Space heater heat recovery system

In a space heating system having a hot air, fuel fired furnace with a cold air inlet passage and a hot air outlet passage, a heat recovery system:

• comprising an exhaust pipe for connecting the furnace to a flue, a damper in said exhaust pipe, a heat exchanger unit having a chamber and a set of water coils therein, said heat exchanger unit being located at least in part below said exhaust pipe, a pipe connected to said exhaust pipe on the anterior side of said damper and extending downwardly to the lower portion of said chamber, a pipe connecting the upper part of said chamber with said exhaust pipe on the posterior side of said damper, a water holding tank, upper and lower conduits connecting said tank with said set of coils, a bank of coils in one of said passages of the furnace, a fan for forcing the furnace exhaust gases through said downwardly extending pipe and the chamber in said heat exchanger unit and returning the gases to said exhaust pipe and water supply and return conduits connecting said holding tanks with said bank of coils heating the air flowing to the space to be heated.