With Temperatures Rising, Homeowners Without Air Conditioning Are Asking What’s the Best Way to Add It

A lot depends on whether your home has heating ducts that could also deliver cooling.

I have a listing coming up later this summer in the Beverly Heights section of Golden. It has hot water baseboard heating, which is wonderful, but that means there are no ducts to distribute air for cooling.

Homes with forced air heating systems have it easy. A “chiller” connected to an outdoor A/C compressor can be mounted above the furnace’s firebox for a few thousand dollars. It uses the same ducts as the furnace, and the forced air unit becomes an “air handler” for delivering the cooled air.

I have previously promoted the idea of using a heat pump to drive that “chiller” unit. Not only does it provide needed cooling, but the heat pump can also provide efficient heating in the winter, leaving the gas furnace idle or used only when it’s colder than the heat pump can handle (below 0º F with today’s cold-climate heat pumps).

But what if there are no ducts, as in my listing in Beverly Heights?

The answer depends partly on the style of the house. Is it one-story, two-story, or split-level? The one-story home is easiest to accommodate with a ductless solution. An A/C compressor can be mounted on the roof, with an air handler in the attic below it. From there, flexible round ducts (not rectangular metal ducts) can direct that air to ceiling vents in the living area and the separate bedrooms, with a return air vent somewhere in between, such as in the ceiling of a hallway.

Alternatively (my preference), a ground-mounted heat pump compressor can be positioned on an unobtrusive side of the house, with two hoses going to each of up to five wall-mounted “mini splits” in those same rooms. The hoses are hidden in square conduits, usually white, measuring 3 or 4 inches square, running around the house at ground level and then up the exterior walls to where the inside mini-split units are located.

I was fortunate to have a flat roof on my former office building, and I was able to put the compressor on the roof and run the two hoses to three different mini-splits entirely on the roof, eliminating visible conduits as well as that ground-mounted compressor.

The conduits don’t have to be run outside, and the mini-splits don’t have to be on an exterior wall. If you visit the Golden Diner at 11th & Jackson in downtown Golden, look for the mini-split on the wall between the kitchen and the serving area.

In a two-story or split-level home, a roof-mounted compressor with an air handler in the attic becomes less optimal. However, it can still work. Cold air pumped into the top level can settle downward, cooling lower levels. An evaporative cooler (aka “swamp cooler”) can work even better, because you can control where the cold air goes by which windows you open. That’s because there is no “return air” with a swamp cooler. The swamp cooler blows outside air into the house, and you must provide ways for that air to escape.

If you’re new to Colorado and came here from a locale with high summer humidity (Brooklyn, in my case), you may not be familiar with evaporative cooling. It works in the same way that a rain shower works. As the rain falls, some of it evaporates, thereby cooling the outside air. In a swamp cooler, a water pump circulates a reservoir of water through membranes on the sides of the unit. A squirrel fan draws outside air through those water-soaked membranes, cooling the air by 10 or more degrees and blows that cooled air into the home. The lower the outdoor humidity and the faster the fan, the more cooling you get.

But that air has to escape, and it will travel through your home based on where there’s an open window. Four inches is the prescribed size of window openings, and you can secure your window so an intruder cannot open it further.

The downside of the swamp cooler is that it requires occasional service, and if the unit is on the roof, that can be difficult or dangerous. The water in the reservoir, which is replenished constantly by a 1/4-inch cold-water pipe from inside your home, becomes dirty over time because of the soot that is being removed from the outside air by the water-soaked membranes through which the air is being pumped. At the end of each cooling season and a couple times during the season, that water needs to be drained, and the membranes rinsed clean or replaced and the reservoir cleaned. At the end of the season, the reservoir and the supply pipe need to be drained to avoid freezing.

A heat-pump system with up to five min-split wall units can work fine on a 2-story or split-level home. The conduits from the compressor to the wall units just have to run further up the outside of the house. Below is a picture of such a compressor with four wall units, each with its own thermostat. That’s the best thing about such a system. You could have the mini-split in your bedroom set at 70 degrees overnight and the other wall units off or set higher. This is far more efficient than cooling your entire house when you go to bed, whatever system you are using.

On our website, www.GoldenRealEstate.com, under the Resources>Service Providers tab, you’ll find three vendors of heat pumps (and regular furnaces) under “Heating & Air Conditioning/HVAC.”