Thank you, what a huge benefit to all of us to have Lincoln's CREE group- a wonderful resource for us non-technical older folks
Yes, it is true Mitsubishi’s new inverter-driven compressors (cold temperature HVACs) are an engineering marvel. Their low temperature models even perform much better at high temps than conventional HVACs, and even many stand alone AC units. Mitsubishi does though obfuscate their efficiency numbers by using this vague COP metric and then give a multiplier in their engineering manuals in a different section, and never ever give the normal efficiency curves for this type of equipment. And it appears they are intentionally trying to hide the kWh (kilowatt hours- this is half of the charges on your Eversource bill the other half is a "delivery charge") to BTU (British thermal Units or "therms") efficiencies Mainly, I am most concerned about the unreliable and inefficient Lincoln electricity distribution system. If there is a power outage in a storm no matter how efficient the HVAC is, there is no heat produced. In this last storm one of the Hive stated they had no electricity for 28 hours and it was not even a big storm. The advantages of gas-fired home furnaces are they are generally not subject to distribution disruption and have a 98% conversion from natural gas to BTUs. That compares with modern gas-fired CCGT electricity power plants which run at best a 62% gas to kWh conversion rate and then send the electricity down our Lincoln grid which has at best an 8% transmission loss. That means our electricity uses ~2X more gas, generating twice the carbon, before any HVAC begins to convert the electricity to heat For the Mitsubishi model MUZ-FH12NAH-1 (one of the best cold temp HVACs) I asked Chat GPT to convert the Mitsubishi published COP numbers to BTU heat delivered per 1kWh: Outdoor ambient temp (degrees f,) BTU heat /1 kWh
47 15,354 (normal above this) 17 8,456 5 7,376 -13 6,824 So I think you can see once you get below 15 degrees Fahrenheit you consume twice the electricity to heat your home ( with 4X the carbon produced) , but the good news is, if you have one of these systems, they continue to heat down to pretty low temperatures as long as there is electricity.
I should be clear; we have this model of cold temp Mitsubishi mini split installed in our home. It is for an auxiliary room without plumbing and we will be installing US-made 24% efficiency solar panels with batteries (unfortunately using Chinese precious metals) to power it and charge our Mitsubishi (coincidentally) hybrid car
I am, I guess, particularly sensitive to this matter, because we moved here from Concord, MA where the electricity costs about a third of what it does here in Lincoln and we had one power outage in 16 years that lasted 4 hours. We have already had 2 outages in a year from a mild storm and a car crash. The old power lines here are badly maintained with trees and bushes hanging all over the lines, but it gives Eversource a license to charge huge delivery bills
With warm regards, Art +1 978.873.3000
Hello All-
Chuck Sizer, a founding member of Lincoln’s CFREE (carbon free residential- everything electric) group and a refrigeration engineer, monitored the coefficiency of performance (CoP) on his Mitsubishi heat pump a few years back when the temperature dropped to subzero temperatures.
Having been at his house and looked at all of the graphs with watt consumption tied in, I was amazed to see that, as Nick suggests, the CoP was able to shadow the temperatures exactly- meaning there was no increase of cost to provide temperature per degree with a heat pump; so the efficiency and economy maintained all the way to -5°. Hvac engineer savant Antis Hartmann echoed Nick’s statement about newer systems having a steady CoP all the way down to -15°.
Lincoln is fortunate to have perhaps the most advanced committee reviewing apparatus, legislation and other initiatives towards more environmentally, sustainable and efficient energy with the CFREE group. Their meetings are advertise through Town’s website and a lot of their information has been posted to YouTube. For any resident consider considering upgrading their heating system, adding solar panels, and/or battery backups, or even considering an EV versus another combustion engine purchase, please reach out and take advantage of this amazing group of community- minded, locally active (slightly nerdy) individuals who have amassed tremendous amounts of information and insight.
Stephen Dirrane
Sent from my iPhone That is unfortunately outdated information. With modern cold climate heat pumps, the heat pumps are more environmentally friendly than natural gas heating at around 15f if you're on the Lincoln basic plan and have a 95% efficient furnace. If you are on the standard plan, it's *always* more environmentally friendly to run the heat pumps instead of gas. The technology has greatly improved recently. Happy to go over the numbers with anyone if they'd like, I'm a bit proponent of heat pumps.
I do agree about power reliability, but battery backup solutions have gotten a lot better recently as well.
-Nick Thank you, Nick, You are correct that point 1 about the unreliable Lincoln electric grid is the most important But you might check your HVAC system: “Areas of the country subjected to temperatures 40 degrees and lower for extended periods are not ideal for a heat pump installation. Why? Well, as the temperature drops, heat pumps work harder to maintain desired comfort levels. This results in more energy use, driving up your utility bill. In addition, once the temperature drops below 40 degrees, most heat pump systems lose their heating efficiency and must switch to emergency heat mode, which utilizes electric resistant heat strips that use more electricity.” And you are correct, below 0 f. the heat strips are almost useless except to generate huge electric bills. It is like heating your home with non-oil-filled electric space heaters Also since Massachusetts generally has very efficient gas-fired/generated electricity on our grid, the extra electricity to generate heat from HVACs consumes vastly more green house gases than direct conversion from gas at our homes Heating with electricity below 32f is bad for the environment. With warm regards, wishing all a peaceful and healthy 2026 Art +1 978.873.3000 I'd push back against number 2 in particular. Cold climate heat pumps typically provide full output down to 5f and still operate at -13f. I and many others use heat pumps as a primary method of HVAC and have had no issue even on the coldest of cold days.
-Nick Rosemary
Erik Lyons - (978) 621-2642 New business, hard working, local
Max heating & cooling Sam or Dan (617) 453-8865 Best in Boston
Do not use HVAC for heating in Lincoln 1. Lincoln’s electric grid is too unreliable (I think Eversource cultivates tree growth over our old fragile power lines) 2. HVACs are not designed for very cold weather which we occasionally have
If you insist on HVACs have a good wood- burning stove in the house With warm regards, Art +1 978.873.3000
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