Changing the Temp on a Rinnai Water Heater

The plumbing in our house was one of the worst things we had to deal with. So bad that the city building inspector called in the state plumbing inspector, who told us it one of the worst cases he’d ever seen. In addition to the tangle of incorrectly routed drains and vents, we had burst pipes and fixtures all over the place.

The cold took its toll on the two hot water heaters we inherited with the house, too. They were completely shot, so we opted to replace them with a single high-efficiency tankless water heater. Whatever our plumber’s other faults, he isn’t afraid to buy quality stuff. He installed a Rinnai (model R75LS), which seems to be the most well-respected brand out there. We’ve been using it for almost two months now, and no complaints. It runs beautifully, and I expect to see some solid energy savings this winter.

Our Rinnai tankless hot water heater is simple and attractive. It's almost too bad it's stuck in our basement.

Install didn’t take him very long, but later that day we noticed that the water wasn’t very hot. I checked the panel, and it was set to 104 degrees. I tried adjusting it up, but couldn’t get it past 120. That’s been reasonably hot, but we’ve got some more heavy-duty cleaning ahead of us – and temps above 130 are a little more useful for scrubbing and disinfecting.

I asked our plumber about it, and he explained that 120 degrees was the default maximum. “They don’t let us set ’em any higher than that,” he said. “If we adjust it up, I can get in trouble with my license. But you can set it as high as you like. Just read the manual.”

The instruction manual wasn’t super helpful, actually – no nicely-illustrated how-to headings. It told me that I’d need to change a dip switch in order to up the maximum to 140 degrees, but it didn’t tell me where the dip switches were. Nothing obvious on the outside of the heater, and nothing useful on the interwebs, so I figured I’d have to take the cover off and poke around. No problem. It was time for another DIY project anyway – even if it was a light one.

First thing was to turn the heater off and remove the cover. It wasn’t obvious, but simple enough: there are four plastic tabs in each corner.

To remove the cover from our Rinnai water heater, the first step was to locate and flip open the plastic tabs in the corners.

Each tab pops up pretty easily, exposing the screw underneath.

The screws for the water heater cover are under plastic tabs.

Get those out of there, and the cover comes right off, exposing all the glorious water heater guts.

The guts of our Rinnai hot water heater are kind of pretty-looking. Seemed a little steampunk to me...

See any dip switches in there? I didn’t, either. Fortunately, there was a wiring diagram on the back side of the cover, which at least gave me a good idea of where to look. The tiny little buggers were hiding underneath a loose plastic cover in the lower right corner of the cabinet.

The dip switches in our Rinnai water heater were hiding behind a small plastic cover.

The manual said I’d need to flip switch #6 to up the maximum water temperature. My clumsy fat fingers somehow got the job done.

The dip switches in the water heater are tiny. My fat stubby fingers had a little trouble.

Then I spotted a note in the manual about elevation: for any altitude higher than 2,000 feet (Deadwood definitely qualifies), at least one dip switch should be adjusted. I checked, and… they were set to the default. My arch-nemesis the plumber strikes again. So I fixed that one, too. Viola.

My stubby fingers managed to flip the water heater dip switches - but it was a little clumsy.

I popped the cover back on, turned on the power and tried adjusting the temperature. Success! It went above 120.

I had to flip the dip switch to get the temp above 120.

I kept it up until it wouldn’t go any higher – 140 degrees. Perfect.

With the dip switch flipped, I can set the hot water heater temperature to 140.

Next step was to run upstairs to the kitchen and do a real-world test. It takes a while to get the hot water into the pipes, but pretty soon it was coming out of the tap a little steamier than usual.

Chaning the temperature produced much steamier water from our kitchen tap.

All told, a 15-minute affair. Easy stuff. Should make cleaning a lot easier… and the baths a bit hotter. Now, if we can just get our clawfoot tubs cleaned up…


141 thoughts on “Changing the Temp on a Rinnai Water Heater

  1. Your post just saved me from wasting time with a service technician! Thanks for the step by step photos. Couldn’t find the tiny dip switches at first, but maybe it’s my poor vision.

  2. Well, i had already called the technician when i found this so i showed it to him and made him do it. thanks! I think it would have taken him longer to do it otherwise. all fixed up with hot water in the far reaches of the house, no matter how cold it is outside.

  3. Thank you so much for posting this! I don’t have the money to hire someone to fix something like this, so I get to do the research and make the change myself (if I can). I found your site right after I took the panel off. The dip switches are soooo tiny that I wanted a clear picture of what they looked like before I attempted anything. I was a little afraid to do anything with the machine because it is hooked up to gas of course, but I said a prayer and just did it!!! Thanks again…you really helped me out!

  4. This was exactly what I was looking for. I don’t know why Rinnai does just add this to the manual. My fiance is very happy now!



  5. Wow ! Great instructions and exactly what I needed. I wanted to raise the temp past 120 F on my RC98HPI but I just couldn’t get the right advice. I went into the box and looked around for the dip switches and didn’t see them. I got a little perplexed and went on the interweb and found this blog. 15 minutes later I had 140F hot water from my unit. I just needed some help finding the freaking switches. Thanks man !

    • I have the same model Rinnai hot water heater (RC98HPi) as you. I would like to increase the temp control through the dip switch. My manual suggest dip switch # 5. Is this the one you changed?

  6. THANK-YOU!!!

    I am extremely happy with the Rinnai, but my wife has complained this winter that “Warm” on the washing machine was really “Cool”.

    The same company that installed the Rinnai, services our furnace. The furnace guy told my wife that the only way to increase the temp above 120 was to take the thing apart and “Reprogram” it. (I knew better.) The young lady at the company told my wife that it would be a $90 house call, plus parts, to bypass the mandatory, by law, 120 degree factory setting. (More training required here.) The sales guy told her that the problem was in the washing machine, that the flow of hot and cold was out of balance. ????Huh????

    Mine is a different model, but your post is accurate enough that it put me in the right neighborhood. Mine has only 7 dip switches, and in a slightly different location, but dip switch #5 did the trick!!

    Again, THANK-YOU!!!

  7. Thanks so much for this information! My husband and I found the dip switch in less than 10 minutes – in the dark with flashlights no less.

  8. This is a great post. Thanks for taking the time to put it together. I have two left thumbs but this made it easy.

    All the best… Collin + Fina (soon Emma due it two weeks)

  9. Thank you Thank You!! We recently updated our faucets to the new environmentally friendly ones(whether we wanted this or not, the only option)and could not get a hot bath with the lower water pressure and 120 degree maximum hot water. Now we can! Thank you again — it was easy!!!

  10. Thanks for this! The manual was clear as mud with no directions for finding the microscopic dip switches. My manual also said to use dip #5 to control temperature. #5 DID NOT WORK> Thanks to your post I tried #6. Success!

  11. GREAT!!!!
    I had spent some time with the manual and with the cover off the heater looking for the DIP switch location. I was close but , your pictures were the key to finding them. Changed #6 and all is well.

  12. We have a Model V2532. Using the photos, I found the microswitches and flipped all of the ones shown on the schematic as controlling temperature (2 thru 6) one at a time, but no change in the max setting on our temperature control. Any ideas?

    • Whoa. It looks like your model is quite a bit different than mine. I found the user manual online, and it says that you should *not* alter the dip switches. It looks like they have a completely different function on your water heater, so you should probably put them back the way they were. It says that in order for you to change your temperature above 140F (which is already pretty hot), you need to use the remote control unit (and if you don’t have one, you’ll need to buy it). It also says that you need to make sure all of your faucets and recirculating units (if you have any) are turned off, otherwise you won’t be able to adjust the temperature.

    • I also have a rinnai V2532W I had to buy a different controller. I had a BC-45-4US controller on it that only went up to 120F My manual says that the MC-45-4US controller is what i needed to get to 140F I purshased one and now im getting 140F

      • Marc, hello!

        I have the same heater and just purchased the MC controller to replace the BC. Is the installation/replacement pretty straightforward? Did you have to cycle the power afterwards or do anything with dip switches to get the higher temperature? I appreciate any guidance.

  13. Thanks so much for posting this – I was just about to purchase the remote controllers for my TWO Rinnai heaters thinking it was the only way (I did not see the dip switches detail in the manual!), and happened across your blog post. My wife and I are now happily at 130 degrees.

  14. Thanks for the info mine is a model 94 but located in a similar spot easy to find with your help. I live at 5900 feet and the unit was factory set at 0-2000 feet. Again thanks for your help

  15. You, sir are a gentleman and a scholar! I just moved into my new house and was severely disappointed with the water temp. Thanks to you I don’t hate taking showers anymore! You’re just fantastic in every way! Remember that, sir!

  16. Had unit installed today, took first bath and what a disappointment for all that money spent ! Water was lukewarm. Read manual, total waste of time, found your amazing pics and in five minutes temp. set at 140 ! Thanks so much for your troubles and helping everyone out.

  17. In my manual it indicated dip switch # 5 to up the maximum water temperature which I tried to no avail and after reading this I tried dip switch # 6 and voila it work perfectly. Thank you so much.

  18. It took my son longer to take the cover off than to get the temp raised. It was so simple when he knew what to do. Thank you, I love the internet.

  19. Thank you! Your post saved me calling my plumber. We have the model RL94i. I also had to change switches #3 (I am at an elevation of 4500 ft) and #6 (allowed higher than 120 degree settings). I found the manual online which confirmed what you posted, but your pictures and explanation were really helpful.

  20. Thank you very much. The user manual was of little use. Your post was golden. 15 minute exercise….from web search to cover to dip switch to hotter water. Thank you. Now the family will stop complaining about the water temperature being too low.

  21. Thanks so much for your clear instructions and the photos. We have a Rinnai R75SL. While my husband was talking to a neighbour I removed the cover, flipped the #6 and had things back together before his return! It took less than 7 minutes, start to finish.

  22. Your post is still helping people. My cover screws were hidden by the same strip but I had to remove the whole strip to get to them but having seen yours helped me find them. And the rest was almost identical. Thanks, it saved me from sitting in my very short crawlspace with a flashlight and tools trying to reason it out. Five minute job!

  23. I followed these instructions and accomplished this in less than 10 mins. I would never have attempted without these detailed instructions. Thanks !!!

  24. I have a 2532 model. I have 2 bath controllers in the house, but no master controller. The manual says the master controller can go to 140 and the bath controller can only go to 120. I don’t find a master controller anywhere. I find the dip switches, but they no longer tell in the manual how to set them…it just says you have to call to change them–which I’m assuming will mean they’ll just tell you no. One of my bath controllers goes to 120, but the other only goes to 114. I’ve played with the dip switches some, but no matter what combination I use, the controllers top off at the same 120 or 114.

    • Wow. I don’t know anything about the model 2532. I Googled it, and it looks quite a bit different from the one I’ve got. I took a look at the user’s manual on the Rinnai website, and it seems to indicate that you won’t be able to crank it above 120 without a master controller. If you don’t have one of those, I think you’re probably stuck at the lower temperature. Can anyone with knowledge of the 2532 confirm that?

      • That’s the 2532, yup. Dip switching in and of itself doesn’t work—requires the new control box or remote.

      • Yes. You need the MC-45-4US to get above 120. But why would you want to? Certainly not to set it to 140 and leave it.

  25. I was also lost when it came to the dipswitch instructions. When I saw your post, I immediately realized what I did wrong, made the adjustment, and voila! 140 degree water! Thanks!!!

  26. Thanks so much for having taken the time to put together such a thorough step by step on how to raise the water temperature. Rinnai should reimburse you for every reply and thank you you’ve gotten.

    • Thanks, Dave. I’m guessing Rinnai isn’t *that* thrilled with my step-by-step (if they wanted it to be easy to crank up the thermostat to near-scalding temperatures, I’m sure they wouldn’t have bothered with the dip switches), but I’m glad it’s been helpful to so many people!

      Now, if I can just finish some of my other step-by-step entries. I haven’t added a new blog post in months…

  27. I see no need to go above 120, unless one wants to wash clothes in real hot water.
    I installed a V2532FFU in new 4br/3ba home in 2004 in Montana. I did a custom manifold water supply system, with water softener, with 1/2 in PEX runs to all fixtures seperately. This reduces water volume and toilet flush pressure problems.
    I set the Rinnai at 110 for showers. 104 to fill the jetted tub, and 120 for dishwasher/laundry. And then I turn on hot water only. The Rinnai can keep up with any 2 fixtures regardless of incoming water temp.
    The whole concept of on-demand hot water is that you heat the water only to the temperature that you need. Why heat it to 140 only to add cold water to cool it back down?
    My gas bill is “pleasant”.

    • I don’t know about anyone else, but we wanted the extra hot water for cleaning. When we moved into the house, it had been vacant for three years and we renovated as we went (in fact, the hot water wasn’t working for the first week we lived in the house – good times had by all). In any case, some of the cleaning/descaling products we used specifically asked for water temperatures in the 130-150 degree range, so it made sense to jack up the temperature.

      We actually turned it back down to 120 about five months ago, now that a lot of those cleaning projects are done. You’re right: that temperature is just fine for showers and most other uses; you just barely turn on the cold water tap for fine-adjusting. Not that I’ve done any sort of Mythbuster-style scientific analysis, but there doesn’t seem to be any difference in our gas bill, though. Just less risk of scalding houseguests.

  28. Awesome document! Thanks a bunch! Just got my unit installed, and it’s maxed at 120 – not quite as hot as I’d like. The owner’s manual wasn’t very clear on where to find the switches. This write-up will be tremendously helpful. Thanks!

  29. I have to follow up on my last reply. I did get it set to 140 degrees. However, had a bit of an issue with my new shower control. Apparently, there’s some sort of sensor in it that won’t allow it to run above 135 deg. So, first shower came out nice and hot but, after a few minutes running the water, the hot completely shut off. After reading the manual for the faucet, I saw the problem, and backed the heater down to 130 degrees. Still more than hot enough. Just wanted to share, in case anyone else encounters this situation.

    • Whoa. That sounds like a fancy shower. What sort is it? We occasionally have our hot water cut out on us, but it usually only happens when we run the shower in the attic. It doesn’t seem nearly fancy enough to have a shut-off in it. We always thought it had something to do with gravity (the attic shower is three floors above the hot water heater) and the low-flow shower head.

      • Your culprit is likely the low-flow showerhead, since not only do these heaters need a decent temperature differential between incoming ‘cold’ water and the desired temp of the hot water, they also need a specific flow rate or higher. If the demand for hot water tapers to a trickle, they shut off.

        So if you’re diluting the hot water with cold at the shower, and the resulting mix is at a low gallons per minute flow rate due to the showerhead restricting the flow, your hot water demand is but a fraction of that choked off flow rate, perhaps not enough to engage the heater. The solution is a bit backward… turn the water temp DOWN such that you’re pulling more hot water than cold, and the heater won’t cut out on you.

  30. Thanks, my wife was questioning the wisdom of our purchase if it meant cold showers. Amazing how much better life is with 10 more degrees of water heat.

    • I’ve gotten a couple of comments from plumbers explaining how turning the temperature up that high is a bad idea – mostly having to do with energy efficiency and the potential for getting scalded. Maybe they’re right, but I’m with you. Sometimes an extra 10 or 20 degrees makes a world of difference in the shower (especially in a cold mountain climate).

  31. You have no idea how thankful I am for this article! Thanks for the pictures also! My husband works away and we just bought a new house, so all of the immediate issues are my responsibility. Needless to say, you have been extremely helpful! 🙂

  32. Thank you so much! I just researched for a while to try to find the SWi switches and no luck and no one to call. But then I found your blog and I am so happy with my new RL75i Thanks again.

  33. With your help I found what is needed for my new RL75i and there is no one to call or any clear instructions, You are awesome!

  34. Wow, thank you! I too, scoured the manual, and those little buggers (tan dip switches) seemed to be mythical! The manual offers zero diagrams as to where they might be located. And as you mentioned, it just tells me to “flip ’em.” That’s great and all, and sounds easy enough, but you either have to be Indiana Jones to find them, or run across this blog. Thank you thank you!

  35. Thank you from having to call a repair man. My Rinnai R75LS was no longer making hot- only barely warm water at the highest (100F) setting. I found the dip switch thanks to your picture. Now it works but I have to set it to 135.. We have pretty cold ground water in the Michigan winters, perhaps the limiting factor from getting steamy hot water. Another thing I noticed is the hot water doesn’t work above a setting of 130F

  36. I own a REU-2424WC-US Commercial Rinnai tankless water heater. The remote I have on it is an MCC-45-4US. In the manual it says it can be set to either of 2 temperature ranges, 96 – 140 or 140 – 180. Out of the box it was set for 140 – 180. I didn’t need it to be that hot so I disconnected the remote controller from the water heater and fixed it at 120 degrees using DIP settings specified in the service manual. I have spoken with Rinnai’s technical support department and so far they told me by installing an MC-45-4US controller I can adjust the temperatures below 140. So I replaced the MCC-45-4US with an MC-45-4US and it still says on the controller 140 – 180. If someone knows if there are some DIP settings that need to be adjusted on the REU-2424WC-US to change the temperature range on the controller to 96 – 140, I would greatly appreciate the info. I’ve been trying to solve this problem for years.

  37. I figured it out. You can set the controllers down to that temperature. Only if Rinnai speaks directly to an authorized service provider. They won’t give that information out to the regular consumer unfortunately.

  38. Thx bud…ten minutes to hotter water and seven minutes of it was removing and re-installing the panel…..140…is much better and my dishwasher thanks you…

  39. I had to call a plumber out….expensive. So I stood next to the plumber while he spoke to their technical support over the phone and provided him the necessary DIP switch settings. After the plumber was given the settings he made the dip setting adjustments on the tankless and the remote finally displayed the 120 degree temperature it had been fixed at manually for the past 2 years. I knew at that point how to then expand the temperature range to 140 after the plumber left using the temperature dip bank numbered 4 – 8. So now my remote can adjust from 96 – 140 degrees. I later read my dishwasher manual which says it can handle hot water temperatures up to 150 degrees. So after cranking the temp up to 140 degrees before running the dishwasher, my stainless steel cutlery comes out sparking now just like yours! If Rinnai ever tells you to replace the remote on your tankless to lower the temperature range on it, its there way of saying they don’t want to share the DIP settings with you, the consumer.

    • What dip switches were changed, Sergio? I have the 2532 and the MC-91 controller, but when I change either #5 or #6, neither allow me to go past 120 degrees…

      • Were you ever able to figure this out Kevin and get your tankless to go up to 140 degrees? Do you have more specific model information for your particular unit? Instead of 2532 it should say something like REU-2532-FFU for example. And your also going to need to get a hold of the service manual written specifically for your exact model tankless unit to figure out the temperature settings as well.

    • You bet. In fact, a lot of manufacturers recommend a water softener to prevent mineral build-up. You hook it up just like you’d hook it up to a regular water heater: water comes from the city straight into the softener, then on to the water heater and the rest of the house. Works like a charm at our place.

  40. Mine does not have switches and there is a warning label mentioning a remote (can’t find one). The unit also keeps resetting itself to 104 degrees, which requires me to go up in the attic and bump up the temperature anytime we want hot water. Any ideas?

    • Hey Dennis: What model do you have? My little how-to seems to work for the R75 series, but I’m not familiar with Rinnai’s other products. Based on some of the comments I’ve gotten on this post, you might have to buy a remote from Rinnai to make any permanent changes.

  41. Aha? Had to put on my reading glasses to see the little switches. It’s putting out hot water. Any idea why it by be resetting itself to 104 degrees? Maybe it will stop doing it after moving the switch. You have been a great help, thanks.

  42. My RL94i still keeps automatically resetting to 104 degrees. I’ve tried setting to the preferred temperature, holding the Priority and Temp Up buttons down at the same time for five seconds until it locks and it still keeps doing the same thing. Have called Rinnai twice and one lady referred me to the manual (great help, lady, thanks). Has anybody else had the same issue? And quick fix solution?

  43. Here’s another thing I found in the manual Dennis. This might point you in the direction of solving your problem. It said this on page 8 of the manual posted by unexpectedvictorian earlier on the thread from, “If a newly installed unit with a remote
    controller has not been powered for
    at least 6 hours then the temperature
    will return to the default setting of
    104º F (40º C) if power is interrupted.”

  44. Thanks, Sergio.

    Although the unit allows remote controllers, we are not using them. I read the earlier post and saw it in the user’s manual but we have not had any electrical issues and it has been plugged in for three days. It’s resetting in less than an hour in most cases.

    Unit was installed with yellow and tan dip switches on (all others off). I moved yellow five to get temperature to 140 degrees and it didn’t work. Moved it back and moved yellow six and it did work. Now I have moved tan switch six to on (is that what you suggest)?

  45. Nice. My manual said switch 5 also. But I was able to determine it should say switch 6 instead. I love the internet and the way we can all share knowledge. In this case I am on the receiving end. Thank you all!

    • Switching both yellow and tan dip number six switches seems to have done the trick, have not had to reset since. The Internet is awesome for this kind of stuff. Thanks unexpectedvictorian and Sergio for all the help.

  46. I have a Rinnai 2424 and it has the same 1-8 switches as yours but is a different model. I flipped #6 and it doesn’t seem to get any hotter. Any suggestions?

      • There is a schematic on the back of the cover and I also have the manual but I can’t tell what the different switches control. There wasn’t anything that just plainly said it in Dave lauguage

    • Take a look at Sergio’s comment up above from earlier this summer. It sounds like you might need to get the dip switch info from an authorized service provider – it seems that Rinnai is hesitant to give that info out directly to consumers.

    • Is this the commercial model or the residential model PortlandDave? I have the commercial model (don’t ask why I have that on a residential unit :p) and dip switch bank #4-8 on my model control temperature. Keep in mind on my previous posts those models where dip switch #6 was adjusted were completely different (newer) models than what we have. Our 2424wc models are one of the first tankless models manufactured here in the US by Rinnai. Our models are completely different animals than the models mostly discussed here in this forum. What dip switch settings might work on these newer models might not necessarily translate (work) on our models. However I do believe your unit is capable of heating water to 140 degrees with the proper dip settings. Do I recommend running/setting a residential or commercial unit at 140 degrees without a remote controller, I strongly recommend against it. In the manual 140 degree water can cause 1st degree burns with 3 seconds of exposure.

      • I knew this heater was fairly old but I never knew how old. I assume it is residential. Age has been a concern because if I call a tech out to the house and he tells me it’s too old to repair or it needs the temperature panel and those are not available, it seems like a waste of money. It doesn’t really give a stable temperature and you can just crack the cold water when the shower is on and you are either cold or very hot. It takes a long time to get the hot water to the kitchen. I have just been thinking about putting in a tank unit…or is that blasphemy on this site?

  47. I never thought about just asking the service provider for the information. All he can do is to say no. Mine is an older one. The model can run with an external temperature control or without it and I don’t have that. I bought this thing used, installed it myself, and just got it to working…sorta. Let’s see what happens when I ask.

    Thanks for your help.

    • Hi Dave, it sounds to me like you may be bumping up against the unit’s flow detector when you open up the cold water valve. My water saving shower head reduces flow such that if it is not mostly or all open it can be very likely to cause the hot water heater to turn off. The first thing I would suggest trying is to reduce the output temperature of the Rinnai so you keep the hot water valve more open. It is an annoying issue. I have a hybrid situation in my house and did not let the tank water heater leave. I put the flow from the Rinnai into the tank water heater and it generally heats up the input water and I let the tank keep itself hot. It may sound crazy but the tank is electric and the main reason I got the Rinnai is for an endless supply of hot water. I am sure it saves me money too because gas is cheap here.

      • Just an FYI for anybody reading these posts, I am not too bright sometimes. My Rinnai water heater kept resetting itself and I had no idea why. Wasn’t until several trips up and down the attic stairs I realized the attic plug was hooked up to the light switch and every time I turned out the attic light when climbing down, I was turning off the heater. LOL.

  48. I have a Rinnai v2532QW that is 10 years old, with the controller that keeps water @ 120°. I live on the AL Gulf Coast and we are expecting temps under 10° tonight. The “Priority” light is on and I have never noticed it on before and do not understand the significance of that event. Can someone tell me what that indicator means? I have hot water but don’t know if I will have if it gets much colder and the ambient water temp drops very much lower.

    • Yes. That indicator basically means that its the master controller of all other controllers when comes to setting temperature for the hot water throughout the house when there are mutlple controllers present. So whatever tempeature your controller is set to with the priority light illuminated, that is the temperature settting for the other controllers throughout the house.

  49. To knock out the most challenging item on the honeydo list during half-time of an NFL playoff game was hugely appreciated. Had no clue how to find that # 6 SWITCH, and would have likely shut off the water, the gas, the power, crowbar opened the cover and had to call multiple service folks to clean up my mess. Thanks for making it so simple.

  50. Nearly 4 years after your post and people still benefitting from it. I completely understand that we don’t want people scalded, but isn’t there a better way to handle this problem than such a stupid approach as this??? Thanks for the help- I was getting worried when I couldn’t find the dip switches.

  51. I did all that .. But now my hot water is turn ice cold in the middle of a shower.. Do anyone know how to fix this problem.. Please help me enjoy my bathing with a hot shower

  52. I know this trhead has mainly been about temp control but I figured I’d give this issue a shot:

    Recently my RL75 has been beeping with an associated “12” errod code (no flame) displayed (and also associated freezing cold water). The Rinnai website suggests to: “check the loose connections and proper voltage on the power supply, PC board and igniter. Ensure that the burner is not clogged and igniter does not contain carbon build-up.” Another website recommended to “make sure there is no obstruction in the venting system that gas combustion chamber gets enough fresh air, and make sure the unit vents the gases out correctly.”

    Ok really? Has anyone dug into their heaters enough to know what any of that stuff even means? I know how to check for “loose connections” but seeing that it’s brand new construction and it’s been working fine for a year, I don’t think that’s it. Any suggestions on what to look for with a “clogged burner,” “carbon build-up on igniter,” or “venting obstruction”?

    Thanks in advance for any help!

    • I woudl check with the gas company. It sounds like they might have shut off your gas. That’ll generate that code sometimes. If you have a gas stove, I would check and see if any of your burners light. This is the simplest cause of this error code. For other causes I would consult a plumber/authorized Rinnai service provider.

  53. I also have 10 year old 2532 Renai model. I tried the #6 dip switch but no luck. Maybe I should use the #5?? Also when I set to 120 degrees it defaults within hours to 108 degrees. I love the Renai but need hotter water with mixing valves here in Calif. Any suggestions??

    • Any chance you figured this out for the 2532? I tried #6 switch with no help. I have the BC 45 controller and some reading leads me to having to change controllers to get above 120 so I have not tried #5 yet. Would appreciate anyone that has been successful with the Continuum 2532 model sharing their experience.

      • If you have an older 2532FFU, you need a MC-45-4US master controller. It will allow a setting of 130 and 140. No settings in between. You can find in eBay. Install in parallel with your existing controller. For instance, the BC-45 in master bath. Put the MC-45 in the kitchen or laundry. This model rinnai can have 3 controllers attached at same time. You use priority button to switch control. You really only need those temps to activate enzymes in detergents. For real efficiency, set it to only what you need. I.e. 108 for shower and turn on hot water only.
        Hope I helped.
        Love my rinnai. 11 years old ans still works like new.
        Great falls, MT

      • Thank you. That is what my research had led me to so I ordered the MC45 this morning from Amazon for cheap. Was actually planning on just replacing the BC45 with the MC45 and still only having one controller. Our issue is the mixing faucet’s in our shower I think. Hopefully we can find a balance between having the shower hot enough and not burning ourselves at one of the sinks that has a hot water only faucet.

      • If you have a pressure sensing or mixing bath faucet, they don’t place nice with on demand water heaters. If your faucet is about the same age as mine, 2004ish, you should be able to ‘reset’ it. Newish faucets sometimes have a max temp adjustment that is set to ‘normal’ by the unknowing plumber. My delta faucet is like this. What that does is mix in some cold…always. Not good with rinnai. I suggest finding the instructions for your faucet. It’s probably just a matter of removing the faucet handle and rotating the little plastic stop to ‘hot’.
        I’m nothing more than a geek who researched the crap out of this stuff a few years back.

  54. Fantastic resource author! I have an RL94, but the process is basically the same. Thank you for saving me time and money!

  55. Hello

    I rang Rinnai as I have a Rinnai 26 Infinity and I know one or a couple of the dip switches will change the max temp past 50 degrees, but there telling me it is a sequence, can you please help I tried #5 and #6 seperately but nothing, can you help please???


    • These Rinanai 26 Infinities sound like they have quite a different setup from my RL94. I found the info about dip switches in my owners manual, so I Googled around for yours and I think I found a copy here: (Please double-check this is your model, though – I’m not sure if this is right.) The information about dip switches are on pages 27 and 28 of the PDF (confusingly, they’re labeled 21 and 22 at the bottom of the pages). The right switch setup depends on your installation configuration, but this should get you started. Looks like you can adjust from 40C all the way up to 85C, depending on your exact model and installation setup. Hope this helps!

  56. I have Rinnai V2532W-US and MC-91 controller and would like to know how to increase temperature from default 120 degrees to 140 degrees. Please help. I am not able to find that information in manual.

  57. I notice a couple of post about the hot water not working when set high. This is a common problem with anti-scald shower controls , which most single control shower fixtures have built in.. They will cut the hot water flow below the heaters minimum flow. This is usually what is happening when a shower starts to get hot and then goes cold then keeps going warm/cold. Adjusting the anti-scald up if its adjustable can help but you may have to lower the heater temp setting. Some people have removed or altered the flow restrictors in the shower head to get better flow and more stable tempratures as well.

  58. I love this site and all your help. We are having a home built and they are installing a R-75 Rinnai tankless hot water heater in our garage. Neighbors who have this same thing have complained about hot water to faucets and lukewarm, never actually near 120. I am wondering if we are going to have this same problem. This site will be very helpful once we are moved in and start using the hot water. Also, it says somewhere that annually it needs “flushed” at a cost of $1500 to keep your warranty in act. Is this true? Please be here early next year so we can look to you for help if we have issues. What a blessing you are! PS this will be our first experience with a tankless. ( 2 bedroom- one level condo )

  59. Does anybody know if there is a way to reduce the required pressure on an RL94i to keep the heater going? It seems many sinks, shower heads, etc. devices to slow water flow and ours continually turns off mid-shower. The only way to get the heat back up is to turn off the cold water and wait or run two things at once.

  60. After searching the net for hours and trying to get advice direct from rinnai (who said they are unable to give advice), I came across this very useful post, great pics n so well written, tried it and now i have hot water, bless. My model is different to the one shown (V1620wb (50) – AK) but the dip switches are the same. Can you please tell me if there is any safety concerns other than people possibly getting scolded. Hmmm, the rinnai guy said something about starting a fire ??? Is #5 dip switch a lower temp? From Brisbane, Australia….

    • So glad it worked for you! As for dangers, I doubt there’s much chance that the higher heat setting will result in increased fire danger. If their product was liable to spontaneously combust, Rinnai wouldn’t even bother giving us the higher temperature as an option through dip switches. Scalding is the real problem: it only takes six seconds of exposure to water at 140F/60C. You’re much safer at temps of 120F/49C. It can still burn, but you’re talking minutes in that case – not a few seconds.

      That said, we’ve been using the higher temperature setting for… geeze, five years now? We have a lot of guests, too, and no one’s even come close to getting burned. BUT! We live in a northern latitude where our water supply is really damn chilly most of the year. I imagine your incoming water is a bit warmer down in Brisbane, so it’s worth being careful. All the same, the warmer hot water supply is really divine for washing clothes, running the dishwasher, cleaning projects, and even running hot baths in big cast iron tubs that tend to shed heat quickly. All around, we’re super glad we turn the thermostat up!

  61. Most people don’t understand. The whole concept of an on demand water heater is to heat the water to the temperature that you need and nothing more. 120 degrees is plenty hot for any household. A typical shower is only about 108 at the most. The most common reason that people want to boost the output of the rinnai is because the bath or shower is not hot enough. It is not the rinnai’s fault. It is usually because of an anti-scald fixture that was installed according to the basic instructions. This will always add cold water at the valve which, to a rinnai user, is counter productive and wastes money. These fixtures need to be adjusted contrary to the instructions in order to take full advantage of the rinnai.
    The other thing is inadequate gas supply. I have seen these water heaters connected to a 1/2 in gas supply and the home owner wonders why the water is not hot enough.
    Most homeowners want to treat on demand water heaters just like a tank water heater…set it and forget it. One must not think like that. You must interact with the water heater several times daily. It is not just about heating the water when you need it. It is about using your hot water more efficiently.
    When installed correctly you should at least have a bath controller in the master bath. I also have one in the kitchen and it can go up to 130 or 140. I never use it. You should set the rinnai for only the temperature that you want and turn on the hot water only. Here’s a concept… Want to do laundry, set it to the correct temperature for the type of laundry (whites:120, colors: 100) and tell the washer hot only. A washing machine should be the only reason one should go above 120. When I fill my jetted tub, I set it to 106. Remember, any time cold water is added to the hot water that you just paid good money to heat, you are wasting energy.

    I’m trying to be helpful here and before y’all start raggin about my incoming water temp or whatever, I live in Montana. My water is cold. The rinnai is all about temperature rise, not output temperature. Has anyone ever measured the water temp on your fixtures? I have and my rinnai is accurate…and I can not get in a 120 degree shower. No way.

    Really hope I can help somebody out there
    Great Falls, MT

  62. How do you switch from Celsius to Fahrenheit? I pushed the buttons to read the most recent error code (my unit was beeping, error code was 12), and now the temperature reads Celsius. Can’t find it in the owners manual.

  63. I appreciated the step by step instructions & pictures, but unfortunately it did not work for me. The water was hot, then cold, hot, then cold… then only cold. I read several posts about not needing water above 120, but my water isn’t hot enough to wash dishes, take a bath or a shower. After reading many of these posts, it makes me wonder if my faucets & shower heads have that anti-scald limitation (cause the water is definitely not 120. I can stand under shower head, turned all the way to hot, and not get scalded or burned – my skin doesn’t even turn pink/red). I have to boil water to wash dishes. I’ll check with the faucet manufacturer about the anti-scald, then go from there.

  64. We just moved into our new home and the water temperature from the Rinnai tankless heater was way cooler than we like. Your pictures helped very much and I was able to do thanks to your instructions. One note, the model we have had different plastic access tabs to get to the cover screws, they are full length of the unit and you have to slide them away (horizontally) to remove them. There are three small tabs on each sides full length access tab, they come off pretty easily and putting them on was also easy, but they are not very heavy duty, treat them gently. Thanks for the help!!!.

  65. Well this may bee an old post BUT IT WAS A GREAT ONE !!! THANK YOU.. My plumber said he could adjust it but I could, just pop off cover and flip a switch. Gee that sounds like what I read in the book !!! Your step by step photos were perfect to follow… BINGO I ADJUSTED IT TO 130… YEAH We won’t mention that I happen to drop on of the screws in my cat box [it sits underneath the unit].. Oh well I fill find it tonight when I clean the box 🙂

  66. Thank you so much! This greatly helped! We are replacing our original tankless heater and are already impressed with how quiet this one is.

  67. I cut the number 6 switch on to get the team to 140. The number 1 switch was already on. Do I leave it on or shut it off


  68. I have the Rennai, model # V53e and would like to adjust my water temperature up from the default setting. I found the dip switches but have not touched them since most of the conversation did not mention my model #. I’m asking if I should flip #5 or #6 for this model. We moved in two months ago and my wife is not satisfied with the water temperature.

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