Cold air blasts first when furnace comes on in winter.

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Old 03-30-14, 01:22 PM
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Cold air blasts first when furnace comes on in winter.

I had a new Payne gas, forced air furnace installed. Each time it turns on to provide heat, I get about a 60-second blast of cold air before it puts out the warm air. This is very annoying and uncomfortable. The installer says there is no fix for this as it has to blow out the cold air from the ducts first before it can provide the warm air. I never had this problem with my old (22 years) furnace. Is there a fix for this situation? Thanks.
 
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Old 03-30-14, 01:38 PM
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Your installer is basically right but where is the cold air coming from ?
Ducts in the wall aren't insulated ?

Your old furnace may have allowed air into the system and gravity flow (hot air rises) kept the cold air at bay.
 
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Old 03-30-14, 01:52 PM
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Cold air blasts first when furnace comes on in winter. Read more: http://www.d

The cold air is coming from the insulated ducts laying in the attic. Does the setting of the blower off-delay have anything to do with this?
 
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Old 03-30-14, 05:02 PM
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RM,
Your 22 yr. old furnace most likely had a mechanical fan/limit switch which didn't allow the blower to come on until the air was heated. The way they do it now is with a timer if the air is heated or not. A very annoying common problem. That's modern technology. Price over comfort.
 
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Old 03-30-14, 05:03 PM
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The blower off delay only controls the amount of time the blower runs after the burners shut off.
Your complaint is quite common since all furnace blowers are now turned on 'x' seconds after the thermostat calls for heat. Blowers used to be controlled by temperature but with the new energy standards manufacturers have to bring the blower on sooner & we have to put up with 'cold blow' unless we are willing to spend big bucks for a blower motor which speeds up gradually so we don't notice the cold air being blown out of the ducts.
 
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Old 03-30-14, 06:16 PM
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Yes, you are correct; the old furnace did have a fan/limit switch. What if I reset the blower delay switch setting to the lowest setting; it is now set at 140 sec. That way the blower would shut down sooner at the end of the heat cycle and the residual warm air still in the ducts might be warm enough to cancel out the cold blast of the next heat cycle. Does that make any sense?
 
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Old 03-30-14, 06:24 PM
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You can try it but you may find the furnace has enough residual heat to trip the high limit. How well are the ducts insulated?
 
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Old 03-30-14, 07:34 PM
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The ducts are non metallic and are wrapped with insulation, just like you find at home depot. I have no idea how well that insulation is; probably not too well. What would happen if it does trip the high limit? Do you think I should give it a try? BTW, to all, thank you very much for your assistance. You moderators are tremendous.
 
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Old 03-30-14, 08:50 PM
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The fan on delay is never adjustable. (fan off delay can be changed)

"Cold blow" is usually from having ductwork in an unconditioned space.

It might be possible to reduce the blower speed so the heat exchanger and ducts warm up faster at the beginning of each cycle, but the temperature rise has to be checked after adjustments are made.
 
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Old 03-31-14, 02:31 PM
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Hey guys, I believe I got rid of the "cold blow". What I did was to set the blower off-delay jumper to the lowest setting of 90, from the factory setting of 120. Now when the blower first comes on I get luke warm air insted of the cold blast. It's not perfect but it sure beats the artic blasts. Once again, many thanks to you all for taking an interest in my problem.
 
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Old 03-31-14, 05:23 PM
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Basically you're leaving warmer air in the ducts at the end of a heating cycle.

One problem you could encounter is that the unit goes into high limit lockout due to a buildup of hot air in the furnace.
 
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Old 03-31-14, 05:37 PM
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"One problem you could encounter is that the unit goes into high limit lockout due to a buildup of hot air in the furnace".

What would happen to the furnace if that should occur? Also what would be the symptoms of a "high limit lockout"? Should I undo what I did?
 
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Old 03-31-14, 06:23 PM
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If the furnace goes into high limit lockout, it will probably run the fan & possibly the venter continously. To reset turn the thermostat off for about 15 seconds. If the limit which trips is a manual reset, you may have to push a button in the blower compartment.
 
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Old 03-31-14, 06:57 PM
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Is it safe to leave the blower off-delay setting at 90 sec? If the furnace should go into high limit lockout should I then put the setting back to 120 sec? The service manual states that the blower off-delay setting can be set to 90, 120, or 160. I would think that the manufacturer would not list an optional setting if it was a potential hazard; I certainly don't want to create a fire hazard here. What is your opinion, please? Thanks.
 
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Old 03-31-14, 07:09 PM
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No fire hazzard. The 90 seconds should be fine but if the limit does trip, then yes put the blower off delay back to 120. The limit comment was, I'm sure, just a heads up as to something which could happen. It probably won't but better to be advised than not.
 
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Old 03-31-14, 07:14 PM
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It wouldn't be a fire hazard. The only way to know if you'll have a lockout issue is by trying the unit set to 90 seconds.
 
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