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 Rinnai tankless water heater noise
Author: swhiting (FL)

My tankless water heater started making a horrible noise when activated. The noise is like the unit is about to shake off the wall. It's mostly noise from vibration of the unit. It lasts several seconds at start-up, then quits.

Any ideas?

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 Re: Rinnai tankless water heater noise
Author: redwood (CT)

I would call an Rinnai Authorized Service Tech. to diagnose and repair the problem.

[www.foreverhotwater.com]

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 Re: Rinnai tankless water heater noise
Author: m & m (MD)

Have a Rinnai tech check it out. It could be dirt/sediment in the flow sensor area which in turn modulates the gas input. If so, it could lead to bigger problems. Do you have a sediment filter on the cold water inlet to the heater?

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 Re: Rinnai tankless water heater noise
Author: joint-runner (MA)

Wheres Scott...when theres a post "should I buy" he chimes right in.Did you try an call Rinnai swhiting?...Hey Red..when you puttin in your tankless?

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 Re: Rinnai tankless water heater noise
Author: redwood (CT)

No Gas here! I wish... I wish... The electric co. is a bigger bunch of thieves than the OPEC crowd ever was! Atomic power... Too Cheap to Meter! I've got a 70's condo! I should dumped a year and a half ago while prices were insane!

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 Re: Rinnai tankless water heater noise
Author: hj (AZ)

Usually that would be a sign of high flame and low flow causing the water to turn to steam in the unit. If so, then the unit has to be diagnosed to find out what is malfunctioning.

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 Re: Rinnai tankless water heater noise
Author: juli (IA)

Hi, I'm having this same problem on a brand new Rinnai heater, what did you discover the problem was?

Thanks
Juli

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 Re: Rinnai tankless water heater noise
Author: gimp (CA)

Could be two things...The venting may not be completely assembled/attached causing the combustion products and fresh air mixing. OR, it could be the combustion fan unit has something in it causing an out of balance wobble. I have found lizards in the fan causing it to make noise. Or wasps or insects. It doesn't take much to go cause a vibration.

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 Re: Rinnai tankless water heater noise
Author: happyras (WA)

My new Rinnai R75Lsi also has extreme vibration at high water flow. It does not vibrate until high flow and high flame, typical of a shower or washing machine fill cycle. I suspected that this fan is being over driven and going into a surge point. I checked the fan inlet and could not find any foreign objects, checked the water inlet strainer with no debris, increased my gas pressure from 5.5" WC to 9.0" WC, and still get the vibration. My one inch pipe run of 30 feet from the meter is more than adequate for 200KBtu. The short combustion vent run is one 90 and one straight 19 inch length out the wall. Removing and or extending the vent, or restricting the intake does not make any real difference. The dip switch settings are all correct, per the installation guide, however there is no Service Manual available to really trouble shoot this unit. I have seen others address vibration with isolation mounts, however I have to believe that this is a controls issue. Does the gas control loop feedback via flame temperature sensors and go into some sort of harmonic hunting? Is there a way to dampen the response on this control? It would be nice to have all the data on this unit. The installation guide is very minimal. There are know real experts here in my state, only installers.

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 Re: Rinnai tankless water heater noise
Author: timed (CA)

happyras-did you solve this problem. I just install a R94LS and am having the same problem. It seems like there is a problem with the exhaust blower or some adjustment to it seems necessary.

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 Re: Rinnai tankless water heater noise
Author: happyras (WA)

Well this seems to be a typical problem that know one wants to admit. Yes the problem is easily solved, at least in most cases. If the home does not have a pressure reducing valve, or if it is defective/set too high, the Rinnai will create this horrible vibration within the exchanger. Installing a proper sized regulator on the cold side prior to the unit is the solution. Typical set point should be 50 psi. You can first put a gauge on the hose bib and see what pressure your getting on the cold water system. Mine was 75 to 80. It seems that Rinnai has a maximum inlet pressure of 150 psi, but this does not mean it will run right at even 80 psi. Now, who else had to figure this one out themselves?

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 Re: Rinnai tankless water heater noise
Author: happyras (WA)

So running with a pressure regulator does work to nearly eliminate the vibration if you set it low enough, but this is just not a good solution. More pressure is needed at the unit to overcome the 50 plus feet of line and fitting loss (8 psi+) and 20 feet of head to the upper floors (6 psi+). Setting the inlet to 45 psi, means about 30 psi upstairs on the third level shower. It just does not make for a happy wife with low shower pressure. I am seeing this to be a common issue with many of these Rinnai units, but also with other brands on other sites. Many have suggested isolation of the piping using hose flex pipe. However, you would think the PEX piping would do the trick, along with the anchoring of the unit to the concrete wall. So I am back to the inlet flow control being the issue. Rinnai technical has no service bullitins, or mention of this issue in their troubleshooting guide. With no error codes, there is no problem! Gas flow regulation is OK per check out procedures. Local installing tech is stumped, anyone not?

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 Re: Rinnai tankless water heater noise
Author: Joe W (IL)

Service Manuals are reserved for Service Personnel not DIYer's. While you may think you know a lot, you're still untrained. You can screw one of these up so bad even the factory might not get it right again.
Vibrations come from a lack of fuel or off fuel/air ratio at burn or power level.
Generally due to lack of gas volume (not pressure) but can also be caused by the fuel/air ratio off at low burn or max burn.
Some Mfrs adjust with old fashion ADJ screws and a Combustion Gas Analyzer (you want to spend $500-1300.00 for one of these), other have the adjustment in the Controller but you need a laptop and the software to get in or others use up/down buttons and diagnose themselves through the Controller/Computer.
Noise you're hearing is a rumble complete with vibration. Transient sometimes at start up and/or shutdown, worse harder to pinpoint when it's intermittent.
Your Mfrs Regional Office should have a Tech that can fix this. I mean direct Mfrs office not just Mfrs Sales Reps (different). Also your Region should have someone like me available. I service Bosch, Noritz, Takagi and Rinnai for going on 5-6 yrs now so I've had to learn to stay in this competitive business. All you have to do is be willing to go to the Mfrs HQ or regional classes for hours or days, sit through Level I, II and III classes, go back annually for remedial, new model or refresher classes.
Read all the manuals they give you and request additional clarification from Mfr's Regional Tech or FE where you need it. SIMPLE.
Note this can happen even if your Gas Pressure and Gas Line Sizing are correct.

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 Re: Rinnai tankless water heater noise
Author: isitdav (VA)

All good advice! For a weekend house the plumber installed a Rinnai 75 LSI and from the start there were vibration problems. Found some problems with the vent/intake pipe had become disconnected to the outside cover w/ error code 12 and would not stay running. With this corrected there was excessive vibration and a "drumming" noise. After inspection for obstructions and debris in the blower housing and air supply that were negative the Mfg. sent another assy. This I installed and it is much more quiet. However the way these are mounted and in my case, to a plywood utility wall common to the bathroom, does make a difference. The plywood transmits the sound to the whole wall and thus into the adjacent room. Had it been installed on two studs it would have been quieter. So now I am about to re-mount using shear shock mounts...

Any ideas where to get these or is there a simpler mounting solution?

Additionally, if there is excessive wind or turbulence blowing over the outside vent fitting will increase unit noise too.

Regards

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 Re: Rinnai tankless water heater noise
Author: happyras (WA)

I appreciate your thorough and open answer to this issue. I have had so called techs come out and they have no clue how to adjust the air fuel ratio. I suspect they are not trained, just installers. I had the gas company inspect the volume and pressure available. With a 1 inch line at a confirmed 7 inches WC, that runs 20 feet to within 5 feet of the Rinnai followed by 3/4 inch line to the unit, they confirmed I was good for up to 300,000 BTU with my current meter. I need 180,000 BTU for full flow service at the Rinnai, and my lines are sufficient. There is a 1/2 inch WC drop accross the meter. They installed a newer style pressure regulator to be certain, but suggeted a meter upgrade from a 175-250 to a 400 CFH model due to the other potential loads on my propery. However this came with a cost of $800 for the meter and $8,000 for the new line on my property. You see, the gas company installed a 5/8 line feeding the meter at 48 psi. However this line, over the 200 plus feet from the main (1.25), is only capable of handling 300,000 BTU of flow. I am convinced that I have sufficient flow and pressure, just not to service everything at once. With that said, I am searching for a real tech that is properly tranined to come adjust my unit with Rinnai tech support. I just can't seem to find one here in the NW. Many claim to be. I have installed many industrial flame control systems on industrial dryers, boilers and air drying hoods, brankd such as Hauk etc, but as you stated, you just need the right tools and training for the device. I always get a factory trained tech for start up. I write this for others to know, it is critical to get a properly trained person to fix this problem. I just wish I could find one locally myself.

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 Re: Rinnai tankless water heater noise
Author: stevieray (CT)

I just installed my Rinnai R75lsi with a 3/4 gas line 5 feet from the 1" main 7 feet from the meter. I started with 7"wc, then increased it to 9.5"wc on a 250 cuft/hr meter. I'm having the exact same problems as Happyras. My water pressure is 75psi, 3/4" copper line. The exhaust vent is 20" long with 1 90degree elbow. The vibration is only when I use the tub and only for about 10 seconds. I will let you know what I find out about fixing this problem.



Edited 1 times.

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 Re: Rinnai tankless water heater noise
Author: happyras (WA)

An old problem, but still a problem. I just helped my lead piping designer install a GE/Rinnai (relabled 94). The installation was flawless, and Neo Industrial. We came close to using flanges to avoid unions. The unit fired perfectly and tested with proper flame control under all flow conditions. No noise.

Close to ripping mine out and buying a new one! Boy this made me reconsider the issues with my Rinnai. I realized my high fire flame is in fact wrong since day one, nice tech support from Rinnai. NOT a single tech in the entire area able to come out and adjust this. So, today I choked the 3/4 inch gas inlet until the flame looked proper, while running full open to the drain, and measured the manifold pressure to spec. Amazing the noise did quit.

I was able to raise the water temp set point, and still get plenty of flow with the choked gas inlet flow. All this time, thinking the techs were right and I had insufficient flow of gas, when in fact it is simply the flame high fire adjustment, boiling the water. Too much manifold pressure.

So, with that said, I guess I need to retire, take some Rinnai training and fill this gap in the market. I did the mechanical engineers solution to control by choking the manual valve to limit pressure at choked flow, since I have no idea how to set the pressure on this modulating control valve. I assume it is controled via the PC board and requires a laptop interface. What happened to the old KISS principle?

In the mean time if someone who can adjust this properly appears, they can adjust mine. I hope this helps someone else abandoned by Rinnai.

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 Re: Rinnai tankless water heater noise
Author: The gas man (SC)

Hi,
I am a Service Technician / Installer. I work for a local Natural Gas company in the South East. I have been reading your post and was wondering why you had to use the service valve to adjust pressure in the Machine. You should be able to adjust the pressure by using a digital manometer and using the potentiometer just above th dipswitches to adjust the high and low fire pressures. This should be the way to adjust the right way. If you need help doing so just e-mail me at dadtodc@gmail.com, or reply to this post.

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 Re: Rinnai tankless water heater noise
Author: hvacsystems (IL)

Throttle down gas pressure at valve suppying gas to unit, Its being oversupplied, do it when unit is making noise

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 Re: Rinnai tankless water heater noise
Author: Bolt-On (WY)

I had a sound in my Rinnai that was like a small pancake air compressor amplified. The whole unit was vibrating strongly. It turned out to be a mouse in the draft inducer fan. It was simple to remove the fan and mouse. Problem solved. It should have come with a screen on the outer ring of the concentric vent fitting. I would install a screen if I kept this unit.

I have concluded the Rinnai is not worth using. I have had unstable water temperature, random shutoffs when filling a tub, scale build-up and error codes, and vinegar flushes to deal with. Now I needed to disassemble the unit to remove a mouse. I am installing a traditional tank type heater tomorrow. The Rinnai is too twitchy for me.

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 Re: Rinnai tankless water heater noise
Author: JM (MA)

I had the same noise. Sounds like a plane doing a fly over. I pulled out the combustion fan and blew it out with compressed air didn't make it spin too fast. Then blew out air intake. Seems to have stopped the noise. Worth a shot. Good Luck. (Update) Sorry guys thought I fixed it with clean out. Next morning it was back. So I cleaned the screen (not much in there), and changed my whole house filter. seems to be fixed. We'll see.



Edited 1 times.

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 Re: Rinnai tankless water heater noise
Author: Starkvegas (MS)

Had same problem with Rinnai 75. Only vibrated when master tub ran wide open (high hot water velocity/rate). Struggled for a year or so just opening faucet to the point just before vibration, but was inconvenient and slow to fill tub for my wife. Figured it was throwing out too much heat and flame when wide open, thereby causing steam burps. Water pressure at unit is 75-90psi, depending on time of year. Couldn't find or figure out how to throttle back gas feed with an adjustment in the unit. Finally tried closing the gas line valve to the unit about halfway and the vibration stopped. The unit now works as advertised. Wondering now why I didn't think of throttling the valve back sooner? Hope this helps.

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 Re: Rinnai tankless water heater noise
Author: ralleia (NE)

We've had a Rinnai tankless for about seven years.

We, too sometimes notice a disturbing noise on startup. The unit groans and then shudders.

This occurred several years ago when we had a deep snow that reached the level of the air intake.

It also seems to occur when we have a strong wind out of the south.

The intake is located on the east side of the house, with a projection of the house immediately to the south of it. I believe that the strong winds create a vacuum effect, which causes the shudder on startup.

I'd have to study the fluid flow of the air to determine how to prevent it from happening.

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 Re: Rinnai tankless water heater noise
Author: Mike Hahn (MD)

Happyras, I installed my rinnai about 12 yrs ago, didn't start having the vibration problems until a couple yrs ago. Read your post awhile back, choked the shutoff valve back seemed to help some, but decided that wasn't it. Talked to a plumber friend who installs them, he insisted it wasn't getting enough gas. Checked WC, was at 7". Bumped up pressure to 8.5. No help, almost re piped with 1" all the way to unit. It was and still is piped in 1" to within 8' of unit.
Read your post again and choked valve down to what I would consider a bout shut. Didn't do that the first time. But this time I choked it back like u sed, until the vibration stopped,.
Shockingly, the damn thing seems to be running fine now. Your idea of the high fire flame boiling the water & creating too much manifold pressure makes perfect sense. Especially for that kind of noise it was making, I just couldn't believe it was the fan.
Thanks for your determination & help with this problem, & shame on the rinnai tech dept leaving the problem to the general public to solve. Nothing like good ole US INGENUITY to figure it out. U didn't build that. Hah, thx again.

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