Trane Tstat T803...temp never moves?

[key1cc]

Key1cc sorry for stealing your thread. I am curious your outcome because I plan on having the same thermostat (Possibly the 802) installed. I am no expert, but I would think you would get some cycling when it is mildly warm outside (like 75-80) and long run times when it is (90-100). What is the outside temp when you notice this short cycling? Thanks

Teddy

Yesterday it was 90 degrees outside....and I'm not sure 6-10 minutes is defined as short cycling. I took the advice of this site and set my cyles per hour from 3 to 2 today at lunchtime. Afterwork I will monitor it closely this evening to see how it does. The temp will be in the low to mid 90's.
My compressor protection time is set at 5 minutes.
Key1

[Cub]

Key,

I've got the 803, too. Do you have humidity control enabled on the stat along with comfort-r? ? How well is it doing?

[teddyc27]

Thanks. Please keep us posted. Just curious, are you using the Comfort-R feature? Where it runs at 50% fan for a minute, then 80% for 8.5 minutes, then if it still needs cooling 100%? From what I have heard it can give longer run times.

Teddy

[key1cc]

I have some results....but 1st I will answer your questions.

I do have comfort R enabled (which is only a timer that runs the blower on low for 1 minute then 80% for the next 7 or 8 minutes then 100% if needed....I think). I am not using the dehumidification feature that dehumidifies by over cooling 3 degrees lower than the set point.

Now the results. I took the advice from the pro's given in this thread and it appears to have worked. (I changed the cycles per hour from 3 to 2 earlier today). At 5:45 PM I begin monitoring as the condenser had just shut off. It was 92F/ 40% humidity outside. Inside was 75 and 44%. The Tstat was set at 75.

It stayed off for 9 minutes then came on for 23 minutes then off for 12 then on for 19 then off for 23.

When i first started the test.....the wife had just finsihed cooking so there was extra heat load from the oven....also the temp outside dropped to 86F/46% by the time I had finished as thunder clouds were approaching.

With all the variables it is still better than the on/off every 6 to 10 minutes I was getting when it was set at 3 cyles per hour (not sure why that is the reccomended setting in the owners manual). I will try monitoring again earlier in the day tomorow hopefully without all the variables.
Key1

[beenthere]

They base that on the unit being sized right for the house.

Over sized systems will tend to short cycle at 3 CPH.

[key1cc]

They base that on the unit being sized right for the house.

Over sized systems will tend to short cycle at 3 CPH.

Question 1. If changing the cph from 3 to 2 is good ....would changing it further from 2 to 1 be better?
Question 2. Isn't it better for the compressor to run longer? and have long off times rather than quickly on and off trying to stay within 1 degree?

Question 3. If I do set it on 1 cycle per hour and during the off time the temp changes more than 1 degree. Would the unit condensor come on even if it ment it would have to run more than 1 cph?

Key1

[beenthere]

Question 1. If changing the cph from 3 to 2 is good ....would changing it further from 2 to 1 be better?

Probably not.


Question 2. Isn't it better for the compressor to run longer? and have long off times rather than quickly on and off trying to stay within 1 degree?

To some extent, yes. There comes a trade off point. The long run time can be too long and then you are not comfortable with the wide temp spread.

Question 3. If I do set it on 1 cycle per hour and during the off time the temp changes more than 1 degree. Would the unit condenser come on even if it ment it would have to run more than 1 cph?

That would depend on how long its previous on time was. It might let it rise further one time then the next. Making it uncomfortable at times.
Key1

Within reason, its better for the compressor to have long runs times.
But, they are made to cycle on and off. All the compressor manufacturers know that compressors will have some short run times at the milder to mid design temps.