[VAL] Re: Carlson heater and Bowen water heater

[RJ Dial <radiodial@xxxxxxxxxxx>]

For the Bowen, that is likely the pilot thermocouple.  Here is a picture -
these things are available from almost anywhere, from RV dealers, to
commercial parts houses (like Grainger), or a small appliance parts dealers.
http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611760728l
For the Carlson, if the pilot is staying lit, and it is the main burner
turning off, that narrows it down to the temp regulation section, usually a
hydraulic (bulb) thermocouple or an external thermostat problem.   An
external control thermostat may be of the milli-volt style or can be
electrically controlled.  I didn't think any of the Carlson's were external
- they were all self-contained, self-regulating, but someone may have
modified it too. Troubleshooting a 'turning off' problem is easier than a
'not turning on' or 'won't shut off' problem.

You've done the right thing, removing it and getting it on the bench.  While
there give it a thorough cleaning and inspection.  Look for rusted burner
cans & flues, leaking or damaged lines, and LPG goo in the intake, lines or
mixing chamber of the regulator,  Check the pilot filter too.  If residue is
found in any, then disassembly and a cleaning of the regulator is in order.
Carb cleaner works the best.  Be very careful of any gaskets and little
parts.  You lose or damage them, you're out'a luck.

It is wise to make it work first on the bench, using a propane tank and a
barbecue regulator and hose.  They come with a standard 5/8" flared female
fitting that will mate up to most RV LPG appliances.

In your case, I'd look for a set of screw terminals on the gas control
(besides the 2 for the pilot, if used). If you have them, then you have an
external thermostat control if you don't have a tiny tube that goes to an
external copper bulb.  Another way to tell is if the temp control knob on
the regulator is marked for some kind of temperature control increments.  If
you have thermocouple bulb type regulation, then it's just a matter of
making sure the tube to it is not blocked with goo, and that the fitting is
tight.  It works by increasing air pressure against a diaphragm in the
control body as it warms up.

Back to your possible electrical type.  Without anything connected to it,
the burner will just burn forever.  A little solenoid in the control body is
activated by the external thermostat.  I you have a Robertshaw style
milli-volt control, an external thermostat will just have two wires coming
out of it, and they attach to the gas control valve terminals.  If you have
a more conventional system, much like a house thermostat, then there will 2
additional wires supplying low-voltage to the thermostat.  You are on your
own figuring out which you have - make sure before proceeding to any other
troubleshooting other than simply replacing the thermostat with a like kind,
or isolating it down to the thermostat with the wide open test mentioned
above.  You can wreck a milli-volt solenoid by applying voltage to the
terminals.


Best of luck,
RJ
VintageAirstream.com
'65 Caravel
'56 Flying Cloud