Heat pumps vs electric oil burners

Q We have the original oil furnace in our 29 year old home. It is hooked up to a tankless water heater and provides all the hot water in the house, including domestic hot water and our baseboard heaters. Our home is approximately 2000 square feet, a traditional Colonial center-hall. Every year when we have the furnace serviced/cleaned, the oil company assures us that the furnace is in good condition and shows no signs of dying soon. However, partly for environmental reasons and partly to avoid being suddenly left without an oven in Massachusetts in January, we think the time has come for a replacement. Our neighborhood has no gas lines. Would it be crazy to replace the oil burner with an electric one and an electric tankless water heater? We have a solar panel on the south side of our roof. In 2021, it produced an average of 18.8 kilowatt hours per day. (In January it averaged around 11; in June, 25.) We love our hot water baseboard heater and have no desire to replace it with a heat pump for various reasons.

SS

A. Although I believe they exist, no one I know has ever installed an electric boiler to heat water for a baseboard heating system. I understand this would be incredibly expensive and you might have problems getting and keeping the water hot enough for baseboard heating. You need an open flame to bring the baseboard heat pipes to 180-190 degrees.

Although you mention that you are not interested in heat pumps, you would certainly be interested in installing them as well as an on-demand water heater. Your current system is about as inefficient as it gets, and with your solar panels helping to reduce electricity costs, you’re a good candidate for heat pumps. The average kilowatt hours per day generated by your solar panels is roughly what the typical New England home uses, so a new electric heat pump and hot water system would consume more than the panels produce . Your electricity bill will definitely increase.

You might consider renting from a solar cooperative; increased demand is allowing more solar farms to be built across the state. With more solar farms powering the Massachusetts grid, we’re reducing our state’s carbon footprint – a win for all of us.

Be aware that if you install a water heater on demand and heat pumps, you can keep your existing boiler to use it sparingly or during prolonged cold snaps as a backup heating system. This will significantly reduce your carbon footprint. The state offers incentives and interest-free loans for the installation of heat pumps.

Q I read your response in the Oct 30 Globe regarding what to do with a dirt basement/crawl space (“Ask the Renovator: Why You Should Choose Only Certified Recycled Products for Your Renovation”) . I laid several millimeters of plastic vapor barrier over my sand/dirt crawl space and ran a dehumidifier, set to 60%. However, the space is not 100% airtight; there are spaces where the vapor barrier meets the walls. I have my pulsed hot water boiler and my hot water storage tank in the crawl space and the necessary plumbing, of course. I thought about pumping in concrete (could be expensive for a 25ft by 30ft footprint), but was concerned about the curing process and the large amount of water vapor it emits. Is this a valid concern?

DS, Newbury

A. Looks like you did your best with the plastic vapor barrier and dehumidification. These will certainly help, but moisture will still seep in around the perimeter. If you were to place a 6 millimeter vapor barrier under a new pour of concrete, this would be ideal for a utility space. The gains you would make in moisture control would far outweigh any short-term introduction of additional moisture as the concrete hardens. If possible, ventilate the space, use fans to ensure air circulation, and keep this dehumidifier running.

Mark Philben is Project Development Manager at Charlie Allen Renovations in Cambridge. Send your questions to [email protected]. Questions are subject to change.