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Topic: Water heater ventilator (Read 1041 times) previous topic - next topic

Water heater ventilator

New to me 1996 U270.

First let me vent (no pun intended).  Did that coach really come with a single function heater, LP only?  Seems strange for a high end coach.  >:(

Now the real question - burner will not keep burning unless I leave the door open (heater grill is cut into the basement door.) I find it hard to believe that the previous owner put up with that, so there must be a secret.  Looking at the 12 volt fuse block, there is a 15 amp fuse labeled "water heater ventilator".  Could that be the secret?  If so, what is suppose to be happening.  The fuse is good.
1996 U270
Build #4846

Re: Water heater ventilator

Reply #1 –
Sounds like the burner needs some adjustment. The Atwood service documentation can give you details. Basically you loosen the TLS (Tiny

Little Screw) on the burner tube. Then slide the tube to 'open' the window to allow additional air through. Makes sure there is nothing blocking the air screen.
 Here is a generic atwood manual. Pic 9 shows the orifice section. Also read the PM instructions.
 
Quote
old_nodaker wrote:        New to me 1996 U270.    First let me vent (no pun intended). Did that coach really come with a  single function heater, LP only? Seems strange for a high end coach. :(    Now the real question - burner will not keep burning unless I leave the  door open (heater grill is cut into the basement door.) I find it hard  to believe that the previous owner put up with that, so there must be a  secret. Looking at the 12 volt fuse block, there is a 15 amp fuse  labeled "water heater ventilator". Could that be the secret? If so, what  is suppose to be happening. The fuse is good.           
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Water heater ventilator

Reply #2 –
http://bryantrv.com/docs2/docs/operating/atwood1.pdf

The U320 models can with a 3 way water heater - electric/propane/engine heat. Not sure on the 270 models.
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Water heater ventilator

Reply #3 –
Need more information on this.

The water heater is pretty simple device.

The propane heater was standard.  Electric was optional on 270.

Another difference between 270, 295 and 320

Does the heater shut off when you close the door, or does the noise just go away?

If you open the door, is the heater re-lit?

Are there any wires sticking out far enough to be hit by the door when it closes, which could cause a disconnect from 12 volt electricity sources?

Are you able to relight the heater electrically from inside the coach by using the switch?

I do not know of any part of the system that would do what you describe and allow you to relight the system.

There is a thermal cutout (a metal tube in a plastic sleeve 1/4" in diameter) that will fail if either, your over pressure valve releases, or you get a blowback from the burner area.  Once the cutout fails, you have to replace it.  Under certain windy conditions in the desert, we expect the cutout to fail.

It is possible you are misinterpreting the situation and the burner is actually burning with the door closed and NOT making any noise due to air flow changes.

Please advise as to what you find.
JON TWORK KB8RSA
Full Time RVer (10+ Years) & Dedicated Boondocker
Retired, Unemployed, Homeless Transients
1996 Foretravel U270-36 w/24' Timberwolf Trailer
I firmly believe that tomorrow holds the possibility for new technologies, astounding discoveries, and a reprieve from my remaining obligations.
Welcome to WeRV2 (Under Construction)
Find Jon: Via Satellite Tracker Datastorm Users
The Second Amendment is in place in case they ignore the others.

Re: Water heater ventilator

Reply #4 –
When I close the door, the burner starts to spit and sputter, similar to if it was in the wind, then it dies (red light comes on).  Once it's cycled off, I'm thinking it won't restart without flipping the switch.  I did open the air more as suggested earlier and that has solved the problem for now.  It still doesn't sound as "healthy" as with the door open,  definite difference in the sound, but it did keep going. 

Okay, since Jon went to the trouble of trying to narrow this down I will answer his questions:
Yes, heater did shut down when I close the door
No, the heater does not re-lite when I open the door
No wires sticking out
Yes, I could re-lite it with the inside switch, but it would only burn a few seconds and die (cycle off)
Not sure what you're saying on this line ("I do not know of any part......"), but I'd guess you're referring to problems, such as the thermal cutout, which keep it from lighting at all. 
So yes, I am aware of the thermal cutout.

I'm now guessing that the fuse that's labeled "water heater ventilator" is just the 12 volt supply to the heater.  I'm also going to guess for now that the problem is the air supply, the door is well gasket-ed, leaving it slightly ajar helped, and as I mentioned, opening the air to the burner helped it.  It is close to being wide open now.

Thanks for your time.




1996 U270
Build #4846

Re: Water heater ventilator

Reply #5 –
Our original 10-gallon water heater was gas only.  For many years, we heated with a 6-gallon electric Hot-Rod (purchased from Camping World) that screwed into tank drain plug opening.  When we replaced our water heater this year, (which we did ourselves) we put in a gas/electric unit.

When our gas burner would not stay lit, I removed the clear plastic round window on the door and bent the door bottom up an 1/8" so more combustion air was available.  Also important to blow out combustion chamber.  Our intake/exhaust grill is also part the compartment door.  If burner air adjustment is out of wack, burner may not stay lit or burn loudly.

Don't know anything about ventilator fuse.  We don't have that fuse.

Re: Water heater ventilator

Reply #6 –
You were correct in the fact that the flame was going out and then the thermocouple was telling the unit to shut down.

I have mine set to a blue flame and minimal noise and it seems to work pretty well.

I suggest if you have it available, to blow out the entire burner area with

HIGH pressure air and see if anything has decided to live in the burner area and built a nest or condo.
JON TWORK KB8RSA
Full Time RVer (10+ Years) & Dedicated Boondocker
Retired, Unemployed, Homeless Transients
1996 Foretravel U270-36 w/24' Timberwolf Trailer
I firmly believe that tomorrow holds the possibility for new technologies, astounding discoveries, and a reprieve from my remaining obligations.
Welcome to WeRV2 (Under Construction)
Find Jon: Via Satellite Tracker Datastorm Users
The Second Amendment is in place in case they ignore the others.

Re: Water heater ventilator

Reply #7 –
My compressor is on loan right now, but should be back in a couple of days so I'll blow it out and give it a try.  Thanks for your attention.
1996 U270
Build #4846

Re: Water heater ventilator

Reply #8 –
Quote from: old_nodaker –
.....................
I'm now guessing that the fuse that's labeled "water heater ventilator" is just the 12 volt supply to the heater.  I'm also going to guess for now that the problem is the air supply, the door is well gasket-ed, leaving it slightly ajar helped, and as I mentioned, opening the air to the burner helped it.  It is close to being wide open.
.....................

All the symptoms seem to point to the burner being air starved, either through air flow adjustment or burner internal blockage.
In 1997, the U295's came standard with the 3 way (Propane, AC Heating Element, Engine) Atwood hot water heater, and in 1998, the U270's did as well.  Prior to 1998, the U270's could be optioned with a  3 way heater.  You should have an "On/Off" household type Light Switch on the lower right corner of the bed pedestal, just below the 12Vdc fuse panel door, to turn the "AC Element Enable Control Function" On/Off, if you have a 3 way Atwood.
I checked my fuses this afternoon when I was at the warehouse, and I also have a 15 amp, 12Vdc fuse (in the#7 location).  It is labeled "Water Heater Ventilator".  I wondered if it wasn't a combined fuse for the water heater 12Vdc control circuits and the kitchen Kool-O-Matic Ventilation Fan.  I pulled the fuse and verified that to be true and I also looked at my schematics, which also substantiated these facts.
Best wishes and let us know if blowing out the burner cavity (or whatever other) does the trick.
Neal
The selected media item is not currently available.
Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Water heater ventilator

Reply #9 –
Okay, I've been ignoring this problem, got back to it today.  I pulled the covers off the vent and pulled off the ignition/nozzle unit.  Everything is clean as a whistle.  Still the same symptoms, will run with the door open, dies with the door closed. 

So, I've been studying the door.  Frankly, I can't see any way for air to get into the unit other than through the exhaust vent.  The housing of the heater sticks outward so it is practically sealed against the door, and then besides that there are gaskets around the heater and also around the perimeter of the door.  I can deal with that with a bit of body work, but I can't understand how the PO's would have put up with it.  Also the bar that runs from the door handle to the left hand latch compresses the gasket that's around the heater housing, and in fact it won't even close far enough to latch on the left side.  Surely it didn't come from the factory like that. 
1996 U270
Build #4846