The outdoor unit of a Fujitsu ductless minisplit system. With the exception of one week in February 2011 where I switched back to the oil boiler to take some data before it went away, the Fujitsu 12RLS has now been heating the house for two years. The dedicated meter for the heat-pump system reads 2,584 kWh. So, it cost about $250 per year to heat our house, in mostly milder-than-normal weather. This is about 1/4 the cost of operating the oil heating system. Most houses in the Northeast have a boiler and forced hot water heating, and most of the rest have a forced-air furnace; both are central heat systems. Without some energy retrofit work, most houses can't be converted over to a single-zone minisplit and have adequate heat throughout the house. In cases where the central heating system is due for replacement, a multizone minisplit may be worth considering. We've done just that at South Mountain Company for a client with a 30-year-old boiler and a poorly designed distribution system.

That system cost over $20,000 installed, though. GBA Encyclopedia: Ductless Minisplit Heat Pumps Will Minisplits Replace Forced-Air Heating and Cooling Systems? Heating a Tight, Well-Insulated House Report on Our Ductless Minisplit Heat Pump New Englanders Love Heat Pumps Heat-Pump Water Heaters in Cold Climates Air-Source or Ground-Source Heat Pump? Are Seven Heads Better Than Three? BLOGS BY MARC ROSENBAUMhome central air conditioner installation Minisplit Heat Pumps and Zero-Net-Energy Homeshome ac repair parts Practical Design Advice for Zero-Net-Energy Homeshow much does a ac unit weigh Ductless Minisplit Performance During Cold Weather A Tough Energy Code Is the Worker’s Friend

Installing a Photovoltaic System Living With Point-Source Heat Seasonal Changes in Electrical Loads A single-zone minisplit costs about $4,000 installed. In cases where the entire house doesn't need to be fully heated, or houses in which a point-source heater can carry the load of the house in mild winter weather, a minisplit can be a great retrofit. In the Pacific Northwest, a major study has been conducted using a single-zone minisplit as a retrofit to the many electrically homes there. On average they have shown a 40% reduction in heating energy, with some homeowners experiencing much higher savings (the ones most likely that kept the doors to the bedrooms open!) In the studied homes, the electric-resistance heating units were left in place, to be used as needed. It's very possible to consider a similar approach in fossil-fuel-heated homes. The best candidates are houses with open plans, so the heat pump can heat a good portion of the kitchen/dining/living space, and houses where the other rooms are located where natural convection (warm air rising) can transport heat to them.

It would be best for the existing heating system to be one that has more than one zone, so that the zone(s) not well heated by the heat pump can still be heated by the existing system. Best suited might be houses where a number of the rooms are not occupied: for example, a large house with a single occupant who needs a bedroom, bath, and the public areas heated, but not the other four bedrooms and two baths. In essence, it's going back to the days when a central hearth kept the public spaces warm and the peripheral spaces were much cooler. These changes will likely be driven by fuel prices, so they are more appropriate where there isn't any natural gas available: houses where oil, propane, and electric resistance are the primary heating fuels. As of the 2009 EIA energy use surveys, there were almost 9 million households in the Northeast (New England and mid-Atlantic states) using those fuels as the main heating source. That's a significant opportunity. Last year, during November and December 2011, our net energy purchased from the grid was 98 kWh — that is, we imported 98 kWh more than we used.

This year, during the same period, that figure was three times higher: 299 kWh net import. For one thing, it was cloudier. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. system made 68 kWh more last year during this time. The larger difference is that we used more electricity: 947 kWh this year vs. 814 kWh last year. I can think of three things: You can see that the big difference is weather-related: it was colder and cloudier. The lower energy use a house has, the larger these year-to-year variations will be on a percentage basis. Yet the benefit of solar-driven, energy-efficient building is that the percentage variations may be high, but the absolute difference in dollars is small. So the difference in our net energy flow over those two months year to year is about $37 total. Marc Rosenbaum is director of engineering at South Mountain Company on the island of Martha's Vineyard in Massachusetts.

He writes a blog called Thriving on Low Carbon.Ductless Air Conditioning Costs Ductless air conditioning is also known as split-system with its condenser unit mounted outside the building, and the evaporating unit mounted inside its climate zone with no ductwork. Refrigeration pipes pass into the building between condenser and evaporator.You will find that the cost of ductless air-conditioning installation varies by type of unit, its cooling-capacity and efficiency rating, and the local labor rate.In the following table the Labor Cost figure is what the able DIY person should expect to save by performing the corresponding tasks.Ductless A/C installation: 600 sq.ft. zone for cooling and heating, with remote control.ItemUnit CostDuctless A/C: mini-split system, 12,000 BTU/h cooling and heating, 115 VAC; with all trim, weather stripping, hardware, and miscellaneous material.$1,206each1$1,206Upgrade: new electrical circuit, 30 feet, 115 VAC, 30 amps breaker; existing load center space;