Rinnai Flush Routine – Tankless Maintenance DIY



I'm a big fan of tankless water heaters if they're properly maintained you're gonna get 20 plus years of life out of them but they need some routine maintenance fairly easy to do yourself I'm gonna show you in this video all the steps that it takes we're going to be doing this on an exterior mounted Rinnai but today's video is gonna work for you whether you have a Rinnai a Takagi a Rheem all the brands and it doesn't matter whether this is mounted inside or out this video is going to work for you okay so tankless units these have a giant gas engine inside and when that gas fires up and heats that water there's a small amount of scale that can happen in the unit the harder your water is and the more that this tankless unit runs the more that scale is gonna build up and we need to get that scale off we need to flush them and descale them now if you've got a hard water situation like I do at my house and a house have a bunch of kids I do mine every 12 months regularly if you have a smaller house one or two people you can probably go more like two years between this and if you have a water softener at your house you can go more like five or maybe even seven years so at this house this one's been installed for eighteen months now it's time to flush this you know if you've gotten a trouble code sometimes it'll flash a zero zero or an L zero that's the time to flush code this video is going to apply to you as well but I would highly suggest flushing it before it makes that code do it on a regular basis every 12 or 18 months and you'll never have a problem assuming it's gonna last 20 plus years okay so today we're gonna be using a flow aid kit this is about 120 130 bucks on Amazon and it's gonna include everything you need to flush you can do it yourself or you could have a plumber do it but trust me it's pretty easy I'm going to show you how now this kits gonna include a couple hoses and these hoses are gonna connect up to the flush couplings here it's all it's going to include a pump and it's gonna give you a quart size of this flow ad scale this is what we're gonna pump through the system it's it's basically a system that's pumping for about 30 to 45 minutes through the boiler system it's gonna take off all that scale and bring us back to brand new so let me show you how to do this first step take off the power we're gonna unplug the power to this unit since this one is mounted on the outside and then we're also gonna turn off the gas line remember any time we turn something off its gonna be perpendicular to the line so they'll turn that off next we're gonna turn off the water from and out of the unit these are nice 90-degree ones the plumbers put on good job and then we're gonna open up these flush valves now if you don't have flush valves like this you're not going to be able to do this process if you have a tankless unit that was installed maybe 10 years ago or a plumber it wasn't familiar with tankless you don't have those stop the video right here you got to get a plumber to put these flush valves on you hopefully if you've got a newer unit they've installed these for you you're good begin you're gonna be good to go so what we're gonna do is hook the hoses up the first thing we're gonna do is hook up to the hot water side and that's where the flush is gonna come out and then we're gonna supply this flush unit or this flush solution I should say through the cold water side okay so then the next thing we're going to do is hook that supply hose on the cold side to the pump this is a little submersible pump it's probably a 5th horsepower pump something like that and once we get this hose connected to it it's going to actually sit down inside of the flow aid and this is what's gonna provide the the power the engine to drive that water through then you're gonna see I've got about a gallon of water in this bucket right here and for every gallon of water we're gonna add one quart of the solution they make it really easy you've got a nice see-through side right here so I'm gonna pour one quart of this solution now if you buy this $20 jug you're gonna get four quarts that you're basically gonna get four flushes so next step we're gonna run the hose from the hot side back into the tank this is what's gonna make that loop for us and then we're gonna open up these valves right here that are going to the flush side okay now we're going to plug the pump in and that's it the second here you're gonna see it pumping through there we go see that summer scible pump all it's doing is just taking that flow aid and now we're just cycling it through the system tells you in the directions 30 to 45 minutes I would recommend probably doing on the higher side of that you're only gonna do this every one to two years and miles will run it for 45 minutes nobody'll time to take a break I'll be back in 45 minutes okay it's been running for 45 minutes we just unplugged this pump and remember we flush this with 45 minutes worth of that fluid to loosen up all the debris inside the tank so there's two final steps now that are critical number one we want to blow some water just some standard Street water through this tank that way anything that's loose is gonna be flushed out and then number two we want to check the filter coming in on this unit so let me show you how to do those two okay now we're gonna turn off the isolation valve on the cold water side in fact we can go ahead and disconnect the hose that was the pump it was pumping the solution in and then we're gonna go ahead and turn on the cold side now you can see we want to take this out of the bucket what we're doing now is we're just flushing street water through the unit's not going to fire up there's no gas and there's no electricity to it and all this is doing is this was just taking a jet stream of water through the tankless boiler system without it firing up we want to run this for about two minutes this is just gonna flush out any impurities that may be got a little bit loose for the sake of time I'm not going to do this for the full two minutes but you get the picture here pretty straightforward okay once we do that we can disconnect the hoses all right now the last step everything's still off right now I'm gonna put the water back off to the unit so everything's off now let's pull this filter out here this filter is right underneath it's sometimes hand tight sometimes you're gonna need your little Leatherman tool and then we're gonna pull that filter out it's a little bit of a circular stainless filter you can see there's just a little bit of junk in there we're gonna clean that out you can blow it out or you could run it under your faucet and this is just cleaning the inlet water coming from the street to make sure no garbage is getting into the tank once that's been cleaned we're gonna pop it back on the unit okay now it's time to put the unit back on so we're gonna reverse all the steps both the isolation valves are turned off we're gonna turn on the cold we're gonna turn on the hot number all these valves are gonna be in line when they're on perpendicular when they're off now we can turn on the gas in the final step plug the unit back in we've got our plug right here on the outside and makes it easy that's it guys this unit is ready to go it'll be another 18 months before I suggest this one get flushed again remember this is super easy but it's vital this unit's gonna last 20 years if we flush this on a regular basis if we don't we're gonna have premature failure and we're gonna flush all that junk into our system which is a huge pain so don't neglect this there'll be a link in the description below for to buy this pump set system or you can make your own and save a couple bucks I also have a parts list there for you if you want to do that you could also buy these from the local hardware store so you don't necessarily have to get them here thanks for joining everybody we'll see you next time

30 Comments

  • furse001

    April 15, 2019

    Avoid this issue entirely, by using a tankless that avoids the scale buildup and need for flushing. https://myheatworks.com/pages/model-3-specs

    Reply
  • Jim Seiler

    April 15, 2019

    Sure, home owners should flush the units themselves.
    But, I'm sorry dude, you've left out a few critical prelimminary steps. Plus if you're running a Rinnia RL mode,l by the time your thermostat screen shows an LCO code you're locked out of the system and it ain't gonna fire till you reset the mother board. Fact is, like every thing else, if you don't know what you're doing, you should consider calling a professional.
    BTW, If you refer to the manual, you'll see that if you've waited a year and a half to flush the unit, you've voided Rinnia's warrenty. Refer to the manual and call a plumber.

    Reply
  • Kentucky Hillbilly

    April 15, 2019

    Don't waste money on the recommended pump. Buy one for around $50.

    Reply
  • Wayne Higgins

    April 15, 2019

    Also the manufacturers manual said nothing about putting those flush valves in so I have ordered them and the flush solution.

    Reply
  • Wayne Higgins

    April 15, 2019

    Thanks for the video, it was very informative. I installed a Eco Tankless Water Heater in a vacation home that we have and it was working fine but not we have a problem with the Shower water starting out hot but then it goes cold and then hot. I know we have hard water. Could this be the cause of the problem and will flushing the system resolve it. We’ve had the unit for about a year. Thanks

    Reply
  • Del Barton

    April 15, 2019

    Thank you for such an informative video.

    Reply
  • Esoteric Tony

    April 15, 2019

    My pump will not pull water. Any ideas on what it could be?

    Reply
  • Romel

    April 15, 2019

    do I need to shut off the main water? or just the power of the tankless heater

    Reply
  • Ted Trimble

    April 15, 2019

    Thanks!

    Reply
  • BobboMax1

    April 15, 2019

    Some tankless water heaters have a filter in the combustion air inlet- it's worth looking for and cleaning that if present. Otherwise, another of Matt's excellent videos.

    Reply
  • Nico Maisuradze

    April 15, 2019

    Easy, straight forward installation.>>>ur2.pl/1103 We installed this in our 2 bedroom 1 bath cottage in Northern WI and I set this to 120. Water is HOT! Compact and takes up almost no space at all and it doesn't make a single sound. I thought there would be a slight "hum" but you don't even know it's there

    Reply
  • Scott b

    April 15, 2019

    With all due respect to Mark, my advice is (1) avoid the kit and build your own with a better quality pump, including (2) two replacement hot/cold washer replacement hoses, which I'd use to replace your existing lines on your (laundry) washer if they're over a year old, and use the old hoses for flushing (or just buy two cheap washer hoses for flushing purposes), (3) a submersible pump off Amazon (either an aquarium pump or 1/2 to 3/4 HP pump with a float valve, 1000-2000 GPM); (4) a 5 gallon pail, and (5) 3-4 gallon's white vinegar from Costco. The pump is the high cost item, and you get what you pay for. You're going to be doing this periodically for years to come, so I'd invest a little more money on it. You can reproduce the kit Mark suggests for about $60, or spend up to $200 to include stainless steel pump. I like the higher flow rate to kick out sediment. (Your pump flow is limited by the size of the 1/2 hose and valves, so don't go overboard on the pump, and don't worry about exceeding the PSI of your city or well water, either.) You pretty much do what Mark suggests, put the pump in the 5 gallon pail, put vinegar in the pail, put both hoses in the vinegar (one attached to the pump) and attach the other ends to the code water intake/hot water exhaust valves, turn on the pump and let it run. I usually let mine run longer than 45 minutes; if I'm going to set up this contraption, I want the inside lines of the tank spotlessly clean. I reuse the vinegar a few times, and eventually recycle the old into use with my household cleaning supplies.

    Reply
  • Scott b

    April 15, 2019

    Add a strainer between the tankless WH and your hot water supply line (i.e. WH exit)!! Had a heck of a time dealing with HW scale in a relatively new Rinnai Tankless water heater. Compared to my original home in Southern California, my Idaho water is "pure". (Didn't check the PH, just know from the symptoms.) However, the PH is high enough to really crud up the works, including check valves, every shower head, and the rest of the system. (Hint: Clogged check valves = cold water flooding backwards in a re-circulation tankless system, which means sudden cold water during your shower.) Anyhow, my blanket recommendation for ANY Tankless system, regardless of your water quality, is to put a clear bowl strainer with a flush valve on your hot water exit line (i.e. out of the WH), to both catch and measure the amount of sediment leaving the system. You can easily flush the filter in second, monthly or bi-monthly. This protects all of your fixtures, including your WH check valves (for recirc systems) from any sediment a tankless WH may throw. There's sediment in every WH system, conventional or tankless, but with a 40 to 60 gallon conventional tank, the sediment can drift to the bottom, and won't end up in the hot water line. In a tankless system, there's no place for the sediment to collect, and it goes right down the pipe to the rest of your fixtures. Solved ALL of my tankless WH problems (along with vinegar flushes three time a year. This worked for me: 9SIAA6U4RC4905 iSpring WSP50 50-Micron. Tried a fiberglass one previously, but it leaked and eventually replaced it with this brass unit. No regrets. (Newegg happened to have the best price on this unit by far (about $50), but you can find them at Amazon, Wal-mart (online), Ebay, and probably, even a good plumbing shop if you're willing to pay about $100. (Lowes, Home Depot – not carried)). It took me about 9 agonizing months of toying with the WH to figure this out. Aside: I built my own house, and yeah, I also had problems finding a plumber that knew enough about tankless WH's to install mine. Ended up reinstalling it myself. Wasn't that difficult – just read the manual, understand the schematic diagram, and add those extra little valves where they tell you to. Condensing WH==PVC exhaust, and cost effective. Very nice. Also, you're going to need to add an expansion tank for a recirc system, a whole house strainer on the mail is a wise idea, a pressure reducer on the intake if needed (So. Cal. city water could range from 60 to 120 PSI, on any given day of the week; you knew it was high when all the plastic sprinkler valves in the neighborhood started blowing out and flooding the street 🙂 , and a condensate neutralizer for a condensing WH, if you're condensate drains into your septic system. I run propane gas into a Rinnai RUR98i, turn the recirc pump on manually which heats the whole 2200 sq foot house within 2 minutes, for about $15.00 in propane a month. Very economical. Great system, but needs to be installed correctly and maintained.

    Reply
  • ninodog10309

    April 15, 2019

    Question. I live in North GA.
    It looks like the water here is soft. Do I need to do this maintenance. If so how often?
    I saw another video they use white vinegar.
    Any input?

    Reply
  • Kevin O'Neal

    April 15, 2019

    Thanks for this video, it was very helpful to flush my Rheem tankless water heater.
    The reason I was researching this to begin with is that we've experienced a slow decline in our hot water pressure in our shower (hot water only, only in the shower), and after determining that it wasn't a problem with any of the mesh screens on my fixtures getting gunked up, I figured this would be my ticket! Unfortunately, it didn't seem to work. I still have low hot water pressure in my shower compared to when I installed the unit a little over a year ago.
    Any ideas for me?

    Reply
  • vblair933

    April 15, 2019

    Matt, thanks so much for the informative video! My husband and I purchased a house with a Rinnai tankless hot water heater and were not aware of the maintenance needed. I was able to flush my own Rinnai all by myself. I didn't even need any help from my hubby. Thank you!

    Reply
  • Bruce Moore

    April 15, 2019

    Matt, when I flushed my Rinnai the flow on the discharge hose degraded. I found I needed to screen the discharge thru some paper towels in a sifter. Also swapped paper towels several times.

    Reply
  • Mike or Jimmy

    April 15, 2019

    You could just get some CLR instead of vinegar would probably work as well mix it quart to a gallon of water let it run through the system for an hour. Then I would use another 5 gallon bucket with 3 gallons of water and flush it for 15 minutes then disconnect and flush the system with the incoming water for another 15 minutes.

    Reply
  • CB Belanger

    April 15, 2019

    Matt, I’ve watched a couple of your tankless water heater videos and when I looked at this know that it was time to descant mine. After watching this video it was straight forward and all went well. Great video. Thx CB

    Reply
  • Drunkis1337

    April 15, 2019

    I learned two things from this video. That they make valves to make flushing your tankless unit easy and I should be flushing it once a year. I guess I should have done more research before installing my unit. Thanks. I've been enjoying your videos.

    Reply
  • jm69charternet

    April 15, 2019

    Hi we have a tankless in our home we moved in the area little over a year ago love the tankless water heater. I do have a problem with the unit making a water hammer sound it did not do that when we moved in but now it does ever once in a while. had a plumber come out last year and descale it but I have been told it may be a vale problem. what do you think?

    Reply
  • Ira Gerstler

    April 15, 2019

    this was very timely thanks for a "REAL how to video"- guess what I'm doing this weekend- every 2 years- forgot to mention how great all that vinegar smells

    Reply
  • ushipb00

    April 15, 2019

    Thanks Matt great video. I will be flushing my two Rinnai RUR's tankless this week. $300 charge for my two units from a plumber, hah, I don't think so!

    Reply
  • Ryan Jones

    April 15, 2019

    Hi Matt, I followed the video and got great results – a ton of gunk was flushed out. But now my kitchen sink doesn't get hot water! The heater isn't being triggered on when I turn the hot water on. Any ideas?

    Reply
  • Vadym Rodionov

    April 15, 2019

    I think you need to take some time and go to inplix website to learn how to make it.

    Reply
  • Ryan Jones

    April 15, 2019

    Hey Matt, super helpful as always. I had no idea I needed to do this.

    I will add that when you initially open the flush values junk will flow out of the heater. So allow both flush lines to flow into an empty bucket first, then wash out the bucket, THEN create your flush mixture. So that you aren't circulating all that unnecessary junk.

    Reply
  • Thor Dehr

    April 15, 2019

    Same deal, vinegar. I usually start with backflushing first, THEN forward flushing it. Filter removed.

    Reply
  • mattbaker333

    April 15, 2019

    Thanks! I just installed a tankless water heater this past October. This is some good info!

    Reply
  • Mangos as Weapons

    April 15, 2019

    I really wish there were more qualified plumbers out there. I've called 3 highly rated plumbing companies in my area and all 3 said they don't install tankless – due to the maintenance involved. After watching this it's unbelievable to me how misleading the local plumbers are to potential customers. I would love to install one of these in my home. ??

    Reply
  • Ed Swindelles

    April 15, 2019

    Hi Matt – Great video as usual, thanks. I've had an indoor Rinnai tankless for three years now, and with pretty hard water I've been flushing yearly. I just created an annual calendar reminder on my phone. I'm using the exact pump and hoses that you linked to in your description, purchased through Amazon, and a 5 gallon bucket from Home Depot. The only difference is that I use 2 gallons of household vinegar as the circulation fluid, instead of what you recommended. This setup has worked great, and I'm really hoping to get that 20 year life you mentioned. 🙂

    Reply

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