Low Load Heating and Cooling Systems

hydronic air handlerMany people who are building homes throughout the country are talking about low load heating and cooling systems.  The discussion centers around how difficult it is to achieve a good low load heating and cooling system.  We have found through designing systems and testing them in a variety of California climates that most homes in California would be considered low heating load houses by national standards.  That's probably not surprising.   What is surprising is that the typical heating equipment installed in California is often bigger than the average sized heating equipment installed in new homes in Minneapolis, Minnesota.  Even poorly insulated homes in the foothills of the Sierras often only require 30,000 Btu/hr on the coldest day of the year.  With air sealing attics, crawl spaces and ductwork and insulation improvements these homes can drop to 18,000 Btu/hr or less on the coldest days of the year.  So low load heating and cooling systems should be the norm in California, yet the industry norm is to install 80-100,000 Btu/hr gas furnaces.  We have spent a lot of time testing homes and find that most of the heating systems installed are only getting a fraction of the energy into the house, most of it lost through leakage and conduction of ductwork located in the attic or crawlspace.  That's an expensive way to make a low load heating system. 

We agree that it's harder to design and commission a low load heating system, you have to be more confident in your designs, and that type of confidence only comes from testing the systems you install, and monitoring them under a variety of building loads.  We have come up with heating and cooling strategies that match our building stock and climate.   Whether you are building a zero net energy house or a passive house we can design a system to meet the low loads of the house.  Even if you live in a normal California house we can help.   We figure that the heating and cooling system of a house has two jobs, first is to keep the home comfortable, otherwise we wouldn't install it, second is to operate at the lowest possible energy consumption, otherwise we might be afraid to us it.