A/C Thermostat Question

[richard5933]

Not a bad thought Peter. Looks like there are a number of such remote sensor thermostats out there. Should the delay relay not work as I hope, this gives me another option.

[richard5933]

Delay relay has been installed. Wasn't really that difficult, as there was 120v available at a terminal strip in the evaporator cabinet which was fed by the circuit breaker for the ventilation fan. Connected the 120v to run the relay, and then re-routed the thermostat wires to go through the relay. I can now set a delay of 3-300 seconds and keep the compressor from running for only 30-45 seconds, which happened when the weather was not too hot and the room had come to temp.

I'll run it for a few weeks and see if it helps. Hopefully I will be able to report on success or failure at rally in Blytheville.

[richard5933]

So now it's next season and I've had a chance to run the a/c a bit with the new delay relay installed. I can say for certain that keeping the compressor running for longer has helped. With the weather only marginally hot, especially at night, it was only running for about 30 seconds at a time before. Now it runs 3 minutes at the minimum. Doesn't sound like a big difference, but it does help remove more humidity from the air.

I think in the end the problem is that the a/c unit is just too large for the small space of the back bedroom. Being too large is no better than being too small - an a/c unit needs to be sized right. Perhaps in Texas or Arizona this would be appropriate, but not for use up here in the north.

[RichardEntrekin]

 

[luvrbus]

MY CC has remote sensors and a weird thermostat to control 3 zones with the AquaHot heat,heat pumps and AC,I am about to figure it out though everyone tells me the thermostats on the Coleman Roof tops will only turn the compressor off and the fan still blows,if I set the zone to automatic when the compressor kicks out on cool or heat the fan will run for less than 2 minutes then shut off,If I set the fan setting on high or low when the compressor kicks out the fans never stop what is up with that  ?   

[chessie4905]

You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.

[luvrbus]

You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.

He could probably do that if the unit had a heat exchanger and both used 1 common duct like automobiles I doubt he has that luxury

[RichardEntrekin]

MY CC has remote sensors and a weird thermostat to control 3 zones with the AquaHot heat,heat pumps and AC,I am about to figure it out though everyone tells me the thermostats on the Coleman Roof tops will only turn the compressor off and the fan still blows,if I set the zone to automatic when the compressor kicks out on cool or heat the fan will run for less than 2 minutes then shut off,If I set the fan setting on high or low when the compressor kicks out the fans never stop what is up with that  ?

I can't be 100% certain without hands on with your thermostats. But if they are like mine, they behave exactly as described on purpose. On the Auto setting, the fan comes on when the temp is more than 1 degree from the setpoint. A minute or so later, the compressor kicks in, when the tstat reaches setpoint, the comp turns off and the fan runs for another minute or so. The purpose of the fan coming on early is ensure the compressor doesn't generate a high head pressure on startup, and it runs for an additional minute to extract the last bit of cool from the evaporator.

When you put the tstat in high or low manual the fan runs all the time to circulate air continuously, and the compressor cycles based on the difference between the air temp and the setpoint. I find this setting VERY useful while driving because it minimizes the temp swings in coach due to the AC coming on and off.

I hope this explains "what's up with that ".

[luvrbus]

Thanks for the explanation Richard that is exactly the way mine works in all 3 zones Lol I thought the tstat maybe screwed up 

[richard5933]

You should be able to blend heated air with the cooled air to control outlet temp, get all the dehumidification without over cooling, just like in cars.

Not sure where the heated air would come from - the a/c units basically operate like a mini split. All they do inside the coach is blow air across the evaporator coil. No heat coil involved.

[sledhead]

I can't be 100% certain without hands on with your thermostats. But if they are like mine, they behave exactly as described on purpose. On the Auto setting, the fan comes on when the temp is more than 1 degree from the setpoint. A minute or so later, the compressor kicks in, when the tstat reaches setpoint, the comp turns off and the fan runs for another minute or so. The purpose of the fan coming on early is ensure the compressor doesn't generate a high head pressure on startup, and it runs for an additional minute to extract the last bit of cool from the evaporator.

When you put the tstat in high or low manual the fan runs all the time to circulate air continuously, and the compressor cycles based on the difference between the air temp and the setpoint. I find this setting VERY useful while driving because it minimizes the temp swings in coach due to the AC coming on and off.

I hope this explains "what's up with that ".

mine works the same way as well for all 3 units

dave 

[chessie4905]

Sorry, I thought you were talking about the coach air, not your cruiseaires.

[richard5933]

Sorry, I thought you were talking about the coach air, not your cruiseaires.

Ok - now your comment makes perfect sense. What you suggested is exactly how the OTR system works.

The problem I'm having is with the house units - Custom Coach built these things using commercial refrigeration parts, and I can turn the bus into a meat locker if I want. The problem comes when I want to hold a steady temp of about 70 and also keep the humidity down. They just cool too fast to properly remove enough moisture.

[chessie4905]

Could you add some kind of heating coil inside of ac output duct and control it with a thermostat or something. May be the guts out of a cube heater or...