Changing out the Alde fluid.

@pak
sorry auto correction. I meant how many heat convectors or radiators.
yes Liberty Lake 

@pak
We have a 2015 Sofitel our expansion tank is in the rear. Am I correct the CS tank is in the front in the bathroom?

@pak
That probably explains why I only had 6 1/2 qtsz shorter hose run. Thanks

For anyone using one of the two inexpensive pumps that have been successfully used to flush the Alde glycol (i.e., the manual pump, and the 12V electric pump), I have tested both for simply pumping water from a lower to a higher container, just to see how they work, and I have an observation to offer..

Both of these act like a siphon when you stop pumping, such that when the source container is lower and the entire line is still filled, the fluid will begin to flow backwards, returning to the source container.  Just turning off the electric pump or stopping manual pumping does not stop this flow. This could also be either an advantage or disadvantage with the source container higher (i.e., no pumping required, but no quick/convenient way to stop the siphon flow).  Just something to be aware of.

If the highest levels of the source & destination containers are similar heights, this may not be an issue.  For my use, I will have an inline on/off valve, or you can add one to your pump output line if you need to pause, just in case, as you may not even notice when backflow is happening when you stop pumping.  A check valve might help, but would only work in one direction.

Also, I previously tested air pressure and found that 15psi moved a gallon of water 3 ft higher in about 30 seconds (2 gal/min).  I later ran the same test with the electric pump and it took 48 secs, so it pumps about a gallon per minute.

Is there a CSS version of this?  

Scott, getting the tubes/stoppers into the tank was straight forward, however,  I should re-bend the copper tube for the offset one as the bend was right at the top of the tank. I held the tubes vertical with a couple of spring type clamps. The tubes were draped over the clothes rod (400) so the right angled bend at the upper end of the copper is not necessary. I shortened the plywood panel and plastic Alde cover to improve future access for topping up.

Forgot to post this revised drawing by @ChanW.
Resizing to 800 doesn't help the fine print, but I sharpened it a bit.  If you want a pdf version, I can send you one.
One thing that doesn't match our T@B, which I only recently discovered while disconnecting convectors..
The line from the top rear convector (with the bleeder valve) goes to our lower side convector, not the upper one as shown; but then it's just a schematic with 2 convectors depicted as one, so not necessarily "wrong" either.
PS: I just discovered that Chan's post above has a higher resolution version, so just get that. 

That's great, @Tabaz!  So you didn't check for corrosion?  When did you last change glycol?
I'm now wondering..  If the auto air bleeder does it all, then what is the little manual screw bleeder for at the upper left of the rear convector?  That is a high spot that could trap air, so I'm wondering if running the pump at high speed would clear that out or not?.
I had already started reassembling ours after fixing up all the convectors when I realized I never took that bleeder elbow out.  Now have done that (with difficulty) & cleaned it up & coated the entire outside of both aluminum connector tubes with conformal coating, so they are nice & clean & smooth now.  Thinking I might skip the heat shrink tubing, since they are hard enough to connect already in that tight space.  I had to pull that tube into the storage space to disconnect it, so no fun trying to climb over the seat to get down into that corner.  This has been one of the longest projects yet for me, but fortunately I kind of enjoy the challenge of it.

ScottG said:

@Tabaz, congrats on getting the glycol changed.

Can you (or others who have done this) elaborate a bit more on your experience refilling the empty system by just pouring glycol into the expansion tank?  Did the glycol mostly trickle in and fill the system with gravity, or did it need to be coaxed in by cycling  the circulator pump?

I'm not convinced this is easier than pumping the fluid in with the adapters (which took me only about five minutes with an empty system), but I can see the advantage for someone who just doesn't want to deal with acquiring or making any additional tools (pumps, adapters, etc.).

Draining, blowing, or vacuuming out the old glycol and then refilling in this manner would be a reasonable alternative for getting the job done.   

On my 2019 400 the system would not fully fill with gravity alone.  I would fill the tank and open the bleed screw to fill the system as much as possible, close the bleed screw, turn on the Alde for 10-15 seconds as the tank almost drained then turn off the Alde, fill the tank, and repeat briefly turning on the Alde and filling the tank about two more times.  This was with the pump(s) set on high (5).

I simply put a large funnel in the expansion tank and used a clean water pitcher.  Poured the new fluid in and stopped when it reached the MAX level on the tank.  Waited a few minutes for the level to drop in the tank, then added more up to the MAX level.  Kept doing this until the level stopped dropping.  At the start of this process, I did open the manual bleed valve thinking it would speed things along, but it didn't, so I closed it.  Once the fluid stabilized at the MAX level, I followed Scott's instructions and turned on the pump on high (without propane or electric heat).  Had to add a few more pitchers of fluid as the air was purged from the system.  After about 10 minutes, the fluid level stabilized near the MAX level indicator.  Key here is to only add fluid up to the MAX level indicator in the tank.  This way you avoid overfilling the circuit.  VERY EASY process.  Mine took a little longer because of my "Basement" Alde circuit for winter camping.

Agree, @Tabaz, only add fluid to the max mark.  I did that when refilling ours, and with the pump speed turned only about halfway up, the tank burped once or twice briefly and then the level dropped close to the min mark.

My Alde Glycol 3-Way Flush Valve Mod:
I think I've been working on this, off & on, for more than a week (or is it a month? ), but I've finally finished; with plenty of help & advice gleaned from others, to whom I say "Thank you very much!" to all contributors & especially to @ScottG for getting things started & keeping them moving. 

I fully expect that having this extra bottom fill port will be worth the effort; as the next time I change the glycol (assuming same type), then I would only need to attach the glycol hose to the new port, flip the valve, open the drain, and push out the old stuff with the new until it reaches the tank.  After closing the drain & switching the valve in the opposite direction, I can then pump in from the bottom to fill the drain part of the hose & the expansion tank to the proper level without needing to access the tank to pour glycol.  It was very easy, even with the lines all empty.

Most of my time was spent dismantling T@B & glycol plumbing parts & then cleaning the corrosion from convector & coupler fittings - something I don't expect to have to repeat, due to extra steps taken to coat or cover exposed surfaces, as discussed under the corrosion topic.  See referenced topics & materials sources listed at the end.

I followed @ScottG's approach to removing old fluid by draining & then starting at the upper Alde hose connections; with the exception that instead of blowing out the convector pipes with air, I wanted to go straight to rinsing with water, which I thought might be more efficient.  To avoid losing track of where I was in the whole process, I jotted down some simple notes with an overall plan that I could refer to, in case of "now where was I?" senior moments (thanks, @ChanW for letting me use your diagram)..

These 5G buckets barely fit, but are handy for fitting all the glycol, plus at least one full rinse and seals with a water-tight top for taking to recycling..

The bucket barely fit under the drain, up against my "Helman scissor jack".  I found that a 1.5" PVC pipe fit snug over the multi-drain outlet, which includes the glycol tank overflow drain.  I think only a few drops came out, due to air pressure changes.

This next adapter assembly I put together was a great help for doing the initial water flush of both Alde & the convector loop. (Thanks, @fstop32! ) I also plan to replace the brass pieces with a second aluminum hose coupler to keep just in case I should ever need to remove the 3-way valve, to take its place.  (Plus a pair of inexpensice hose-pinching clamps to facilitate the replacement).

The photo below shows how the adapter fits to the incoming water hose and Alde output hose..
Tip:  Since this outgoing hose is filled with glycol and is at a low point in the convector loop relative to the other end at the expansion tank, I was concerned about leakage upon disconnecting it (per @ScottG's warning).  To mitigate, before disconnecting, I grabbed the hose in both hands & squeezed as hard as I could a few times to pump some of the glycol into the tank & out the drain, as the check valve only allows it to go in that direction, and I could hear some fluid drain out.  So, only minor leakage into the pan placed underneath (a carryout food container), though I still tried to keep the end of the hose elevated while connecting the adapter valve for flushing & tipped the open bleeder assembly upwards while plugging.  After flushing, I plugged the hose with a barbed PVC plug & hose clip on until blowing out the line.
The new 3-way valve is mounted at lower right below the AC outlet, with 3/4" barbed stainless steel fittings enlarged with heat shrink tubing, but not yet connected.

Next, was using the adapter to connect directly to the Alde output for flushing (check valve/bleeder assembly removed temporarily)..

Below, the adapter was connected to the convector loop hose for flushing.  Note that the double angled garden hose valves allow easier positioning and, more importantly, provides two shut off valves for dis/connecting, to avoid spills..
(And did you know that a cork from a wine bottle fits perfectly into the check valve pipe?  Prevents drips.)

My intent below was to show my point of view when controlling the actual pumping.  The inline pump switch is on the seat at left (plugged into 12V socket at back corner cabinet), and brass valve at right needs to be opened & closed at same time whenever pump is turned on/off.  Valve on hose cannot be left open, or fluid may be siphoned to or from the jug.  This position also allows me to monitor the tank level for appropriate filling & to avoid overfilling.

Below is the 12V pump..
Like others have done, I replaced the flimsy battery clamps with the socket plug.  Yet another good use for heat shrink tubing.  The pump is only about 1.5" in diameter, so can fit into jugs with a large cap like the 2G one I saved from kitty litter.

It helped to stick a small flashlight in the corner on top of the glycol tank to light it up & easily see the level (except in this empty tank!    see last photo for a level) ..

Since I had this photo of the hoses going to convectors & tank, I thought I'd label them for reference..

Below was the system being flushed with distilled water..
I initially used 3Gs of tap water for rinsing, followed by 3Gs of distilled water, then air.  After all the corrosion cleanup & reassembly, I flushed again with 3Gs of distilled water, then blew out & refilled with glycol. 
One thing I never forgot from my quantitative analysis chemistry course in college was that 3 rinses of small volume is better at reducing contamination than one large volume rinse. While that may be true of the glassware we used, in this case it takes a large volume as well to hit all the surfaces & crevices.  

And after draining, being blown out with 15 lbs max of compressed air, under manual control with a trigger & being held to the opening of the tube connected to the 3-way valve..

Fresh glycol going in..  Blue arrow shows control valve; green arrow shows direction of flow into Alde through pump.  By rotating the blue valve handle to the opposite direction, the tube going up to the expansion tank can be filled.  I overfilled the convector loop with an extra pint or two, before closing the drain & filling the expansion tank.

Closer view of the 3-way valve in the normal operating position, with flow going straight through the valve, as indicated by red arrows on top of the valve.  I added the "off" arrow on the handle to indicate that whichever direction it's pointing, that pipe is disconnected & the other two are connected.

Below is an example of the hose-pinching pliers I got for use on either side of the above valve, in case I should ever need to remove it and insert the previously shown adapter assembly in its place..


When I did the final fill of the of the tank using the valve, I stopped it at the Max line.  Then, after returning the valve to the normal operating position, I turned on the Alde pump (by using the "Cont" setting instead of "Therm" on the pump settings menu) & increased the speed by turning the knob on the back of the pump at base of Alde (some pumps have a remote switch) to about midway for  less than a minute until it burped, then the level dropped to close to the Min line.  I may add more later.  Next I ran the Alde for a heat test by turning on the gas, turning on my Alde 12V kill switch & control panel, then increasing the thermostat 20 degrees above ambient temp for 45 mins.  It was plenty warm everywhere.

I still have 3/4 of a gallon of fresh glycol left over.  Will probably be testing what's in the system before long for pH, etc, to get a baseline.
The End!
We hope.

5-24-2021 Followup:
I used my pH meter & refractometer to check pH and specific gravity, after running the pump for a few minutes to ensure good mixing:
pH = 9.7
SpGr = 1.261
Propylene freezing protection = -26°C (= -15°F)
For comparison, a year ago in June, the 3-yr old fluid measured:
pH = 9.6
SpGr = 1.308
Propylene freezing protection = -32°C (= -26°F)
The Amazon listing for the Century TF1 glycol states "-20 Below", while the label shows "Haze Point -34°F".

So, the pH appears to be fine/normal, but I'm not quite sure what to make of the specific gravity measurement, but it would appear that I've either got some dilution effect from residual rinse water, or the glycol itself is more dilute (or the  old glycol had either lost water content or gained dissolved solids, which is possible with all the corrosion that was found).  Either way, the temperature protection is more than adequate, and the difference is only about 3.5%.
I did run calibration checks with a pH=6.86 buffer for the pH meter, and with distilled water in the refractometer to verify the zero line calibration. 

Here's an example view in my refractometer (using it outside on a sunny day, or in a well-lit room, makes it easy to use)..

Above is just a manufacturer image, not my results.  I use the scale at left for glycol & battery acid specific gravity & propylene scale for freeze protection, plus the bottom zero line for distilled water to verify calibration.  I'm a retired med tech/clinical lab manager, so have been familiar with the refractometer device for many years, which is the lab reference method for urine s.g. testing.

References: