One problem that many people have when wanting to install a low flow showerhead is working out if their hot water system will work with it. Some instant hot water systems don’t work if there is not a high enough water flow. This really goes against the current trend of conserving water, and leaves a gap in knowledge about the compatibility of instant hot water systems and low flow shower heads.
When determining if you can install a low flow (9 liter per minute, 8 L/min, 7.5 L/min, or lower) you need to work out what the lowest water flow is that your hot water system requires to work.
To use us as an example, we have a Rinnai R1200 High Capacity Continuous Flow Hot Water System. It is not a storage system, so there is no tank of hot water, but rather it heats the water on demand.
The first step in finding out if a low flow shower head is compatible was to check your hot water system manual. If you are lucky, or well organised, you should have the manual in your house. Unfortunately for us, we got no manuals at all when we purchased this house, so we had to rely on Google to help us find the manual.
After much searching, we finally found the service manual for our hot water system. Somewhere in the manual you will need to find the minimum operating water flow. In our case the rating for the Rinnai R1200 is 2.4 L/min, which is well under the rating of 7.5 litres / minute of a new three star, low flow shower head.
Remember that although your shower head will be putting through 7.5L / min, not all of that is hot water. You will need to take into account your hot and cold water flow balance when working out the compatibility of a new showerhead with your system.