Why are some rooms hotter or colder than others?

20 12 2012

Having some rooms hotter or colder than others is a problem that can be found in almost every home.  There are many factors that could be the potential culprit, but the two most common are differing thermal criteria and/or improper system design.

Differing thermal criteria refers to actual construction qualities of a room.  In other words, the surface area of external walls, ceilings, and floors and the insulation values in each.  The size and type of windows and which way the windows face in relation to the sun.  Basically, it is any attribute of a room that can be a source of potential heat loss during winter or heat gain during summer.  If you have a room that has a significantly different thermal criteria than the rest of the house, then that room will need heating and cooling at different times than the rest of the house because it is gaining or losing heat at a different rate.  For instance, bonus rooms over a garage have a different thermal criteria because they have unconditioned space under them.  A sunroom will gain heat quicker during summer because of the amount of windows.  Now, if the thermostat for your system is located within the main body of the house and not in that room, then it will not know that the room needs heating or cooling because where it is located doesn’t need it.  This leads to uncomfortable temperatures in the room in question.  Solutions to fix these types of temperature issues range from installing zoning on your existing heating or cooling system or installing a new, typically much smaller, heating or cooling system just for that room (most common smaller system is a mini-split aka ductless heat pump).

Improper system design also leads to uncomfortable rooms.  This means that your heating or cooling system was not installed correctly to take care of the room.  Improper system design can range from under or oversized systems to the most common which is improperly sized or designed ductwork.  The best way to determine if it is a design aspect is to have a design consultant do a manual-j load calculation on your home (Brady Flanary does not charge for this service).  A design consultant can note the thermal criteria of every room and determine how much air flow every room needs and what size system is the best fit for your home.  Then compare that information to the actual design of what you have now.

So, if you have a problem room, take a look around.  If the culprit isn’t obvious, then give the experts a call.  Just know that there are always solutions to any heating or air conditioning problem.


Let your system Blow!

3 12 2012

Your heating and cooling system is all about air flow.  The systems efficiency, its lifespan, and your homes comfort are dependent on it.  Your heating and cooling system relies on air flow to effectively transfer heat either into your home during winter our out of your home during summer.  If you restrict the air flow then the system can not work correctly.  Here are some common mistakes that homeowners make:

1) Shutting off vents – Do not shut off vents.  Many homeowners will shut vents off to areas of the home that are not commonly used thinking that they are redirecting conditioned air to where it is needed.  In all actuality they are just restricting how much air the system can produce and putting the system under stress.  In addition, those areas that are now not conditioned become additional sources of heat loss and heat gain making the system work even harder to maintain temperature in the home.

2) Forgetting to change the air filter – This is by far the number one cause of system failure.  Every heating and cooling system has an air filter.  Most filters need to be changed every month.  Keeping your air filter clean will extend your system’s life and improve its efficiency.

3) Installing filters in the supply air vents – The only place a filter should be located is in the return air ductwork or on the return air side of the system.  The return side of a system is where the air leaves the home and flows towards the system.  Do not install filter material in the supply air vents (where the warm and cool air comes out).  Here again, these added restrictions make the system work harder.

4) Letting shrubs or debris build up around the outdoor unit – if you are talking about a heat pump or an air conditioning unit then air flow is just as important outside as it is inside.  Just like the indoor portion of your system, the outdoor portion needs proper air flow through it as well.  Make sure to keep all shrubs and debris away from your outdoor unit.  Also make sure not to build fences or walls too close to your outdoor unit.  And finally, it is a good idea to wash your outdoor unit with a hose.  Do not use high pressure water.  A simple garden hose will do.  The object is to rinse off the coil of the outdoor unit.

The easiest way to understand the importance of proper air flow is to think of your furnace or air conditioning system as your heart and your ductwork and vents as your veins.  If your veins clog then you will have a heart attack.  Same principle with your heating and cooling system, if you block air flow then the system will be under stress and eventually will give out.