Question about Rinnai Desa Vent-Free Infrared Gas Heater: Vent-Free Infrared Gas Heater(18,000 BTU)

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Rinnai 650 thermocouple replacement

I am replacing my old thermocouple with a new one, but the new one doesnt allow for the wire leaving the ignition switch to be connected to the loop. what do do with this "spare" wire?

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Is this an oem replacement try to get an exact replacement or a retrofit kit

Posted on Jul 26, 2009


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This is regarding my Rinnai gas heater Model 1260 S.When On button is pressed, it burns and glows the plate but when released , Gas stopped and it turns off.

problem is proberly the thermocouple burnt out .FSD
(fail safe device) normally you push the button in and the pilot light or flame is ignited,this flame heats the thermocouple that generates a small voltage that holds the gas valve open.
if the thermocouple is burnt out or not set correctly in the flame or the pilot flame is to small , as you say when you release the button it goes out, looks like you need a new thermocouple.

Nov 24, 2016 | Rinnai Heating & Cooling

1 Answer

Hi there i have an old rinnai tankless water heater model # REU-502 and i need a new thermocouple (pilot won't stay lit after i hold it on for ever)i have the original manual but no one locally can he

That unit has a 5 year warranty on the parts that you are talking about. The unit also is proprietary and you have to contact them for service.

Mar 31, 2014 | Rinnai Heating & Cooling

1 Answer

Rinnai gas heater not staying ignited

Blocked pilot flame too small or thermocouple needs replacing

May 27, 2012 | Heating & Cooling

1 Answer

I "think" I have pinpointed the problem but want confirmation before I buy this part. the sequence of "lighting " the pilot is working fine and the water flow is circulating as it should. when I "turn"...

To keep the Pilot running... TYPICALLY the instructions say hold the pilot down for 30 seconds to allow the thermocouple to assume control... If extending that 30 seconds a wee bit does not work and your "pilot" keeps going out...

You have indeed found your "trouble"

The obvious defferences being length (first
(see generic parts below)

Follow the instructions on the replacement &
- DO NOT overtighten...!!

Amazon com replacement thermocouple

Carnac the Magnificent

Mar 11, 2017 | Rinnai Desa Vent-Free Infrared Gas Heater:...

1 Answer

I have a 5 year old glo-warm ventless heater(propane)that needs a new thermocouple. the old one has an extra wire soldered to it that looks like a grounding wire? all the replacement thermocouples do not...

Since the thermocouple body is made of metal, and often these have a copper or brass sleeve, that *should* provide good grounding for the thermocouple.

Obviously some engineer at the heater company did not agree with this, so he added an extra ground wire.

Most gas valves are not all that sensitive to exactly how many microvolts the thermocouple feeds to it.

My guess would be that if there is a cheap metal bracket that holds the thermocouple, such as unplated steel or tin, the extra ground wire counteracts the effects of corrosion over time.

So if the heater were stored in a damp garage, the thermocouple connection would get corroded, and the heater would not stay lit. The fix is the extra ground wire.

There are two types of failures with thermocouples: the safe-failure is when the gas is shut-off, even when flame is present, and the unsafe failure would be when gas is not shut off, even when no flame is present.

If the thermocouple somehow was not adequately grounded, then the most likely failure would be a 'safe failure' , such that the burner would not stay lit.

You could rig up some sort of extra grounding wire, but unless the part is subject to extreme vibration or is in an extreme (wet/salty) environment, it's probably not needed.

Of course, to be safe, do a flame blow-out test after you install the new part. While it's highly unlikely that an unsafe failure could occur, better safe than sorry.

Oct 21, 2009 | Rinnai Desa Vent-Free Infrared Gas Heater:...

1 Answer

Gas boiler doesnt ignite

Clean the pilot assembly and replace the thermocouple. I suspect that the thermocouple that is installed now is getting tired and is failing. While you do that, clean any debris off the burner(s) and look for any sensors that may need a cleaning as well. You could have a bad connection on the gas valve so check all wire connections for corrosion and clean. Yes the gas valve could be bad not allowing the main burner to ignite but check everything else first.

Oct 20, 2009 | Heating & Cooling

1 Answer

Pilot lights but when ignition pops back up the flame goes out

will either be the unitrol control box or the thermocouple, when you push down you are holding two magnets together and waiting for a small charge to be created from the probe in the flame , if this is not working you have no charge and the magnets won;t stick to allow the valve to open, change the thermo and see if that works first, its way cheaper than a new controler

Nov 25, 2008 | Rinnai Desa Vent-Free Infrared Gas Heater:...

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