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Posted by ransley on October 14, 2009, 7:13 am
> Got a new Coleman 95.5 gas furnace.
> The fan is quite a bit noisier than my old unit.
> Measures 73 dB in the hallway under the return vent.
> That's "C" weighted.
> I pulled off the vent covers and measured the airflow
> coming out of the rectangular holes in the floor
> with a thermocouple anemometer.
> I've got 800 linear feet/minute from the 4x10" vents
> and 1200 from the 2x10" vents.
> With 67F indoor air temp, the air coming out of the
> vents is 115F. (my 37 year-old furnace was 150F.)
> I added an air conditioner evaporator that provides
> additional turbulence to the air flow, but the objectional
> noise sounds like blower noise coming out the return vent.
> So, The objective is to lower the fan noise.
> Looks like I've got plenty of room for temperature
> rise due to lower air flow.
> I expect I can get the installer to come change the fan motor tap.
> What are the pros and cons of turning the fan speed
> down?
> thanks, mike
If its new you shouldnt mess with it, let the installer do it, at
least until you learn more. Im no pro but ive done what you describe
with mine. First you cant just lower blower speed without knowing the
temp the heat exchanger is at. You need a probe thermometer in the
exchanger to measure it, your manual gives the exact range that is
safe to operate it at, go higher than the range by lowering blower
speed and you can kill the exchanger in a few years and void the
warranty. On mine a lower speed made no difference in sound. Get a
taylor digital probe, its used for cooking and often for cooking meat.
I drilled a hole just above the heat exchanger to measure my temp. But
odds are its incorrect now as your installer never tested and set
everything up right, so you could get it set for free after you verify
what the temp is.
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Posted by Tony Hwang on October 15, 2009, 8:45 pm
ransley wrote:
>> Got a new Coleman 95.5 gas furnace.
>> The fan is quite a bit noisier than my old unit.
>> Measures 73 dB in the hallway under the return vent.
>> That's "C" weighted.
>> I pulled off the vent covers and measured the airflow
>> coming out of the rectangular holes in the floor
>> with a thermocouple anemometer.
>> I've got 800 linear feet/minute from the 4x10" vents
>> and 1200 from the 2x10" vents.
>> With 67F indoor air temp, the air coming out of the
>> vents is 115F. (my 37 year-old furnace was 150F.)
>> I added an air conditioner evaporator that provides
>> additional turbulence to the air flow, but the objectional
>> noise sounds like blower noise coming out the return vent.
>> So, The objective is to lower the fan noise.
>> Looks like I've got plenty of room for temperature
>> rise due to lower air flow.
>> I expect I can get the installer to come change the fan motor tap.
>> What are the pros and cons of turning the fan speed
>> down?
>> thanks, mike
>
> If its new you shouldnt mess with it, let the installer do it, at
> least until you learn more. Im no pro but ive done what you describe
> with mine. First you cant just lower blower speed without knowing the
> temp the heat exchanger is at. You need a probe thermometer in the
> exchanger to measure it, your manual gives the exact range that is
> safe to operate it at, go higher than the range by lowering blower
> speed and you can kill the exchanger in a few years and void the
> warranty. On mine a lower speed made no difference in sound. Get a
> taylor digital probe, its used for cooking and often for cooking meat.
> I drilled a hole just above the heat exchanger to measure my temp. But
> odds are its incorrect now as your installer never tested and set
> everything up right, so you could get it set for free after you verify
> what the temp is.
Hmm,
Now you can have a DVM with temp. probe. With my meter I can read temp.
any where within a minute.
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Posted by Stormin Mormon on October 14, 2009, 9:32 am
Pro: Less noise
Con: Reduced air filtration
Heat exchanger gets hotter, more thermal stress
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
What are the pros and cons of turning the fan speed
down?
thanks, mike
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Posted by Bob F on October 14, 2009, 11:20 am
spamme0 wrote:
> Got a new Coleman 95.5 gas furnace.
> The fan is quite a bit noisier than my old unit.
> Measures 73 dB in the hallway under the return vent.
> That's "C" weighted.
> I pulled off the vent covers and measured the airflow
> coming out of the rectangular holes in the floor
> with a thermocouple anemometer.
> I've got 800 linear feet/minute from the 4x10" vents
> and 1200 from the 2x10" vents.
> With 67F indoor air temp, the air coming out of the
> vents is 115F. (my 37 year-old furnace was 150F.)
> I added an air conditioner evaporator that provides
> additional turbulence to the air flow, but the objectional
> noise sounds like blower noise coming out the return vent.
> So, The objective is to lower the fan noise.
> Looks like I've got plenty of room for temperature
> rise due to lower air flow.
> I expect I can get the installer to come change the fan motor tap.
> What are the pros and cons of turning the fan speed
> down?
Read the installation manual for the specs for your unit. You want to keep the
temp rise within specs. Get the manual from the manufacturer if you don't have
it. You may be able to download it from their website, or call and ask them for
it. The manual will detail how to change the speed.
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> The fan is quite a bit noisier than my old unit.
> Measures 73 dB in the hallway under the return vent.
> That's "C" weighted.
> I pulled off the vent covers and measured the airflow
> coming out of the rectangular holes in the floor
> with a thermocouple anemometer.
> I've got 800 linear feet/minute from the 4x10" vents
> and 1200 from the 2x10" vents.
> With 67F indoor air temp, the air coming out of the
> vents is 115F. (my 37 year-old furnace was 150F.)
> I added an air conditioner evaporator that provides
> additional turbulence to the air flow, but the objectional
> noise sounds like blower noise coming out the return vent.
> So, The objective is to lower the fan noise.
> Looks like I've got plenty of room for temperature
> rise due to lower air flow.
> I expect I can get the installer to come change the fan motor tap.
> What are the pros and cons of turning the fan speed
> down?
> thanks, mike