New Furnace installation problem?
 

I hired an established 20 year American Standard authorized "Customer
Care" Dealer size and install an AUY080 variable speed 2 stage high
efficiency natural gas furnace in my house last fall. It replaced a 30+
year furnace. Over the past two months we've had a number of nights
that fell to around -8 to -11 F, about as low as it ever gets for this
area. During this time, the furnace has never needed the second stage
at all. In fact, the only time the second stage goes on is when the 2
stage thermostat is manually increased more than 2 degrees.

There are return ducts in almost every room upstairs. The return air
flow is very noisy (to my taste), even in the rooms farthest from the
middle of the house, where the furnace is located. The supply ducts are
not noisy at all. When the second stage is on, the increased airflow is
very loud in my opinion. This wouldn't be a problem for the heating
season, but full fan is used for cooling.

I'm ready to give the contractor a call and ask him about this. But I'd
like to get more informed first. How much (if ever) should second stage
be needed? Is it normal to put up with a constant rumbling of air in
return ducts? The opening in the (upflow) furnace side between the side
return duct and the furnace is smaller than the blower, leaving me to
wonder if this is at least part of the return noise problem. How long
should the on cycle times be, for a 30F degree day, for example?

My house is a split level, about 1700 sq ft, 1350 "livable" and is in
eastern Massachusetts.

Thanks!

Was it noisy before, so the ductwork is the same? How long are your
cycle times, longer cycle times put less wear on your equipment,

m Ransley wrote:

Was it noisy before, so the ductwork is the same? How long are your
cycle times, longer cycle times put less wear on your equipment,

To be honest, I don't remember exactly how loud the old furnace
sounded. I bought the house early fall last year. Because the heat
exchanger was suspect when I had it inspected before the heating season,
I didn't give it a chance to run much. But I do know that on 2nd
stage/full fan, it definately is louder than the old furnace.

The ductwork is the same. Cycle times vary from 12-35 minutes,
depending on outdoor temp. This is with the Braeburn thermostat set to
1 degree differential. (Default was 0.5 degree).
..

"Greg Johnson" wrote in message
...
I hired an established 20 year American Standard authorized "Customer
Care" Dealer size and install an AUY080 variable speed 2 stage high
efficiency natural gas furnace in my house last fall. It replaced a 30+
year furnace. Over the past two months we've had a number of nights
that fell to around -8 to -11 F, about as low as it ever gets for this
area. During this time, the furnace has never needed the second stage
at all. In fact, the only time the second stage goes on is when the 2
stage thermostat is manually increased more than 2 degrees.

There are return ducts in almost every room upstairs. The return air
flow is very noisy (to my taste), even in the rooms farthest from the
middle of the house, where the furnace is located. The supply ducts are
not noisy at all. When the second stage is on, the increased airflow is
very loud in my opinion. This wouldn't be a problem for the heating
season, but full fan is used for cooling.

I'm ready to give the contractor a call and ask him about this. But I'd
like to get more informed first. How much (if ever) should second stage
be needed? Is it normal to put up with a constant rumbling of air in
return ducts? The opening in the (upflow) furnace side between the side
return duct and the furnace is smaller than the blower, leaving me to
wonder if this is at least part of the return noise problem. How long
should the on cycle times be, for a 30F degree day, for example?

My house is a split level, about 1700 sq ft, 1350 "livable" and is in
eastern Massachusetts.

Thanks!

This is Turtle.

Most HVAC contractor will set the btu rating of the heat run time at about 90%
at Maxium Temperature outside as you say -8ºF to -11ºF . The reason of the long
run time here is you have the two stage gas furnace and first stage will tend to
run a long time for the second stage is if it gets in trouble and falls behind.

TURTLE

"Greg Johnson" wrote in message
...


m Ransley wrote:

Was it noisy before, so the ductwork is the same? How long are your
cycle times, longer cycle times put less wear on your equipment,

To be honest, I don't remember exactly how loud the old furnace
sounded. I bought the house early fall last year. Because the heat
exchanger was suspect when I had it inspected before the heating season,
I didn't give it a chance to run much. But I do know that on 2nd
stage/full fan, it definately is louder than the old furnace.

The ductwork is the same. Cycle times vary from 12-35 minutes,
depending on outdoor temp. This is with the Braeburn thermostat set to
1 degree differential. (Default was 0.5 degree).

Newer furnaces have to move more air to reach a lower Delta T across the
heat exchanger. Therefore if the ducting is inadequate, it will be noisy and
very displeasing.

~kjpro~

On Mon, 31 Jan 2005 22:24:02 -0500, Greg Johnson
wrote:

I hired an established 20 year American Standard authorized "Customer
Care" Dealer size and install an AUY080 variable speed 2 stage high
efficiency natural gas furnace in my house last fall. It replaced a 30+
year furnace. Over the past two months we've had a number of nights
that fell to around -8 to -11 F, about as low as it ever gets for this
area. During this time, the furnace has never needed the second stage
at all. In fact, the only time the second stage goes on is when the 2
stage thermostat is manually increased more than 2 degrees.

There are return ducts in almost every room upstairs. The return air
flow is very noisy (to my taste), even in the rooms farthest from the
middle of the house, where the furnace is located. The supply ducts are
not noisy at all. When the second stage is on, the increased airflow is
very loud in my opinion. This wouldn't be a problem for the heating
season, but full fan is used for cooling.

I'm ready to give the contractor a call and ask him about this. But I'd
like to get more informed first. How much (if ever) should second stage
be needed? Is it normal to put up with a constant rumbling of air in
return ducts? The opening in the (upflow) furnace side between the side
return duct and the furnace is smaller than the blower, leaving me to
wonder if this is at least part of the return noise problem. How long
should the on cycle times be, for a 30F degree day, for example?

My house is a split level, about 1700 sq ft, 1350 "livable" and is in
eastern Massachusetts.

Thanks!


Of course the second stage should be needed. It all depends though of
how or if they did a proper load calculation of your home to determine
the proper size furnace needed. At -10 degrees outside you should be
seeing the second stage of heat coming on unless the design outdoor
temperature in your part of the world is -40 or something?
Should ductwork be noisy? No, not if properly sized and installed.
This however is very hard to find as many companies just slap it in
and run. You have to find someone good, period.
On cycle length just depends. Thats just a guess over the internet.
Have your contractor back out and go over these things with him. If
you arent satisfied, try another contractor.
Bubba

~KJPRO~ wrote:

"Greg Johnson" wrote in message
...


m Ransley wrote:

Was it noisy before, so the ductwork is the same? How long are your
cycle times, longer cycle times put less wear on your equipment,

To be honest, I don't remember exactly how loud the old furnace
sounded. I bought the house early fall last year. Because the heat
exchanger was suspect when I had it inspected before the heating season,
I didn't give it a chance to run much. But I do know that on 2nd
stage/full fan, it definately is louder than the old furnace.

The ductwork is the same. Cycle times vary from 12-35 minutes,
depending on outdoor temp. This is with the Braeburn thermostat set to
1 degree differential. (Default was 0.5 degree).

Newer furnaces have to move more air to reach a lower Delta T across the
heat exchanger. Therefore if the ducting is inadequate, it will be noisy and
very displeasing.

I understand that, both the return ductwork and the warm air duct work are
similarily sized, yet the warm air ducts are nearly silent while the return
ducts are noisy. I assume that American Standard's dealer sized the system
properly for the ducts, is that an unreasonable expectation to make?