Suburban SW6DE slow ignition

[Angus_NB]

I have a new Suburban SW6DE water heater.
I use it on 12 volt only.
When I turn on the switch the water heater does light but doesn't seem to light as fast as it should.
There is a small explosion every time. As if propane is building up before it lights.
I've had a licensed "propane guy" check the gas flow, he says it's correct.

Voltage is good, usually above 11v.

What could be causing this? Misaligned electrode or too much gap maybe?

Thanks

[Angus_NB]

The problem has been resolved.
It was a defective 12 volt control board.
I swapped it out for one that I knew was ok and the problem is gone.

[Angus_NB]

I checked everything again.
Took the tube off and made sure it was clean.
Checked all gaps for the electrode.
Rechecked the wiring and voltage.
Everything looks right.

I couldn't get a good look at the spark in the daylight, will have to try some evening.
The heater will light right away using a BBQ lighter.

krobbe; It does seem like a propane buildup before spark is causing the problem.
We are only 800' above sea level.
I may just replace the igniter to see if that helps but I will try closing the gap a little.

[krobbe]

I had an issue with my fridge not lighting at higher altitudes. It worked fine at lower altitudes, but when I got into the mountains it wouldn't lite reliably. I checked voltage, cleaned terminals and pulled out and cleaned the burner/igniter but it still wouldn't re-lite reliably. I finally adjusted the spark gap closer and it works every time now. I'm guessing that the gap needed to be closer because of the lower oxygen level.
Maybe in your case, the propane is building up before lighting off. Try adjusting the gap closer so the spark is stronger.

[Angus_NB]

Hi hawkeye-08

Yes the Suburban has a 15 second delay to purge the system. I'm used to that.
My problem isn't the delay, it's the violent ignition. 🙂

[Angus_NB]

Hi Jetcare. I appreciate the help.

No, it didn't light correctly after checking the spark gap.
The gap between the electrodes appears to be correct, 1/8".

The heater isn't at my home. I will be where it is tomorrow.
The service manual that I found shows the electrode at .356 from the center of the tube and .531" from the electrode to the end of the tube. I'll check these tomorrow.
I also need to verify the 12v connections. The last time I tried it I noticed that the light isn't coming on at all during ignition.

Observing the bang is a tad dangerous. 🙂 I can video it, zoomed from a distance. Better to rely on video than my memory anyway.

Thanks

[hawkeye-08]

My water heater has a 16 sec delay on start. I toggle the rocker switch, the switch lights up along with the fault switch next to it. I count to 16 and the water heater ignites. Says it is supposed to do that in the manual. I am not near the trailer right now to check what brand I have. Check your manual and see if it is normal to have the delay.

We bought our trailer used and our first outing was one of learning about the trailer. The water heater ignited immediately on gas (no delay) and I starting troubleshooting a problem when at home it would not start immediately, but rather turn on fault. It took some studying (and help on this forum) to get the information that the initial behavior was the problem and the delay was the correct behavior.

If I recall, the manual said something about the delay being for "purge". Perhaps yours is not purging and there is more gas there than expected?? Just guessing.

[jetcare]

Did it light properly when you said the spark was correct? If so, you have not proven the spark is good. Stand there and have someone turn on the LP switch. You need to be able to observe what happens when you get the bang. Do this and report back. We are trying to help.

[Angus_NB]

I checked the spark last night, it appears to be correct.

[Angus_NB]

I'm happy you are done. 🙂 You seem more intent on arguing than actually helping.

I do appreciate suggestions but you are ignoring parts of my posts.
I did say it was NEW but also said that I had checked the tube as you suggested. I also said I've had a licensed propane installer check it.
As for the battery, yes running a battery down to 11 volts repeatedly will shorten it's life. I can live with that and it doesn't have anything to do with the water heater problem.

[Old-Biscuit]

It may be NEW but doesn't mean it can't have obstruction in combustion chamber or burner tube not aligned or orifice slightly blocked.

Flame should NOT shoot out anytime.........

But hey it's NEW so how could anything be wrong :S

And battery voltage is still to low..........you are damaging batteries by allowing them to go below 12.3V

But hey........11V is still within range :S


I'm done

[Angus_NB]

It's not dirty, it's new, but I have checked it anyway.
There is only flame shooting out during the initial startup. It burns correctly when running after startup.

Thanks

[Old-Biscuit]

Angus_NB wrote:
It's more than a poof but less than a bang. 🙂
Flame comes out about 8" from the cover.

It's the same every time, even while connected to shore power.

This is not installed in my 3 year old trailer.

I'll check the electrode.

Flame comes out from cover.....

Combustion/exhaust chamber obstructed.......mud dabbers nest or even spider webs. Run a wire thru then tie rag on end and pull rag back thru

Burner tube not aligned with gas valve. Propane is low pressure and needs to flow down center of tube to properly mix with air
If propane bounces down sides of burner tube it will not mix and be fuel rich

Orifice......needs to be clean/clear
Unscrew from gas valve and soak in alcohol then blow out with air

[Angus_NB]

It's more than a poof but less than a bang. 🙂
Flame comes out about 8" from the cover.

It's the same every time, even while connected to shore power.

This is not installed in my 3 year old trailer.

I'll check the electrode.

[jetcare]

As a repairman, I sometimes see the spark jumping from the ceramic portion of the igniter to metal and not across the electrode to the to ground rod. This results in the mini explosion you describe. You can go out and watch it light if have someone else turn the switch on. It is easier to see this if you do it later in the evening near dusk or place something like a ball cap over the igniter area to block the sunlight during the test. It may light properly 2-3 times and then spark in the wrong location.