Stubborn hydro hot burner

[Al Lewis]

More hydro hot issues. I have read many postings on this subject but have not read a problem just like mine. The diesel burner will not fire up from a cold start. If I let the electric element work for a couple hours then the diesel will fire up. It seem to keep working if it is used once a day.  Let it set a few days and it will not fire again. I have the shop manual and have done the maintenance items. Also I have tested the ignition coil and replaced the flame sensor. I have not checked the fuel pressure or changed the wabasto control module. I am thinking it is a temperature sensitivity problem in the controller but they are expensive. Has anyone seen or fixed a problem like this?

[Fred Brooks]

                Hi Al,

      One of the ways that I use to isolate an intermittent issue like that is this. With the wabasto unit cold, remove the unit so you can have access to the nozzle. Purchase 2 feet of 1" clear vinyl tubing from Ace hardware. Put the tubing over the nozzle and the other end in a bucket. Next put a piece of tape over the photo electric cell next to the nozzle. Have someone turn on the unit while you observe the ignitor probes for spark and diesel flow into the clear tubing. This will prove the start-up cycle. This is a dangerous test so be careful. If you are not comfortable, have a qualified RV technician with wabasto experience perform it. My guess would be the ignition module. Hope this helps, Fred

[Al Lewis]

Thanks Fred

Interesting technique. Probably safer than what I might have tried. I know it is injecting fuel because when it does not fire the exhaust gets loaded up with raw fuel. When it fires it put out a lot of white smoke until the excess fuel is gone. I had it firing yesterday afternoon and turned everything off. This morning it fired the first time. Some time ago I got it to fire by putting a hair dryer on the control box. Then I put a bag of ice on the unit but it continued to fire. It is not a real trouble issue, just man vs machine and I am still losing. Fortunately my time is plentiful and free. Oh, I have had the ignition module out and it fired and it fired 100 times from an external power source without issue.

[David T. Richelderfer]

"Oh, I have had the ignition module out and it fired and it fired 100 times from an external power source without issue."

Your coach batteries are all good and strong?  When Mike Flowerday worked on my AquaHot two years ago he indicated when the igniter starts getting weak it will fire intermittently more and more often, and the problem gets worse when cold.

[Marty and Suzie Schenck]

Al, try going to www.rvhyrdronicheaterrepair.com and joining that forum. It is a wealth of info and help. It has helped me several times and saved me money on parts. Marty

[Al Lewis]

Thanks Marty.  I am working on that.  To David:batteries are good.  I have been alerted about flakey ignitor modules which is why I tested it 100 times.  I will try appling heat to the ignitor with a hair dryer since your guy indicated they don't like cold.  Right now when I test it every day it works.  I have to let it set a few days I guess to get back to the fail mode.   Al

[Bob Stone]

Minor correction to the website in reply #4 above. I believe the URL should read:
www.rvhydronicheaterrepair.com