Hot water reticulation loop (Ring-main) basics by the ITS Heat Pumps & Solar technical team.
Do you hate waiting for your shower to warm up in the morning?
A common way to avoid this is to install a hot water ring-main. This type of system works by circulating hot water around your house to minimise the amount of waiting time and water wasted when you open a tap.
Consider an ordinary hot water system. You’ll have a hot water cylinder somewhere in your house. If you have a large home, the distance between your water heater and your bathroom might be quite a long way.
When you open a hot tap, water has to run from your water heater all the way down to the tap. If the pipes are cold, it will cause the water to cool down along the way so you’ll have cold water coming out of the hot tap until all the pipes have warmed up between your water heater and your tap.
The ring-main solution has a small return pipe installed with allow water to flow back to the water heater. A circulating pump keeps the hot water moving slowly around the system, so that hot water is always available within a couple of metres of each hot water fixture.
The pump is controlled by a thermostat attached to the hot water return pipe. This turns the circulating pump on when the pipe cools down.
The only drawback with a hot water ring-main system is that the pipe thermal losses will increase. This increases your water heating costs. But, if the pipes are properly insulated and you are using a very efficient heat source like a heat pump, this increase is minimal.
If properly designed and installed, a hot water ring-main will provide you with hot water on tap almost instantly, which is essential especially in larger and more up-market homes.