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Comfort engineering

To kill time during layovers on our recent trip, I read Bill Bryson’s fact-filled exploration of human health and comfort, “At Home“. In the book, Mr. Bryson emphasizes how many of the technologies in our homes are brand new relative to the length of time that mankind has roamed the Earth. For 99% of our history there was no plumbing, no electricity, and certainly no air conditioning.

Consider our home, “only” 259 years old. If I was able to transport back in time and explain to the house’s first owner that one day a device on the wall would allow him to regulate the indoor temperature to a specified degree year-round, he would surely declare me mad and have me committed to the loony bin.

So, in a strange way I’m slightly ashamed to be the one to install central heat and air-conditioning in William Reed’s Ordinary. Even during our grandparents’ lifetimes, it wasn’t a technology that was universally attainable or expected. All the former owners of our house lived without it. In the summer, porches, shade trees and a languid pace made life tolerable. In the winter, fires, extra layers of clothing, and thick blankets offset the chill. When it comes right down to it, living several months without heat wasn’t THAT bad. It was frequently uncomfortable, but life carried on normally, just with thick sweaters on. A colleague of mine once asked his grandmother how folks got along before air-conditioning. Her response: “In the summer, people were hot.” As a society, we could benefit from stepping back to appreciate the everyday luxuries that we take for granted.

I was determined not to let the urgency of our discomfort negatively impact the quality of the HVAC installation. On a job site, the mechanical guys are the ones that cut the big holes, and there’s no end to the devastation they could unleash on a house of this vintage if left unsupervised. I gathered three estimates and selected Newcomb and Company of Raleigh based largely on their reputation and their willingness to think things through before being awarded the job.

There were two simple rules I established for the system’s installation:

1) No ducts can cross the basement – this room has a storied past as a tavern, a happy future as my man cave/grog hall and ceiling beams way too low for any big pipes to run below them.

2) Aside from tactfully placed condensor units and air grilles, the installation should be invisible, with no awkward protuberances in the corners of rooms that betray a lack of planning or forethought.

Fortunately, our estimator listened to these concerns, worked with me to develop a plan that addressed them and assembled a crew that was capable of following through once we pulled the trigger.

A modern heating and cooling system requires an impressive network of connections to bring it to life: supply and return air ducts, a power line, a gas line, a combustion air intake, an exhaust air outlet, a condensate drain, an overflow condensate drain, a condensate pump, a refrigerant line and a low-voltage wire to the thermostat. So even though the indoor units are the size of a large suitcase, the spaghetti of pipes, wires and hoses that surround them eats up a lot of space.

furnace

The Ordinary House is spread out over no fewer than five floor levels. Because of this, we ended up with three separate HVAC systems, with 6.5 tons of cooling capacity and 180,000 btu’s of heating. There were several situations where it simply wouldn’t have been possible to run a duct from point A to point B. So, we ended up with one system for the library, one for the main floor, and one for the upstairs. This setup has two built-in advantages. First, we’ll never be without heat because of a mechanical failure again. If one system goes belly up, there are two more to keep us warm. And second, three systems = built-in zoning. By programming the thermostats to reflect our daily schedule, I can be sure that we’re only paying to heat and cool the parts of the house that we’re actively using.

Based on the amused expression that spread across the HVAC contractor’s face at the mere mention of the words “heat pump” (he likened our house’s walls to the bottom of a colander), we opted for high-efficiency gas furnaces to provide heat. These units run at 96% efficiency, extracting residual heat from their own exhaust, and squeezing 96 cents worth of hot air out of every dollar we spend on natural gas (recall that our boiler was probably running at only half this efficiency). Additionally, the furnaces are two-stage, meaning that they can run in a “low” stage the majority of the time, saving fuel, decreasing wear on the equipment, and preventing too-quick temperature swings.

The air conditioning units are also two-stage. On low, the systems have long, low-speed cooling cycles that are extremely energy efficient. If the units reach their set temperature but detect high humidity levels, they activate a dehumidification mode, running the blower fans at imperceptible speeds, edging the humidity down without over-cooling the house. The swamp-like conditions of the past few weeks have given this feature a workout.

All three systems have 4″ thick pleated media filters that are more effective at scrubbing the air than standard filters. With 200 years of dust floating around, they’ll certainly be busy.

The thermostats that control these systems are fairly simple to use, but employ all sorts of fancy algorithms to determine run times and optimize efficiencies. Given the challenges of regulating temperatures in a leaky old house, the ‘stats have done a remarkable job of maintaining a steady, comfortable temperature without overworking the equipment. Heating or cooling, the systems run in low speed most of the time, which becomes obvious when the energy bills show up in the mail.  Our natural gas bill was halved compared to when we were running the boiler, and it was only heating half the house due to a malfunctioning circulation pump.

The upstairs unit is in the attic, where the temperatures are less than ideal for cooling equipment in the summer. But the steep pitch on the roof makes access a breeze and we were able to run ducts to all the upstairs rooms without any difficulty.  The return grille sits inconspicuously in the ceiling of the hall outside our master bedroom. To get the gas line, refrigerant line and condensate drain to the attic, I bought some extra lengths of downspout from my gutter man and had them disguise the pipes and hoses in it where they run up the side of the house.

downspout for gas line

The downspout butts into the underside of the soffit, and opens directly into the attic. From the street, you’d never know that the downspout isn’t integral to the gutter system. We were fortunate to be able to reuse the electrical circuit from the old attic fan to power the unit. Otherwise, we might have had to tear off plaster to fish a wire from the basement to the attic.

The main downstairs unit is in the old boiler room, consolidated to a corner that I’ll one day enclose as a utility room. Because the crawlspace under the kitchen is all of 12″ tall, we supplied the air to this room through the risers of the stairs that lead to the dining room.

stair supply grilles

Finding a way to return the air for this system was tricky. In the end, I elected to bring it through one of the wainscot panels in the living room. On the other side of the wall, a metal box punches through the floor to the crawlspace below.

return box

When we relocate the kitchen to this room, I plan to hide the box in a base cabinet. Since the return is in a visible location in the living room, we invested in a decorative cast aluminum cover that’s pleasing to the eye. When the grille gets painted, it’ll look tailor-made for the spot.

return grille

The library unit lives in the crawlspace below that room. It has a return grille that punches through the wall of the closet beneath the stairs to the slave quarters.

library return

The same closet provides a home for a supply duct and the electrical lines running between the new electrical panel and the air-conditioning units.

So far, all three systems have heated and cooled flawlessly. The equipment seems to be sized correctly, with no short-cycling or struggling to meet set points. Our energy bills are reasonable for a house of this vintage, and best of all, we’re completely comfortable. The install was enormously expensive, a total pain the ass, and absolutely worth it. Despite the stress, I’m glad I was the one to introduce central air to the Ordinary House. With any luck, our new systems will keep us comfortable for several decades until the next wave of mechanical technology comes along. Whatever that may be, I just hope it requires smaller holes.

Anybody need five window units?

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9 Comments Post a comment
  1. Weezie #

    Actually, it was pretty bad there in January, and there was one weekend when I was ready to move to a dog-friendly hotel and put a for-sale sign in the front yard. The hotel was booked (I looked), and we toughed it out. Even for a few weeks after we got heat, we both still cringed when walking into the downstairs bathroom because it had been about the same temperature as the inside of our fridge for the TWELVE WEEKS FROM THANKSGIVING TO MID-FEBRUARY that we didn’t have heat (I counted). It was worth it in the end, and that bathroom became nice and warm. Reid did such a good job planning and managing the installation that is was much less of a headache than it could have been, and he couldn’t have done a better job figuring out how to make the vents as unobtrusive as possible. I’m glad I hired him.

    June 12, 2013
  2. Leslie #

    While I’m all about preservation and restoration, I am also a HUGE fan of AC and heat!

    June 13, 2013
    • jrh #

      Likewise! One of the points I’m hoping to get across with this post they don’t have to be mutually exclusive.

      June 18, 2013
  3. Leslie #

    Remember Mike Mulligan and the Steam Shovel? That’s what the AC unit reminds me of!

    June 13, 2013
    • jrh #

      I can see the resemblance…

      June 18, 2013
  4. Cat #

    Please tell me where you purchased the return bents used on the stair risers!!! Thank you.

    January 25, 2016
    • jrh #

      The vent covers in the stair risers were provided by the HVAC installation crew. They’re nothing special, just standard 2 1/4″ x 10″ grilles.

      January 25, 2016

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