We’ve had the solar unit in for 8 months and the sacrificial anode has been replaced 3 times in the tank to try and combat the build up of pressure in the tank. To date this has not fixed the issue. We were told that we weren’t using enough hot water, so what happens when you go away for the weekend? The copper water pipes have changed colour due to the excessive heat and plastic around the solar return pipe has melted.
It seems that not enough research and development has gone into this product and we a paying the price for it.

Having reliable Rinnai products in the past I thought I would fork out the money for the best efficient hot water system Rinnai offered. I purchased the Sunmaster with the evacuated tubes and instant gas booster. Boy was this a mistake..

The Bad - The system had issues from the day it was installed. Day 1- The first issue was the temperature sensor on the evacuated tube manifold was faulty. The sensor was indicating a high temperature all the time causing the circulating pump to run 24 hours a day. Day 35 - circulating pump started making...

We built a house and moved in November 2016 with this unit being installed brand new shortly after. Since then the Rinnai Sunmaster (Model: REU-VR1620WS-AK) has been in gradual decline. We first noticed the water starting to take longer and longer to heat up, then the water temperature started to decrease. Next we had an issue with an overflow valve which resulted in the constant flow of water. This was eventually fixed as it is a known fault but it took a couple of calls for them to acknowledge this and more wasted water which resulted in a ri...

Five years on the unit still does not work and Rinnai seem to have their heads in the sand. The problem appears to be in the sensors, and the PCB. Don’t waste your money!!

Built new house in 2013 and installed rinnai evacuated tube solar hot water system, the system is 6.5 years old and the hot water cylinder has let go, it is leaking and has massive calcium build up inside, my plumber says don't worry warranty will cover, rinnai informs us it's not under warranty as older than 5 years, they basically said bad luck buy a new one, they have longer warrantys now, i got no where with them, they tried to blame our tank water which is not right, we previously lived 2 k's away in same street and had rheem cylinder in...

initial unit,off peak electric boosted floor mounted 315 L tank with 25 evacuated tube solar collector installed before Christmas 2016,
Household of 4 adults,Port Pirie SA ,where the sun signs almost everyday,most days with careful shower timing can get 4 showers but add a visitor to stay or for lunch and usually run out of hot water and need to turn daylight electric boost on
never performed very well and had continuing list of problems,pumps,sensors,etc and eventually tank and some tubes replaced March 2019,
since then have complained about ...

My unit has now failed for the 9th time in 3 1/2 years. The problem seems to be in the design or manufacture of the pump control system. As a result at night the pumps moves the hot water from the tank and cools it down on the roof. Rinnai are totally unhelpful. The ad hoc solution has been to put a timer in the power supply to the pump so it cannot run at night. To make matters worse the problem is intermittent.

A new Sunmaster with evacuated tubes, no older than three months started to fail about 2 weeks ago and the installation plumber had a shot at repairing it but only made it worse. Started with the hot water spitting pretty violently and has now reached the point at where there is pretty much no flow at all. Called Rinnia service who subsequently called an agent who said we would have to wait 2 days for a service call. That will mean we are 4 days without hot water. I used to have a high opinion of Rinnia but would now like them to remove the system and will be asking them to do so, it is clearly not fit for purpose and their service arrangements are far from optimal.

My rinnai 315 sunmaster tank has corroded out. 5 years 2 months after install. Warranty is only 5 years. Rang rinnai to get their help - hoping for some goodwill support, maybe a discount on replacing it. Too sad, too bad mate, nothing we can do. The tanks are made in china - the vitreous enamel lining would have been poor quality - and it rusted out well before it should have. My last aussie made tank lasted 17 years. Same water quality, the only thing that has change is the poor quality materials used by rinnai. Now $1780 to replace the tank. That's $350 a year for 5 years. Would have been cheaper to forget solar all together, just pay the power bills, and have a hws that lasts for 10 years or something.