Thursday, February 23, 2012

House of Many Windows

So how has our House of Many Windows fared so far this winter?

On average, when the sun shines brightly, afternoon temperatures reach 71-72 °F, and on cloudy and rainy days, they reach 68-69 °F. At night the temperature rarely drops to 65 °F and never below that, and the lowest temperature we've seen all winter was 63 °F at 10 p.m. on a cold, snowy December 24, just as we entered the house after two weeks in sunny, warm California.

These temperatures feel much more comfortable than the low 60's °F we kept in our previous house to save natural gas. And the tile floors are surprising. Most of the time we are comfortable in stocking feet.

When the sun shines brightly, even on the coldest days, we may not build a fire in the masonry stove. And other times we fire it up once and a few times twice a day, early morning and evening. The stove raises the house temperature only one or two °F, but that has been sufficient.

And this is without our PAHS heat exchanger air handling system hooked up! The house has four upper 6-inch diameter tubes running from the ceiling to a 4-foot square pit under the garage floor and four more lower 6-inch diameter tubes exiting at floor level through the back walls and also running to the pit. Two sets of four-each, 6-inch diameter tubes, upper and lower, then run from the pit to two small exterior structures where incoming air will be filtered. Right now nothing else is installed in the pit, so the incoming and outgoing air that should be split between the upper and lower tubes in heat-exchanger fashion just mixes together in the pit, and no heat exchanging takes place. We plugged the four upper tubes from the house to avoid losing too much heat into the ground, and the lower tubes were left open to bring in fresh air. The air entering through the lower tubes is around 60-62 °F, which probably accounts for some of the temperature drop at night.

A sufficient amount of air enters through the lower tubes to keep the house fresh at all times.  The masonry stove draws its combustion air directly from the entry room, creating a slight vacuum throughout the house that brings in even more fresh, invigorating air through the lower tubes. Humidity levels have remained nearly constant the past few months at slightly below 50%. When showering, we save electricity and add some moisture by not running the exhaust fans.

The masonry stove sits right next to the back wall in the entry room, and some of its heat travels into the soil under the floor and behind the wall. The eight tubes to the house pass right next to this wall at floor level and pick up some of this heat. Thus running the stove may temper the incoming air a little.

Insulated drapes also help our House of Many Windows. We fabricated R-7 Warm Window Insulated Drapes for the six large window sets and the patio door. The transom windows do not have drapes. The insulated drapes significantly reduce radiated heat-loss after the sun goes down and on cloudy, rainy days. It is significantly more comfortable sitting near the windows at night with the shades drawn. However, we almost always keep them open during the day, rain or shine, because we love their east and south views.

Our house and garage has seven smoke and carbon monoxide detectors connected to a common grid. That's right, seven! And when one goes off they all go off! I recently visited the "My Masonry Heater and Others" website at On that webpage the author writes, and I quote, f). This shocked me and shocks everyone when they first hear it, but I'm completely comfortable with it now. The kit came with a door for the TOP of the chimney. A long wire goes down through the chimney, out a tiny hole. You open the door with the wire just before you build a fire. Then you close the door after the fire has burned down to charcoal but before the charcoal has burned out. I had a carbon monoxide alarm and fretted about it at first, but no more. This is not a coal stove and it does not seem to generate significant amounts of CO

Well, our masonry stove is the same brand as the author's and has a chimney damper and a CO alarm mounted on the ceiling just a few feet away. And when I took the author's advice and closed the damper before the charcoal has burned out, the seven CO alarms complained loudly and loudly in unison for several minutes after I'd run through the house, opening nearly twenty windows and doors, canceling any heat-loss savings I might have had from closing the damper before the charcoal has burned out. Don't do it! CO is too dangerous, and the stove masons know what they are talking about. The fire must be completely out before closing the chimney damper! I found that closing the damper with even a handful or so of live coals would set off the CO alarms. Since I have to believe that our new CO alarms are working correctly, and I don't want to find out what too much CO could do to us, I will close the chimney damper down to a two-inch crack or so and let the hot coals take another couple hours or more to burn completely out. This might waste a little more heat, but we have more honey locust and hedge trees than we can burn in our lifetimes.

Here are a few other lessons I've learned and should have known before building this house. The masonry stove should have been more centrally located in the house for better heat distribution. It is located in the entry room between the garage and house. This location is convenient, because we store the wood in the garage and move it to the stove without tracking through the house. On the positive side, we like lounging in the warm and comfortable entry room next to the masonry stove with its full view into the the sun room, especially at night with the overhead lights out in the entry room, but on in the sun room. Also the rising moon's halo when shining in through the east-facing sunroom roof with all the lights are off is quite fascinating.

A plenum is located next to the wall and above the ceiling between the entry room and house, close to the masonry stove, but not directly in line it. A fan in the plenum draws in heated air rising from the stove and distributes it through ductwork running above the ceiling the full length of the house. The air exits into all rooms through openings at ceiling level. The problem is, warm air rises, so the stratosphere is extra warm, while air around us land lubbers is not. I should have directed the air down through the walls to floor level, but doing that will now take some major surgery and won't happen any time soon unless we really need to feel the heat.

I placed a thermometer next to the plenum and noted that the air entering it ranges from about 75-85 °F after the stove has been fired and burned down to coals. That air is just warm and not hot as would be coming from a furnace, so the plenum fan must run for twelve hours or more to move the warm air as it is slowly released from the stove. Furthermore, some of the heat released from the stove is absorbed by the brick and concrete walls just two inches away from its back side and flows into the soil outside. I use a fan to blow air through the opening behind the stove and move some of the heat toward the plenum before it can flow into the ground.