Dometic 182 high/low flame problem

[dschaftlein]

So I've been trying to figure this out for a while now but can't find a solution. I hope someone can steer me in the right direction.

my dometic 182b is working well, too well... with the thermostat at the coldest setting the temps are typically around -5c, causing all of my food to freeze.
If i turn the thermostat down I can see the flame change from full flame to low flame. it stays lit for 15-30 min, then the flame flickers and goes out. shortly thereafter I can hear the solenoid valve click and shut the propane supply to the burner off. I'd like to get the low flame working to see if i can reduce the temps.

-I've cleaned the burner, intake and exhaust pipes and sealed the burn box.
-Ive tested the thermocouple: 6-7 millivolts on high flame and 2-3 millivolts on low flame. the flame goes out before the solenoid valve shuts the gas supply off.
-My westy propane take has a new regulator and i've bench tested it with a bbq tank and new regulator (although i haven't test the output pressure of either)
-I've taken the solenoid valve apart and everything seems clean and functioning.


tonight I will see if the low flame stays lit with the burn box open...


any ideas?

[davevickery]

You could check what pressure your regulator is putting out.
I would also clean the gas jet. You can unscrew it from the burner box without taking the whole burner assembly apart. When you first take it out, sip some water and blow the water through the jet. Do it again after you clean it and see if it squirts easier. That is most likely the problem or some piece of crud in the LP line. In case it is related to the flue being a little clogged, I would blow compressed air through that both ways too.

I have tested my thermocouple gas safety valve and it will go all the way down to 1 millivolt before the magnet shuts off the gas supply. So yours is a little low at 7-8 millivolts but it won't (and apparently isn't) affecting the shutoff. It does make the little LED light dimmer and harder to see. I wouldn't worry about that though.

I keep the dial on mine set at around 8-9 o'clock position. It doesn't affect the inside temps during the day but at night it keeps things from freezing if I am up in the mountains where it gets down to 40s or less at night.

[DanHoug]

if you have one, put the gas jet in an ultrasonic cleaner for an hour. since it runs up to 30 minutes on low, the thermocouple is positioned correctly but the flame is extinguishing. this can happen from :

- thermocouple low voltage. seems not in your case. it operates fine on high and for a long while on low.

- air infiltration due to a bad 'orange' gasket. maybe. seal the pan up with high temp silicone sealer.

- air pipe blockage. hornets, spiders, dirt, etc.

- partially clogged jet.... just putting out too little flame for reliability. the odor mercaptans in propane leave a deposit on everything including the gas jet itself. the orifice is too small for a welding tip cleaner so you have to use solvents or ultrasonic blasting. that whiteish deposit is hard to dissolve with solvents so my go to is ultrasonic zapping.

while you're back in there, polish the end of the sight tube on your blue jeans and it makes the flame much more visible.
_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[dschaftlein]

thanks for the advice, I'll check the jet and propane pressure. if anything I would imagine the bbq regulator would be supplying too much pressure.

the rest all seems fine, I've been pulling the fridge every year and doing a through cleaning, sealing and maintenance. I've cleaned the jet before but not recently.

[dschaftlein]

Problem solved... the gasket between the combustion chamber and exhaust pipe was leaking very slightly.

Feels so good to have a working thermostat again!

[DanHoug]

did you use silicone or make a gasket for that location?
_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[dschaftlein]

I used hight temp silicone. I finger tightened the screws then tightened them down after letting the silicone dry for 30-40 min

[dschaftlein]

I thought the problem was solved but after continued long term bench testing the low flame still blows out.

I would really like to have a functional thermostat that i can run on low flame. the high flame works great and freezes all my food!

am I trying to fix a problem that can never be fixed? for those of you out there that still use the dometic, do you have a working low flame?

the only part i haven't replaced is the jet which i'll be looking at next.

-tested pressure and replaced regulator
-slealed burn box and intake an ex. pipes perfectly.
-replaced thermostat switch, thermocouple and safety valve
-cleaned everything very thoroughly

[davevickery]

What does the flame look like when it goes from high to low? There might be some youtube videos of the 2 flame sizes. Did you clean the LP jet?

[dschaftlein]

I did clean the LP jet with solvent. I may have used a small wire to clean it years ago. which is why i want to try a new jet. the flame looks good to me on high and low, nice and blue, maybe slightly yellow on low flame.