describe your situation and you tell me if I’m on the right track.
1)You have a high efficiency furnace with probably two white plastic pipes leaving it – both through the roof.
2)Somewhere on your return air duct is a pipe or flexible duct which introduces outside fresh air into the return air duct.
3)When there is a call for heat from the thermostat, FIRST the small inducer motor (which sucks in combustion air from the outside and discharges combustion gases to the outside) begins to operate. Only after it is up to speed (typically 10 to 15 seconds) then SECONDLY, the igniter begins to glow bright orange. After the igniter glows bright orange for a period of time, the gas valve release gas into the combustion chamber.
4)After a period of combustion warm up (typically 15 to 45 seconds), the furnace’s blower (some people mistakenly call this the fan) begins to circulate warm air through the ductwork. After the furnace’s blower circulates air for a while, the gas valve terminates the flow of gas but the main furnace blower continues to run.
5)The cycle then repeats itself many times before finally satisfying the thermostat (as opposed to a constant ignition and flame until the thermostat is satisfied).
IF this is the case, re-post and we can help you diagnose. Pay particular attention to the nomenclature used!
2006-11-21 10:14:34 · answer #2 · answered by frogpaws 2 · 0⤊ 0⤋
As per anothers answer, it does seem that your terminology could be off. Vent means the structures in which the flue gas, or spent fuel travels. Ducting is the apparatus in which the warm, and comforting air travels to the various grills in your home. It is possible that you have a 90% eff. furnace, and they are vented with PVC pipe, usually 2 or 3 inches in size. Some of the manufactures require a 2 pipe system to the outside, while others only require 1. Recycled air, a guy can get into a lot of trouble trying to give a definitive answer, unless everyone is on the same page of definitions, I can assume that you are referring to the air inside of your home being recycled into the furnace to be heated, blown through he grills and returned to be heated again?? Also depending on what the building codes are in your area, and the combustion air available in your situation, a duct, usually 4 to 6 inches in size, maybe required to provide the remaining air to your home, as to not deplete the oxygen levels. The best answer, and safest, is have an experienced and licensed technician look this system over and advise you. I hope I have given you some of what you are looking for, but people get killed every year due to these issues, and trying to solve these issue without all of the pertant info needed.
2006-11-21 14:03:32 · answer #3 · answered by Leo C 2 · 0⤊ 0⤋
Maybe I'm missing something here , but it appears that you may have a short-cycle problem (probably the flame sensor's oxidized)
Get an HVAC tech to check it out, and at the same time ask him about your other concerns.
It is NOT recommended that you modify anything whatsoever on the system prior to an assessment by an HVAC professional.
Good luck.
2006-11-25 02:08:31 · answer #4 · answered by Huero 5 · 0⤊ 0⤋
You furnace is showing classic indicators of shutting down on severe cut back. you have a blockage interior the filter out or your return air vents are blocked or you have countless vents closed....or your cut back sensor/change is going undesirable. in case you have a severe performance furnace, it takes in clean air and exhausts by percentpipe...basically circulate away those on my own....if in fact that's what you have. verify your ductwork for blockage, verify your vents and in case you do no longer detect a difficulty, call a heating tech to analyze your cut back. HVAC tech for 10 years
2016-12-10 13:15:11 · answer #5 · answered by Anonymous · 0⤊ 0⤋