Rinnai Convector Gas Heater - Code 12

[matth]

I have a Rinnai Convector gas heater that after about 5 minutes of use comes up with a code 12 error (and stops).

A couple of heater service guys said that it is not worth fixing (being 15 years old) but it was a good heater when it worked so I am keen to resurrect it.

My first thought was that the heater is just dirty - so I stripped it all apart and cleaned out the 15 years of dust and other contaminates.  It was actually not too bad.  After reassembling it and hooking it up I still get the error.

Looking for some advice on where I should start looking next.   Before it cuts out it runs perfectly.  I am suspecting it is something to do with the heater warming up.

Unfortunately I cannot locate what the Error code 12 actually refers to.

[SeanB]

Photos of the control board will probably show either a bulging capacitor or a capacitive dropper with failing capacitor.

[oldway]

Why not contact them ?

http://www.rinnai.com.au/contact-us/

Does it need a chimney?
In this case, perhaps a clogged chimney?

[BradC]

On my newer model code 12 is for "Incomplete combustion / Flame Failure"

If it's not an electronics failure, I'd look for a blocked solenoid / jet or a problem with the thermocouples.

Of course this info is for the RCE-371H / RCE-471-571-671TR series, so may not apply to yours.

[matth]

Thanks for the advice.

The model is a 406TR.  It is a unflued heater (no chimney). 

I am trying to find what signal generates the Code 12 error.   I actually have a second heater of this type I can test the parts on.

Matt

[matth]

Ok, did some major surgery last night.

I decided to strip the heater down and give it a clean and do some testing.   

All looked ok.  Took the flame sensor out and hooked it up to the multimeter.   Threw some heat on it and it appeared to be giving off a good voltage.
Next I check the overheat thermistors - they too check out ok.

So I decided the start pulling apart the gas feed.   I checked there was power to all the solenoids but gas does not appear to be exiting the solenoid/POV valve so I am suspecting there is a problem somewhere inside the POV valve.   I check all the solenoids with a meter and they look ok.   I can hear them click when the unit starts up.

Being a gas system I am debating whether I should delve inside the valve and see what I might find.   Unfortunately parts are no longer available for this unit.

[BradC]

Just do it.

When I got back from overseas the tenants in my house told me the Rinnai built-in gas heater in the lounge had died. They got a gas guy out to look at it who condemned it immediately as irreparable and Rinnai said it was 40 years old and certainly not supportable with spares.
I stripped it down to find a small insect of some kind inside one of the valves and the igniter mechanism needing some lubrication. A couple of lazy hours and it was all good, and has been for the last 5 years.

You have nothing to lose. Just make sure it goes back together the same way it came apart and that everything is properly sealed up when you put it back together. Most bits of gas gear are able to be stripped and cleaned if you are careful. When you are done, knock up a simple water manometer and do a proper leak test on the inlet just to be sure.

Don't force anything and proceed carefully. Don't poke valves or orifices or you risk scratching them. Same as carby jets, you can significantly alter flow rates with a mis-placed scratch. Compressed air is your friend, but be careful as most valve seals are designed for a couple of PSI at most.