Gravity Hot Water System

Gravity fed water systems require the following.

Gravity hot water system.

As the water cools at the end of the loop where the last part of the loop is not insulated it is thermo siphoned back into the hot water heater. Because gravity is the only force pushing the water through the pipes a gravity fed system is often referred to as a low pressure system. An intake that is screened from debris and submerged sufficiently to ensure no air enters the pipeline a properly sized pipe diameter considering the pipeline length the elevation difference the energy available to move water and the water flow required. It is also the least efficient.

A gravity hot water system works because the heated water which is lighter rises through the loop. As water heats it expands displacing the cooler and less dense cooler water throughout the system. If you are in a swimming pool you will notice that the temperature of the water becomes colder as you go deeper in the pool. A vent pipe is also included as a safety feature.

Typically such a heating system has a cold water tank in the loft or attic of the house a boiler on the ground floor and a hot water cylinder somewhere between these two. A gravity hot water heating system is the oldest and simplest system to heat homes. A gravity hot water recirculation loop works by allowing the laws of nature to come into play. A gravity fed heating system uses the force of gravity to circulate water in the heating system.

When you re first filling these systems you have to start with all the radiator vents open and fill one floor at a time. Most gravity systems had the radiators connected bottom to bottom. Hot water tends to rise while cold water tends to descend at the bottom of a contained space. In a gravity system the circulation of water is due primarily to thermal and density differences between hot and cold water.