Now you can see the flow rate for these heaters has changed. It means you can run a shower and maybe wash your hands at the same time. What happens when you try to run say the 3 showers as in the first example? Well the heater knows you want to get 120º F water out of it, so it will restrict the flow to ensure you will always get the desired temperature. So when all three showers are running the water will trickle out if you take the 4.8 GPM and divide that by 3 means you will only get 1.6 GPM to each fixture.
Now to solve this problem you can goto the next size larger models, or if your temperature rise and fixture demand is to great for even the larger models you can install multiple units. If you installed two of the units which they link up with each other so they will only fire both units when there is a demand. You would get 9.6 GPM out of a two unit tankless water heater system using the above models.
I do hope this information helps a little in sizing a tankless water heater for your needs. You can always call us at 1-800-924-5758 and ask for us to come out and do a free home or building evaluation and provide a free estimate to install a tankless water heater system for you.
Thank you for taking your time to read this page. Look forward to more pages about plumbing. If you have any type of questions about plumbing and would like to see a page written up about your question go ahead and contact us with the question.