I thought Rinnai was going to be good...

[user 33491]

I'm about at my wits end with this Rinnai tankless water heater. When I first installed it, it worked OK. However, when the wind would blow it would go code 12. I assumed the wind was blowing down the vent and putting out the flame. But then it started going code 12 with no wind. I started watching Youtube videos about it and the only thing I didn't do that was recommended by the experts is to put a regulator on the gas line. I had installed a 1/2" flexible appliance gas line and assumed that was part of the problem. My tankless is about 50 feet from my meter. There is a 3/4" line from the meter most of the way. There is about a 3 foot section from the 3/4" where it reduces to 1/2". I can't remove that 3 feet unless I pull up the floor. So, I just bushed it back to 3/4" and the last 4 feet of line before the heater is 3/4" with a Pietro Fiorentini regulator. I have a 2# tag on my meter. All of this is supposed to be correct and most are saying that the 1/2" section shouldn't matter. When I first fired it up after replacing the flex line and installing all black pipe, it went code 12 again right away. I thought maybe there was air in the line so I continued to try. I got 1 shower out of it that was OK. After that, it will not get hot. When hot water is turned on, it fires up, roars like a freight train passing my house for a few seconds then shuts off. It does this 3 times then goes code 12. So, now that everything is installed as suggested, I can't get any hot water.

Ideas? Should I rip it off the wall and go buy a tank? Not impressed with Rinnai...

 

[Twowaxhack]

Your gas lines are improper. Correct your piping so the heater will have a chance at working properly.

 

[GReynolds929]

What's the regulator set to? What is the static and dynamic pressure at the water heater?

 

[user 33491]

Your gas lines are improper. Correct your piping so the heater will have a chance at working properly.

How so? It's exactly as described by Rinnai and other plumbers I've seen. The only deficiency is that 3 foot section of 1/2" pipe that no one says will matter.

 

[user 33491]

What's the regulator set to? What is the static and dynamic pressure at the water heater?

All I can tell you is it has a black spring per the recommendations. I don't know how to get these readings. I can adjust it but I'll be doing it blind. It was working a lot better before I put the regulator in.

 

[Twowaxhack]

What type gas does the unit say it needs ? Better check on the side of the unit.

Better check your gas pressure with a manometer.

 

[MicEd69]

How long did it work "OK"?

You say your heater is about 50 feet from your meter, so I assume you are on natural gas. What is the supply pressure of your natural gas if that is correct? You would not need a regulator if your natural gas pressure the standard ~7" of water column. If you have a supply pressure of 2-5 psi, then you would need a regulator at every natural gas user. And as you have appeared to have operated the heater initially without a regulator, that would have been rather dangerous, and I don't think that is your problem. And I doubt the short run of 1/2" pipe is your problem either. But you do need to verify the gas pressure while your unit is operating to see if you are starving the heater.

And by the way, you said you "bushed" the piping back up to 3/4". Pipe bushings are not allowed in natural gas service.

 

[user 33491]

How long did it work "OK"?

You say your heater is about 50 feet from your meter, so I assume you are on natural gas. What is the supply pressure of your natural gas if that is correct? You would not need a regulator if your natural gas pressure the standard ~7" of water column. If you have a supply pressure of 2-5 psi, then you would need a regulator at every natural gas user. And as you have appeared to have operated the heater initially without a regulator, that would have been rather dangerous, and I don't think that is your problem. And I doubt the short run of 1/2" pipe is your problem either. But you do need to verify the gas pressure while your unit is operating to see if you are starving the heater.

And by the way, you said you "bushed" the piping back up to 3/4". Pipe bushings are not allowed in natural gas service.

Now that's the kind of detailed information I appreciate. Thank you. Yes, it's NG and it worked ok on the initial setup for a few weeks till the wind started blowing. All I can say about the pressure is the meter has the 2# tag on it. It sounds like the regulator was a bad idea (Youtube. What do you expect?) There are no regulators anywhere else in the house. I have another tanked water heater, 2 gas stoves, and 2 furnaces. None of them have regulators except the built in one on the furnaces. So, I'm probably starving it since I don't even know where the regulator is set. Based on the way the unit acts, low rumbling on high demand and throwing code 12's, I think it's starved.

As you can see, I'm capable of doing the labor, I just don't have the tools to measure gas pressure or flow. That's where I'm getting hung up. If you can tell me a way to do that without spending big money on equipment, I would try it. I don't mind buying a tool but if it's a 1 time use I'm not going to spend a lot. I see manometers online for around $100. That's reasonable. If you think the skill level is over my head, I'm ready to throw in the towel and call an expert.

 

[GReynolds929]

here is a good price on a decent brand.

Manometer

 

[user 33491]

here is a good price on a decent brand.

Manometer

Perfect! Thank you.

 

[user 33491]

Well, MicEd69, it was just a little input from you and I was able to figure out the problem. AND it had nothing to do with my gas lines.

Since it was working better before I put the regulator in, and you said I shouldn't need it, I took it out. But that didn't change a thing. It still short cycled. So I started tearing into it thinking there must be something else going on. I had a 4 inch PVC venting the unit that I removed. Then I fired it up again and it worked better than it ever has. Constant hot water with no noise coming from the unit. I noticed that the exhaust really only comes out the center pipe, not the entire 4 inch opening. So I got a smaller PVC pipe. SMALLER?? That just didn't make any sense but it did the trick. This thing finally works the way it should.

 

[MicEd69]

Well, MicEd69, it was just a little input from you and I was able to figure out the problem. AND it had nothing to do with my gas lines.

Since it was working better before I put the regulator in, and you said I shouldn't need it, I took it out. But that didn't change a thing. It still short cycled. So I started tearing into it thinking there must be something else going on. I had a 4 inch PVC venting the unit that I removed. Then I fired it up again and it worked better than it ever has. Constant hot water with no noise coming from the unit. I noticed that the exhaust really only comes out the center pipe, not the entire 4 inch opening. So I got a smaller PVC pipe. SMALLER?? That just didn't make any sense but it did the trick. This thing finally works the way it should.

Great. I was pretty sure it wasn't the gas supply. But you may want to delve deeper into how the combustion air comes into the unit and how the unit is vented. You may need/want a double pipe. The smaller inner pipe is the vent, as you have found out, and the larger annular space is the combustion air intake. Without the smaller inner pipe, your unit would have been sucking in its exhaust and trying to use it as combustion air which was making it starved for oxygen.

 

[Twowaxhack]

The gas supply is still most likely incorrect.

The vent is definitely incorrect.

I’d suggest having the unit checked by a qualified serviceman with the necessary tools.

 

[user 33491]

The gas supply is still most likely incorrect.

The vent is definitely incorrect.

I’d suggest having the unit checked by a qualified serviceman with the necessary tools.

I asked you how my gas line is incorrect but you never answered. Your comments are of no value. Try asking questions or providing constructive comments. This is a DIY site afterall. People come here looking for help, not criticism.

 

[GReynolds929]

"The only deficiency is that 3 foot section of 1/2" pipe"

This is how it is incorrect. Doesn't matter that the unit may operate fine or others say it's not a problem. It is not piped correctly which makes it an incorrect install. It is a restriction and choke point for the flow of gas, and it is not allowed. There is a good chance it can cause issues down the road.

Did you happen to measure your gas pressure yet, and verify that the regulator is or isn't needed?

 

[Twowaxhack]

I asked you how my gas line is incorrect but you never answered. Your comments are of no value. Try asking questions or providing constructive comments. This is a DIY site afterall. People come here looking for help, not criticism.

Screw you

You’re a complete idiot.

 

[MicEd69]

"The only deficiency is that 3 foot section of 1/2" pipe"

This is how it is incorrect. Doesn't matter that the unit may operate fine or others say it's not a problem. It is not piped correctly which makes it an incorrect install. It is a restriction and choke point for the flow of gas, and it is not allowed. There is a good chance it can cause issues down the road.

Did you happen to measure your gas pressure yet, and verify that the regulator is or isn't needed?

I would not be too concerned about a 3-foot section of 1/2" pipe if the unit worked for several weeks. But as the OP stated he has 2 gas stoves, 2 furnaces, and another tank water heater, the entire gas piping layout really should be analyzed. Too many people just add a connection here and there for this and that which can end up changing the operations of other gas users.

But using a bushing in gas service is wrong.

But as the OP has quit the forum, we may never know.

 

[GReynolds929]

I would not be too concerned about a 3-foot section of 1/2" pipe if the unit worked for several weeks. But as the OP stated he has 2 gas stoves, 2 furnaces, and another tank water heater, the entire gas piping layout really should be analyzed. Too many people just add a connection here and there for this and that which can end up changing the operations of other gas users.

But using a bushing in gas service is wrong.

But as the OP has quit the forum, we may never know.

Just because something works a certain way for a specific purpose doesn't mean it is correct or properly done. OP asked what was incorrect, not if it would work installed like that. For a line servicing just the tankless it may work fine but I wouldn't leave it that way if I had to service the unit. We also don't know what his gas pressure system is. If he does have a 2# system like he thinks and removes the regulator that could be catastrophic.

 

[MicEd69]

Just because something works a certain way for a specific purpose doesn't mean it is correct or properly done. OP asked what was incorrect, not if it would work installed like that. For a line servicing just the tankless it may work fine but I wouldn't leave it that way if I had to service the unit. We also don't know what his gas pressure system is. If he does have a 2# system like he thinks and removes the regulator that could be catastrophic.

The OP is an DIYer and doesn't understand gas systems, which makes him dangerous. If you read all his posts, you will see that while he says his meter has a 2# tag on it, I'm not sure that means it is a 2-psi meter. He says he doesn't have a regulator at his gas stoves or his tanked water heater. And his initial installation for the tankless was without a regulator, then he added one, and now he has since taken it back out.

What is really "incorrect" is the bushing between the 1/2 and 3/4 pipes. Changing pipe sizes isn't correct either, but his concern is that to replace that would require taking up the floor. As he has already recognized that the 1/2" section isn't the way he should be doing it, but that "some" have said that will not cause his issues.

Bottom line, he has left this forum, so we will never know unless we hear about a natural gas explosion in Ogden Utah.

 

[waternwavs]

I'm about at my wits end with this Rinnai tankless water heater. When I first installed it, it worked OK. However, when the wind would blow it would go code 12. I assumed the wind was blowing down the vent and putting out the flame. But then it started going code 12 with no wind. I started watching Youtube videos about it and the only thing I didn't do that was recommended by the experts is to put a regulator on the gas line. I had installed a 1/2" flexible appliance gas line and assumed that was part of the problem. My tankless is about 50 feet from my meter. There is a 3/4" line from the meter most of the way. There is about a 3 foot section from the 3/4" where it reduces to 1/2". I can't remove that 3 feet unless I pull up the floor. So, I just bushed it back to 3/4" and the last 4 feet of line before the heater is 3/4" with a Pietro Fiorentini regulator. I have a 2# tag on my meter. All of this is supposed to be correct and most are saying that the 1/2" section shouldn't matter. When I first fired it up after replacing the flex line and installing all black pipe, it went code 12 again right away. I thought maybe there was air in the line so I continued to try. I got 1 shower out of it that was OK. After that, it will not get hot. When hot water is turned on, it fires up, roars like a freight train passing my house for a few seconds then shuts off. It does this 3 times then goes code 12. So, now that everything is installed as suggested, I can't get any hot water.

Ideas? Should I rip it off the wall and go buy a tank? Not impressed with Rinnai...

Call the engineers at Rinnai. They told me you never want the starve these things for fuel. Have the gas company check your gas pressure (probably not an issue but they do it for free).