Hi Bruce. Sounds like you have a leaking hose on your coolant loop thru the w/h compartment. The age of your coach suggests its probably time to start replacing all of those hoses. Not easy.
The Webasto has several componants which need attention. If your unit attemps to start and won't , you may need to clean the fuel jet. Or the ignitor coil may be bad. All of this was discussed in a thread originally started by Mango Mike. Look under articles for this.