The OH Light keeps coming on although the temperature never exceeded 100 degrees.

I have a couple of thoughts. You may have air in the boiler water circuit at the loop that feeds the tank. You'll have to find the vent in the loop to get it out. Second, the automatic valve that opens for hot water may not be opening fully. Have you felt both the boiler water lines that go in and out of the tank? If the water going in is hot and the line out is very cold you have very little boiler water going through the loop. Make sure the isolation valves on the loop are open. Is your boiler full of water? If the boiler loop lines are hot going in and coming out, the tank is full of rust or debris and no water can get to the fins on the internal tubing to pick up heat. If that's the case there is no repair and its time to get a new tank. Hope this helps good luck.

A thermostat only cuts the heating off when the temperature it is set to is reached while the heating is on. If the heating is set to off then the thermostat will do nothing.
Generally you want to think about when you want your heating to come one and off by using the timer and then the thermostat is just used to ensure that you don't waste energy by exceeding the maximum comfortable temperature.

Hope this helps a little.

Hi, It sounds to me like you have covered all of the basis. The evaporator coil should be clean if you keep your filter clean and the condensation is showing that it is cooling properly. Normally, when the temperature increases outside, you will loose as much as 35% of your units efficency as it it working very hard. 77 degrees is very good temperature if the outdoor temperature is in the triple digits or a little less. It may be that your thermostat is off just a little also. If you clean your coils and keep it up like he said, that is great! I wish more people would do this. You should have a 18 to 25 degree temperature difference between the supply air from you vents and the return air at your filter. Example, if your supply air is 56 degrees, and the return air is 76 degrees, a 20 degree difference or TD, that is excellent. You can check this with a thermometer. I live in Northern Ca and it gets up to 116 degrees here in Redding!! We are lucky to have it 80 degrees in our home, no kidding!!. If you are unhappy, call this tech about it and see what he says. Your indoor coil is fine if you have no ice and I know you keep your filter clean. If you lost a capacitor again, you would have no cooling. Like I say, keep a eye on it, it could be the stat not accurate. Check the supply at the vents and filter to see what you have. If its lower then 18 degrees or higher then 25, you have a problem. If you are in the triple digits, this will cause this. I wish you the best and keep up the good work on that unit! That' great! Please keep me posted and please be kind when rating me as I know you will. Let me know the out come.
Sincerely,
Shastalaker7
A/C, Heating, & Refrigeration Contractor

Try using a garden hose to wash down the condensor coil (the coil that is exposed to the outside air).
During the cooler times when it seems to be working, check the temperature difference of the air coming out against the temperature of the air coming in (room temperature air). The temperature should be approximately 16 to 22degF difference. If you are not getting at least 16degF air, you most likely need to have your unit serviced to see if professionial cleaning or a recharge is needed. If you are getting the temperature difference but not getting the amount of cooling you need during hot weather, it could be a capacity problem. You can perform a quick test by using the calculator on this site:
http://www.goodhousekeeping.com/home/air-conditioner-calculator.

I hope you find this information helpful. Good Luck! :-)

Your temperature control is way out of calibration or, it's wired wrong. Remove it and check it in a glass of water. Use an ohm meter across the heater wires. As you add hot wwater, the heater contacts should open.

HMMM, I am not quite sure exactly what your setup is. My first question is how are you reading humidity and is it accurate. Second if you are maintain 69 degrees, is it hot and humid outside? If your unit is low on charge, the evaporator (indoor) coil will maintain a warmer temp reducing its ability to reduce humidity but if it is hot outside, you would not be keeping at 69 degrees. If this is a new system my best guess is that the system is over sized. I know a lot of people want a big AC unit to cool down quick but if the unit comes on, runs for 2 minutes and shuts off, It is not running long enough to remove any humidity from the air,thus proper sizing is extremely important. Let me know exactly what your situation is and lets see if we can get it fixed.
seth

100 degrees f? That is way too cold Either you have the wrong thermostat or it is wide open. 180 degrees is nominal and give you the best performance.. With AC on, expect 190 to 200 degrees. We are talking farhrnheit and not ccelsius, correct?

Normal operation. If in doubt place a high temp theromoter on range top to see if it exceeds 600-900 degrees
The basic idea is "burn baby, burn!" Self-cleaning ovens use an approximately 900 degrees Fahrenheit (482 degrees Celsius) temperature cycle to burn off spills leftover from baking, without the use of any chemicals. A self-cleaning oven is designed with a mechanical interlock (patented in 1982) to keep the oven door locked and closed during and soon after the high-temperature cleaning cycle, which can be approximately three hours. The door stays locked to prevent burn injuries. You can open the oven door after the oven cools to approximately 600 F (315 C).