Sizing a Rinnai tankless heater

This is a another question I get asked a lot by different contractors and homeowners.
Here is a list of the Rinnai unites and what there good for.
V5.3 - 1 bath and 1 kitchen
V6.5 - 2 baths and 1 kitchen
V or RL 7.5 3 - baths and 1 kitchen
V or RL 9.4 4- baths and 1 Kitchen
RU 160- 3 baths and 1 kitchen
RU 199- 4 baths and 1 kitchen
RUR 160 - 3 baths and 1 kitchen
RUR 199 - 4 baths and 1 kitchen
This should give you a good guide in the correct size for you needs.
If you would like to ask a question or would like to get a Rinnai guy sticker please e mail me at [e-mail]
I hope you enjoy this video,
Mike
PLEASE USE A LICENSED PLUMBER TRAINES IN RINNAI LEVEL THREE TRAINING. FOLLOW ALL STATE AND NATIONAL PLUMBING AND GAS CODES AND TO FILE A PERMIT AND OBTAIN AN INSPECTION FROM YOUR LOCAL BUILDING DEPARTMENT.

[@oneslickguy]

Awesome video, Mike always takes the time. Spent over 1/2 hour on the phone with a random person (me) after an email to him. Thankful to have such an expert in the industry.

[@TheBuddylab]

Thank you very much

[@ryanlinton9123]

This guy is as good as they come! Anytime I call with questions he’s always available with expert advice! Thanks Mike!!

[@ThatTanklessGuy]

No problem

[@abhinavgaur13]

Mike advised me a third time over phone when I had a question regarding gas pipe sizing for my Rinnai .. It was very detailed and informative. Thanks Mike.. You are among the few popular youtubers who walk the talk of helping out their subscribers.. Much appreciated !! :)

[@cbaykal001]

great video Mike. thanks for the guidance you provided me . My RUR 160 is still running and no issues with 3B & 1K sufficient.

[@TheBuddylab]

Thank you very much I’m glad I could help

[@digitalQ33]

Hi Mike - Just a quick note to let you know I purchased an RL94i unit because of all your great videos. Installation was flawless, love the unit, thank you & keep up the great work!

[@toms.7194]

WOW, Mike you and your videos are awsome. Just talked to you about my Rinnai RL75IP which I will install in my remote Alaska cabin. Now I have all the answers I need. Thanks again for your help. Maybe a short specific video in the future about installing a propane version of the Rinnai with a 100 lbs bottle outside the cabin would be very helpful for some Rinnai-Users. Thank you so much, keep up the great work.

[@mikec2473]

Good detailed information as always.

[@TheBuddylab]

Thank you very much

[@KenTarrant]

Love your videos Mike. Hi from Newfoundland, Canada. I have a 98RUCi propane and waiting on delivery of the Hugo backup all the way from California! I think I will add a bigger battery though probably a 55 amp hour if it will fit.

[@ThatTanklessGuy]

great unit that my house the video was shot at. he also has a larger unit called a Sigma

[@ScottHill-cd3ie]

Hi Mike - Have watched many of your Rinnai videos and appreciate all your excellent information. Working on home that has 2 Kitchens (1 Kitchen not used that much - both have dishwashers), 1 bathroom with double sink/double shower, and 3 other bathrooms with single showers. 1 cloths washer. 1 single bathroom with no shower. There are also 2 garages each with a hot water suspended heaters, 33,000 btu maximum per units. Would like to see if there is an arrangement that you might recommend for something like this? The home currently has a large preheated water storage tank (coming from geo units) and then a large 80 gallon electric hot water tank. Can provide more details if this is something you might want to chime in on. Thank you.

[@mike-md]

Great job Mike! Thanks for taking the time!

[@danielsimas4101]

Mike, I’m looking to install an RU180 or the RU199 because I’m concerned about the colder New England winters. The home is rented to students and ABNB during the summer. It’s a four bedroom, two full baths, laundry and laundry sink, with a full kitchen on the upper floor and a kitchenette on the ground floor. I didn’t get the recirculate model only because the utility room is central to the home and not at either end; so the runs are equidistant. Which unit is better and if needed could I add a recirculating feature late if it’s an issue

[@ThatTanklessGuy]

I would go with the RU199 that would work great, but if you were considering recirculating in the future get the RUR199 it would be Cheever in the long run. I hope this helped. Mike

[@patrickwalsh7790]

Hi Mike, I know the groundwater temperature is a lot colder in New Hampshire than Florida... do you think an rucs75ip would be adequate for two full baths and a kitchen. plan to set it at 120 degrees. according to the rinnai groundwater temp map NH is in the 42 degree zone. thanks for your help

[@TheBuddylab]

Yes it would be sufficient

[@patrickwalsh7790]

@@TheBuddylab thank you

[@KenTarrant]

Hi Mike, I have a water softener do you still think it's necessary to flush the heat exchanger. It was installed in 2017. Is there a interval for burner cleaning?

[@mikepatchak4650]

Mike I installed a RU199I with a dedicated 3/4" circulation line and an GTK15 pump. The heater works great but the water is not circulating through my loop. The pump is running and the pipe at the pump and atleast 20' heats up. but the hot water doesnt' get through the whole loop. I am starting to think my loop is to long and has numerous pex fittings. What can I do to get water through the system?

[@Sylvan_dB]

I'm considering a Rinnai RU199IN to replace a Voyager 130K BTUH 45 gallon tank which provides domestic hot water and hydronic air handler heat. The system was designed for 160F (normal winter) to 180F water so I think I need to add the commercial controller for higher temperatures (I have a mixing valve for the DHW). 52F supply water temperature. Maybe I need a buffer/storage tank? Hard water (about 12gpg but varies by season) and 45 year old steel pipe in the rest of the house and not anxious to add a softener until I repipe. Is there any problem with using a polyphosphate treatment on the cold feed to the hot water? Recommend a different approach? Is this a sane plan?

[@ThatTanklessGuy]

Call me at [phone] tomorrow after 5pm eastern time and I will go over it with you Mike

[@jeffreyferland313]

Hi Mike! Great videos. Should I be considering a tankless if where I live has cold winters and colder water from the taps? I live close to Toronto so it is not Florida. What has been your feedback about this? Which unit do you recommend if any. I have 4 baths with one extra big tub and one kitchen. There are 4 of us living in the house which like long hot showers. Oh yeah and we also hand wash a lot of dishes. We also like the idea of being able to fill the large Kiddie pool in the back from time to time.

[@retiredperson4054]

What about sizing for a home with 3 baths with showers, 1 kitchen (with Dishwasher) AND under-slab radiant heating PEX system (for the basement family room)? What Condensing unit would you recommend? Don't want to be an "Uncle Bob"!

[@ThatTanklessGuy]

I would use an I series boiler the 150,000 BTU unit

[@retiredperson4054]

@@ThatTanklessGuy Will that 150K Rinnai Boiler serve as both domestic hot water heater and provide the under-slab heat for a 28x40 foot (1,120 square feet) basement floor? Double checking to be sure as the Rinnai site for that says "Heat Only"... Not sure what that means?

[@retiredperson4054]

@@ThatTanklessGuy I looked at the Rinnai website the 1 Series Boiler 150 K is NOT a combination unit --- the next sized i series boiler that is a combination boiler/domestic water heater is the I series i120CN.

[@theplumber585]

Hey Mike if you are installing a tankless water heater for a small restaurant do you recommend using a small un energized buffer tank? I was told to make sure I use an expansion tank if there is a hand spray at the dish pit. Ill be installing the CU199iN.

[@ThatTanklessGuy]

You definitely need a expansion tank but no buffer tank.do you have a dishwasher and if you do how big is it. In restaurants I install CU 199 heaters there commercial where a RUR199 is more for residential

[@theplumber585]

@@ThatTanklessGuy Yes there is a dishwasher is only uses 1.1 GPM and another small one that uses less than one. I was told that the hand rinse on/off and be trouble some for the on demands. Thanks for getting back!

[@robl3505]

Hey Mike, builder is putting in a Rinnai RE160 for a 3 bath 1 kitchen house is this big enough? I didn’t hear you mention the RE series in the video

[@ThatTanklessGuy]

That's to small it should be at least a RX199

[@scraig5218]

Hello Mike. First, let me say that your channel is extremely informative and greatly appreciated. I would like to speak with you about replacing a 75 gal AO Smith pro max, with (2) RL75s or (2) RL94s and using the ez connect. There is a dedicated 1/2” recirculating line. Maybe there are different models you would suggest. I can email or call at your convenience. Thank you

[@pegh18]

Hi Mike - Thanks for this video. It's so helpful! We just installed a Rinnai RU180 I in a house built in 1982 which we just bought and are renovating. Location: Hendersonville NC (elevation 2200 ft). It's a 3375 sq ft 2 story brick home. The Rinnai unit is not getting the water as hot as the old (1982!) tank water heater did. My plumber adjusted the unit to 140 degrees and that helped a little. He also put heat tapes and insulation around all the new pex piping he just ran. It's still barely warm enough for a shower. We currently have only 1 shower operating and are renovating 2 additional baths. I'm concerned we won't have enough hot water for 2 or 3 showers to be operating at once. What might be the solution??? Thank you in advance for any help you can offer. -- Peg

[@kgabest]

Hi there, my contractor is going to install a RU199 for my 2.5 bath, 1 kitchen house. Base on this video it is overcapacity. Will this cause any issues? Thank you.

[@jimmyrobinson6372]

Witch do you recommend a tankless inside or outside of the home?