How a thermostat works part 4 what is cycle rate and why should I care?
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- Опубликовано: 24 янв 2021
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This video explains thermostat cycle rate setting, what it is, how it should be set, and why it is important.
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Very well done and I certainly appreciate it. CPH is a very confusing terminology, this video helps tremendously.
one of a kind video, very well explained, us technicians need to be educated with this information, thanks
Thank you for your in-depth coverage of this topic. I for one, like to know the how/why things work. We replaced our old thermostat and verified it was set to a 3-cycle rate. HUGE difference in the comfort of our home this morning ... especially since it is 15 degrees in Ohio today.
Thanks for sharing
Thank you.
For me, understanding the thermostat is very helpful because gas heating, in UK, requires a different training than in refrigeration area.
Thanks good advice and information
Wow awesome video
This is by far the best video on the CPH setting...
Thank you! Good luck!
Thanks for sharing
Thanks for the info in this! My WI apt has hydronic heating and after our last cold burst, maintenance hired a company to come and work on the building's boiler and the heating has just been super amped up since. We live on the second floor and never needed to turn the heat on in 4 years. I pulled the cover to our thermostat and saw the cycle rate was set at .8 so I turned it down to .3. Hopefully that will solve it. I'll try to come back and update in a few days after seeing what works or doesn't work.
Very helpful. My heat pump seems to run short periods at certain conditions. It maintains the set point plus or minus 0.5degree. The energy used, the strain of starting, and initial cold efficiency makes this not a good option. The thermostat CPH default is 5, but might be set higher as recommended for heat pump. I'll have to confirm that tomorrow. Thanks for explanation. I've always wondered about the mercury bulb sliding resistor coil was!
Great series of videos! What would you use to test whether a thermostat is reading and reporting the correct ambient temperature?
Thank you! Most modern digital thermostats have very accurate temperature sensors and I don't usually have a reason to doubt them. That being said, a calibrated digital thermometer with a bead probe positioned inside the thermostat housing as close to the actual temperature sensor as possible will be the way to do it. See my video on how to calibrate a thermometer.
You should know that HVAC thermostats sense temperature a little differently than standalone thermometers do. Because of the way they are constructed, they sense a combination of the air temperature and the wall temperature. This is by design. Anything you do to try to measure that at the same time can change the dynamics of that system. Also, modern thermostats are packed with intelligence which will take that temperature reading and make decisions based on it. That decision making process is never transparent or obvious to you. It is more complicated than simply looking at temperature alone and responding to it. Generally, the more expensive the thermostat, the more advanced that decision making process is. This is why you can buy a thermostat for $50 and also buy one for $300.
Speaking as a person who has spent considerable time verifying that thermostats are reading accurately, I have realized that most of that time was not impactful and that thermostats are generally pretty accurate. The most helpful thing I was able to find was cold drafts flowing through the wall cavity and through the hole behind the thermostat.
If you have a hydronic boiler reset like the hydrostat 3250+ burning oil is it best to set the cycles per hour to 1 and let the 3250+ do its thing or leave on the 3 CPH as T-stat indicates?
How are you feeling about the nest learning thermostat?
My thermostat has slow,med and high .so if my hp cycles a little more than I want,can I change it to slow or fast? Default is med.Also what do you recommend cycle rate for emergency heat also?
What number of cycles does the 1.2 amp setting on an anticipator correspond to?
What cycle rate should. be set for a central air conditioner?
What if you have a high, medium and low cycle rate what do you set it on for the best Heating in your house and Cooling in Michigan
Thanks for the tutorial. You are the first person to have clearly explained cycles per hour. But I have a question, which hopefully you could answer. Do you think that there is a discernible difference between 3 and 4 cycles per hour such that it may be better in certain circumstances to do 4 instead of the 3?
Glad you liked it. Back in the old mercury bulb thermostat days, cycle rate was determined by a heat anticipator which had a sweep type of adjustment. Electronic thermostats replaced this with a 3, 6, or 9 CPH adjustment. Today, many thermostats have even more steps for finer adjustment. I don't think there will really be a noticeable difference between 3 and 4 CPH. My recommendation is to set for the lowest setting you can get away with without overshooting the temperature setpoint. If overshooting occurs, set the CPH higher until overshooting isn't a problem anymore.
@@hvacservicementor Thanks for the reply.
One more question if I could indulge your patience: May the cycles setting also be affected by how wide the dead band is set at? I am guessing that when it comes to cycles, the key is to avoid short-cycling; but if the dead band is set to a differential of more than 3 degrees, would worrying about the cycles per hour even be an issue?
Thanks again.
@@juliotorres3618 Most residential thermostats do not have an adjustable deadband unless you are looking at the difference between the cooling setpoint and the heating setpoint in auto changeover mode.
Auto changeover will have you select a heating setpoint and a cooling setpoint. when the temp falls below the heating setpoint, the heat runs. When the temperature rises above the cooling setpoint, the AC runs. There must be a deadband of separation between these setpoints or else we would be rapidly banging back and forth between heating and cooling. This deadband typically defaults to two degrees and is sometimes adjustable higher. For example, if cooling is set to 75, heating can be set no higher than 73. Attempting to set cooling lower than 75 will also drive down the heating setpoint as well to maintain that separation. This would be the two degrees deadband.
A user may wish to be energy conscious and say they want the cooling to maintain 78degrees and the heating to maintain 68degrees. This would be a ten degree deadband.
Within the individual heating or cooling mode, the deadband is typically non adjustable and will generally be between .5 and 1degree F. Sometimes this deadband is also known as swing. A setpoint of 70deg with a 1 degree swing will produce actual temperatures between 69.5 to 70.5.
Remember that the cycle rate does not directly control how many times per hour the furnace runs. There are several other factors that influence this more directly such as system output capacity and sizing. How quickly the house is naturally gaining or losing heat. And the thermostats own factory set PID loop programming. A cycle rate setting actually directly influences when the burner or compressor or hydronic zone valve or electric heat strip will turn off in anticipation of achieving setpoint.
This is why they used to be called heating or cooling anticipators.
@@hvacservicementor Thanks again. I have a thermostat that allows me to decide between cooling or heating. I had my dead band set to a 3-degree differential. I have now changed it to a 4-degree difference, 66-70 degrees.
ive got a new electric furance its set to 3 cyles but they only run last like 3-5mins then it shuts off doesnt run long enough to heat up and keep the room temp at 70 what have it set too it short cyles
I have an Aprilaire 8444 thermostat and it has a setting adjustment called stage rate and the settings rang from off to 5 minutes exactly what does that mean is that similar to cycle rate because I noticed when we had it installed that even though we always set our heat to 74 and if it's really cold out the room temperature will say 73 for a few minutes before the thermostat calls for heat and when we adjusted that setting to 1 it cured that problem and now it comes on when the room temperature says 74 but if we have it in cooling we keep it set to 76 and if it's mild out it will kick the ac on exactly at 76 but if it's above 70 degrees outside it will say 77 on the room temperature for several minutes before kicking it on and adjusting the stage rate settings didn't really solve that problem in cooling but it's still keeping it comfortable for us but was just wondering if it's the way it's supposed to work
Some thermostats have a 2- 3° range from current room temperature to when the heat pump system will turn on . If your thermostat has a 2° change when you have the home set at 74°, 76° will make the thermostat start to heat or cool the home. What has been explained in this video is run time once the system has started, to increase the time or decrease the time . The instruction manual explains the cycle rate. I just read it myself 😂😂
I have a Honeywell Chronotherm the anticipator has numbers
.20, .30, .40, .50, .60 it is a steam boiler with gas fuel rated at 1.15 volts 60hz ok the card where should my anticipator be set to by default?
OK here is a puzzle for you. I have a carrier HVAC that is only a a year old. It has been routinely serviced by the pros. It is set on a 4 cycles per hour cycle rate and a swing differential of less than one because the temp never changes.. If I set the AC on say 81 w/outside temp say 95, it runs for about 25 minutes then shuts off for about 55 minutes which is mathematically a cycle rate of less than one. If I set it to 78, it still runs about 25 minutes but stays off for about 35 minutes which is a cycle rate of ONE. If it is 75 outside and I set the stat at 75, it will come on for about 10 minutes but stay off for almost 3 hours which is a cycle rate of way less than one. So I dont get the mumbo jumbo about cycle rate when the difference is made by the temp outside. And right now at 330 am the outside temp is about 73 and the stat is set to 81 and it has not run since 10 pm - not once so to me cycle rate is meaningless. And dont give me any crap about my unit may be too small or too big. Everything Ive read says it will wear out quicker if it short cycles and will use more energy but then turns right around an says if it long cycles it will use more energy, which is like saying if you drive your car fast it will use more gas but if you slow it down it it will use more. Cannot be both ways. Any suggestions. My unit is not too big or little and is in perfect condition. BTW at the end of the run cycle I am starting to get cold and after the shut off cycle I start to get hot. All the techs that have checked it out say it's OK and normal but according to the internet my unit has a gremlin inside. Please someone give some advice.
Cycle rate only applys to heating
@@simonmarx34 No it doesn't. You can change the cycle rate for air conditioners as well.
Thank you
You're welcome
You didn’t mention heat pumps. Is 3 the recommended starting point for heat pumps?
How many cycles would 1.0 amps give you?
Anyone has experimented with this setting on a heat pump with only 22F rise in heat mode?
Do fewer cycles use less fuel?
Not necessarily. I believe is depends on the efficiency and stage of your furnace
I asked my tech to explain this, and he had no idea. It was kinda sad/ frustrating... Guess who's getting this video, lol
my customer complains that unit shuts off, stays off 15 minutes then comes on for 2 minutes and off again. Is this a cycle rate problem.I like that the unit stays off 15 minuted.
If the unit only runs for two minutes every 15 minutes, that is four starts per hour and only 8 minutes of run time per hour. I think there is probably more to the story.
Thank's for this. Does this apply to heat pumps that also cool? They're common in the mid-Atlantic region.
I set my heat pump to 3 to get longer runtimes ... it's about temperature fluctuation what you can handle versus start and stop. Start and stop a compressor more often, will shorten the life and it will draw the higher amps when starting.
Why would I want my gas furnace to start up 9 times a hour vs. 3 times a hour? For my comfort he says?? The degree swing setting from digital thermostat manufactures was perfect. This CPH B.S. is planned furnace obsolescence.
The first few mins of start up is the most inefficient. Even more so for heatpump. Everything is cold.
Your furnace is losing some energy heating the vents up as the hot air moves through them.
Another note is a longer cycle gets a better balance of room to a centain degree.
Seems this guy is treading in the swing definition, but doesn't quite.
So maybe he isn't trying to.
Because swing is a very easy thing to explain. And a great reason to be informed of it. Especially if you have heatpump or your getting a lot of cycling of your furnace each hr.
Gosh I just want to know how to change the cycle; not a history of thermostats. This is the 10th video I’ve searched for which is nothing more than blah blah blah about the history of thermostats. Just tell me how to adjust the cycle time SMH
He did tell you, download the thermostats manual, and find it in there.
Omg, get to the point then a history lesson. 😊
History is important. Everything we have now is based on what came before.
@@hvacservicementor this is where we are as a society. Why you have men on the side of the road with women changing their tires and men that can't use a grill..... many other examples. Point is ignore well don't ignore but smile and know that will be a service call for a small business person. Know this is reason why service calls have went from major issues to simple adjustments most of the time. Simply ask location and post phone num er of local business. Heck make deal where you get finders fee. I will be searching out mire of hour videos. We are going to upgrade our heating system that was built in late 80s. 2000 sq fr two story home with an evaporative cooking master cool ac and whatever heating system used back then. Any advice or systems to avoid??
You didn’t mention heat pumps. Is 3 the recommended starting point for heat pumps?
3 is a good starting point. The lower the discharge temperature, and the lower the mass of the heater, the longer the cycles can be.