Heat anticipator again
#1
Member
Thread Starter
Heat anticipator again
My Honeywell stats have settings for 9, 6, 3, or 1 CPH. Electric, regular forced air, hi efficiency forced air and radiant, respectively. I am not happy with the cycling at 3 CPH for my high-efficiency furnace.
I want the furnace to stay on longer when heating up from the weekday temp of 60 to the evening temp of 68. For example, it will run for 20 minutes and get the temp to 63 degrees, then shut down, purge and turn back on twice more before the house gets to 68. This seems stupid. I'd rather have it run 12 minutes at low stage and the rest of the time at high stage until the call is satisfied.
If I want the cycles to be longer, should I set it to 1 for radiant heat or 6 for regular forced air?
Thanks.
I want the furnace to stay on longer when heating up from the weekday temp of 60 to the evening temp of 68. For example, it will run for 20 minutes and get the temp to 63 degrees, then shut down, purge and turn back on twice more before the house gets to 68. This seems stupid. I'd rather have it run 12 minutes at low stage and the rest of the time at high stage until the call is satisfied.
If I want the cycles to be longer, should I set it to 1 for radiant heat or 6 for regular forced air?
Thanks.
#2
Maybe this link will help.
This is for Honeywell's Thermostat Wizard
http://yourhome.honeywell.com/yourho...rd/Wizard.aspx
It will even help you figure out the model of your thermostat if you don't know that info.
Hope this helps...
This is for Honeywell's Thermostat Wizard
http://yourhome.honeywell.com/yourho...rd/Wizard.aspx
It will even help you figure out the model of your thermostat if you don't know that info.
Hope this helps...
#3
Member
Thread Starter
Thanks, I've got the T8602D2000. Unfortunately their online help does not address heat anticipator settings, presumably since this is more often a dealer issue, and my stats are "tradeline" or whatever they call it, meaning they are sold only by dealers of one type, but not big boxes and so on.
#4
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The closest item I could find on their site with directions:
http://customer.honeywell.com/techli...0s/69-1567.pdf
See also:
http://customer.honeywell.com/Honeyw...ACHEHINT=Guest
for all thermostats listed.
Good luck.
http://customer.honeywell.com/techli...0s/69-1567.pdf
See also:
http://customer.honeywell.com/Honeyw...ACHEHINT=Guest
for all thermostats listed.
Good luck.
#5
I found this page that has both Installation and Owners manuals. Just look for T8600 that might cover the T8602.
http://www.airconnectweb.com/links.php#
I also cannot find anything on heat anticipator settings.
http://www.airconnectweb.com/links.php#
I also cannot find anything on heat anticipator settings.
#6
Member
Thread Starter
Thanks Pete I really appreciate it.
Unfortunately I have all the installer and consumer documentation that the contractor left behind, covering all the various programming settings, but nowhere does it tell me how the CPH settings compare to analog heat anticipator.
It seems to me the type of question somebody who knows the biz could answer. I was thinking radiant at 1 CPH would be right, but then again radiant would probably take the longest for the heat to reach the stat.
On the other hand, 9 CPH doesn't sound right because it seems like that would mean it would cycle on and off every 6-7 minutes. So it would help if I knew some baseline info, like which way is up!
I googled CPH with Heat Anticipator and after my own old threads on the topic, I got this article which discusses CPH in some detail:
http://www.alainc.com/Articles/article7Ribble.html
But nobody seems to be able to tell me why my stat would be cycling the furnace OFF when the room temp is nowhere near the stat's set point. The brief discussion I had with my HVAC contractor was not illuminating.
Unfortunately I have all the installer and consumer documentation that the contractor left behind, covering all the various programming settings, but nowhere does it tell me how the CPH settings compare to analog heat anticipator.
It seems to me the type of question somebody who knows the biz could answer. I was thinking radiant at 1 CPH would be right, but then again radiant would probably take the longest for the heat to reach the stat.
On the other hand, 9 CPH doesn't sound right because it seems like that would mean it would cycle on and off every 6-7 minutes. So it would help if I knew some baseline info, like which way is up!
I googled CPH with Heat Anticipator and after my own old threads on the topic, I got this article which discusses CPH in some detail:
http://www.alainc.com/Articles/article7Ribble.html
But nobody seems to be able to tell me why my stat would be cycling the furnace OFF when the room temp is nowhere near the stat's set point. The brief discussion I had with my HVAC contractor was not illuminating.
#7
1 cph is continuous run. The reason they invented the anticipator was to 'anticipate' the heat rise that would happen after the thermostat stopped calling for heat. With no anticipator and cast iron radiators or an 800 lb converted coal furnace, the room temp could rise another 5-7 degrees after the thermostat was satisfied. The anticipator, when adjusted correctly, would stop the furnace just in time to allow the residual heat to just reach the setpoint. It was done with a heating element inside the thermostat and based on the current draw of the control that was connected to the thermostat, a starting point could be set for the adjustment. Most modern heating systems don't have anywhere near the mass of the old ones so there is usually much less residual heat to anticipate. If you want a longer run, set the cycle rate at 1 and if the room overheats, set it to 2. Work your way up until it works the way you want. Let us know if your experimentation leads to any interesting findings. Thanks.
Ken
Ken
#8
Member
Thread Starter
Thanks. I will try 1 and see if it overshoots significantly. Unfortunately there is no 2 setting.
#9
Sorry about that. I was using the example to show the effect of cycling. I think the off time is only about 5 minutes. I will try to find out from honeywell how long the off cycle is between on cycles.
Ken
Ken
#10
What is the avg run time, down time and how may time an hour are you getting at 3?
How long have you had the t-stat?
What is the outdoor temps when you notice these short runs?
How big is the furnace (BTU?, and sq footage of the home?
How long have you had the t-stat?
What is the outdoor temps when you notice these short runs?
How big is the furnace (BTU?, and sq footage of the home?
#11
Member
Thread Starter
Down time is usually just enough for the purge cycle to run. That is, the stat stops calling, the furnace purges, and then the stat starts calling again within a few minutes. I often hear the stat relay click to stop the call for heat but I don't often pay attention to when it starts calling for heat again. I think the purge runs for about three minutes so I'd say five minutes maximum between the stat's stop and start calls.
I'd say 2-3 cycles per hour. I am not using the PID function, the intelligent setting, AIR I think they call it. For example if I want 68 deg. at 5 PM, the furnace starts at 5 PM, not at 3:30 PM to make sure the temp is 68 at 5:00. The reason for this is that I didn't want the furnace cranking up at 4:30 or 5:00 AM to get things heated up to 68 by 6 AM. I'd rather have it blasting on high stage at 6:15 in the bathroom than get the whole zone to 68 by 6 or 6:30 or whatever.
2. I have had one stat since fall 2000, and the other since December 2001. We didn't start using the second floor zone until March 2002, when we got the remodeling to a livable level. The zone controller is a MABS 2 EZ.
Below are all the stat settings and readings.
Option-1st floor-2nd floor-Description-Setting
2 0 0 Fan Conventional
4 3 3 Heat Cycle High Eff
12 0 0 Changeover Auto
13 1 1 AIR Conventional
14 0 0 Display Fahrenheit
16 1 1 Clock 24h
19 0 0 Heat Fan no extended
20 0 0 Cool Fan no extended
24 1 1 Outdoor Temp Sensor yes
30 3 3 Deadband 3 deg. F
34 90 90 Setpoint Heat, hi limit 90 F
35 45 45 Setpoint Cool, lo limit 45 F
37 0 0 Display Temp Actual
Info
71 010 091 Mfg. Date Jan 2000, Sep 2001
72 315 328 Software ID code
73 306 449 Software revision number
74 647 647 EEPROM ID code
3. The outside temps are usually low 20s and below; that's when the house gets down to 60 during the day. If it's around 30 or above, the house does not lose as much heat, usually bottoming at 64 or so.
4. The home is about 1800 sq. ft. The furnace is:
Trane
XV90
62K-93K BTU output
TUY100R9V4V3
#12
Holy cow.. I can see why you have the short run time.. A 100k on a 1,800 home... Unless you got a single pane glass, no insulation in the walls? Did they do a load calc on the home?
What is the model # on the zone board?
What is the model # on the zone board?
#14
Member
Thread Starter
What difference would all that make to the heating system controls? We're not hitting the high limit.
The zone controller is a MABS EZ-2. It sets the high stage and has a ZoneMAX ZMS. I can't recall that it or the furnace high limit has ever been tripped. And I can hear the stat relay clicking to stop the heat call.
#15
Member
Thread Starter
Yes. W2 is connected from the zone controller to the furnace board and it is set to go to high stage at 12 minutes.
#16
Yes. W2 is connected from the zone controller to the furnace board and it is set to go to high stage at 12 minutes.
#17
Member
Thread Starter
It's only from 7-8 AM or in very cold weather that both zones have overlapping or simultaneous calls for heat, therefore keeping the furnace on for longer. To the best of my knowledge the MABS does not have a heat anticipator circuit and since the stats are single stage, they do not know when the furnace is on high or low.
I really need to try the 1 CPH setting to see what difference that makes.
#18
That's not right.. That furnace should be staying on till you'v reach set point. Almost sounds like it's cycling on and off on limit or something...