Code 12 on Rinnai RE199iP

jparkerri

I just installed a new Rinnai RE199iP (propane) and it works fine until I open up a nearby faucet to full flow. Then I hear the flameout and get the code 12. I've used 3/4" black pipe direct from the propane tanks and the distance is at the outer edge of what's allowed for the 199K Btu's (95 feet). I've checked the pressure at the unit to be 13.5"WC. I set the forced low and forced high to the specs in the literature (1.00 and 3.92). I set the temp to 120 deg but also tried at less. For normal use that works, I see that only one side of the burners is on. When I open the full flow faucet, all the burners go on but ultimately flameout and code 12 happens. are there any adjustments I can make (forced low or high, etc.) to prevent the flameouts and code 12? What do the forced low and high settings control? Am I just too close to the max for pipe length? Can I adjust the regulator on the propane tanks to provide more pressure? Thanks for any suggestions.

Slimpickins

You need to check your gas press. The max is 13"wc and min is 8" If you're dropping below 8", that's your issue. If gas pressures are good, I'd check your venting.

pecmsg

199,000 BTU/h ?

yellowdog

3/4 black iron at 95 feet is only good for 180,000 btu's. You need a larger pipe.

jparkerri

In the Rinnai manual, they quote 197K btu/hr at 100ft of schedule 40 metallic pipe. Is it different for black pipe?

yellowdog

I use the Rego charts, not a boiler manufacturers recommendation.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1807854#Comment_1807854

Number of 90° ells and 45° fittings make a huge difference.

GGross

197,000 BTU/hr according to michigan mechanical code book, LP @ 11" wc 0.5" drop

without factoring any elbows or valves into the equation you are right on the edge of it being correct sized, so if this length didn't include any valves or elbows (depending on the valve, can add more than 10 feet) you might be undersized.

Really easy way to tell is to get your manometer out and check gas pressure

check static pressure (pressure before unit fires.)

record the drop at ignition (unit lights, pressure drops what is that number?)

run unit to high fire, record the pressure at full fire

shut unit down, record the lock up pressure after shutdown

This will tell you what you need to know, you are aiming for less than a 0.5" wc pressure drop from static, without ever going below the rated minimum, or above.

Teemok

You have two flame detection rods. It might be that the second flame rod, for one reason or another, is not able to sense the flame of the high fire burners. Could be something fouling it in the burner chamber or an uneven flame. Check the rod, wiring connections and wire continuity.

The above described dynamic gas pressure drop test is necessary to prove if limited gas supply volume might be a cause. I have seen units run with near 2" pressure drops. Not that that's OK or in spec, just that they don't always instantly lock out from more than a 0.5" gas pressure drop.

jparkerri

I have about 30 feet of 3/4" schedule 40 black pipe from the tank/regulator that I can't really replace. If I replace the next 70 feet with 1" pipe to the tankless water heater (199K btu/hr) how do I calculate if it can handle the load? As long as the 30' of 3/4" can handle the 199K and the 70' of 1" can handle 199K, will that work?

Teemok

It's the total equivalent feet of the run you want not just the pipe lengths. A non full port valve or small diameter or long flex connector is a common problem. A 3/4" 90 is like 2.5ft. There are charts available. Prove a gas pressure drop problem before you go changing any piping. It could be something else.

jparkerri

Thanks Teemok. Are all fittings the problem or just those that change the direction like angles and Tees? The couplers and valves have the same or larger inner diameter as the pipe itself. Do I need to add the 2.5 feet for those too?

Teemok

It's the total pipe lines resistance to flow you are trying to estimate. Couplings and true full port valves are negligible. Through the barrel of a Tee has some the branch a lot. Bends and restrictions are the main issues. Here's the thing, the pipe equivalence math is an educated guess. The comparison of a static and dynamic gas pressure measurement is real world condition. If the real world gas dynamic pressure drop is only 1"w.c. I'd be looking for a problem beyond a slightly restrictive gas line.

jparkerri

Thanks again. I researched everything online and found out I was way over the acceptable pipe length for my tankless water heater. I moved it closer to the propane source (which removed more than 50' of pipe) and now it's working fine at full flow. I did find out that 3/4" 90 deg angles are worth 2 feet of 3/4" pipe length while couplers aren't even included in the tables. It also turns out the 1' of 1" pipe is equal to about 0.31' of 3/4" pipe. I was going to replace some of the 3/4" with 1" but I don't think I need to now.

Slimpickins

Have you called tech support yet? They won't even talk to you if you don't have a manometer on hand. If your gas pressures are good, your venting is the next thing to check. The vent fittings may not be fully engaged and exhaust gases may contaminate the intake air. You can check that by temporarily popping the vent off the unit and see what it does. Make sure you open some windows and doors. Rinnai makes a good product and they are all tested before leaving the factory so usually it's an installation problem.