instant hot water is a no go

[jeff_gates]

We are almost done with building the shop/garage and cant get the tankless
to work.

We are running on 1000 gl propane tank about 250 feet away from the regulator then 8 feet into the tankless. We know that we had air in the line so we connected a burner to the line and ran it until we had good flame. When we turn on the hot water the burner comes on for some time, and gets a little warm before we get an error code 12. We connected a Analog Gas Pressure and are in the range but no luck.
any ideas?

Jeff

 

[eddieK]

Instant?

Tankless are about endless supply ONCE it gets hot, not about instant hot water. Instant hot water is from using a circ pump.

IF the unit also has a 110v control system, the polarity may be reversed. Reverse the hot and neutral wires for simple test. ALSO - Propane gas pressure should be about 10 inches mercury verse 3 for natural gas. This unit may also have a flame sensor, make certain it is in the flame.

 

[PCustoms]

What brand heater?

I'm sure if you read the manual or google the brand and error code 12 it will point you in a direction

 

[Jackfre]

Error code 12 says it is a Rinnai, correct? Model? Could well be a venting issue. Is it concentric vent? EC12 says that it established flame, but was unable to hold it.

 

[jeff_gates]

it's a Takagi T-KJr2-IN-LP Indoor Tankless Water Heater, Propane

 

[jeff_gates]

Vent looks good we doubled check it, when running we get 12.5-13 inches mercury before if flames out with code 12. We will reverse the hot and neutral wires next.

 

[mrobins297aaa]

make sure you have it vented correctly, I vented mine thru the wall and had the vent pipe running level thru the wall and I was getting a error code because I was getting moisture backing up into the draft blower, after I re-read the instructions it said to make sure the vent pipe is pitched down toward the outside.........I changed that and have not got another error code........

 

[eddieK]

Vent looks good we doubled check it, when running we get 12.5-13 inches mercury before if flames out with code 12. We will reverse the hot and neutral wires next.

That sounds like it's over firing...and the limit is shutting it down...is there any chance this was a natural gas unit that was converted...Orifices and SPRING.

Your propane tank is supposed to send up to 14 inches of mercury and your gas valve is used to regulate that to 10...on the units I've installed.

On the units internal gas valve,( where the gas line is connected) there are two ports for reading gas pressure, inlet and outlet...in should be above 12...out should be adjusted to 10.

You do that by calling for fire off and when the in-shot burner lights - you adjust the spring with a manometer connected to the outlet port.

image hosting 12mbcertificity.com

 

[Jackfre]

I just went thru this on another site and the high gas pressure was blowing out the flame. You may have adequate pressure, but as Eddie says, is it the right pressure from low to high. Does the syastem pressure drop when the unit starts? How much? I would suggest that you set the low fire gas pressure (low fire gets adjusted first on all modulating appliances) and then set the high pressure.

 

[Milton Shaw]

Eddiek, the pressure for gas is inches of water column not mercury. You have the numbers right but not the measurement range. A comparison would be 33 feet of water equals 29.7 inches mercury.

 

[eddieK]

Eddiek, the pressure for gas is inches of water column not mercury. You have the numbers right but not the measurement range. A comparison would be 33 feet of water equals 29.7 inches mercury.

You are correct...I tend to forget these things.

Both my analog and digital use neither...they just measure the pressure and provide readout (In WC) as you correctly stated. Sometimes too much knowledge just confuses the issue...

 

[jeff_gates]

It cost $200 bucks to remove the shipping plug from the exhaust hole.

 

[larry4406]

It cost $200 bucks to remove the shipping plug from the exhaust hole.

So plugged exhaust was the culprit?

 

[jeff_gates]

Correct, it was a plugged exhaust. I wasn't there when it was installed, my contractor installed it, it shipped with a black round plug in the top. to keep junk out of it.