White Rodgers 1F97 Thermostat Behavior

Captain Who

And "spring loaded" ???? LOL It's a digital thermostat, and a quite expensive one at that.

Fred

Captain Who said:

Okay Fred. It isn't an older model. It's a new revision of an older model. I just bought it. But you seem to be unable to answer my question of why the "off times" are in exact one minute increments to the exact second. I figured you were too pig headed to address that

As I said, I can't answer that question, I'm not familiar with White Rodgers thermostats or your system. I did look up the capabilities of that Stat though.No mention of any Heat Loss calculation capability. Applications don't even reference Steam, just Hot water zone heat, as well as forced air and Cooling. Also, it appears the .6F is the only Differential for the heating option. The 1.2F is for use with Cooling. Don't know what you will get if you try the 1.2F option for heat.

THERMOSTAT APPLICATION GUIDE

Description

Heat Only Systems

Millivolt Heat Only Systems – Floor or Wall Furnaces

Cool Only Systems

Gas or Oil Heat

Electric Furnace

Hydronic (Hot Water) Zone Heat – 2 Wires

Hydronic (Hot Water) Zone Heat – 3 Wires

Wired Remote Temperature Sensor (Indoor/Outdoor)

Electrical Rating:

Battery Power . . . . . . . . . . . . . . . . . . . . . . . . . mV to 30 VAC, NEC Class II, 50/60 Hz or DC

Input-Hardwire . . . . . . . . . . . . . . . . . . . . . . . . 20 to 30 VAC

Terminal Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A per terminal, 2.5A maximum all terminals combined

Setpoint Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 to 99°F (7 to 32°C)

Differential (Single Stage) . . . . . . . . . . . . . . . . . . . Heat 0.6°F; Cool 1.2°F

Differential (Multi-Stage) . . . . . . . . . . . . . . . . . . . . Heat 0.6°F; Cool 1.2°F

Differential (Heat Pump) . . . . . . . . . . . . . . . . . . . . Heat 1.2°F; Cool 1.5°F

Operating Ambient . . . . . . . . . . . . . . . . . . . . . . . . . 32°F to +105°F (0 to +41°C)

Operating Humidity . . . . . . . . . . . . . . . . . . . . . . . . 90% non-condensing max.

Shipping Temperature Range . . . . . . . . . . . . . . . . -4 to +150°F (-20 to +65°C)

Dimensions Thermostat . . . . . . . . . . . . . . . . . . . . . 4.6"H x 5.9"W x 1.2"D

Captain Who

You don't have to be familiar with my system. That's my data Fred. It's DATA! If the thermostat were operating ENTIRELY

Captain Who

off of it's internal sensor, the odds of the "off times" being exact minute increments on eight sequential cycles is miniscule, to say the least. You were right about the deaf ears.

Fred

It is your data Captian Who. Unfortunately "data" by itself is neither meaningful nor useful if it can't be validated to be good data. We need not take this converstaion any further. My comments were in the interest of the short, short, short "On Times" and not intended to be a personal attack. If you are happy that your data is 100% correct and that there aren't any other possible factors in play, then I'm happy for you and I'm happy that this discussion is done.

Mark N

What were you using to time the events? A data logger has no bias. Three people timing the same event will give you 3 different times every time. I have no inside knowledge of how White Rogers thermostats operate. I highly doubt they have an internal processor to calculate heat loss. When the temperature drops to the set point minus the differential the thermostat will turn on the heat, because it is a switch that operates on temperature change. Go to www.carolfey.com and read some of the articles in her library that deal with thermostats and anticipators.

Captain Who

What was I using to time the events? Uhh it's a high tech item called a clock (on my computer). Yes it is accurate. It is set to update automatically to the atomic clock every 10 minutes. Yeah I'm done with this.

icesailor

Many electronic thermostats suggest/require an isolation relay to go between the thermostat and the power source of the appliance it is to run. Especially when issues of voltage and polarity become an issue.

Sounds like maybe you might need an isolation relay.

Captain Who

Nope, not sure why you think that (thanks though). I'm not reporting any major problem in this thread of a power interruption to the tstat. Just making some observations on how my thermostat's algorithms seem to function on the 0.6 F (fast) setting. I'm now trying the 1.2 F (slow) setting today and the burn time was around 15m as far as the thermostat was concerned, which was reduced by around 13 sec for the flue damper to close and 90 sec for the darn CycleGard to do its testing, so about 13:19.

I did have to install an isolation relay when I first put in the predecessor to this thermostat (which failed after 7 yrs), in order to get steady power to it. Took me a bit to figure out what was wrong there at first. Of course my instructions from White Rodgers gave absolutely NO guidance on the possible necessity of an isolation relay so I was on my own.

icesailor

You didn't say that in your OP.

What I said was that " Many electronic thermostats suggest/require an isolation relay".

I didn't say that yours did.

I've also found that many electronic thermostat I/O sheets are lacking in clarity. Possible it occurs in the translation from Chinese to English. Sometimes, if and when you read the manuals, you notice strange English Syntax. Mistakes in translations.

Captain Who

More data (1/5/2015, Mon, cycle speed = 1.2 F (slow)):

tstat ON___tstat OFF___Therm #1_Therm #2___tstat display___remote display___Wind/Gusts___Outdoor Temp/Wind Chill

Recovery from Setback (53 F, programmed to end 7:45am):
7:25:09am___N.A___59.4___59.1___57___57___16/24___39/30
N.A.___8:12:57am___64.2___60.2___61___61___18/25___38/28

Steady State (setpoint 61 F):
9:43:57am___N.A.___65.1___64.2___61___61___23/39___38/27
N.A.___9:57:57am___65.9___64.2___61___61___23/39___38/27
1:25:57pm___N.A.___64.6___64.4___61___61___22/30___35/23
N.A.___1:40:57pm___64.6___64.0___61___61___22/30___35/23
3:51:57pm___N.A.___64.6___64.2___61___61___20/32___33/21
N.A.___4:08:57pm___64.6___64.0___61___61___20/32___33/21
5:41:57pm___N.A.___N.A.___N.A.___61___61___15/25___30/19
N.A.___5:58:57pm___64.9___64.2___61___61___15/25___30/19
8:38:57pm___N.A.___64.9___64.4___61___61___21/24___26/12
N.A.___8:55:57pm___65.5___64.2___61___61___14/-___25/13


Temperature felt warmer and more comfortable after the burns than it did on the 0.6 F (fast) setting, due to radiators heated further across, however longer off times resulted in noticeably less comfort before the next burn due to colder radiators.

Adjustments to determine Burner On times:
1) 90 secs (1:30) to do the Intermittent CycleGard Tests which take place at 10 m intervals after each burn starts
2) 13 secs every time the flue damper has to close before burner will fire
3) Pressuretrol interrupted burner an undetermined number of times (est. 3) towards the end of recovery only. Other firings after recovery did not develop noticeable pressure on 0-3psi gauge

Cycle Desc.___Cycle time (off to off)___tstat call duration___Burner ON___% ON current cycle___% ON day cumulative (after recovery)


Recovery___N.A.___47:48___40 min est.___N.A.___N.A.
Cycle #1___1:45:00___14:00___12:04___11.5%___11.5%
Cycle #2___3:43:00___15:00___13:04___5.9%___7.7%
Cycle #3___2:28:00___17:00___15:04___10.2%___8.4%
Cycle #4___1:50:00___17:00___15:04___13.7%___9.4%
Cycle #5___2:57:00___17:00___15:04___8.5%___9.2%

Avg. Temp = 33.7 F
Avg. Wind Chill = 22.5 F
Avg. Wind Speed = 19.4 mph
Avg. Cumulative Duty Cycle for 5 Steady State Cycles = 9.2%

Once again, it is perfectly clear from the data that the algorithm employed by this thermostat calculates the on and off time to be in exact intervals of one minute, to the nearest second. So it is obvious that it is employing some sort of temperature ascent and descent learning at each moment based upon the heat loss due to the ambient conditions at any given time and the heating performance of the burner + radiator system. It calculates this so as to not overshoot or undershoot the setpoint according to what its internal temperature sensor is actually reading, within the tolerance specified (in this case 1.2 F). It also uses an algorithm to start recovery some time before the programmed recovery time in order to attempt to have the room heated to the setpoint at the desired time.