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Subject Author Date
temperature swing value Tony Sivori 04-15-2007
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Posted by on April 15, 2007, 11:39 pm
wrote:

>
>>
>>>Noon-Air wrote:
>>>>
>>>>>What is a typical number of degrees for the temperature swing for a
>>>>>programmable thermostat?
>>>>
>>>>
>>>> 1 degree
>>>
>>>... or less
>>
>> It's called 'deadband', and I call Bullshit on both answers.
>
>Ummm.... no
>
>> Anything less than 2 F, you're gonna get severe short cycling.
>
>If the system is properly sized, 1 degree is reasonable and works just fine
>and no short cycling unless you are within a degree or 2 of the design temp
>limits. At that point, you may have the system cycle off for less than the 5
>minute compressor delay-on-break timer, but it will run for 30 or 40 minutes
>before it cycles off again.
>If you have a short cycling problem with a 1 degree deadband under normal
>usage, then your system is grossly oversized.
>
>> By example - TotalLine programmables won't LET you set less
>> than 1, and the range is 1 - 6.
>
>I wouldn't ever go less than 1 degree, that would be counter productive.
>
>>>>>Would adding three degrees save noticeably (say,
>>>>>five to ten percent) on the heat and cooling bill?
>>>>
>>>>
>>>> no
>>
>> Correct. Only lowering the setpoint in winter, raising it in
>> summer, will save money ( for whatever period of time during the day
>> the setpoint is closer to outside temps ).
>
>I normally recommend that programmable stats be set in heat mode for 68 - 70
>degrees during the day (6am - 10pm) and set back to 60 - 62 degrees at night

        Those are the numbers I set my refrigerator at :-)


>(10pm - 6am), and for A/C mode, 76 degrees 24hr.
>
>>>I don't know about 5-10%, but it might result in noticeable savings.
>>>
>>>>
>>>>
>>>>>--
>>>>>Tony Sivori
>>>>>
>>>>
>>>>
>>>>
>>
>> --
>> Click here every day to feed an animal that needs you today !!!
>> http://www.theanimalrescuesite.com/
>>
>> Paul ( pjm @ pobox . com ) - remove spaces to email me
>> 'Some days, it's just not worth chewing through the restraints.'
>> 'With sufficient thrust, pigs fly just fine.'
>> HVAC/R program for Palm PDA's
>> Free demo now available online http://pmilligan.net/palm/
>

--
Click here every day to feed an animal that needs you today !!!
http://www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo now available online http://pmilligan.net/palm/

Electric Radiant Heat 468x60
Posted by on April 16, 2007, 2:03 am

>
> >Noon-Air wrote:
> >>
> >>>What is a typical number of degrees for the temperature swing for a
> >>>programmable thermostat?
> >>
> >>
> >> 1 degree
> >
> >... or less
>
> It's called 'deadband', and I call Bullshit on both answers.


Actually, Honeywell refers to 'deadband' as the temperature difference
between Heating and Cooling temperatures when using autochangover (options
are normally 2 - 9 degrees).

They refer to 'temperature differential' or 'cycle rate' (CPH) when they are
talking about temperature swing. Typically, 2-10 CPH or .5 - 3 degrees are
pretty normal for most manufactures (this range covers a variety of
equipment).






Posted by Tony Sivori on April 15, 2007, 9:45 pm
Noon-Air wrote:

>
>> What is a typical number of degrees for the temperature swing for a
>> programmable thermostat?
>
> 1 degree

Thanks for the info.

>>Would adding three degrees save noticeably (say,
>> five to ten percent) on the heat and cooling bill?
>
> no

A great idea, while it lasted.

--
Tony Sivori


Posted by udarrell on April 15, 2007, 9:52 pm
Tony Sivori wrote:

>What is a typical number of degrees for the temperature swing for a
>programmable thermostat? Would adding three degrees save noticeably (say,
>five to ten percent) on the heat and cooling bill?
>
>
Increasing the temp differential of the room TH could make a difference
in the operating SEER because starting and stopping, or short cycling,
wastes energy to get the evaporator cold, and/or, the heat exchanger in
a gas or oil furnace hot enough to deliver warm air to the conditioned
space.

This is a major reason why the proper BTUH sizing of equipment is so
important to efficient operation. It extends the run-time & reduces the
number of start-up cycles.
My old oil furnace runs a long time using fuel, too much of which goes
up the chimney before it the blower kicks in. - udarrell

--
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