[Tim]

There are various shut-offs on your bus Tim, shut-offs for the engine/webasto, hot water heater loop and the coolant loop to the dash for the blend of hot water for heat and A/C temp. The valves above your hot water heater will close off the engine coolant and Webasto leaving you with hot water only from your 110v switch.

[Bill]

Thanks Tom,

I thought I read that you shut those two valves above the water heaters to avoid scalding water. Is there any other reason why you would shut off those valves? If you had a hose leak you could shut the valves.

Where is the coolant loop for the dash air? I think I read that you shut those off in the summer to help your A/C blow colder? One valve on mine is low driver side of engine in the rear under the fan assembly and the other is in the webasto compartment.

Finally, why would you shut off the engine/webasto loop? If a leak is found in a line.

[Archived]

I think it is foolhardy and dangerous to allow the engine to heat the water unless the engine coolant flow is shut off when the HW tank temp reaches a safe level.

I have added a small thermostat and a 24V solenoid valve to shut off coolant flow so the HW tank will not exceed the electric heating element limit of 125 degrees.

Some have suggested only cracking the valves to allow the tank to heat up via the engine, but all that does is make it take longer for the contents of the HW tank to reach 200 degrees.

[Archived]

I answered your post above Tim, rather than try to repeat everything.

[Archived]

Thanks Tom,

As I sit here at Campground ETLC, the campground host, a guy named Jeff, said that there is a solenoid for “dash air buses” that should close and prevent the hot water from effecting the dash A/C, so you shouldn’t have to close that hot water loop.

But I now know where all the coolant shut-offs are if I get a leak.

[Bill]

The solenoid blends hot coolant with your A/C to allow the cold air temp to be adjusted as well as giving you dash heat in the winter. When that happens, you will see the Webasto light come on while you’re running the A/C allowing coolant to mix with your dash air. If that solenoid doesn’t close call the way, it affects the cold air being generated by your A/C. I had that happen years ago and had to have the solenoid replaced at Prevost. The Tech gave me the tip about shutting off the loop in the summer to assure the coldest dash air.

So so you can tell your Campground Tech solenoids do fail and if so, you’ll be giving him your pension income to troubleshoot your dash A/C and after replacing the compressor, dryer, expansion valve and freon, your dash air still won’t be as cold as Jon’s left knee from his OTR dash vent.

[Archived]

Being lazy and getting lazier I am inclined to start problem resolution with the easy stuff.

This is a good example. While it may not be easy to access and replace the valve it is likely far easier and much cheaper to risk the cost of the valve, replace it and see if that did the job. A solenoid valve coil is easily tested with an ohm meter, but even if it checks OK as long as the tech is at the valve just replace it.

I now use the same approach with respect to the suspension for example. If the coach leans I can spend a lot of time isolating the leak, but if the coach is near the point where age starts to affect reliability, I just go ahead and start replacing them all, beginning with the valves where it is leaning. It is really satisfying finding some obscure internal leak in a valve after hours of investigation, but often it just takes less time to replace stuff starting with the obvious and working down the scale of difficulty.

I bet Jeff agrees in trouble shooting leaks that sometimes instead of spending the hours required, it just makes sense to start replacing parts like push in fittings, valves, etc.