What I can't understand about those operating a hydronic heating system is why you don't keep the system full at all times with an antifreeze solution. Propylene Glycol and distilled water is a non-toxic alternative to ethylene glycol. Either way you don't need to worry about freezing.
In a bricks and stick situation you're relying on the electricity never going out Those at the end of the power line will have anti-freeze.
Art
Art the heating tubes are filled with coolant all the time. It is the fresh water lines that have to be filled with potable coolant to winterize.
If that were true, then the boilers wouldn't freeze.
Woody and Sitka wrote: "You can't simply drain and blow out the fresh water lines in the Oasis/Aquahot as there will be some water that always remains in the lower sections of the heat exchange spiral, which will freeze and burst. Water must be purged with anti-freeze to winterize properly. The shop that "winterized" your coach just cost themselves or your insurance $10-20CB for a new Oasis. You'll probably find pex fittings that froze and cracked for years to come."
The boilers do not freeze. The potable water lines that rap it freeze. There is about 30 loops that will hold water if gravity drained is used. Must be winterized or will be damaged.
Found my leak U320 Aqua hot (https://www.foreforums.com/index.php?topic=40885.0)
Even blown out, water will remain in the loops and cause the copper coil to split.
Two other potential trouble areas as the water line to an icemaker in a fridge and the water fill lines to a washer/dryer. Neither of those can successfully be blown out.
Art, the Aqua Hot is also our water heater and has the same weakness as your propane water heater.
How do the Aqua Hot system make potable hot water? I'm familiar with more than my share of burst tankless coil systems because the owner/operator didn't understand the difference between the heating side and the fresh water side of a hydronic heating system. Plus a younger friend installed a gas-fired tankless system in his home to provide potable hot water and radiant heat. Real-world data showed than a well insulated electric tank was less expensive to operate for potable hot water. All I know about the radiant heating system was that the cats had their favorite place to sleep. Jim H. would also be the same guy who while working for Reed & Cole tipped his crane over in the parking lot of the Kittery Trading Post, Kittery Maine while getting ready to install the jib.
During the week of 20F weather we had here recently I was impressed by how well our propane water heater held its temperature over night. Although it took longer to "get hot" than it does on the 100F days.
Check out Scott's Aquahot repair thread above. His pix show the copper pipe wrapped around the "boiler" tank to transfer heat from the tank to the fresh water...older system used external wrap and the newer style uses the heat exchanger loop inside the boiler fluid tank. Domestic hot water and heat exchanger fluid (GRAS anti-freeze) in the newer models are completely isolated in both systems.
Thank you! So the Aqua Hot systems ARE just a sticks and bricks hydronic system writ small. Given the need to winterize I think that there would be a factory or aftermarket system to pump RV antifreeze / propylene glycol and water, into the system. You know, make it easy for the owners.
Res777 would have missed out on much pain if he could have told the garage to look in the basement for a suitcase and follow the instructions inside. "Blowing out the lines" has always had a hit or miss aspect I never liked.
Actually I sent them this right out of the Oasis owners manual along with pictures where all the drain valves were located.
Apparently Oasis internal heat exchanger coils are wound vertically allowing them to drain most of the fresh water, unlike Aquahot which are horizonally wound and trapped water, which will freeze and cause pipe ruptures is almost guaranteed.
If you had 10 minutes of water draining from your fresh water tank when you picked it up, they did a very haphazard winterization to your coach, hoping for the best. Hope your diagnosis and repairs are an easy fix and modest $.
A younger friend of mine changed careers after tipping over a 150T crane* in the parking lot of the Kittery Trading Post. After his purchase of a contracting company was finished I warned him that everyone he employs, with the best of intentions, will be trying to put him out of business. He thought that was the most hateful thing I'd ever said, until it happened to him.
Making up a box of some sort with the hoses and pump to add liquid to your water tank is something you need to have ready and with detailed instructions might have saved your water system. That being said, with any luck your 2008 Fortravel Nimbus will have PEX plumbing.
* A checklist would have saved the day.
I would never trust just blowing out the water lines for winterizing.
My 95 uses a Primus heating system. It requires a 50/50 blend of water and antifreeze be circulated through out.
I still have a 10 gal water heater that it heats.
I MUST drain the water heater and all tanks and lines for winter storage.
I bite the bullet and use about 20 gal of the non toxic RV antifreeze. I run this antifreeze through the washer and dishwasher.
10 gal in the water heater, a few gal though the dishwasher, washer, and all the water pipes and a gallon for each and every drain.
Don't forget to flush out the outside faucet with RV antifreeze.
The cost of the non toxic antifreeze is minor compared to tracking down water leaks and split pipes in the spring.