Plumbing

Plumbing questions? Ask a plumber and get answers ASAP.

Ask an Expert,
Get an Answer ASAP!

This answer was rated:

I have Rinnai RUCS75 tankless water heater and I need to…

I have Rinnai RUCS75...

I have Rinnai RUCS75 tankless water heater and I need to know the dip switch settings to get the maximum heat output because I cannot run a bath or shower or any 2 faucets at the same time and get hot water out. This has been extremely stressful. I need hot water for my family. Please help.

Contractor's Assistant: Did you double-check the thermostat's settings? And what about the filters?

There is no thermostat control.

Contractor's Assistant: Do you plan on doing the work yourself?

I've already installed it and just need to know which switches to turn on. So yes.

Contractor's Assistant: Anything else we should know to help you best?

Just the switch settings to get the maximum efficiency please.

Show More
Show Less
Ask Your Own Plumbing Question
Answered in 1 hour by:
3/10/2018
Mike R.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 3,149
Experience: 20 years of plumbing experience, including high end homes and service work.
Verified

Hi, I'm Mike and I have 20+ years of experience in the home improvement field. I'll be glad to assist you today.

Ask Your Own Plumbing Question

Is this a new installation or existing? Have you already referred to the manual for the dip switch settings and adjusted them?

Ask Your Own Plumbing Question

Are you getting consistent hot water just not hot enough or is it intermittently hot and warm?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
It's a new install. The temperature is only consistent with small faucets with a limited volume flow and it is only warm. When I run the bath or shower it's cold and it's obvious that it's not hot enough to keep up with the volume.
Customer reply replied 4 months ago
I've been searching and have found that a lot of people have this same issue with tankless heaters. The factory settings are set at a low temperature for safety reasons. I have found the answer to my problem with other brands and models but not mine.
Customer reply replied 4 months ago
When I get warm water out of a faucet I have only the hot valve on 100% and it's still nowhere near ideal.

The temperature is consistent though? The dip switch settings are in the manual. Do you have it? The water flow is much lower for hot water than cold water?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
I recently installed a new kitchen sink faucet with a color changing LED sprayer that ranges from blue to green to red based on the temperature of the water. It has flickered into the red a few times for only a brief second. This should give you an idea that the water is not hot by any factory standard.

The water should still be pretty warm even on the factory setting. There may be other issues that are causing this. Do you have the manual to refer to the dip switch settings? Did you install the water heater yourself? When opening a sink faucet, is the hot water flow much lower than the cold?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
I have the manual but it isn't helpful at all. It only talks about flipping 1 of the switches if it's in a high altitude location. No, the flow/ pressure is the same as the cold valve.
Customer reply replied 4 months ago
It's only warm when only the hot valve is open. Does not get hot.

Do you have the manual with you? Will you look at page 54 and see if it has temperature dip switch settings there? I have a manual here but just want to confirm it is the correct one.

Ask Your Own Plumbing Question

I do have the picture. Do you have the manual and are the temperature dip switch settings on page 54 of that manual?

Ask Your Own Plumbing Question

That is just the quick reference guide. Do you not have the full manual?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
I'm looking for it. I think my fiance must have put it away somewhere.

I see. Do you also have the optional temperature controller or no? Or is there a display on the unit? Some have the display and some do not and the controller is optional.

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
No controller. Just a 2 digit digital display.

What is the current maximum temperature setting on the display?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
It does not tell temperature. There are no buttons. When I turn the water on it only displays " 1 "

Oh, alright. There are a few different models of Rinnai water heaters. It is hard to wrap my head around which one it is sometimes. So, in the manual (when you find it) the switches on SW1 should be SW5 on SW6 on to set it to 140 degrees but certainly confirm in the manual. That should be on page 54 of the manual. Right now it looks like it is set for 120 degrees but even at 120 it should get better than warm. Was this water heater a replacement for a tank water heater?

Ask Your Own Plumbing Question

What size and type is the gas line on the water heater? Is it natural gas or propane?

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
it replaced a tank heater. Natural gas. I used a 3/4" gas line because I know 1/2" isn't enough.

Flex line or black iron? Is the gas pipe coming directly from the meter and how long is the line?

Ask Your Own Plumbing Question

Very good. So it was just the settings. I wanted to be sure that it was not something else like fuel etc. Technically the gas line is still too small but it does not mean that it will not work just fine. The inner diameter of 3/4 flex line is smaller than black iron. If you do start to have issues with error codes relating to failed firing that would be where to start but chances are it will be totally fine and not cause an issue at all.

Ask Your Own Plumbing Question
Customer reply replied 4 months ago
I'm so happy! My fiance is too! Now she can take a hot bath. We are so grateful. Thank you thank you thank you!

You are very welcome. If anything else comes up I am happy to continue to help even after positively rating my service. Happy hot watering!

Mike R.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 3,149
Experience: 20 years of plumbing experience, including high end homes and service work.
Verified
Mike R. and 87 other Plumbing Specialists are ready to help you
Ask your own question now
Customer reply replied 4 months ago
I just noticed that the iron pipe gas line is only 1/2"
Should I redo all fittings back to where I can do 3/4" or is 1/2 plenty?

The iron pipe size is actually has the same inner diameter as the 3/4" flex. It should be fine but if you do have problems in the future you know where to start. You may actually have an oversized meter and excellent gas pressure that will keep it running fine.

Ask Your Own Plumbing Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a plumberLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Mike R. Your Own Question
Mike R.
Mike R.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 3,149
3,149 Satisfied Customers
Experience: 20 years of plumbing experience, including high end homes and service work.

Mike R. is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Marc

Marc

Plumber

1,127 satisfied customers

Plumbing heating & home maintenance contractor

Jerry

Jerry

Plumber

786 satisfied customers

over 20 years residential plumbing experience.

Theplumber717

Theplumber717

Plumber, Hvac Tech

656 satisfied customers

Lic Plumbing contractor, 28/yrs res,com,repair,Universal HVAC Tech

Phil

Phil

Mechanical Engineer.

632 satisfied customers

Retired mech. contractor, shop owner, 51 yrs experience.

Mario

Mario

Master Plumber

604 satisfied customers

Master Plumber, Fire Sprinkler, and Jobbing Spec.

Bud

Bud

Plumber

538 satisfied customers

22 Years Field Experience - 17 Years Business Ownership - Residential or Light Commercial

Rick Mather

Rick Mather

Building Inspector

498 satisfied customers

Assistant Building Official, HVAC Tech

< Previous | Next >

Related Plumbing Questions
Need a water heater recommendation for my garage in slab
Need a water heater recommendation for my garage in slab heatingPlease see attached document for btu requirements… read more
Rick
Rick
Supervisor
24,233 satisfied customers
I have a new rinnai v53 outdoor tankless heater feeding a
I have a new rinnai v53 outdoor tankless heater feeding a sink, inside shower and outside shower. It works only if shower head is removed or on full blast, if you try and make it warm not hot by and c… read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,710 satisfied customers
We have a tankless water heater from Rinnai located in our
We have a tankless water heater from Rinnai located in our attic. It takes 60 seconds to get water to our shower or faucets in our master bath which is located right below the water heater. Also about… read more
Mike R.
Mike R.
Plumber
3,149 satisfied customers
Turned on sink faucet (full on) - no hot water after 4
turned on sink faucet (full on) - no hot water after 4 minutes, then also turned on 2nd faucet - hot water finally started flowing. flow sensor switch problem?… read more
Rick
Rick
Supervisor
24,233 satisfied customers
Water flow completely stopped coming out when the hot water
Water flow completely stopped coming out when the hot water faucet is turned on. Could there have been some overload? Washer and bath was working momentarily before. Just all water flow stopped on hot… read more
Mike R.
Mike R.
Plumber
3,149 satisfied customers
How do I identify and order a Rinnai water flow sensor?
I have a Rinnai Tankless Water Heater RU80i. The diagram that came with my unit shows Dip Switch settings for RU80i/LPG. However, the illustration provided for the Water Flow Sensor Assembly does not … read more
Mike R.
Mike R.
Plumber
3,149 satisfied customers
I need a tankless natural gas hot water heater. After much
I need a tankless natural gas hot water heater. After much Internet research and Talking to people , I have about chosen the Rinnai R98i model. I found a seemingly better brand and Model but Price did… read more
Hauserplb
Hauserplb
Associate Degree
340 satisfied customers
6 unit apartment. Dishwasher in each. No laundry except 1 75
6 unit apartment. Dishwasher in each. No laundry except 1 75 gal wtr htr died. Put in 10gpm rinnai tankless. Will this be enough? If I upsiZe basement pipes from half to 3/4 will it help....or do I ne… read more
qwasert
qwasert
Residential Journeyman Plumber
Vocational, Technical or Trade Scho
543 satisfied customers
We have a Rheem sealed gas water heater approximately 7 years
We have a Rheem sealed gas water heater approximately 7 years old that runs out of hot water after about a 15 minute shower. Is there any way to repair this unit or is it on its last legs so we need t… read more
Rick
Rick
Supervisor
24,233 satisfied customers
Just in the past few weeks, weve been getting spurts of cold
Just in the past few weeks, we've been getting spurts of cold water in our faucets and shower, and have no idea what could be causing it. It happens right after the pump tank cuts on. We've replaced t… read more
Theplumber717
Theplumber717
Plumber, Hvac Tech
Vocational, Technical or Trade Scho
656 satisfied customers
Sometimes when taking a shower, i get cooler water if not cold
Sometimes when taking a shower, i get cooler water if not cold water for a moment or two, then water temperature is ok again. Is there some maintenance I need to do to the water heater to prevent this… read more
Jerry
Jerry
Plumber
High School or GED
786 satisfied customers
I am having trouble with my Rinnai tankless hot water system.
I am having trouble with my Rinnai tankless hot water system. I am getting hot water in my showers and sinks, but in the bath tubs it only gets hot for a minute or two and then gets cold.… read more
Plumbing Pro
Plumbing Pro
Licensed Plumbing Contarctor
Vocational, Technical or Trade Scho
1,248 satisfied customers
I have a fairly new Rinnai R 53 tankless hot water heater,
I have a fairly new Rinnai R 53 tankless hot water heater, I had it put in 2007 when I bought the house.its a ver small house with one tiny bath room. I have been working on the following issue for a … read more
Plumbing Pro
Plumbing Pro
Licensed Plumbing Contarctor
Vocational, Technical or Trade Scho
1,248 satisfied customers
have a rinnai infinity controller with a rinnai 24 water heater,
have a rinnai infinity controller with a rinnai 24 water heater, family of five dont have long showers water temp is set at 55 to me it is not hot at all i would class it as tepid and as for the gas u… read more
Plumbing Pro
Plumbing Pro
Licensed Plumbing Contarctor
Vocational, Technical or Trade Scho
1,248 satisfied customers
We have a tankless R85 Rinnai water heater. We love it. However,
We have a tankless R85 Rinnai water heater. We love it. However, it seems that the heater shuts off if the water flow isn't high. Is there any way we can adjust it so that the heater keeps heating eve… read more
cruzmark
cruzmark
Foreman
Vocational, Technical or Trade Scho
I have installed a new shower faucet in the bath room upstairs.
I have installed a new shower faucet in the bath room upstairs. A plumber did this. I also had another plumber can and istall an new tankless water tank to replace the 2 regular gas hot water tanks. T… read more
cruzmark
cruzmark
Foreman
Vocational, Technical or Trade Scho
i have a tankless hot water sytem using my oil burner. I cannot
i have a tankless hot water sytem using my oil burner. I cannot get a full tub of hot water in the bath on the 2nd floor. What is the best way to adjust the valving to improve the situation?… read more
Rightway Plumbing
Rightway Plumbing
Owner
Vocational, Technical or Trade Scho
228 satisfied customers
I have an American Standard 1040 series shower tub valve in
I have an American Standard 1040 series shower tub valve in my house. The hot water from our water heater works fine for everything in the house but the bath tub. The adjustment screw is all the way o… read more
service tech72
service tech72
Vocational, Technical or Trade Scho
141 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x