How to Set Up Your Rinnai Properly at Your Home

Do you own a Rinnai hot water system or would like one?

Before you make any decision about your Rinnai, please make sure you plan to set it up correctly.

We’ve all heard the saying the customer is always right, but sometimes they are just dead wrong. And in this video, we show you a classic example of where they’ve asked for something, it got delivered, but what a shambles, what a debacle.

The Situation

The customer had a Rinnai 26, which is a great unit. It’s got controllers on it and everything. Back in the day all the years ago, the owners seemed to think that the most important thing was for him not to lose pressure when he was using two taps at the same time. So the plumber at the time seemed to suggest to just run a 20 mil main and then feed all the lines off that and the owner took on the idea.

So this is what they came out with. We’ve got a big 20 mil cold main but with a tap that only has the standard washer, which means a standard hole. So it’s really only feeding it through that tiny little hole, which is the same as having a small 15 mil pipe. It’s got the 20 mil hot main that goes up the roof. Then it goes to the two bathrooms on one side of the house, kitchen at the front of the house, then also the laundry and bathroom at the back of the house.

Now, just for instance, if you want to turn the laundry tap on, we show you in the video the way that the hot water would go. It’d go up the 20 mil hot main to the roof, then all the way to the back of the house. Then it goes bac down to the hot pipe that reduces down to 15 mil. It then goes all the way back to the line that goes to the bathroom and the shower and everything. Then it goes up into the roof space again, on top of the bathroom, then goes across and down to the laundry. So when they turn the hot water tap on, that whole 20 mil main has to empty out the cold water before they get any hot water at the laundry.

The Call

So the owner’s given us a call. He saw video about how we set up the continuous flow hot water system with a manifold, Rinnai or something alike, and he said, “Look, it must be something like this. Can you come and check it out?”

We have a hotline that comes up from the hot water system. That line goes off to the kitchen sink and two bathrooms. One side goes off to the laundry and the other bathroom down the other end of the house. W

We also show you up on the roof and the set up of the pipes. We’re going to just run separate lines throughout the whole job. Three lines from one side of the house. One line is going to feed the kitchen and the outdoor shower. The other one’s for the main, the bathroom, the ensuite, and the second ensuite too. All in 15 mil joining all the way down to the hot water system into its own manifold. Each one of those lines will still be running off the bigger pipe. So it’s going to have the same result, but we’re not going to blow as much water.

From the hot water system it’s going to go up, have a line that goes directly to the ensuite, and then another line that goes directly to the laundry. It’s going to cut some serious time of how long it’s coming through.

We did the before test to see how long the water takes to get to the laundry. And also how much water its blowing before it actually gets hot. If you keeo watchin, you’ll see how it took a minute and 30 seconds using probably about 11 liters of water. Nice cold water straight down the sink or to the garden or into the pool.

The Result

The hot water system was all installed. It’s got the large water main. It’s very important for Rinnai 26 to have that 20 mil main feeding it to make it work correctly. It loves a lot of water. So this is what we give that this time. Out the bottom, you’ve got a 20 mil that comes out. And then we’ve got the whole manifold system that is under the cover.

We’ve put a flashing around it just to protect it from the sun and a lot going on under there. All the five different linesare feeding off the main 20 mil main, and they go all the way up into the ceiling. So it’s going to work beautifully.

We then did another test at the laundry that used to take a minute and a half and about 11 liters for the hot water to come out. You’ll see the difference that it makes. The hot water system’s just set to 50 degrees. It took 28-29 seconds and about 4 liters of water before it gets. hot. So we save at least a minute of your time and about six liters of water.

You probably use the laundry say once a day maybe if you’re lucky. So that’s probably about 42 liters a week you’re saving. 2,184 liters a year, and tha’ts only on one tap now. This house has got five people in it and has showers and everything going at the same time, basins and all that stuff, so it’s got to be bucket loads of water that they save. So, it’s definitely worth doing, and also you’re saving the gas as well. It’s good to set it up properly like this customer has.


That’s how you set up a manifold system correctly on an existing house for a Rinnai or something similar. It’s a lot harder to fit on a retro, but if you’re building a new house, ask your plumber to set it up like this, because they can hide it all inside the wall, and it’s a lot easier to do. And if your plumber’s not sure about how it’s done or what you’re talking about, don’t show them the video, just draw it for him. And then he’ll think it’s your idea, and he’ll think you’re amazing. So try and do that. And if you need any plumbing done around the house, give Beautiful Plumbing a call, and we’ll be happy to come out and give you a hand.