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Frequently Asked Questions

The menu topics are representative of questions we have answered about the equipment and systems we install and service. While the laws of physics haven’t changed lately, technology is evolving constantly, and our role at NMD is to understand how this evolution affects our systems and customers.  We are constantly learning about new techniques and approaches to HVAC and plumbing systems so that we can provide intelligent responses to your queries.

Our goal is to be Martha’s Vineyard’s premier plumbing and HVAC shop – we welcome your questions you may have about your plumbing and HVAC system.

Annual Maintenance: Why so important?

Annual Maintenance is very important to maintain the safe and effective operation of the heating, cooling, plumbing, and ventilating systems in your home. The good old days:  A hot water boiler with radiators and one thermostat for the whole house. In the old days, many people had an oil or propane fired boiler connected to hot water radiators that needed very little…

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Energy Efficiency: Its import and impact?

Federal regulations are driving the ever-increasing energy efficiency of modern equipment.  It is no longer possible to get inefficient (and simple, robust, tough, easy to service, and easy to maintain) equipment. No more R22 systems: Heating and cooling equipment using R22 is no longer being made and is unavailable.  This means that all AC and heat pump units will use R410a and…

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Geothermal Rescue: What is it?

Geothermal systems have worked in a reliable and trouble-free fashion since the 1930s.  There was a tremendous surge of interest in geothermal systems in the mid 1930s by electric utilities as they realized that the heat pump approach was a wonderful way to even out their winter and summer power loads.  The geothermal heat pump systems they installed were still in use…

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Heat Pump or Furnace: Which is better?

We often get asked which is a better choice, an air source heat pump or a furnace?  There are drawbacks and benefits to both and we will discuss some of them below. Furnace benefits: As a source of heating, propane has a lot of energy per gallon.  A modest sized furnace can put out a lot of heat very easily.  Modern furnaces…

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Internet Thermostat Issues?

The “Nest” Thermostat We have had numerous reliability and operational issues with the Nest thermostat that make us reluctant to sell or service it.   Because it requires a source of power and doesn’t have batteries, it can be connected in various “power stealing” configurations beyond just connecting to Red and Common wires from the system transformer.   While this “power stealing”…

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Power Quality and the Aging Vineyard Electrical Grid

The electrical grid on Martha’s Vineyard was never designed for everyone to have air conditioning.  Air conditioners use a lot of power during the summer when it is hottest out and create a huge demand on the Vineyard grid.  NStar routinely brings out emergency generators and temporarily installs them at the Tisbury and Oak Bluffs landfills in an attempt to stabilize the…

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Rodent Prevention and Hungry Mice?

One of the downsides of air source heat pumps is that they are very attractive to mice.  Unlike geothermal heat pumps or furnaces which live in the basement of the building, air source heat pumps are outside, it is nice and warm inside the heat pump itself, and it is the idle safe spot for mice make a winter home. Unfortunately, the…

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Your Heat Pump Outside: Snow, ice, and defrost

The modern air source heat pump is a marvel of efficiency and automatic operation.  It works well down to 0 F, accomodates snow and freezing weather, and automatically clears away the accumulated frost on the outside coil.  That being said, the heat pump does need your assistance to work effectively.   It is important that you clear away any snow that builds…

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