Brivis ducted heater issues.

[loanrangie]

Not sure if anyone is familiar with the buffalo gas heaters but we are having issues without our 20+yo HE5 model. Heater will either start and run fine for a few hours or the reset light will flash and it blows cold, i pulled out the burners and checked the jets which are all clear. When first starting the igniter glows to ignite the gas but it seems like the gas isnt being released, but after a few resets it starts and burners light nothing is wrong but then only for 15mins or so. Its an old unit and most parts are obsolete so not worth a service call and would like to try and keep it going at least til late spring while we work out how to pay for a new unit.

[Homestar]

Have you checked the thermocouple operation? If this fails or isn’t working properly it will cut the gas supply at the gas valve.

[loanrangie]

Have you checked the thermocouple operation? If this fails or isn’t working properly it will cut the gas supply at the gas valve.Hi mate, I can't for the life of me find a thermocouple. It doesn't have a pilot light instead it has an electric element that glows red to ignite the gas and its working fine every time.

[Homestar]

Well I’m out of ideas then. 😇

[Bigbjorn]

There must be some sort of safety device in there to stop gas flow until required. Usually a bimetallic strip that opens a simple valve to allow gas flow when heated and shut it off when not.

[loanrangie]

There must be some sort of safety device in there to stop gas flow until required. Usually a bimetallic strip that opens a simple valve to allow gas flow when heated and shut it off when not.I've searched and the only part I can't work out its purpose is the metal rod sitting horizontal with a wire attached, doesn't seem like a suitable place for a thermocouple type device.
Done lots of googling and can find SFA about these heaters yet they are one of the most popular models.
https://uploads.tapatalk-cdn.com/20190824/91629e1ec52ce477e7a8a4d9f5f9927d.jpg

[theelms66]

Need a better picture of the schematics in the top of your pic.

[loanrangie]

Hopefully this is clear enough.https://uploads.tapatalk-cdn.com/20190824/835a132016eb8ac61057fa28b95ee2a9.jpg

[Dorian]

The metal rod with one wire attached is called a flame rod and it should be in a ceramic holder keeping it electrically isolated from the frame of the heater..
When you start the burner the controller will allow a small time for the flame to catch (normally only 30 secs or so)..
The controller has by now put a DC voltage on the flame rod and is looking for current leakage. The flame is conductive, but the leakage would only be a couple of milli amps, but it’s a goldilocks thing, not too small etc
There is nothing special about the rod and is usually just a nickel carbon steel to be able to handle the heat.
Almost every problem I’ve had with gas fired burners has been flame rods. They often get covered in crud and loose connection with the wire when it gets hot or the crud “shorts” the flame rod to ground. The other problem I’ve seen is the flame rod has drooped to the edge of the flame, so it started but once everything heats up the flame contracts, the rod is no longer in the flame.
The usual caveats about voiding your insurance apply.

Cheers Glen

[loanrangie]

The metal rod with one wire attached is called a flame rod and it should be in a ceramic holder keeping it electrically isolated from the frame of the heater..
When you start the burner the controller will allow a small time for the flame to catch (normally only 30 secs or so)..
The controller has by now put a DC voltage on the flame rod and is looking for current leakage. The flame is conductive, but the leakage would only be a couple of milli amps, but it’s a goldilocks thing, not too small etc
There is nothing special about the rod and is usually just a nickel carbon steel to be able to handle the heat.
Almost every problem I’ve had with gas fired burners has been flame rods. They often get covered in crud and loose connection with the wire when it gets hot or the crud “shorts” the flame rod to ground. The other problem I’ve seen is the flame rod has drooped to the edge of the flame, so it started but once everything heats up the flame contracts, the rod is no longer in the flame.
The usual caveats about voiding your insurance apply.

Cheers GlenThanks Glen rod is rubber mounted and I was careful to keep it isolated from the surrounding metal, should I give the rod a light sand to clean it ?

[Dorian]

Thanks Glen rod is rubber mounted and I was careful to keep it isolated from the surrounding metal, should I give the rod a light sand to clean it ?

So bear in mind I would usually walk into the combustion chamber to do this but the standards are the same, so the principles should be the same.
The crud is usually “oily” deposits from the combustion process. A light clean with a scotchbrite and metho will take these off, if it’s got a lot of corrosion you may need wet and dry, but you want clean metal.
Look at the electrical connection from the rod to the wire make sure it’s free from corrosion. For me it was always a lug and a couple of nuts threaded onto the rod.
Wipe down the insulator as well but if this was the problem it would usually fail prechecks and not light.
Lastly if the rod or the burner has moved there may not be enough flame on the rod to get a “connection” So check that it’s in the blue / orange part of the flame.

Cheers Glen

[loanrangie]

The rod, if we are talking about the same item, isn't in the flame path. The only item that is ,is the igniter element.
I assume you work with industrial furnaces ?

[rick130]

The rod, if we are talking about the same item, isn't in the flame path. The only item that is ,is the igniter element.
I assume you work with industrial furnaces ?Odd?

I thought there should be a thermocouple in the flame?

I've had limited experience with gas, but usually it's a faulty TC or the TC has moved and needs repositioning.

[Beachy]

There is no thermocouple on that unit
the pilot will be going onto something metal it will be connected to 1 of the white wires at the bottom .it could be turning it’s self off for over temperature
l am sure the parts are available you where probably told that by a younger tradesman that’s the common reply when they don’t know how to fix it find a bloke with plenty of experience because most of those parts are generic

[loanrangie]

There is no thermocouple on that unit
the pilot will be going onto something metal it will be connected to 1 of the white wires at the bottom .it could be turning it’s self off for over temperature
l am sure the parts are available you where probably told that by a younger tradesman that’s the common reply when they don’t know how to fix it find a bloke with plenty of experience because most of those parts are genericI haven't spoken to anyone yet but the search I did said the major parts like the control valve are obsolete, the only item anywhere near the flame is the igniter element which glows red hot to light the gas but stops when there is no flow.
Oddly we had it on this morning for a few hours without issue which has me stumped.

[Bigbjorn]

There is a plethora of information on the internet about that brand of heater. Surely there is something there to guide you.

[loanrangie]

There is a plethora of information on the internet about that brand of heater. Surely there is something there to guide you.

Pretty much all advertising or different models and no troubleshooting info for this model.