Rinnai Error Code 12 mitigation strategies

NorthernGirl

Hi there. This is probably not your usual Rinnai code 12 post.... I have a Rinnai V75IP propane tankless hot water heater that I bought new 3 1/2 months ago, in June. I hired a plumber/electrician to install it, but he was not a certified Rinnai technician. Ever since it was installed, I have encountered the dreaded Code 12 problem, where it periodically cuts out and stops producing hot water, beeps, and flashes a Code 12. It does not reset itself--I have to turn the hot water completely off, wait a moment, and then turn it on very slowly, to just a trickle to make it work again. At that point, I can very slowly open up the faucet and usually get it to keep producing hot water, but if I open up the faucet too much too fast, it will kick off and flash Code 12 again. I rarely get the Code 12 problem at my kitchen sink, which has a lower flow rate, but my bathtub, shower, and utility sink faucets have higher flow rates, and this inevitably happens at some point whenever I use those. Cold showers are the worst.

Now, I am reasonably sure, after reading threads here and talking with some plumbers and pretty much everyone in town, that the problem is that my (former) plumber installed this with a 1/2" propane line instead of 3/4", over about a 20' run. I may also have an insufficient regulator. I don't think there is actually anything wrong with the heater itself, only the installation. I understand that I need to have this propane line, and possibly regulator, replaced. Unfortunately, I was laid off from work, and I'm afraid it will be several months at best before I can afford to have this line replaced. To complicate matters, I live in rural Alaska, and can't hire a Rinnai technician. In fact, we have a serious shortage of plumbers in this little town, so my options are very limited, and despite the popularity of this very model of Rinnai in our town, our resident plumbers seem to know very little about them, and don't care to learn. My original plumber messed up every aspect of my system so badly that I'm not willing to let him work on my house anymore, even to fix his mistakes. The next plumber I hired has advised me on what to do, but he backed out after realizing what a mess my first plumber made, and he doesn't want to deal with it. Tried hiring a third plumber, but he's booked up for the next two months. And, the fourth plumber in town is a drug addict. At this stage, I have to try to make this work as best I can until I can secure a plumber, and the means to pay him.

So, I'm looking for stop-gap measures I can take to make this Rinnai sort of work until I can get the line replaced. One plumber suggested that I partially close the ball valve on the water line going into the Rinnai, to restrict the flow so it has less water to heat at one time. I did that, and I think it's sort of helping, so that it cuts out less frequently. But is operating my water heater like this bad for the heater? Is it putting undue strain on the unit? He also had me replace my regulator. I calculated my maximum propane use (between the water heater and my propane range) and consulted the propane shop on which regulator to use, but this plumber was surprised when he saw what they gave me--so I'm still not entirely confident that I have the right regulator. It's better than what I originally had, but still not cutting it.

Would it help matters if I put flow restrictors on my shower and faucets?

Is this problem going to get worse as winter sets in and my incoming water is much colder, so I have a much bigger temperature rise? I am on a rain catchment system, so my water can be quite cold in the winter. I thought I was buying a more powerful water heater than I really needed, just to ensure hot water in the winter, but it doesn't seem to be the case.

Is there anything else I can do?

Thanks in advance for the help!

Jack

The responsibility lies with your first plumber. Given your circumstances, I'd push him to make the gas line right. I am certain from what you are describing that it is the gas line. That is a reliable unit when properly installed. Where in rural Alaska are you

NorthernGirl

Thanks so much for taking the time to respond, Jack. I realize the responsibility is with my plumber, and were he competent, I would have him replace the line, but I really don't trust his work and I don't want him to ever work on my house again. I did give him one last chance to fix this and the other crazy things he did to my house--he removed a flow restrictor and a 90 degree elbow in the gas line to improve the flow, and installed the bigger but possibly still undersized regulator, and those steps improved the functionality of my water heater (reduced the frequency of the code 12 errors), but did not solve the problem. So, at this point, I'd rather pay another plumber to replace the propane line than get the original plumber to honor the warranty on his work. However, it will be a while before I can do that--6 to 8 weeks before another plumber is available, plus I have limited funds right now.

I was able to limp along with this system for a while, just being careful not to turn the hot water on too high too fast, but that was when I had a submersible well pump in my rain catchment tank. This week, after problems with that system that revealed to me that the pump wasn't installed appropriately (it's not meant to be installed horizontally or in a holding tank), I had the submersible pump replaced with a shallow well jet pump. That system is working much better for me and has increased my water pressure, but the increase in water pressure seems to be tripping the code 12 more often, so that now I'm unable to fill my bathtub without tripping that code. I was a very sad woman trying to take a bath last night.

In the meantime, are there any short-term fixes that might make the heater function properly? And, more importantly, am I damaging the heater or shortening its lifespan by operating it like this?

Thank you for your time!

NorthernGirl

PS, I am in Southeast Alaska, north of Juneau. Not on the road system, so I can't bring in a plumber from Juneau.

lchmb

restricting the flow through the unit simply means it doesnt fire to hi on a call. Which means you dont run out of pressure. I cant imagion restricting the flow would hurt the unit but it's only going to get worse as you get colder (less pressure from LP as temps drop). Not really many other options other than replace the line. Maybe get trac pipe and fittings. Get 3/4 then have the original installer make the connections if he's certified...

j a_2

Did the unit come via an online purchase or from a local supply house...Sorry your having such issues

j a_2

How did you come about deciding on this type of unit?

NorthernGirl

Thank you for the responses. I ordered the water heater online, after it was recommended by a number of people in my community. It's probably the most popular model here.

Larry Weingarten

Hello, A thought to get you by would be to temporarily use one or two five gallon propane tanks to supply the heater directly (with a regulator), and capping off the present supply line.

Yours, Larry

NorthernGirl

Update. Thanks for your input, everyone. I replaced the 1/2" rigid propane line with 3/4 inch Tracpipe, and I replaced the regulator, as recommended by the local propane shop. Attaching a photo of the regulator (it's covered now, though the photo doesn't show that). The Rinnai is working a little better, in that water at the kitchen sink is hotter and I'm not getting the Code 12 error at the shower, but I still get it at the bathtub faucet, even when I open the faucet only about a third of the way. I guess I could get by on showers, but I have just invested all of the money I had into plumbing and a nice, clawfoot bathtub, and it would break my heart not to take baths this winter.

Any ideas? Is it possible that my Rinnai is actually the problem? All I am running off this propane line is the Rinnai and an oven/range.

Thank you for your help!

Jamie Hall

No, the Rinnai isn't the problem -- directly. It's inadequate gas pressure as it ramps the firing rate up. Keep at it -- you are going in the right direction anyway.

Larry Weingarten

Hello, Has anyone actually tested the gas pressure at the heater as it begins to fire and ramps up? That could be useful info to have.

Yours, Larry

Leon82

If you have the manual you may be able to lower the max fan speed. This will reduce the output of the heater untill you can get the proper sized line in there

NorthernGirl

Thanks, guys. I'll see if I can get my hands on a manometer and air compressor this weekend.
Leon, I do have the manual, but I don't think I want to reduce the output of the heater. I replaced the gas line and regulator and am still having the code 12 from the tub faucet.

Leon82

can you throttle the tub faucet and not get an alarm?

If not your not getting the full output anyway. The tub faucet it going to make the heater run at full output.

NorthernGirl

Leon, if I turn on the tub faucet at just a trickle, I can slowly open it a little at a time until it's about 30% open before it errors out. I tried restricting the hot water flow to the tub and it doesn't seem to help.

Leon82

If you have a hot water shut-off you can close it untill it will only allow the amount of water before it will trigger an alarm if you don't want to lower the fan speed

NorthernGirl

Thanks, Leon. Yes, that's what I meant by restricting the hot water flow to the tub. Didn't seem to help, at least at a flow that would be reasonable for filling the tub. Since that same shutoff also feeds the shower, it's easier and more practical for me to regulate the hot water flow at the faucet and be conservative, than to have to switch the shutoff back and forth between shower and tub use.

As for lowering the fan speed, wouldn't that be counterproductive? Seems like I want more output, not less, unless I'm understanding you wrong.

I also have the ball valve on the water going into the heater partially closed to slow the flow of water into the heater--I think that's helping, but it's hard to tell.

Leon82

Yes you will get less output, but it seems that any more flow than the shower will trigger an alarm so you are not actually getting full output.

The heater will run on maybe 3 to 4 inches of water column on natural gas. (Adjust for propane). So if you drop the fan speed untill it doesn't go under the minimum gas pressure you simply avoid the alarm.

It is a bandaid for undersize piping.it will save you a trip to the utility room if you open the tub too much.

This may not be an alterable parameter on your unit however

NorthernGirl

Thanks for the explanation, Leon. I no longer have undersized piping, though. Upgraded the piping and the regulator and still have a problem.

Jamie Hall

I hope this isn't a totally irrelevant suggestion, but... what size propane tank(s) are you using, and how cold is it? One problem which sometimes occurs with LP is that if the tank or tanks are not large enough, and the weather is cold, there simply isn't enough LP evaporating to supply the unit -- particularly thirsty critters like your Rinnai (and other tankless units). Has this been checked?

Brewbeer

Agree with the small tanks freezing up, when you are drawing on them hard they get cold and pressure coming out of the tanks drops.
I use a large turkey fryer on my homebrew set up, and during below freezing weather tanks that were less than half full would need to be swapped out with fresh tanks to keep the jet burner at full power.
@NorthernGirl keeping the tanks full helps, and keeping the tanks in a warm environment helps too.

NorthernGirl

Thanks for the suggestion re. tank size, Jamie and Brewbeer. I am on small, portable tanks and I've wondered if that was a factor. The guys at the propane shop told me their size shouldn't be an issue, but knowing how propane reacts to cold temps, what you said makes sense. I've been trying to put off going to a big tank, but that might very well be the problem here. Thank you.

Jamie Hall

@NorthernGirl -- you might find this table helpful.

https://www.bakersgas.com/vaporization-rates-propane-tanks.html

It doesn't get down to your small tank size, but the rates are more or less proportional to tank size.

From the information I have on your Rinnai, and making two assumptions: that it occasionally gets down to -10F where you are and your LP tank is outside, I would say that you need at least a 250 gallon tank to provide enough gas.

NorthernGirl

Thanks so much, Jamie. This is a huge help! Wonder why none of the plumbers I've consulted, nor the guys at the propane shop thought of this (I did ask about tank size!). At this stage I probably won't get around to upgrading to a big tank until springtime, but at least I can make sure to keep the tanks full, and maybe build an insulated box around them with a lightbulb to help keep them warm.

Jamie Hall

People don't think about it -- until it gets cold and they wonder why their equipment doesn't work. The insulated box and lightbulb is a good idea.

And good luck to it!

DavyLane

Just in case you're still having troubles, or someone else is. If the concentric exhaust/intake is not sealed/seated properly, it will work fine when there is little demand, but when there is greater demand the pressure from the exhaust may seep into the intake causing an error 12. Just sayin'.