Auxiliary heater and hose replacement

[Americanrascal]

I've been engaged in a project to replace all my hoses and belts on my 2016 38Q Adventurer. I've finished my radiator hoses , but I am scratching my head about a few things on my auxiliary heater that runs off the engine to heat the hot water tank with engine heat, and I think to heat the coach area also. I believe its time to change these hoses out at 7 year of age also which may be quite a chore.

I went into the on line schematic drawings trying to lay out and plan the the project. I found one line coming out of the auxiliary heater in the drawings but a void for the second line. When crawled underneath to trace the lines I found 2 lines from the heater back to the rear water tank which makes sense. I am unclear as to why the second line is not shown.

Also I know there are 2 lines coming out of the engine I assume to the auxiliary heater but I have yet to see where they terminate- even though I see them right under the dog house cover. I have yet to find the drawings for that sector of the project.

On the chassis heat drawing I do see one line coming off the engine 3 port water valve and I am wondering if that's the one that connects to the open port on the Auxiliary heater? Something doesn't add up as the drawing are leaving me with an extra hose with 2 ports only on the aux heater? (2 back to the water heater and one off the engine).

I also can't figure out for the life of me how one would ever access the auxiliary heater. I can see the 2 hose attachments but no panel or access to the heater itself if i needed to ever get to the core for a repair.

Looks like I'll need about 70 + ft of 5/8 high temp heater hose. Any suggestions on best practices to snake it through the conduit for that length?

Please share any guidance or advice you may have.

Thanks

Joe

[Morich]

Well, they may have done it again and left us guessing!
I might guess that they left off one of the hoses from back to front, whether feed from front or return, maybe they just felt like drawing one and got tired??

But I think it may be that there should be two for the two ports! Then at the water heater there are also two connections that about have to be connected to and from the heater and engine as the heat source.

Digging in the chassis heater drawings, I see two hoses coming off the engine and tee into two hose going toward the rear. Just stubbed out on the drawings, so more guessing involved???

Hot water out of the engine going to the front dash heater if calling for heat, then to the water heater if you have the motoraid option for hot water off the engine heat as well as tee to the rear aux heat if it is calling for heat. Then there has to be return line, even if not shown.

Exactly where??


For how to ever get to the rear heat unit, not much help either but did you get to the parts breakdown of that rear heater?
Not much help on how to get to it but maybe some ideas if you can see what and where the parts break down?
It looks like there are bolt holes on the top left side of the cover, so maybe drops down to remove??
Lots more guessing!




Any chance of getting to a tube and feel which gets hot before the other as hot water moves from front to rear, so at least one might guess which is feed and the other return?

[Americanrascal]

Thanks Richard. I think they left some of the interconnections out for sure. I got some more feedback on IRV2 on the process which helps also.

Not much chance of feeling for hose temp near the aux heater. The line connections sits very high up underneath the chassis and the clamps will be difficult to reach.

Finding the Tee to help figure this out seems essential to the project so I have some crawling around to do under the doghouse and the chassis.

The diagrams on the guts of the aux heater can be easily viewed, but no info on access or how the thing is mounted, or how WBGO thought one might be able to gain access is provided. While crawling around under there yesterday I could not visually see anyway to get to the box . Heater cores do fail and over the past 60 + years I've had a few that leaked. I only found and visually see the 2 heater hose connections. Nothing urgent there but would sure like to understand how they got it installed and how they ever intended for anyone to access that box????

I am also contemplating which type of high temp hose to use, the new silicone type or the old rubber reinforced type like what's on there. The silicone would be nice but that stuff is very pricey!

It would be wonderful if I can get this done as failure of one of these hoses could be a big problem.

Many thanks --- Joe

[Morich]

I'm thinkiing this is likely to be a bear to get it out!

Just looking at the drawings and nothing to back the idea, it looks like getting the heater core out might be meant to happen one of two ways??
Do they mean to take the side panel with the core attached off? I'm guessing it has something like the frame setting too close! They show holes for screws, etc but I'm betting no room to swing it out, even if one could get the hoses off the back..

Or if one had something like a mile long extenstion or air tool maybe to get to the bolts holding the whole thing up, do they take them out and drop the whole ton of stuff down before swinging the core out?


Lots easier for me to just throw theories around and some of them may be killers to get it done when laying on our back under the RV!

I wonder if there is any chance of taking it someplace and let them look it over for an estimate? IF one could get lucky enough to find the right situation, like at a small shop, maybe letting them look at it and you might get some ideas on what they would plan?

I would be in the spot where it would not work for me to start! But if you got somebody who had done something like it, they might give some really good pointers that let you decide if it is doable for you??

Things that can be done on a lift are sometimes just not possible without.
Wish you luck and feel free to ignore my bad ideas!!

[Americanrascal]

I think I have had an "Ah -Ha" moment. I went out and was rummaging around looking for access to the mystery auxiliary heater box and may have found the service access!

On the 2016 era 38Q, if one opens the outer access door to the hydraulic jack system reservoir and pump, you will see a large metal panel with screws holding it in place. I am pretty sure that is the mystery auxiliary heater box access. It lies above and behind the hydraulic pump/reservoir and behind the forward slide ram. With the slide and ram retracted you can only see part of it but with the ram extended, access to the panel, which I now believe opens once screws are removed, should be OK!

From what I see, from underneath, access to the heater hoses is quite a stretch and must be done from under the chassis, possibly sitting up and reaching upwards to the outer exterior panel where the pipes extend to the hose connection. I think (hope) I can reach them to change them out. Then I'll need to snake the lines back to the hot water tank through the conduit to connect again. That should be fun.

I think the panel I viewed must be the outer one adjacent to the squirrel cage blower on the left side of the pic in Richards drawing.

For the purpose of this project I think I'll leave the auxiliary heater box alone and simply try to make the connections with the new hoses. Based on what was offered on IRV2, it looks like I'll need about 100 feet of hose (2 50'sections), which I still need to order.

I still need to get inside the doghouse or over the bell housing from underneath to find the mystery tee.

Been wondering how many folks with 6-10 year old rigs have ever changed these hoses for preventive maintenance?

Thanks Richard for the input, it has been helpful.

[Morich]

Okay, sounds like you've got a pretty good view of where and what.
Maybe time to move to tools for geting the hose snaked in?

I went a long time running wires across ceilings with poor tools like a fish tape that was always going the wrong direction. Once I officially "retired" from that job, I found there was a much better tool for moving things in a straighter line like these "rings" they seem to show along the frame.

Are you up on flexible rods for pulling/pushing things like wires?

https://www.harborfreight.com/3-16-i...hoCCa0QAvD_BwE

This is one that is cheap enough that I got one even though I only use it once a year!

The idea is that it has various tips to tie on what you want to move and then the rods are flexible enough that you can often bend it to fit in some hole and as you push it further, you can add more and more length up to 33 feet.
Whether it works better to go along underneath and get a whole bunch of the pole in and then tie on the hose or tie together and try to "guide" both through is still a learning thing!
I might go with putting the pole in as far as seems possible, then crawl back to tie on the hose and try pulling it in???

Knee pads or a teen ager handy?
Twelve year old grandkids are great for this but mine have aged out!

[Americanrascal]

Yes I am familiar with the rods for snaking wire and the nearby Harbor Freight stocks that product. In fact I already have 4 sections of the rods, but I may use the method outlined in the IRV2 forum by Skip426. In that response he took the existing hose and the new hose and married them with a short piece of dowel (11/16 by 6 inches). He then applied screws to the end of each hose and used that set up to pull the new hose through to the water heater at the end of the rig. He had someone feed the new hose through the front bumper area as he snaked it back to the rear of the rig

The majority of the run is in flexible split conduit. I noticed that after 7 years its a bit brittle thus I may make it easier and replace a good bit of the conduit, installing it at the same time. I can grab that at nearby HD. The long run down the chassis rail is rather open and easy to access. The hardest part seems to be reaching the ends to connect to the aux heater and then accessing the rear of the water heater for same from under the rig at the rear.

On paper this seems now to be a relatively easy project, but its essential maintenance for aging heater hose. I've come to find out though that when working on this motorhome the easiest DIY projects sometimes turn into nightmares!

It looks like the most reasonably priced 5/8" hose is available online through NAPA in 50 ft sections. I may have some excess but it looks like the most effective approach to getting the material needed for the project.

I'll try to get some pics once I get started and post them for anyone to see. SKIP426 on IRV2 did some helpful pics in his post.

No teeenagers around to help out (grands are on the opposite side of the country LOL), but a neighbor has offered to lend a hand feeding the line. (The DW could also but I don't think she wants to play motorhome mechanic)

I am hoping I will outlive the heat exchanger coil or squirrel cage in the aux heater so I don't have to get into it. But at least now I have an idea where it is, and how it is set up.

Many thanks Morich for your excellent research and guidance on this project!

Joe

[Morich]

I hate to admit it but I had a midnight thought about how crazy to try the rods as using the old pipe as a pull is much better. I guess I was running a whole new one and leaving the old? Or more likely just missing the obvious!

How much coolant to lose? I'm thinking it may be better to try to drain most of it out as opening in three different places means a lot of it gets spilled and that stuff gets everything slippery, so maybe just going at draing as much as possible and all in one sessions may be just as good as lsowly getting wet all over?

[Americanrascal]

Originally Posted by Morich

....

How much coolant to lose? I'm thinking it may be better to try to drain most of it out as opening in three different places means a lot of it gets spilled and that stuff gets everything slippery, so maybe just going at draing as much as possible and all in one sessions may be just as good as lsowly getting wet all over?

As my coolant is relatively new and fresh- about 4 weeks old. I intend to drain down a good bit of the system to save and reuse it (at $18.00 a gallon it ain't cheap!). I may lose a gallon or so in the process but it will be good to sleep well at night knowing my hoses are new.