Propex burn out

[kevtherev]

Repair is a damn sight cheaper than a new one, should be pleased really

[ghost123uk]

Propex decided to burn out today. Not sure where (will pull it out at the weekend) but interior filled up with smoke that smelt distinctly electrical. Fan?

From a topic of mine, ages ago, titled Re: Edited = Propex compact 1600 and motor repair

my motor is noisy and sounds like it needs attention.

Any joy yet Ralph ?

[CovKid]

No, with a lad in tow and Christmas prep, hard to find a moment to investigate. Its not exactly easily accessible. Hoping I can tackle it over Christmas though. I'm hopeful that photos I take will help pinpoint cause. Motor does sound a possibility John. If so, damage may not be as great but do Propex stock motors for compact 1600 models, thats the question.

[ghost123uk]

Motor does sound a possibility John. If so, damage may not be as great but do Propex stock motors for compact 1600 models, that's the question.

Yes they do. The bearings are not a serviceable part, being spot welded in place. I ended up fitting a new motor, irrc it was around £75 (twas a while ago now ). The newer spec motors they supply are a little different, they are more efficient, quieter and draw a bit less current than the old spec ones. Check with them, as irrc there is an adapter plate or summat required to fit the newer style motor, though I could be wrong there

Also note = It is easy to fit the fan back on the shaft the wrong way around. It still sucks and blows the right way, but much less efficiently than when it is the correct way around. If you get it wrong it causes a shortage of air to the burner, which in turn causes a poor flame, which in turn causes the flame sensor to keep turning off the gas supply solenoid. The thing will run, but randomly cuts out. It took me AGES to figure out what was going on, including fitting a new flame sensor, which of course did not fix it. The annoying thing was that I kept re-assembling using the required silicone case sealant. This makes it much harder/messier etc to take it to bits again to investigate any issues. It's been uber reliable since I got it sorted though.

[CovKid]

Progress.

First day I've had when temperature outside seemed bearable enough to investigate.

Fuse for Propex intact. Started Propex, and amazingly it went through normal routine and fired up! However, if I move the black box, it cuts out straight away. Must be either a wiring fault between box and heater unit or black box has an internal fault. Doesn't seem so bad based on that. If I remember rightly (can't get in there to see at mo) that box is connected by a four prong plug. If so, perhaps I can just disconnect that and see whats occured...

E D I T: No, bit more involved. It appears that on the cable that goes from thermostat to heater, the black wire has got hot and melted in places. Wonder why?

Black box is wired straight into heater - thermostat cable has the four prong plug and thats the one showing evidence of damage although that could have spread depending on route of circuit.

Guess I'll need to refer to installation diagram as it probably melted the line in other places too - probably inside heater too. The heater itself isn't dead (phew!) but I'll need to ascertain what fault caused that wire to get hot. It would certainly explain the smell of burning plastic. Presumably it didn't actually short and thats why fuse (though showing minor signs of heat) didn't blow.

Anyone got a proper diagram rather than the simplistic installation diagram?

[Oldiebut goodie]

I would say that the fan is getting tight leading to high current drain. I would also hazard a guess that too high a fuse rating has been used hence the insulation melting before fuse has blown.
Bearings are tighter when hot and vice versa which could be why it started with the current low temperatures.

[CovKid]

You could well be right. As tomorrow is supposed to be warmer, I'll pull it all out, check all connections, replace that wire and any others that are burnt and lube fan. That may be enough until I buy a new fan anyway. I can't see what else would draw that much.

[BOXY]

I don't know if its any help, but here's a photo of my X1's innards, and a felt-tip wiring diagram I drew at the time.

[CovKid]

Many thanks Mr Box

Yes, very helpful. As its the 12v line and gas solenoid and fan are first along the line, fan looks highly likely. Can't see it being the gas switch. I'll try a rewire and lube then but order a new fan asap. I think John said they were £75 although it does make you wonder what other motor would work in there - and indeed the source of the existing one. Someone sure makes them

[marlinowner]

I would say that the fan is getting tight leading to high current drain. I would also hazard a guess that too high a fuse rating has been used hence the insulation melting before fuse has blown.
Bearings are tighter when hot and vice versa which could be why it started with the current low temperatures.

I learnt this the hard way when I had a heater motor that struggled to run on a Porsche 944. One day it got hot enough to set the heater plasticwork on fire and ended with the car burnt out. And yes the fuse had been uprated because it kept blowing...

[CovKid]

There are LOADS of 12v motors around (even on ebay the list is extensive). Would be useful to know what the rpm and spindle size of the motor is. When I get it out tomorrow I'll see whats what. I'm inclined to source a motor myself in this instance. As long as its good quality, similar spec and quiet, I see no reason why I can't modify case to suit. The existing one runs ok though. Perhaps lube is all thats needed.

[ghost123uk]

Ralph, have you measured the current flowing down the wire that was melted (and is now presumably replaced)?
Mine pulls 2.1 Amps when warm. If yours is similar then (as I know you know) the fan motor is likely not the culprit.
There was on mine a fairly "nasty" grommet affair where the wires entered the main casing. I replaced it with one made out of a slightly modified normal round grommet. I am wondering if your live feed wire has chaffed against the casing where it enters it.

[CovKid]

Aye John. After thinking about this overnight, even if the fan was somehow getting tight, it made no indication that it had slowed down (even when place filled up with smoke) and that wire had got seriously hot. For such a condition I'd be thinking it was a dead short. The fact that movement of the black box shut it down immediately smacks of a rogue cable/wire somewhere.

With the unit and black box removed today, it should be self evident what caused this. I'll be checking all wires throughout and tracing through. Will take pics

[CovKid]

Propex unit removed (just). Now let the fun begin....

Right, it appears that the wire that got hot is the thickest one to unit circled. Thats not my propex - just showing it for reference. Will upload pics shortly.

When moved, that wire snapped about an inch away. It still doesn't answer why it got that hot though. Inadequate earth?

Everything else appears intact.

[Oldiebut goodie]

Draws up a chair.....