Archive for June 23, 2010

Electric Heat and Preparations

I can’t believe it, but in just two days, we’ll be on our way to Bilbao, Spain for a month of adventure.  In the few days we’ve been back in our home since our trip Back East, I haven’t had much time to add posts about K&J’s house, perhaps I’ll have more time after we settle in.

Until then, here’s a quick post about K&J’s innovative heating system.

Central PA is a challenging place to keep warm. The winters are dreary at times (although winter sun is not all that unusual) and it can get mighty cold.  I recall a February morning when the temp was -19 F (!)  It doesn’t usually get that cold, but it dips below freezing sometime in December and doesn’t come up for more than an hour or two till March.

Combine that with a region where natural gas distribution is spotty at best and you’ve got a prescription for very high heating bills.  Here are the typical options:

Biomass:  OK, that’s just a fancy name for wood fires, but it’s the option of choice for most folks who are out of the towns and in the woods.  Trees are a plentiful and renewable resource. Most of the tree-covered hill sides in the region have been clear cut at least twice since the colonial days.  This region has a rich history in the early iron smelting days and wood (charcoal) was the only fuel for the process.  Today, wood stoves are common and are often used to supplement other heating systems.  There’s a downside, of course. I remember driving to the child care provider on cold still mornings and seeing the uniform blue haze settled in over the valleys.  Modern high-efficiency stoves help alleviate this, but it’s naive to think that this is an energy source with low environmental impact.

Propane:  There’s a delivery infrastructure that you can use to refill your local propane supply and use a force-air gas furnace, but that’s pricey.  Winter bills in excess of $1,000 would not be uncommon.

Electric/Baseboard:  This method uses a larger electric water heater (often sharing the task with the domestic hot water appliance) and uses the water to carry heat to radiators in every room.  These systems have come a long way since the clanking radiator and can be finely controlled, but electric is still a tough way to make heat.

Electric/Heat Pump:  This is what we had when we lived there.  Just a big central AC unit that can run both ways.  In the summer you extract heat from the air in the house and reject it to the outside.  In the winter, you extract heat from the outside air and move it into the house.  While the engineering principles are sound, practical limitations always get in the way.  You’re always pushing heat up hill, rejecting it to humid 95 degree air in the summer (which means the coils have to be much hotter) and trying to collect it from bone dry 10 degree F air in the winter (again, the outside coils must be colder than the air to move the heat that way.  Our own experience was that the ehat pump worked fine for about 90% of time when the outside air was between 20 and 90 degrees F.  Any colder and the supplemental duct heaters kicked in (image a 2 kW toaster in your furnace ducts).  Any hotter and, well, you just moved slower and spent more time in the basement.

Solar Heat:  In temperate and cold climates, solar heaters are engineered frames that are glazed and sealed from the outside air to prevent convective losses.  Inside, water is heated by the solar radiation that penetrates the glazing and the hot water can be used for domestic hot water and space heating.  More on this later.

Solar Thermal Panels

Variations and combinations:  This is what or friends did.  You can avoid the shortcomings of heat pumps by exchanging heat with ground water.  in this case, your always conducting heat downhill and the efficiency skyrockets.  Combine this with a couple high-efficiency wood stoves and some solar heaters and you’ve got a system that incorporates the best features of each technology but with none of the shortcomings.

More on that later.

June 23, 2010 at 11:25 pm Leave a comment

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