home grid

home grid

Hydronic Baseboard

Hydronic means hot water.  These traditional fin style baseboard units are very common and very effective.  They use high-temperature water (160-180ºF) from a boiler (also called a hydronic … Read more

Steam Radiators

Cast Iron steam radiators became popular in the late 19th century and were often fired in coal, then oil, and now on gas. Housing stock dating from this … Read more

Forced Hot Air Floor Register

Centrally Ducted Forced Air 

Centrally ducted forced air systems could be used for heating, cooling, or both. These systems have two parts: a) the appliance, which creates the hot or cold air … Read more

Fan-convector

Fan Convectors

Each of these fan convector heat emitters receives hot water from the central-heating boiler. First, the water passes through a coil inside the unit. Then a fan blows … Read more

Mini-Split Heat Pumps

Ductless Mini-Split, Cold Climate Heat Pumps (CCHPs) are single room heaters. A conduit, which houses the power cable, refrigerant tubing, suction tubing, and a condensate drain  runs to each … Read more

Wall-vented gas heater

Direct-Vent Gas Heaters

Direct-vent gas heaters have the advantage of combusting the fuel right in the room where heat is needed, instead of remotely like a central heating furnace. Some models … Read more

Heat Loss

The two variables of of heat loss are a) geographic location, and b) building performance. Together they will determine the quantity of heat needed to maintain comfort.

Geographic location drives the building's “design day." Your design day is the difference in temperature between the inside and outside of your house on the theoretical coldest day of the year; so in the northeast we calculate a day that is -10ºf outside and comfortable 68ºf inside. This is referred to as the “delta-T” value. A typical delta-T for the northeast is 78º.

Building performance is the big one because there’s nothing we can do about geographic location. Today we can build a really tight thermal envelope, but most of our heating pollution comes from the millions of homes built over the last 100-150 years. We are getting better at buttoning-up those old buildings with insulation and weather sealing but weatherization is still  never going to be enough to overcome the heat loss from a 78º delta-T. That means we need heating systems that can quickly put a whole lot of heat back into those old houses on the days that are really cold.