Changing out the Alde fluid.

gregndeb

Here is an addendum to my earlier post in 2020 about changing fluid.  I added clarification and some different ways to do it.

This is an addendum to my 2020 fluid changing notes.  This is what I did when converting from the older “yellow” Century fluid to the newer Rohmer fluid.  I still went with my theory to minimize fluid waste and not create air pockets.  I did NOT flush my system with distilled water or DI water.  I preferred not to introduce any potential of adding anything that might be corrosive (including water).  Thus our system only had old fluid, maybe a small air bubble here or there and the new fluid.   

 

Expansion tank

To clarify, the fluid line GOING TO the expansion tank is on the lower right side.  The molded reservoir has a lower depression in that area.  (This is counter intuitive to me, I would think that the suction would be from the lowest possible point.  This would permit some operation, just in case one was low on fluid.)  There may be other reasons that I am not aware.  Here’s a picture.  Inlet to the reservoir is to the right.  Suction from the reservoir is center, elightly left.

 

Note I have a plumbing “test plug” as my cap, as our original cap didn’t fit very well.  We did get some splashing out of that reservoir into our closet.  The test plug has worked well enough that I haven’t been motivated to change the reservoir yet. 

 

Removing excess fluid

My previous procedure to remove the excess fluid was to put a tube down the inlet and suck the fluid out with a small pump (drill pump, or similar). 

This time, I removed the drain plug from the Alde System and only let out a slight amount of fluid.  I just drained the reservoir dry, plus maybe a little more.  (It was maybe a quart of fluid, that’s it.)  That prevented the introduction of air bubbles.  I reinserted the plug, but didn’t reinstall the hose clamp, YET!

The drain of our 2018-CS trailer is located about 10 inches ahead of the drivers-side tire.

 

I then did the earlier procedure to flush out the old and replace with new fluid.  That system has worked well for me.  If you have both rubber adapters inserted into the fittings on the bottom of the reservoir, there is no leakage.  (You don’t have to press very hard ether.)

After that was completed, I drained out the tiny amount of old fluid that was in the drain area.  I just removed and quickly reinserted the drain plug.  It was a little messy, but was done quickly.  Maybe there was ½ cup of fluid.  THEN you can reinstall the hose clamp on the drain.

 

Other trailer model thoughts:

I have used my setup on our 2018-CS (no bathroom) and an earlier 320.  We had sufficient room to use that setup.  Alde used to have a setup that they would lend (with a deposit) to users but that was prior to them being part of Truma.  Note that their setup is a little shorter overall.  The suction side only draws from the reservoir tank, which would not capture the older fluid very well.  Here is a picture from an older Alde manual.

gregndeb

Oh yeah, I put a footswitch on the pump.  That allowed me to hold the plumbing adapter in place and start things rolling.  I had one assistant that checked the color of the fluid and supplied the new fluid when needed.  

Jake_Elwood_and_us

  Just finished doing my glycol exchange.

 This instruction is for my 2021 400 with the upgraded double drain. YMMV.

  1) Pinch close the middle part of the double drain with needle nose vice grips.

  2) Hook up the glycol fill line to the port which goes to the Alde pump and start pumping.

  3) Keep an eye on the reservior to make sure it does not overfill.

  4) Allow the return line to drain into a 5 gallon bucket until 3.5 gallons have been returned.

  5) Pinch off the fill port and cap off both ports.

  6) Run the glycol pump on high (5) for 20 minutes to allow mixing and air removal.

  7) Lower pump to 2 and start heating, check reservoir level and bleed as necessary.

  Done!

glesieutre

Horigan said:

I tried the shop vac method and it worked great at getting all the fluid out.  <...>

I have a 2015 Max-S and, now retired, finally got around to doing this myself -- in preparation to address anticipated convector corrosion. I decided to go this route to eliminate the need to push more than two gallons of new glycol in (while pushing out the old). I can report that it worked well for me, and that I won't hesitate to do it again. 

I am now intimately familiar with the workings of my Alde system. (I will report on the corrosion adventure in another thread.) 

My approach is something like this: 

1. Ensure Alde system is off at control panel
2. Remove energy for Alde heat (unplug from 120VAC power and close propane)
3. Open the drain valve at bottom of trailer and collect old glycol from the internal reservoir  
4. Disconnect hose at top of Alde unit (under the bench) to break vacuum and drain additional glycol
5. Reconnect hose at top of Alde and disconnect hose at bottom of Alde (so that shop-vac suction does not drive the circulation pump) 
6. Remove cover from Alde reservoir
7. Use shop vac (with attachments) to suck glycol from the reservoir (where the return hose at the center bottom enters the reservoir) to remove remainder of system glycol
8. Reconnect the hose at bottom of Alde
9. Close the bottom drain valve 

Refilling with either distilled/deionized water to flush, or with new glycol, the approach is the same: 

1. Set circulator pump speed to 5 (under the bench, red arrow nominally set at 3)
2. Using a large funnel or a hand pump, fill internal reservoir (to the max line)
3. Turn on Alde system at control panel, and set thermostat so that it asks for heat
4. When the circulator pump empties the reservoir, turn off the Alde system and refill the reservoir 
5. Repeat this process (3, 4) until the fluid level stabilizes 
6. Run the system for several minutes to remove air (automatic)
7. Top off the fluid in the reservoir so that it is near the max line
8. Reset the circulator speed to 3, button things up and restore heat sources (120VAC, propane)

Using this approach, I collected, then added, just short of 2 gallons. A water flush retained some color, but I think this method removes essentially all of the fluid for practical purposes. 

Thanks for everyone who described their approaches and experiences here. It was (and continues to be) extremely helpful to me. 









{edit}

pthomas745 said:

Enquiring minds will need to know: what sizes are those nicely done PVC pipes?  And, those "rubber "gaskets"?  How did you make those, or are they some sort of standard part?  Fittings/adapters  for the PVC to the shop vac pipe?

Here is some information about the "suction adapter" -- 



The black connection to the shop vac rigid tube is a: "2-1/2 in. Power Tool Adapter Accessory Shop Vac Attachment." I got it at Home Depot: https://www.homedepot.com/p/RIDGID-2-1-2-in-Power-Tool-Adapter-Accessory-Shop-Vac-Attachment-for-RIDGID-Wet-Dry-Vacuums-VT1407/100206293. Perhaps it could be adapted for other diameters, or something similar is available for other brands. The smallest diameter is called 1", but the ID is just less than 7/8". I might have used duct tape on the shop vac side. 

The long pipe is a 3/4 in. x 2 ft. CPVC Water Supply Pipe. The actual OD is 7/8". https://www.homedepot.com/p/Charlotte-Pipe-3-4-in-x-2-ft-CPVC-Water-Supply-Pipe-CTS-12007-0200R/203019298. It's a tight fit into the preceding adapter, but the adapter is flexible, and it works. 

The short pipe is a 1/2 in. x 2 ft. CPVC Water Supply Pipe, cut to 11.25 in. length. The actual OD is 5/8". https://www.homedepot.com/p/Charlotte-Pipe-1-2-in-x-2-ft-CPVC-Water-Supply-Pipe-CTS-12005-0200R/203019249 Others might have to adjust this length to ensure clearance above the back shelf, to minimize height, or to ensure it is downhill to the shop vac. 

The connecting elbow is a 3/4 in. x 1/2 in. CPVC-CTS 90-Degree Slip x Slip Reducing Elbow Fitting. https://www.homedepot.com/p/NIBCO-3-4-in-x-1-2-in-CPVC-CTS-90-Degree-Slip-x-Slip-Reducing-Elbow-Fitting-U4707R3412/100346346

I did not glue these pieces together, nor did I tape them. 

The two black neoprene washers are 2" OD and 1/2" ID (measured), with one cut down to 1.5" OD. I got them at Ace Hardware. Prior to insertion in the glycol reservoir, I put the washers at the lower end of the short pipe, with the smaller diameter one at the bottom. They slide up a little, and differently, as the pipe descends and everything gets seated.  

Hope that helps someone! 

pthomas745

Enquiring minds will need to know: what sizes are those nicely done PVC pipes?  And, those "rubber "gaskets"?  How did you make those, or are they some sort of standard part?  Fittings/adapters  for the PVC to the shop vac pipe?

This is really going to help some owners who may have issues getting easy access to the expansion tank. 

DanWeitzel

I used the shop vac procedure when changing Alde fluid and found it completely drained the system.  I had bulging issues so had to remove the convectors to make repairs.  There was no fluid in the system after draining.  2016 T@B QMax.

glesieutre

pthomas745 said:

Enquiring minds will need to know: what sizes are those nicely done PVC pipes?  And, those "rubber "gaskets"?  How did you make those, or are they some sort of standard part?  Fittings/adapters  for the PVC to the shop vac pipe?

Thanks, I edited my original post/comment. 

pthomas745

@glesieutre Thank you very much.  It is always nice to see the mods to the mods.  @Dalehelman , who developed the "shop vac" idea, would approve, I'm sure.

This will certainly help someone in the future.

subkron

@Jake_Elwood_and_us
Nice.

- I'm assuming you used an external fluid pump between the fresh Alde source and the input hose connection (not the Alde pump), which pump did you use?
- Did you notice any level change in the reservoir during this transfer?
- Do you have any info on the hoses you used to connect to the bottom ports to the fill/return jugs?

Thanks.

Jake_Elwood_and_us

subkron I used this pump.

https://www.amazon.com/dp/B00J8331U6?ref=ppx_yo2ov_dt_b_fed_asin_title

  When I do this again I will use two of these pumps. One to push the replacement glycol in with and one to help pull out the old. I found the gravity draining needs a bit of help and I didn't like the idea of using a powered vacuum. The reservoir does drop when pushing the fluid in but with an additional pump it will go faster.

  The hoses that come with the pump are good enough to complete the project, I just used a couple of barbed fittings and a 1/2" MPT/FPT to couple together from the local ACE hardware store to adapt from one hose size to another. I will edit later when I can take a picture. I also poured the 3.5 gallons of glycol into a new clean bucket so I didn't have to keep moving the hose out of one bottle of fluid to another. Since the hose curls up at the bottom of the bucket I weighed it down with another filled bottle to keep the hose at the bottom.

jalars8

I am preparing to do the DIY glycol fluid exchange on my 2018 320S using the adapters fabricated out of 3/8" OD copper toilet supply tube with the #2 drilled out stoppers, the Performance Tool hand pump, etc.  The instructions and the schematic indicate that the inlet adapter through which the new fluid is pumped is to be modified (with two 45 degree bends) and goes into the offset opening and not the opening directly below the expansion tank opening on top.  In looking at my tank, it wasn't clear to me that that is correct.  Feeling the tubes coming out of the bottom of the expansion tank (since I can't see them)  it seems that the rubber tube that is attached to the direct opening goes to the circulator pump and Alde boiler which would make it the intake and that the rubber tube coming out of the offset opening bends toward the direction of the convectors which would make it the outlet.  How am I going wrong on this?   I'm sure the answer to this is somewhere in the forum but I haven't found it.  

ScottG

@jalars8, you may not be wrong. The flow schematic shown in the DIY manual is consistent with what is shown in Alde's literature, and with the way my 2015 is configured.

That said, I vaguely recall at least one other report of the expansion tank in a newer T@B being plumbed in the opposite manner. I don't know if this is an official change to the installation protocol, or just something done out of convenience when the campers are assembled. Regardless, you are well served to confirm the orientation of the hookups on your own unit.

From a functional perspective, I doubt it makes much of a difference how those lines are hooked up.

DanWeitzel

When I used the shop vac method I placed the vac suction on the hole directly below the fill opening.  This completely pulled all the fluid out of the system on our 2016 T@B QMax. 

AnOldUR

@jalars8 I'm not sure if there has been changes as @ScottG said was possible, but the picture attached shows how our 2020 320S is plumbed. The pump draws glycol from the tanks offset port. From there the glycol is pushed through the Alde and heated. It then passes through the convectors before returning to  the center port in the expansion tank. I believe that it draws from the higher port in the expansion tank so that there is less chance of debris being sucked into the pump.

DanWeitzel

Here is a pic of our 2016 T@B system showing the same flow direction.  

jalars8

My tank is different but can't provide a photo because of its position.  On my tank, the offset opening is on the left (left of the direct opening) and is also the lower opening.  It looks like with my tank, it draws from the higher port in the direct position and the fluid comes back through the lower port to the left.  

ScottG

I wonder if the design of the tank has changed with regard to which port is offset. Regardless, the three preceding reports all indicate that the outflow (i.e., back to the Alde via the circulator pump) is through the higher port, and the return (from the convectors) is through the lower port.

It's never been explicitly clear why the posts are at different levels, but this is the configuration shown in the Alde manuals. 

Paul1

I bought a 2019 Tab 320S about a month ago. The Alde appeared to be running fine for a test run of a couple hours. The previous owner had never changed the fluid so I knew I would need to check for corrosion after reading numerous post and watching videos, mainly from Mark on you tube and after finding this forum, Scott G. with his very informative instruction manual for Alde fluid change. I have installed some new hose pieces , after shortening the corroded convection ends, ( about an inch or so from each end on both back convectors).  I have some fluid and preparing for the refill. I have a few questions hopefully can be answered here. 
1. Has anyone that shortened their convectors noticed any changes in performance? 
2. Has anyone put a shut-off valve at the drain plug location to facilitate a more controlled drain flow?
3. Has anyone put any isolating valves at strategic locations to facilitate removal of specific components?
4  Has anyone needed to replace their auto-bleed assembly and / or non-return valve, and if so , why ? 

 Many thanks to all that have shared their experiences here!

pthomas745

@Paul1 great stuff!  Do you have any photos of the corrosion you found?  Was it as "bulgy" as the images you saw in Mark Turney's video?  The video shows some "worst case" scenarios. There have been a whole range of corrosion noted in the threads, all the way down to completely collapsed convector "stubs".

If you haven't seen it: there is a whole thread about the corrosion here, and several owners have cut off corroded stub ends, or even taken out parts of the "convectors" to gain new "stub ends" to connect hoses.

https://tab-rv.vanillacommunity.com/discussion/13226/corrosion-of-alde-convectors/p1

That is another huge thread, but if you page through and look at photos, etc, you should find the owners who had to modify their convectors because of corrosion.  Most owners just needed to clean the corrosion away.

2: Why hasn't anyone thought of this before?  There are several threads where owners had the entire glycol drain under the trailer swept away by road debris.  A valve makes a lot of sense.

3.  If you have read through this thread, there have been many modifications to various things like changing the tank location, and adding various valves at the correct spots to make removing the glycol easier.  There are several places in the trailer where it would seem easy to "block" the flow from one segment to the other. Or places that can be opened and make the draining of the glycol even easier.  (The 180 degree bend on my 2017 at the end of the convector under the passenger bench comes to my mind.)  The longer you stare at the Alde, and look over this thread, the more some of these things seem obvious.

4.  The Auto Air Bleed Valves have failed.  When they get "stuck" they simply dump glycol flowing through the system out under the trailer through the black tube attached to the side of the valve.  The first few threads here explains what can happen.  Replacing is not hard, but this is where your idea of isolating valves would really help. https://www.google.com/search?q=auto+air+bleed+valve+failure++site:tab-rv.vanillacommunity.com&amp;client=firefox-b-1-d&amp;sca_esv=5a02a879fec8af02&amp;sxsrf=ADLYWIJ2Z50gPUt_2V8QvtK5H1O5d9_5dg:1729439449587&amp;ei=2SYVZ4zKI6fakPIPz7nw6Qg&amp;ved=&amp;uact=5&amp;oq=auto+air+bleed+valve+failure++site:tab-rv.vanillacommunity.com&amp;gs_lp=Egxnd3Mtd2l6LXNlcnAiPmF1dG8gYWlyIGJsZWVkIHZhbHZlIGZhaWx1cmUgIHNpdGU6dGFiLXJ2LnZhbmlsbGFjb21tdW5pdHkuY29tSMxMUIkKWLdHcAJ4AJABAJgBWKABhQ6qAQI0NLgBA8gBAPgBAZgCAKACAJgDAIgGAZIHAKAHvA8&amp;sclient=gws-wiz-serp

I opened up my glycol loop at the "non return" valve to drain my glycol. This is one of the "points of attack" the smart owners here discovered while back engineering the glycol loop. I took out the valve to clean it and had a look at it.  It is an aluminum tube, with a plastic valve inside that appears pretty robust.  There have been failures of this valve due to corrosion, etc.  The biggest problem seems to be techs who don't remember how the valve should be installed, put it in backwards, and....glycol won't flow.  An owner over at Facebook had their glycol changed, and the techs put the valve in backwards.  Apparently, they were too lazy to go through the whole "run the pump to drive out the air process".  When the owners discovered there was no heat, they were advised to "turn the pump up to 5" to drive the air out of the system.  And, eventually burned out the pump!

I suppose the non-return valve can fail without being corroded, etc,  but I'm not sure if anyone has reported that happening.

Many times in the various glycol changing threads owners have shown there is more than one way to get this job done, and deal with the Alde in general. There have been several modifications to the basic process.  When different owners with different skills put their own creative ideas into this, the whole process will improve and change.

Paul1

@pthomas745 Thank you for your reply. I refilled my system with what I believe is the same product that was in before, the Century yellow/green. I had also replaced the check valve I ordered from Truma. The old one was allowing flow in either direction. I had also filled the main unit with glycol while I was taking my time to work on the other parts. Before the refill, I actually drained out the main unit and double checked the glycol for any debris or tell tale signs of the condition of it. All looks good for now. I then just took the hand pump that Scott G. had recommended and put the discharge hose into the alde tank  through the input line back to the pump. It only took a couple of minutes the see the glycol flowing back to the tank. System seems to be running fine so far with no alarms . I did get a few pictures of the convector ends. There was similar to most I have seen here.  I actually pulled off the hoses and checked every connection as well. I did replace the 5 aluminum connectors with the new plastic ones.  Hopefully I do not see the bulges again for a while . I am thank for this forum and everyone that contributed their experience , that enabled me to move forward to complete this project. I am not sure yet which way I will go for the next time. Perhaps the extra drain on the passenger side could be the easiest. I will likely be tempted to pull off a couple of clamps anyway just to check the convector ends.    

fstop32

@Paul1 on your list of questions...
#1: I had to shorten my long convectors in the rear because I couldn't find new replacements at the time I needed them.  I had to remove about 2.5" of the "fins" which I calculated to be about 3.5% of the total finned area so I know it's less efficient but very minimally and it wasn't noticeable at all.

I did add a second drain "T" on the opposite side of my T@b at the same general location as the original drain (both are at the low points of the system).  This did make draining the most amount of liquid from my system much more effective.  To @pthomas745 point though I did double my chances of road rubble draining my glycol by ripping off my drain!    After thinking about that a bit I think I might install something on the undercarriage to act as a bit of a block to fend off the offending rubble and maybe save my drain tube and glycol.

qhumberd

Just did our second flush and fill:

Posting here for an update on method and results.

https://tab-rv.vanillacommunity.com/discussion/17441/anybody-done-a-diy-glycol-exchange-on-a-400#latest

Carsoncitysmith

Help!  I am trying to change out the yellow fluid from my Alde to install the blue Truma/Rhomar fluid.  2021 400 model,  I am following ScottG's 2021 Appendix A.  I got a full gallon out from the Alde drain plug.  I disconnected the hoses from the bottom of my fluid reservoir, closed the drain plug and blew out almost a quart more of fluid using a hand air pump and compressed air.  I stopped because I was just getting air coming out the line.  
Then I opened the drain plug and got about a pint out.
My reservoir was half full when I started.  I understand there is about 3 gallons of fluid in there.  I am missing 2.7? gallons of fluid that does not come out when blown through.  
I can't seem to be able to remove the Air Bleeder.  I can squeeze the clamp but I can't pull the bleeder.  I can't seem to pull any of the tubing off the Alde or the Flow water heater.

 I think I have figured out the flow chart on my system, please admire my photo and attempts to understand the flow.



I think 2pump at the bottom of the screen is receiving glycol from the expansion tank and pumping it into the bottom of the Alde unit and that return flow from the water heater is entering the Alde unit also at the lower entrance.  I think heated fluid is coming out of the Alde unit "boiler body", going to the bleeder and non return valve and then into the water heater, the "Flow", the red unit at the top of the screen.
Then I think hot fluid comes out of the water heater and some goes off the top of the screen into the convector at the back of the trailer, through the other convectors and back to the Reservoir.  A second pump is involved. 

Somewhere in here there is 2.7 gallons of yellow fluid but compressed air passes straight through. 

I am hoping I can avoid disconnecting fluid hoses as described in Appendix A.

Does any one know if I have a manual air bleeder in my 2021 400 and where it might be?

Should I just start pumping water through the system until it runs clear?

I got my blue Rhomar fluid from Amazon, one gallon at a time after 2 month's delay, "out of stock".

Thank you hive mind, 

P Smith
Carson City NV

Horigan

Do you have the small frig under the stove and the large closet with the expansion tank in the corner?  If so, you can use a shop vac to pull the remaining fluid from the hose going to the expansion tank.  It's the hose with fluid in it after the draining you did.  That will remove all the fluid, and water when you rinse the system.

On my 2019 there is a bleed valve in the bathroom.  Just take the top off the heat exchanger cover and you'll see it.  At some point they added more bleed valves, but your 2021 may be like my 2019.

pthomas745

I'm going to guess here: you have drained half of the Alde glycol "loop". You need to either push the old glycol out by pumping new glycol in...or, get access to the rest of the "loop". 

Someone else should confirm this: but on my 2017 320, the glycol comes out of the Alde, through the Auto Air bleed valve, and then through the non return valve just downstream from the valve.  In your diagram, your arrow points toward the non-return valve, and that seems to be "backwards". 

If that exposed aluminum part just past the Bleed Valve is the non-return valve, you could simply disconnect the hose connectors close to the Bleed Valve, free the non return valve, and simply "blow" the rest of the glycol back through the loop, around to the expansion tank, and out the drain.

Please, though someone...check my work here!

qhumberd

@Carsoncitysmith based upon your comment and picture, maybe I can clarify:


I think 2pump at the bottom of the screen is receiving glycol from the expansion tank and pumping it into the bottom of the Alde unit and that return flow from the water heater is entering the Alde unit also at the lower entrance.  I think heated fluid is coming out of the Alde unit "boiler body", going to the bleeder and non return valve and then into the water heater, the "Flow", the red unit at the top of the screen.
Then I think hot fluid comes out of the water heater and some goes off the top of the screen into the convector at the back of the trailer, through the other convectors and back to the Reservoir.  A second pump is involved. 

The original change out instructions for glycol did not address the 2 pump system that is involved with the Flow tank. On my 2019, like yours, the "2pump" in your picture is the main heat circulation pump, and turns on when the thermostat calls for heat. The "pump" in your picture is for the Flow tank and ONLY turns on when you set the hot water to the highest setting and automatically turns off after about 20-30 minutes. Now when "pump" is on the main "2pump" does not run, so as to direct all heat from the boiler to the hot water system in the Flow tank.

Rather than taking stuff apart, I would think it might be easier to use water (?distilled since you are changing to Rhomar) and just pump several gallons of that thru the system till it all runs clear. On my 2019 400 it took about 5 gallons to run out the yellow Century. Then pump in the new glycol and follow the steps to clear the system. The more you take apart the more air will be in the system to clear out later.

And, as @Horigan said, you will need to identify the bleeders to truly get out all the air. My 2019, like his, just has the one in the bath, but more have been added in later models.

Here is a diagram you can use to compare with yours. Best of luck and happy flushing.

Carsoncitysmith

Thank you all for your prompt consideration and responses.
Quick correction: I am missing 1.7 gallons not 2.7.  Simple math error. 
I have the small fridge and large closet.  I do not see an easy way to pop off the plastic cover above my shower control in the bathroom to look for an air bleeder valve but I do find a suspicious and likely candidate below the kitchen sink, see photo and please confirm. 



I tried shop vac suction on the return line at the reservoir and got only teaspoons of fluid, like blowing air the same direction. 
I can not identify the non return valve on my system.  I have been thinking it was in the base of the brass bleeder unit, as suggested by ScottG's diagram.  I see soft rubber hoses and straight aluminum tubes.

Thank you QHumberd for the side view above.  That is very similar to my system and easier to read.
I wonder why cold water enters the Alde and exits hot while we have the Flow unit next door to heat water. 

All things considered I now plan to buy A LOT of distilled water to flush through to get out the Century yellow junk, but I am concerned that I will end up with 1.7 gallons of water in the lines.
That problem remains unresolved.  Does anyone think that opening the air bleeder will release the fluid?

Curse Rhomar for selling diluted glycol, doubling transportation costs and not allowing water to be left in the lines.

Thanks again,
P.

pthomas745

@Carsoncitysmith that is a "bleed valve".  We can help sorting this out for you, give it a bit of time for the 400 experts to have a look. 

Carsoncitysmith

Thanks.  Meanwhile I will push some distilled water through the lines to at least get rid of some more of the yellow junk.  That bleed valve sucked some air immediately and I pulled a few more Tbsp s of yellow out with the shop vac.  1.7 gallons of glycol still in there someplace. 

Carsoncitysmith

Progress:  I pumped in 2 gallons of distilled water.  At the 1.7 gallon point I got about two quarts of yellow glycol out followed by .7 gallons of dilute glycol, mostly water, just yellowish.  And then hand pumping air I got nothing but air out. I am loading the compressor for more air but I do not expect much results from that. 

My whole problem is thinking that my glycol system holds a total of 3 gallons of fluid.  Which seems like everyone's opinion, including the Alde Truma tech person I spoke to.  Can anyone confirm or deny that assumption?

Otherwise, where is the missing gallon of fluid hiding and how do I get it out?   Maybe fill with water and run the circulation pump?  I expect a freeze tonight here.