Propane Cooktop Flare Up

[FishAR]

Just getting around to seeing about this, wife brought it up the other day. During the winter in Florida every now and then the front burner on the 3 burner stove top would flare up. Flame jump up a foot or so with a poof sound like you'd just lit a gasoline fire.

I told wife to use the other burners and see if they did it, apparently being hard headed as a mule she never did, she loves the front burner.

Regulator? 

Is there something in the cooktop that could cause this?

I had a coleman road trip grill hooked up to the outside propane connection run through the same regulators off the main tank and it never flared up like that.

[Rick A]

Dangerous. If the propane is leaking and it builds up it could turn into very nasty situation while you are sleeping. All of the burners work off the same regulator so it’s that front unit. Turn the gas off. My guess is that burner is clogged and it’s building pressure in the pipe/burner head unit and suddenly explodes. In essence that is what’s happening, a delayed ignition and an explosion. 

[OhReally]

Does sound like the regulator. Very little quality control in regulator manufacturing and they fail often.

If it were something burning off the burner you would have seen a flame color change but not a foot high flare like you describe. If your front burner is the first in the gas line that might also indicate why it's the only one to flare.

-Jamie 

[timaz996]

(Every now and then) As I understand, is this just when she is lighting the burner? Or when it is being used. 

[FishAR]

Should have clarified in original post

This happens while cooking, flame is already lit and doing fine. Not during ignition. And after reminding myself what a foot is by looking at my tape measure, probably more like an 6-8 inch flare up.

[Tom Cherry]

STOP…. Get the Marshall (most likely) PN from the old Regulator and contact Marshall.  Order the new one.  There are, memory, two different sizes or BTU output.  I went through this for someone else many years ago.  I can’t recall the right one.  Most likely you have an AquaHot Instead of a furnace and a hot water heater but Marshall supplied the tank and regulator like it was for a gas water heater and a gas furnace and gas cook top and a gas refrigerator.  You can Google the Marshall number on the regulator.  You will, I think, find 2 listings….and there is no designation on yours.  So Marshall tech support can help.  
I apologize for my memory.  Here is one that was probably the OEM.  Look at yours.  This is a high output 2 stage (two “domes”) model.  175K will definitely work.  If you have a 2 stage, this is the replacement.  We have a 20 GALLON tank….

https://www.vintagetrailersupply.com/marshall-one-tank-regulator-for-horizontal-mounting-includes-pol-vts-2403/

If you have a single stage, one big dome, then it is in the 75K range.  You need a horizontal Mount style….

The other option, buy the largest one.  There is not that much difference in price.  Sometimes the regulators get oil in them.  The Marcaptan  (memory and spelling) is the “stink” oil added to alert you to a leak,  if they put in too much, it messes up the regulator..  Usually low flow.  But your flare up sounds like a diaphragm issue.  Don’t  be penny wise.  A faulty regulator is dangerous.  If you have a 20 pound (home BBQ) Grill with a regulator attached and a hose with pipe thread fittings, you can remove the output line from the Marshall and use pipe thread adapters to hook it up to your MH line , the one you pulled off.  That small tank, fully filled, will work on the cook top.  If it doesn’t flare, then you know you have a regulator issue.  
 

if you don’t feel comfortable, drive to a propane distributor and have them measure and performance test the regulator’s output.  But, installing a new one, sized properly, as long as you understand how to disconnect and replace is the best bet.  Remember, this is a LEFT HANDED POL or nut holding the regulator to the tank.  No amount of brute force treating it as a RIGHT HAND thread will remove it.  The outlet fitting is a standard NTP RH thread.

Good luck.  Keep us posted.