Cycles per hour - http://www.hvacmechanic.com/ Forums
Original message
| p2021
 |  "Cycles per hour"
, posted Thu 6 Nov 16:57  
Is there such thing as cycles per hour, never owning a forced air system it seems to me that the burner fires often?
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Replies:
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| Ad Mech 2
| "Re(1):Cycles per hour" , posted Thu 6 Nov 21:20:
There really isn't a standard.
However, the furnace shouldn't cycle repeatedly. Longer run times are more efficient and easier on the furnace.
Some conditions that can cause frequent cycling are:
- Over-sized furnace (BTU and/or tonnage)
- Drafts or poor insulation
- Poor thermostat placement (i.e. outside wall or near door)
- Kids just won't keep the doors/windows closed
- Dirty filters causing unit to overheat and trip on high-limit
- Dirty evaporator (if installed)
- Closed or partially closed supply vents (high-limit again)
- Blower fan is dirty
- Blower motor is too slow (not enough air) or is too fast (cavitating)
- Mal-adjusted heat anticipator on T-stat (temperature differential on an electronic t-stat)
Randy
[this message was edited by Ad Mech 2 on Thu 6 Nov 21:28] |
| | p2021
| "Re(2):Cycles per hour" , posted Fri 7 Nov 00:27
I have been trying to eliminate some of the reasons u listed and can do so with many of them……….. all seem to make sense. Whats bother some is ...because their is no standard how does one know if the furnace is being worked to hard (e.g. coming on and off to much). I know their is so many variables when addressing this question.
What about thermostats I have come to understand that the newer electronic programmable units have off a cycles per hour aspect to them and can be set accordingly. I suppose this setting could be helpful if Iam concerned thats its coming on to much?
When I was at home depot tonight I thought it was the Chromethe III (spelling ?) had a temperature range feature. Where potentially the furnance would call for heat and shut off when programed within this temperature range? Does this sound familar?
Bascially it seems that their is two maybe three ways to limit frequent cycles. 1) Getting a thermo with a cycles per hour feature assuming their is one. 2) Getting the old round thermo with the heat anticpators. 3) assuming what i saw tonignt was right getting a thermo that has a temp range feature.
Which would u recommend. Common sense would be that older homes like mine will never be as energy efficent as todays homes and will always experice a greater degree of heat loss hence causing the thermosat to call for heat more often. Is their a specific thermostat which techs recommend for my situation or that anyone here could recommemd
And what models are they. Or any other suggestions?
PS sorry for the long message iam new at this!
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| | Xenos
Webmaster 
| "Re(3):Cycles per hour" , posted Fri 7 Nov 17:09
Most electronic thermostats use Cycles per hour for anticipation. I know the Honeywell T8600 series of thermostats offer 1,3,6 or 9 heating CPH.
Xenos.
The best way to escape a problem is to solve it.
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| | Ad Mech 2
| "Re(4):Cycles per hour" , posted Sat 8 Nov 01:43
Poor insulation is easy to check. Get the house to a comfortable temp on a cold day and shut off the furnace. If the temp drops pretty quickly, your furnace and t-stat are just trying to do their jobs.
If not done already, have the unit serviced and cleaned. This should cover most of the points. Don't be afraid to express your concerns about cycling to the technician.
As for T-stats, don't loose site of the fact that they are just a switch. Some types and models have added features to help efficiency, but in the end, they just start the furnace at temp y and stop it at temp x. A programmable t-stat can really save you money, but it won't compensate for a 'sick' system.
Randy
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