Hot water demand system suitable for retrofit

A hot water recovery system comprising:

• a hot water source;
• a hot water delivery line connected between said hot water source and at least one plumbing fixture;
• a cold water delivery line connection between said plumbing fixture, a cold water source and said hot water source;
• pump means, interconnected between said hot and cold water delivery lines, at a point remote from said hot water source, for circulation of water from the hot water delivery line through the cold water delivery line and into the hot water source;
• control means for causing the pump means to circulate water from the hot water line into the cold water line proximate said plumbing fixture and back to the hot water source when a hot water valve on said plumbing fixture is turned on;
• and
• temperature sensor means, connected to said control means for causing said control means to stop the pump means to prevent heated water from being circulated through the cold water delivery line.