Heating/heater issues?

Question

This is what this house has: a gas heater, electric ingiter, fan (blower). This is what's happening: Thermostat controls heater system (of course). 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 making heat, and the fan continues to blow, 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)

I have discovered tonight that the fan's inlet/intake comes from a chimney/stack/ducting leading to the roof, outside...fresh air circulation, NOT recycled air circulation.

My questions:

Shouldn't the air (blower) 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?

I am planning to modify the blower induction to be recycled, instead of fresh air. What, if any, danger to my family and the house am i risking?

If i switch to recycled air induction, would I be violating any codes? Why is this code in place? (if this a code issue)

[The heating system is vented, other than having fresh air circulation, and the sheet metal barriers (i forget the proper word at the moment) to the A/C system (which shares the ventilation system with the heating system) are in place.]

Answer 1

When you say "Then, gas expulsion is stopped (thus ceasing HEAT)" -- I assume you mean when the thermostat shuts it off. If your gas is shutting off BEFORE the desired temperature is achieved then you may need a new thermostat.

Gas furnaces are designed to draw in fresh air (from outside the home) to prevent oxygen depletion, and carbon monoxide build up in the home. DO NOT change your system without contacting a local heating system contractor, and/or building code inspector. Lives could be at stake.

You MAY be able to adjust the amount of time your blower runs after the burners shut off. The fan runs those extra seconds to clear the bonnet of heated air. See your owner's manual.

An alternative is to consider switching your furnace to all electric, and eliminate the threat of carbon monoxide.

Answer 2

Ok, yes the blower return air(intake) should come from inside the area being conditioned, or heated. You should have a return air run to each room of the house except the kitchen and any bathrooms. Now, some installations have a duct bringing outside air to the furnace room and it is ducted into the return air duct with a damper that regulates the amount of air being brought in from outside. This setting is usually only 5-10% outside air. Sounds like to me you have 100% outside air. You might check just to make sure that somewhere you may have some return air grilles(registers) in the bedrooms, dining room, living room, etc. etc. Make sure that the duct going outside doesnt tie into a return air duct somewhere. A way to check this is as follows:
Find the furnace's nameplate. This will have the brand name, model number, serial number, etc. etc. What we are looking for is the temperature rise. A common temperature rise is 40-70 degrees. Temperature rise is the difference between the supply air and the return air. Get a thermometer and check both air temperatures. Check the supply temperature downstream a little from the furnace. If the temperature rise is low, then you probably have way to much outside air coming in. Take the blower door off of the furnace. Get a air filter that will cover the door opening. Tape down the door switch so the furnace will run. Start the furnace and try the temperature rise again. It should come up into the range on the nameplate. If it does. you may need to eliminate outside air and add more return air inside the house. What did the air conditioner do this summer?? Did it cool the house adequatley?? Were the run cycles relatively short?? The easiest way to de-rate an air conditioner system is to add outside air. The reduces the capacity of the system. If you have a 3 ton air conditioner, adding outside air may make it a 2 ton or lower. If the furnace works better by leaving the door off, run the furnace that way until someone fixes the duct problem. Hope this helps!!! Good luck!!!!

Answer 3

This one guy is right to some extent: some, not all houses are air vented through the outside to get fresh air or, the air in the area is not enough to give air to the furnace keeping the furnace lit. There fore the air from the outside, another thought is "it's fresh air and better" maybe?
Don't change anything around. Have someone that knows, don't fool around yourself, take a look at the heat ranges of the thermostats, one that controls the shut-off may be set to low creating the fan to run at a to low of a temperature. This can be adjusted to a higher temperature causing it to shut off while the furnace is still warm. The "kick-in" can be adjusted also to kick-in at a higher temperature.

Answer 4

When the blower comes on does it blow the flame around if so you may have a bad heat exchanger.If you stop taking the combustion air from outside you need to know if you have enough combustion air in the area the furnace is in (ie not a closet).I would continue to take the air fom outside rather than possibly create a draft with the furnace trying to get combustio air.Also this keeps you safer in the case of a heat exchanger failure.


the other techs answer is worth listening to as well.

Answer 5

vent to outside is exhaust blower runs to cool exchanger down safety issue call a proffesional

Answer 6

talking as a individual with adventure of what your question is approximately i could inform you that that may no longer a speedy restoration subject. a toddler with "subjects" is extremely no longer likely to "open up" to fully all and sundry. the final suggestion i ought to grant to you is to maintain this nameless, with the flexibility to reproduction and communicate with the aid of written language will help those infants extra suitable than you will ever be attentive to.