Monday, February 4, 2008

Heating a Home

Heating Systems

All too many times I have seen heating systems that have been designed for homes more as an after thought than taking center stage as they should in cold climates. Way too often heating costs are much higher than they should be simply because the system was not well thought out. In today’s world of escalating energy costs before the ink hits the paper for the building prints you should have a good idea of how you are going to heat your home. By preplanning how you are going to heat, the house can be built in such a way that you are not only going to save on your heating bills, but the house is going to be comfortably warm too.

Keep in mind that heat is transferred in three ways, Convection, Conduction and Radiation. All of us are familiar with Convection and know that hot air rises. We also know that different materials conduct heat at different rates. However, many of us find that the movement of heat by radiation can be bit puzzling even though we experience it everyday when we feel the warmth of the sun.

By thinking about how heat is transferred and remembering that heat moves from warm to cold we can build a home that is not only comfortable but economical to heat. The fact that Pan Abode Homes are made of wood helps us in our quest for comfortable inexpensive heat. This is because wood has a low *U-factor. In other words wood does a good job of not conducting heat away from where we want it even though it has a relatively low R-value. Additionally the thermal mass of wood will help keep temperatures uniform within the living quarters through a 24 hour day by slowly absorbing and then releasing heat.

If we build the ceilings of our homes relatively airtight we can assure that the transfer of heat via convection will not rob our homes of the *BTU’s that we have generated to heat the home. If we not only insulate well but use materials such as wood that have low conductivity rates this too will help insure we keep the warm air where we want it. The same is true of our floors; lower conductive materials will help keep our home warm.

Now to that mysterious heat; radiation. Radiant heat is a form of energy that travels via electromagnetic waves. These waves do not heat the air they travel through. They release there energy when they hit an object, like people, furniture, floors and walls. In turn those objects release some of that energy in the form of convection or conductive heat. By properly placing windows we can gain significant heat in our homes via solar radiation. If those homes contain large masses of materials such as wood that have a low conductivity rates then the energy is stored for later use. If we then combing in floor radiant heat which works much the same as the radiant heat from the sun we can insure economical, comfortable heat all the time. By heating a surface such as the floor of the home heat is transferred via radiation until it hits another object. This is why people often feel warmer in a home with radiant heat even though the air temperature is cooler than in a home with other forms of heat.

As you can more than likely tell I’m a fan of in floor radiant heating. I’m certainly not a heating expert, but even with my limited knowledge I could nearly write a book on all the attributes of radiant heat. In my own Post and Beam Pan Abode Home, a custom Pan Abode Homes Cutter Design we used Warmboard to hold the PEX tubing for the in floor heating. Of course the design team at Pan Abode did a great job of working with us to insure that the Warmboard worked for our application. Since we were building in Southeast Alaska we knew we would be working in some very tough conditions so we elected not to install the Warmboard until the house was weathered in. This meant that all the rough openings for doors, ceiling heights and so forth had to be part of the design.

Now that we have been heating with the radiant heat for about a year I’m even more pleased with it than I thought I would be. I had read several times that ceiling fans were not necessary with radiant heated homes because there is not much heat loss via convection currents. I found this hard to believe so a ceiling fan was installed in our cathedral ceiling home because I was sure the 2nd floor would be roasting without it. Man was I wrong, as there is truly little to no temperature rise from the 1st to the 2nd floor. I find the only time the fan gets any use is when my grandson are visiting and that is because little kids find that turning off and on a ceiling fan is fun. So far the only problem we have had with the radiant heat is the fact that some of the zones don’t turn on very often because the woodstove more than heats the main living areas. And, because the house has a tight ceiling, convection currents of warm air rising don’t have anywhere to escape so even with the woodstove on, the 2nd floor is seldom much hotter than the 1st floor.

For anyone who is reading this and wants to know how a single 50 gallon hot water heater supplies the BTU’s for the in floor heat please e-mail me. I can be reached at southeastcedarhomes@gmail.com. I’d be happy to pass on what I learned designing and putting together our heating system. You can also see photos at this link: Heating System

* U-factor is a measurement of the ability of materials to conduct heat. The lower the conductance the lower the U-factor.
*1 BTU or British Thermal Unit = 1 degree Fahrenheit raise in temperature of one pound of water. Or about the equivalent of burning one wood match.

2 comments:

Mary said...

Marcel,

The information about the way our homes are heated is interesting and informative. I enjoyed reading it.

Blessings,
Mary

Tracey Pullman said...

You may have one of the many types of heating systems that you will be needing in your home.