In Dec 07 I had a complete Carrier AC/Gas Heating System installed in my home to replace my original system when my house was built in 1983.We upgraded the new system to 3-TON AC as the old AC was 2 and half ton. Since the new system was installed in the winter time it was not until the hot weather started in May that a problem arose. The first conclusion of the problem was that the coil was aligne incorrect the second was that we needed more air return so an addition vent was added. Now the third conclusion is that when we went from 2and half ton AC to 3 tons that my old duct system is not able to carry the addition output by the 3-ton unit. IS THIS CORRECT THAT I NEED TO HAVE A NEW DUCT SYSTEM INSTALLED. AS THE HEAT BUILDS UP INSIDE THE HOUSE AND INSIDE TEMP. GOES UP THE AC RUNS ALL THE TIME AND CANNOT CATCH WITH THE DESIRED TEMP- for example if we put a temp of 72, and inside temp goes up to 78, the unit cannot catch up and runs continously. IT IS NOT UNTIL THE EVENING HOURS THAT THE TEMPS EQUAL.

Ultra high efficiency boilers have become one of the best buys in home heating. These high efficiency boilers have changed dramatically from the first pulse boilers that I had the privilege of installing twenty years ago. Today’s condensing boilers are much more reliable and will not shake and rattle the windows of your house like those old beasts did.

If you are looking to purchase or install a new boiler for your new or existing heating system then you need to look a condensing boiler to heat your home with. In the past twenty years the condensing gas boiler has evolved to be a reliable, very efficient way to heat your home.

Radiant heating systems with the right design feature can easily heat your home at temperatures that use just warm water. At these temperatures the water is pulling the exhaust temperature of the boiler to very low points. This gives you extremely efficient boiler operation.
The boilers of today are made to operate continually at temperatures of 100F or less. At these temperatures it is not uncommon to have the combustion analyzer give me readings of 98-99 % efficiency. To get these types of readings and still heat your home the heating system has to be designed to work at these temperatures.

The right condensing gas boiler coupled with the right heat transfer system to get the heat into your home the right way will give you the most efficient heating system possible with today’s technologies.

Do a bit of research and find a heating contractor that knows exactly how to install a condensing boiler with a radiant heating system properly. For your radiant heating system to perform well at these temperatures, your boiler will need to be installed in exactly the right way. There is not a lot of room for error when designing very high efficiency heating systems. To wring every BTU of heat out of the fuel that is being burnt means that you are also on the ragged edge of supplying just enough heat to the building to over come the heat loss of the building at any given time.
http://www.fixya.com/support/r3706364-gas_boiler_condensing_best_features

http://www.fixya.com/support/r3597748-the_extra_benefit_of_a_modulating_boiler

http://www.fixya.com/support/r3583943-condensing_gas_boilers__the_best_radiant