Getting a Solar Array is Easy. Getting Rid of Oil-fired Heating Systems is a Challenge
The 20kW solar array, which is located up hill and invisible from the house, will provide the electricity needed for the new electricity-driven heating system which will replace oil heat. (Images: Oliver Ames)
Eve Endicott
When I saw the place my sons chose for a family compound in southern Vermont, replacing one owned farther north, I worried about how they would afford to pay for heat on top of the high taxes. Environmentally conscious and spurred by the declining federal tax credit, I hoped the property’s two aging oil tanks could be replaced with solar. The purchase-and-sale agreement was written to allow for an assessment of the property’s solar potential, which was quickly performed by Southern Vermont Solar (SVS). A few months later, SVS had installed a 52 panel, 20kW, ground-mounted array high on a hill behind the house, out of sight, hooked up by wiring in a long, deep, invisible trench.
It turned out that getting the solar array up and running was the easy part. Converting the heating systems to run on electricity was more challenging. The larger, older house promised to be straightforward. A mini-split heat pump for the semi-detached playroom and a ducted heat pump for the forced hot-air system in the rest of the house, would afford both heat and (rarely needed) cooling. Both heat pumps qualified for rebates from the state.
A compact Envi 450-watt heater in the bathroom and basement keeps pipes warm.
The small, modern guest cottage on the property was more difficult. It had a combination of radiant heat and radiators, with a boiler that also heated the domestic hot water, thus burning oil year-round. Being new to the area, I reached out for suggestions of contractors. One highly recommended company’s representative personified man-splaining. I told him we wanted a small system in the cottage, which we expected to use intermittently, relying largely on a woodstove when people were there and small electric heaters to warm pipes when they weren’t. The contractor came back with a proposal for a huge air-to-water heat pump and separate hot water heater that would cost over $50,000, warning me that I would be ‘liable’ in any future sale if we undersized the system. Fortunately, I knew that was nonsense. A subsequent bid from a different contractor for a similar system came in at half that amount. Buyer beware.
With the cost for an air-to-water heat pump for the cottage still high, however, but the oil tank in the cottage almost empty and ready for removal, the immediate need was to heat domestic hot water. We embarked on a long and frustrating assessment of heat pump hot water heaters. Their tanks were too tall for the cottage’s low-ceilinged basement. An enclosure in the garage would be needed. Everyone (plumbers and Efficiency Vermont) had a different opinion about the necessary size of such an enclosure, from 4 feet x 4 feet to 10 feet x 10 feet or larger. Whatever size it was, it would be expensive, and the heat pump would generate cold air that would need venting. Finally, we wanted to be able to turn the heat pump on and off remotely, so as not to heat water when it wasn’t needed while having it hot when guests arrived, but our new contractor didn’t use the “smart” heat pumps.
Finally, I had a brainstorm. What about an electric, on-demand system? The contractor was dubious that there was enough ‘juice’ in our already almost-full electric panel. “How much would we need,” I asked? Answer: at least 50 amps for the shower and sink in the main bathroom, 50 for the kitchen sink, 25 for the second bathroom sink, and more for the laundry and dishwasher – over 150 amps! Why, I wondered, would we need to be running the washing machine or dishwasher at the same time as the shower – or for that matter, running three sinks simultaneously? And weren’t we supposed to be washing clothes in cold water now? Ultimately, the family installed a very affordable 80-amp system and it works just fine. The fact that it only runs when people need it suits the intermittent needs of a guest cottage perfectly, with the bonus that, if guests are numerous or showers are long, no one ever runs out of hot water.
Replacing the previously oil-fired hydronic heating system in the cottage with one that can use the solar-generated energy is more of a challenge. For the moment, the woodstove and two or three oil-filled space heaters do the job when people are there. When they aren’t, a small, wall-mounted, quiet Envi heater in the bath/laundry room and another one in the basement keep those rooms and the pipes warm even in the dead of winter, using only 450 watts each.
There is probably an air-to-water heat pump in our future, especially if the cost comes down and the state continues to offer a significant rebate. One issue is that some rooms in the cottage get very hot in summer, and air-to-water systems don’t really offer cooling, unlike air-to-air systems. That may change with new technology.
Meanwhile, the family will be saying goodbye to oil at last, trying to do our part to help fight climate change!
Eve Endicott is a regular reader of G.E.T.whose family’s home is in Brookline, Vermont. She has enjoyed a 45-year career in land conservation and still volunteers for land trusts.
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