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?
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?
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".
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.
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.
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)
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?
Maybe the temperature rise (per time unit) of the house is important
Kind of an overall performance measure?
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
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
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.