Rheem Tankless Water Heater Code 11 (No Ignition)

[sheltonfilms]

Water heater model: RTG-95DVLN (natural gas) 2014 build date

So had this heater for 2 1/2 years and just the other day I got code 11. No issues up until this point.

Thinks I have checked:

Igniter sparks during startup.
All solenoids are getting power and show correct resistances according to service manual.
Removed and cleaned burner unit and manifold with compressed air.
Check concentric vent for obstructions by looking into it from outside (comes out top of unit into immediate 90 out of wall unit is mounted on, 1.5' run).
When blower comes on there is good suction on outer pipe and good flow coming out middle pipe.

Now on to gas. I don't have a manometer but I made a quick and dirty one using clear tube and a ruler. There is a port on the gas inlet port. I zeroed out my makeshift manometer and turned the gas on and got 10" w.c. (spec is 7-11" for my unit). When I turn the unit on the pressure drops immediately to zero when the gas solenoid valve opens.

I have 3/4" iron pipe from meter (directly on other side of wall unit is attached) and it runs about 3 feet and splits to the rest of the house and the other split is to regulator for the tankless heater. From there it is only 2 feet of pipe to the unit.

I can turn on all 5 burners on my gas range (55,000 btus total) and it is fine. My tankless is 200,000 btus on full blast.

Another note. I can smell gas when I'm in front of the exhaust vent but it seems it is more prevalent on the first startup. It doesn't smell strong until I let the unit sit and try to start it up again.

Bad regulator for the water heater?

 

[havasu]

This may help?

[ame]https://www.youtube.com/watch?v=QsmIyYexRzM[/ame]

 

[sheltonfilms]

Thanks for the video but I already cleaned the burner.

Actually solved it today:

Was looking at the regulator that was for the tankless unit that was installed outside. All the main diagrams didn't have the brass "bolt" seen in the picture below that I have. Well I found out it's a vent limiter and its for indoor installations only. It is so that if the diaphram ruptures it doesn't release gas into the house at a rate greater than ANSI standards. The reason it is not rated for outdoors is #1 it isn't designed to handle corrosion, #2 regulators placed outdoors don't require them.

Sure enough after unscrewing it the unit fired up fine. Crazy how something so mall can kill a 200k btu appliance. The vent limiter was full of sediment and corrosion and the ballvalve was stuck inside.

Called my builder (even though I was out of warranty) and pretty much told him I want them to provide me with the vent protector piece that is suppose to go there instead of the vent limiter he agreed and told me to document everything so that he could pass this along to the contractor.

Hope this helps someone.

 

[havasu]

Excellent. Thank you for the follow up.

 

[minercraftal]

Been install a new one can’t get fire comes out, final solution is the gas valve was stick close, and knocked it open with a screw driver.

 

[costamesa]

Water heater model: RTG-95DVLN (natural gas) 2014 build date

So had this heater for 2 1/2 years and just the other day I got code 11. No issues up until this point.

Thinks I have checked:

Igniter sparks during startup.
All solenoids are getting power and show correct resistances according to service manual.
Removed and cleaned burner unit and manifold with compressed air.
Check concentric vent for obstructions by looking into it from outside (comes out top of unit into immediate 90 out of wall unit is mounted on, 1.5' run).
When blower comes on there is good suction on outer pipe and good flow coming out middle pipe.

Now on to gas. I don't have a manometer but I made a quick and dirty one using clear tube and a ruler. There is a port on the gas inlet port. I zeroed out my makeshift manometer and turned the gas on and got 10" w.c. (spec is 7-11" for my unit). When I turn the unit on the pressure drops immediately to zero when the gas solenoid valve opens.

I have 3/4" iron pipe from meter (directly on other side of wall unit is attached) and it runs about 3 feet and splits to the rest of the house and the other split is to regulator for the tankless heater. From there it is only 2 feet of pipe to the unit.

I can turn on all 5 burners on my gas range (55,000 btus total) and it is fine. My tankless is 200,000 btus on full blast.

Another note. I can smell gas when I'm in front of the exhaust vent but it seems it is more prevalent on the first startup. It doesn't smell strong until I let the unit sit and try to start it up again.

Bad regulator for the water heater?

Shelton,

Not sure if you're still around on this, but I want to thank you for the very detailed post.
It's identical to my situation and I'm hoping I can find a resolution to my issue.

I'll borrow your format:

Water heater model: Rheem RTG-84DVLN (natural gas) 2015 build date

I bought the home in 2021 from the original owner and I have not experienced any issues until recently with this intermittent code 11 and no hot water.


Things I have checked:

• Initially thought it was the ignition coil so I bought a new one and replaced it. Spark test shows there is spark.
• I cleaned the flame rods and ignition rod. I peeked inside and the burner looked clean enough.
• I flushed the unit twice. Once with a solution and then a second time with white vinegar.
• I cleaned out the cold water inlet filter.
• I had the gas company come out and do a manometer reading and it showed I'm at 8.5 WC.
• I checked the water pressure, and depending on the faucet I'm using it is between 11-25 GPM.
• I bought a multimeter and the solenoids are getting power and show correct resistance.

I spoke to multiple Rheem techs and the last one mentioned it might be a venting issue.

Does anyone here have any other ideas or do you guys think it's also because of the vent and how I would go about cleaning or replacing it?

Any help is welcomed and appreciated!

P.S.

I attached pictures of the venting. Not sure what happened to the outside where it looks like something fell on it, but that has been like that since I bought the home and there were never any issues until recently. I checked inside with a camera and nothing looks to be lodged in there.

I also included pictures from inside so you can all see the vent coming in. It goes off to the left at 90 degrees.

Thanks again for anyone taking time to read and answer!

 

[wpns]

I checked the water pressure, and depending on the faucet I'm using it is between 11-25 GPM.

My brain is having a hard time with this. Pressure is PSI, Pounds per Square Inch (and 11-25 is way too low) whereas flow is GPM, Gallons Per Minute, (and 11-25 is way too high). Can you try again?

 

[costamesa]

My brain is having a hard time with this. Pressure is PSI, Pounds per Square Inch (and 11-25 is way too low) whereas flow is GPM, Gallons Per Minute, (and 11-25 is way too high). Can you try again?

WPNS, yes, thank you for the correction.

I meant to say, I checked the flow on the Rheem remote while in diagnostic mode and it showed the flow at 11-25 GPM.

The tankless water heater is on the first floor. On that same floor I have a home office and a bathroom and a laundry room. The bathroom faucet showed at 11 GPM and the laundry faucet--that gushes out with no fury to spare--was showing at 25 GPM.

 

[wpns]

I'll take your word for it (can fill a one-gallon container in 2.4 seconds?), but that's an 8.4 GPM heater, so there's an imbalance in there somewhere. Anyway, try opening doors and windows so there's plenty of fresh air to feed the unit, and see if that helps.

Does it happen at particular times of the day? Can you crack a faucet enough to get it to fire up and once it's running open it all the way?

 

[costamesa]

I'll take your word for it (can fill a one-gallon container in 2.4 seconds?), but that's an 8.4 GPM heater, so there's an imbalance in there somewhere. Anyway, try opening doors and windows so there's plenty of fresh air to feed the unit, and see if that helps.

Does it happen at particular times of the day? Can you crack a faucet enough to get it to fire up and once it's running open it all the way?

The GPM I'm going off what the Rheem remote reads on diagnostics mode, so don't take my word for it, take its lol.

And you're right, that is odd when I think of how an 8.4 GPM heater flows at 11GPM+ so I'm not sure about the imbalance. But a little while back, one of my sprinklers broke and I went through 80k gallons over 2 months without realizing it (I'm billed for water every 2 months). I still haven't fixed the sprinkler. I just keep the manual shut off on outside.

When it happens it's speratic. It went on earlier this morning and then I left for the gym. Since coming back, it's not turning on at all. So it looks like another cold shower today.

But yes, once I get it going, it stays on hot, unless I turn it off and try to turn it back on again.

It's to the point where I might just give up and buy a new one.

If I buy an electric tankless one, would it be safe to just keep the manual shut-off valve for the gas off at all times?

It's either that or not giving up and trying to fix this. But paying someone to diagnose might be a waste since I've been looking at everything.

 

[Twowaxhack]

Might be liters per minute

 

[costamesa]

Might be liters per minute

That makes sense.

11 liters=about 3 gl and 25 liters = about 6.5 gl, so it might have been reading 3 gl for the bathroom faucet and 6.5gl on the laundry room faucet.

After not working all morning from getting back from the gym, the hot water started working when I lit it with the hot water valve from the unit.

So again, it's intermittent and not knowing what's causing me is causing me to go bananas.

Who can help solve this puzzle?!

 

[wpns]

Call Rheem and ask who in your area is certified to work on them? Call local plumbers and ask if they work on these systems?

 

[costamesa]

Call Rheem and ask who in your area is certified to work on them? Call local plumbers and ask if they work on these systems?

I was hoping to solve it myself with the help of this forum.

I just don't know what else they can do that I haven't done to diagnose the issue.
I prefer to avoid paying someone to diagnose just for them to either not be able to figure it out or just to tell me what I already know if that makes sense.

 

[Twowaxhack]

That makes sense.

11 liters=about 3 gl and 25 liters = about 6.5 gl, so it might have been reading 3 gl for the bathroom faucet and 6.5gl on the laundry room faucet.

After not working all morning from getting back from the gym, the hot water started working when I lit it with the hot water valve from the unit.

So again, it's intermittent and not knowing what's causing me is causing me to go bananas.

Who can help solve this puzzle?!

A plumber who works on Rheem units.

 

[wpns]

You need someone who is familiar with them, who can check all the things. Sounds like you've checked what you can, and it needs a professional.

 

[costamesa]

A plumber who works on Rheem units.

LOL

I hear ya

 

[costamesa]

You need someone who is familiar with them, who can check all the things. Sounds like you've checked what you can, and it needs a professional.

I guess the consensus is bringing in a thrid party.

I appreciate for those that helped.

Thanks, all.

 

[costamesa]

I wanted to let you all know that the issue was finally resolved. I hired a professional to come to the home. I advised him of everything I had already done. He blew the unit with an air compressor (I had used the cans) and that solved the issue.

 

[MPlumb]

I know it's later in 2024 after your last message, but I actually signed up to this forum to see if you had any other info about what the pro did, specifically. I have this same intermittent code "11" issue where it'll sometimes work fine, other times it won't fire up and will display that error.

FYI, the service manual (found it in a few places online) says that the flow rate is indeed GPM, but it's in *.* format, so for me the service code 1Y for flow rate is showing 14. That means 1.4 GPM. That would mean your readings of 11 and 25 would be 1.1 and 2.5 GPM... not sure if that seems right. In my case, 1.4 GPM makes sense because that's what I get in my laundry sink (closest sink to the remote) and it has some rinky dink flex lines feeding the faucet itself. Definitely not a high flow.

Anyway, I've done the same kind of troubleshooting as you except checking the gas water column. I wouldn't think it's an issue - I've had this setup for I think 16-17 years and it just started acting up a few days ago.

I did remove the burner and gave it a good clean. It was pretty cruddy - I hadn't done that since it was installed, so there was plenty of that white residue and some green (copper, I guess?) "dust". Blew all of that out using an electric duster (like a vacuum motor in reverse, in a handheld thing). Also blew out where the water flows through the heat exchanger area and up/out the exhaust (mine is an outdoor model, RTG-74XN-2).

Put it all back together and it worked okay for a day, then started throwing the error again. I pulled the burner back out (getting good at it now), and this time I was more thorough, using my air compressor and carefully going through all of the gas tubes, blowing both in and out to make sure if I dislodged anything one way, I'd blow it back out the other way. I did get more "dust" the second time but not nearly as much, and I'm fairly sure that I got out whatever I could.

(EDIT: Forgot to mention, I consistently get spark, all the time... even when I get the error, it's sparking like it should when trying to start up)

I didn't really focus on the gas valve though. I hit it with the blower but not the compressed air. I'd only be able to hit the output of them (where the gas tubes attach) and I'm not sure what an actual Rheem tech would do... remove the gas valve and blow the inlet side of it as well? Would you need to apply some voltages to the solenoids to open them up and blow _through_ them?

As for the solenoids on the gas valves, I got good readings on all 4 of the solenoids (the main one, plus the 3 separate ones since the RTG-74 has 3 burner sections). About 1.2K ohm reading on each, and when operating I got about 104-106 V as expected.

The PGFR (proportional gas flow regulator) readings were also in spec. When I had it running (opening up the relief valve on the unit to get it flowing), I was reading between 3.5V - 4.5V. Resistance reading on that was about 60 ohm, so pretty much in the middle of the 40-80 ohm it said it should be.

I also put some deoxit on the plugs/connectors the last time I measured things, in case it was just some light corrosion. It's an outdoor unit after all, but sheltered from direct weather, but the PCB and all the connectors looked really good... surprisingly good for something outdoors for so many years even though it's under an eave and deck. The PCB does look to have a coating so I'm sure it's fine, but those connectors... you have to wonder.

So far, after my 2nd burner cleaning and using the deoxit, I've only had that code 11 a single time over the past 24-48 hours, so maybe it's better? I'm still not sure what I'll do if it comes back. Aside from taking the gas valve out and giving it as much cleaning as I can, I'm stumped. I've looked online for replacement parts for that gas valve but everywhere says they're out of stock, so I guess this would become trash if it's a bad valve unit.

So, if you happen to know more details about what they did to clean out that valve, that'd be great.