Nautilus Settings Change w/Tankless Water Heater?

[MarkB]

Apologies if this has been covered - I did a quick scan of the topics and didn't see it. Just brought my 2022 Reflection 340RDS home. I was happy to see the Furrion tankless water heater installed. After reviewing the plumbing diagrams for the Nautilus, the red valve is clearly the water heater bypass valve. To winterize the tankless heater, you should obviously NOT bypass it. The "standard" instructions on the P1 are for a tank-based water heater (you would drain the tank and then bypass it for winterizing). Just looking for some confirmation that I am looking at this correctly. I didn't (yet) do a deep dive in the Owner's Manual so it may be covered there. If people follow the Nautilus instructions exactly and they have a tankless heater they will have a mess on their hands in the spring.

[Cate&Rob]

MarkB
Hi Mark,

Welcome to our owners technical forum. When you have a chance, have a look at our welcome post. https://gdrvowners.com/forum/main-fo...to-new-members . This will help you set up your signature and navigate the forum.

You may quite likely not find any reference to the tankless water heater in you Grand Design owners manual. With the many component changes caused by supply shortages, these last minute revisions have not been incorporated into the owners manuals. Not to say that this is OK . . . it just is-what-it-is.

There are two "theories" on antifreeze and water heaters. Some believe that antifreeze should be kept out of a water heater and some believe that it is better to put a small amount of antifreeze into an empty water heater. An "empty" (tank style) water heater is never completely empty of water. I would suggest that you follow the Furrion information for winterizing the water heater that came with this appliance. Once you have the water heater drained . . . or drained and refilled with antifreeze . . . or drained, filled with antifreeze and drained again . . . putting the Nautilus valve in the water heater bypass position will allow you to use or winterize the rest of the water system without affecting the water heater.

Rob

[ncitro]

MarkB To expand a bit more, since the Furrion tankless water heater requires winterization before the rest of the rig (39 degrees and below), you'd need to use the bypass valve in order to winterize the water heater and still have water in your rig if camping in those conditions.

[MarkB]

Update: The Furrion owner's manual says to EITHER blow out the unit OR fill it with anti-freeze to winterize. The GD owner's manual has the exact same text (direct copy/paste). So, my original concern is valid. The instructions on the Nautilus panel have you bypass the water heater to winterize. This is going to present some problems for people who don't understand what they are doing and just blindly follow the instructions. They will leave water in the tankless water heater lines and will have a mess on their hands come spring. Also, per ncitro's comment above, there really isn't a straightforward way to JUST winterize the water heater.

[TedS]

Is the Nautilus plumbed to bypass the tankless water heater?

[Cate&Rob]

Is the Nautilus plumbed to bypass the tankless water heater?

The Nautilus panel bypasses the water heater by switching the supply to the water heater to the output of the water heater. This system counts on the water heater outflow check valve to prevent back flow into the water heater. I mention this because these check valves are notorious for failing . . . I would not trust that this check valve had kept water out of the water heater.

I am not familiar with the tankless water heater, but if it has a drain plug, it could be bypassed using the Nautilus valve and then drained using its drain plug. This might be sufficient for using the trailer in shoulder seasons without hot water, but for winter storage I would still use winterizing the water system with antifreeze to also winterize the water heater with antifreeze.

Rob

[TedS]

But it is tankless. No tank. What is there to drain?

[Cate&Rob]

But it is tankless. No tank. What is there to drain?

There are still tubes full of water. The same tubes that Furrion claims must be drained below 39F to prevent freeze damage.

Rob

[Country Campers]

Here are some pics of the inner workings of the tankless heater,




Brian

[Jlawles2]

From what I read on the tankless Furrion, there is a heat exchanger and a mixing chamber that would be of concern.

[TedS]

IM-FHA00046_V1.0_Multi-v1579835638826.pdf

Here is the Furrion manual. It describes installation, use, and winterization. It shows optional bypass plumbing. Is the Nautilus panel plumbed to bypass the water heater?