Can I Install Low Flow Shower Head with Instant Hotwater

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.

Rinnai R1200 Service ManualTo 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.

6 Replies to “Can I Install Low Flow Shower Head with Instant Hotwater”

  1. EdwardThirlwall

    I’ve never agreed with on the spot water heaters. I just find them horribly inefficient and so difficult to maintain. It’s definitely not as flexible as one with a storage tank – at least if I forget to switch the heater on, there’s a high chance of some hot water being left over from the last time it was on.

  2. FarrellMackennon

    We get a lot of emergency plumbing calls for these issues of lacking pressure in London. Especially for people who stay in high rise buildings and want something to be done about their water flow when they’ve just moved in. Best bet would really get your original contractors to do a proper assessment and get them to finalise the water pressure before they declare the job finished..

  3. melbrandle

    Instant hot water would be much easier to set up if you have your own water storage system within your property area. If you don’t, then it will definitely be much tougher to achieve that because of the distance between your outlet and the water supply. Nevertheless, it is still not entirely impossible and with extra effort it can be attained.

  4. JamesSimon1

    We recently moved into a new apartment. Apparently the previous tenants didn’t see fit to leave the shower head. They actually took it with them! So, rather than take showers out of the open end of a pipe, we decided to look into some of these new shower heads. Maybe a plumber will have some expertise in the matter.
    http://www.samslocalplumbing.com.au

  5. PaulChau

    An instant hot water system is much easier to install as compared to a hot water storage tank that needs much longer to heat up the water. You can choose to fix a low-flow shower head which can easily be obtained at a hardware store. You would simply need to change the existing end of the pipe to match your preference.

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