heating up so slow

I have a 2,000 sqft house. I suspect the heating system (Trane) is not working properly because it takes one hour to raise the temperature four degrees.
The service man from the company which installed the unit last summer told me the system works fine. He said the supply air is 105 degree and return air is 71 degree and usually he only gets 101 degree for supply air.
I don't have much experience with gas heat and wonder if a supply air of 105 degree is normal. Any thoughts?
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From what temp are you reheating, it sounds like you are one of the few with a properly sized furnace. Heating units should be sized to run near consistantly at the years coldest temp. Are you there yet?
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What did you expect an 8f hr. degree rise. Mine is near 2 hrf on total heat, you are kidding yourself and us here. Go to sleeep.
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wrote:

Look at the Rating plate label on your furnace where the model, serial number, and electric ratings are. You will see a "temp rise" range of something like 35-65 or 40-70 etc. The air temperature going into your furnace and coming out should have a differential within that range while providing enough air flow to properly heat your home. Your 34 degrees just "aint goina cut it". Bubba
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It sounds normal to me. The ideal system is the one that will take a long time to increase the temperature. Oversize units will heat fast, but they also will be less able to maintain any specific temperature and will be less efficient. It sounds like yours is good.

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On Thu, 24 Jan 2008 07:08:02 -0500, "Joseph Meehan"

As usual mr. Meehan is wrong. If I had a model number I could tell you what the temp rise should be but the usual temp rise is about 70 degrees which yours is nowhere near if your readings are correct.
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On Thu, 24 Jan 2008 17:39:46 -0500, HVACTECH2 wrote:

Ding, Ding, Ding, Ding, Ding! We have a winner (although the 70 is usually a range such as 40 - 70) Bubba
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On Thu, 24 Jan 2008 07:08:02 -0500, "Joseph Meehan"

Bubba
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John-
Sounds about right...as everyone has posted.
You want a system that can just barely keep up on the coldest day in its design life.
I've done some heating experiments in a couple homes and 4 degrees per hour is about in the middle of the performance I've measured.
When I allow my house to "soak" for a weekend away & the outside temp is in the low 50's, high 40's the house settles near 50..... brrrrr!
My home heats at about 6 deg per hour...... approx 1 deg rise in 10 minutes. I have run this experiment a couple times.
During "normal" duty it runs about 10 minutes on, 20 minutes off.
When its really cold outside (well, cold for SoCal, low 30's). The gas furnace runs nearly constantly to keep the house at 62 over night)
cheers Bob
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wrote:

Bzzzztttt! Wrong answer Bob. Try again. Bubba

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Bubba-
While the temperature rise across the furnace is important and too little can indicative of an under performing system, does that really tell the whole story?
I know you HVAC guys think you have a monopoly on all knowledge HVAC but maybe a you should consider a little thermo / heat transfer.....you know, think outside of your box.
Could it be possible that a furnace with too little temperature rise can still heat the house adequately?
Or could a furnace with "correct" temp rise be incapable of heating the house adequately?
hmmm?
Maybe the temperature rise (per time unit) of the house is important too? Kind of an overall performance measure?
hmmm?
cheers Bob
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Thanks for your responses. My furnace is Trane xv80. I did an Internet search and found the temperature rise to be 30 - 60 degrees. Mine is 34 degrees. It is within the spec, albeit at the low end. Should I worry about it?
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John-
Per the service visit & the info you found on the web (did you confirm it against the furnace rating label?) the furnace performance is within spec.

Well, if the furnace keeps your house warm......I guess not.
Maybe Bubba & Red Have something to add?
cheers Bob
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What Darrell said. I just learned the "check the gas meter" trick a couple weeks ago.
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wrote:

These are 2 stage furnaces. is the second stage working?
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Sounds about right...for AC on the warmest day.

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Red-
How about a real answer?
cheers Bob
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Red Green wrote:

to know how much air is flowing. It doesn't matter what the air temperature is if there isn't enough mass flowing; the heating will be insufficient. Also, since the measurements you have were obtained during the summer, you may have heat loss due to poor duct placement and/or lack of insulation. Measure the air temperature into the living space at several locations and coming from the furnace (at the furnace) to assess this.
Boden
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insufficient<<<<
yup, now we're talking a little more science.......... not just mindless tech manual following.
knowing the gas consumption is helpful
cheers Bob
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