Changing out the Alde fluid.

tybladesmith · January 2020

@ScottG, I agree totally. I am happy to collaborate with you on protocol if you like. I still want to test a method for an unmodified 320S before I send you a draft of my experience. The hand pump works well, and trying to disconnect the expansion tank may be unnecessary. $400 could buy all the parts to duplicate the Alde pump system. PM me any time.

ScottG · January 2020

Thanks, @tybladesmith. Much of what I have in mind is based on your experiences refilling your system after your winterizing mods.

I've tried to avoid brain-dumping too much here as there is already a lot of vague and sometimes contradictory info in the mix. When I get a chance to actually organize my thoughts I'll send 'em off to you!

mickietucs · January 2020

@ScottG - thanks for writing back. Although a gravity drain may seem simple enough to a lot of folks, I don't feel I have capability of doing it (nor the inclination)! "Bleed the system, auto bleeder, getting fittings, hand pump" - naw...Last year when I was up at my dealer in Phx, I asked them if they'd do it and they turned me down (we didn't even get to discussing a price)! I'm contacting various Alde Service places which are along my route this summer and will try to find someone to do it for a reasonable price. Thanks.

tybladesmith · January 2020

Thanks @ScottG, I feel the same way and am sorry for continuing the brain drain. We can problem solve on the side! I will forward coherent thoughts as available by PM.

ScottG · January 2020

I hear you, @mickietucs. Regardless, you might stand a better chance of getting someone (even another owner) to help you locally with a simple drain and fill rather than a complete pump-driven power flush. Good luck!

No apologies necessary, @tybladesmith. Given the dearth of official guidance on this topic, the bits and pieces contributed by owners have been really important and I hope members keep chiming in if they feel they have something to add.

Throughout this process it's become evident that in most cases the glycol probably lasts a lot longer then we have been led to believe. Regardless, having taken on this crusade I intend to see it through! :-)

gregndeb · February 2020

@ScottG and @tybladesmith, I confirmed what you already knew, the drain tee is off the reservoir to ALDE cold inlet. I also did consider using a drill-powered pump, as mentioned real early in this thread. I'm concerned that the lubrication that is shipped with the pump could contaminate the glycol solution. For grins I ran a new drill pump in a washtub with a bunch of water. After doing that for a few gallons, there was still grease in the drill pump. I suppose it's needed to make the pump last, but might leave some contamination within the Alde fluid. I suspect that most harbor Freight transfer pumps in the $60-100 range might have the same contamination issues. I think that I'm back to trying the following:
1) Use a sureflo pump (or pumps), like the Alde system
2) Remove the Alde drain and drain what you can. Replace the drain
3) Add a drain tee in the line between the radiator and the reservoir.
4) Open that drain and push new fluid in through the reservoir outlet. I think some types of toilet fill pipes have a half-round rubber washer with flange that would create a sufficient seal on the outlet pipe, inside the reservoir.
5) Once fluid is changed, close the drain tee. Fill the reservoir, then draw from the reservoir and pump through the same pipe to the reservoir outlet. That should bleed the system. (The only question might be is one sureflow pump or do we need 2, like the Alde tool?)

In all this is sounding like a big project. I may not want to attempt this a week before cold-weather camping!

ScottG · February 2020

@gregndeb, thanks for the confirmation regarding the layout of the CS heating loop. CS (particularly non CS-S) owners are in the minority here so there is not as much common understanding about those models. Am I also correct that your Alde reservoir is in the cabinet at the driver's side front of the trailer?

Good point about the lubricant in the drill-pump. The manual pump I purchased had the same issue, but I was able to disassemble it and wipe out what appeared to be an abundance of petroleum jelly.

I think you and I have the same idea only with different placement of the new drain/fill tee. Your suggestion may even be better with the CS layout. In your scheme, you could even consider filling through the existing glycol drain with the help of a few well placed clamps. Ultimately I think any approach that allows you to pump in glycol in the proper direction will work.

I'm still not convinced an electric pump is required for filling or bleeding, but it would certainly work and may facilitate the process if you are willing to shell out the coin for it. Just make sure your connections are tight as spills will happen fast with a powered pump!

BrianZ · February 2020

Hey @ScottG, I've enjoyed catching up on these old discussions of a topic in search of the elusive definitive answers about replacing glycol, and all the great recent contributions as well as your nice diagrams.

Your last comment about pumping glycol "in the proper direction" made me wonder whether you meant the chosen direction for a particular method, or that there is only one direction that can work (e.g., the normal direction of flow for the built-in circulation pump)? I was under the impression that when the built-in pump is not in use, that it should allow flow in either direction; otherwise, the Alde glycol would not drain out as it apparently does when the low-point drain plug is removed.

I ask, because I have been contemplating a possible pump-less method of draining & filling glycol in the opposite direction of the normal circulation. To illustrate, I've borrowed one of your nice diagrams (hope you don't mind) to show what I'm considering as a possible solution by using compressed air applied to the expansion tank to empty the system (& possibly to fill it at least partially)..

UPDATE (2-28-20): THIS IDEA WILL NOT WORK due to a one-way valve inside the Alde output pipe that prevents backflow (see my later message)..

After opening the drain plug to drain by gravity about a gallon (minus the glycol in the loop of convector pipes), then clamping off both the hose between drain & expansion tank, as well as the overflow drain tube, then compressed air could be applied to the tank's air vent tube in order to push out the remaining glycol in the convector pipes. I have calculated (see blue area) an estimate of the volume of these pipes (about a gallon) by measuring the length of the pipe route & doubling that since it's a loop. I've read that the convector pipes have a 22mm diameter (or about 7/8").

The above procedure might allow the complete removal of old glycol, as desired, and should not require very much pressure. By comparison, even a 28" tall column of water exerts a pressure of only one psi. I should also say that I have not tried this yet, but until I can, I'm offering up the idea to see what others may think. So far, I've only seen one mention of trying air pressure at the tank, but clamping of the open tubes wasn't stated, though it would be necessary for this to work.

As for filling the system, that may be another story. I'm thinking that the convector tubes could be filled in the same manner, by adding glycol to the tank & pushing it through the convector tubes until it starts coming out of the open drain. Then close the drain, remove clamps, add more glycol to the tank, and turn on the pump. After that, I'm not sure the front half inside the Alde could be easily filled without trapping air inside the Alde. Although the automatic bleeder is at the top of the Alde, I'd be worried about whether this could work. So, filling might need to be done in a more conventional manner.

In any case, here are some photos, showing the location of the narrow overflow tube (a hemostat might work nicely for clamping this tube, and it could be clamped near the floor where it's easy to reach), and the similar air vent tube..

The air vent tube can be easily slipped out of its holder & the end brought over to where it can be easily reached.

Below is a similar tube with a barbed adapter that could be used for applying compressed air using a rubber-tipped blower type handle on the air hose. If or when I do this, I would likely try less than 10psi on the pressure regulator at first.

Again, none of the above has been tested, but it's probably what I will do when the time comes, at least for emptying the old glycol. I still need to test our glycol with my pH meter & refractometer.

Filling from the bottom with a hand pump, possibly with judicious use of a clamp, seems like it may be the ideal way to aim for, or else just pumping or pouring into the tank. I also wonder if there is a type of drain fitting that would facilitate connecting the hose from a hand pump to the drain, for filling from the low point.

ScottG · February 2020

@BrianZ, my original idea was to duplicate the flush/fill function of the original Alde service pump as simply and economically as possible. By flushing and filling the system using forced fluid, introduction of excess air into the system is presumably kept to a minimum.

The pump directions indicate the system is filled from the glycol reservoir outflow, so that is how I defined the "proper" direction of flow. This is also the same direction that the glycol flows when the cabin heat is being used. I have no idea if forcing glycol through the system in the opposite direction would also work, or if it could potentially damage the pump.

My current thinking--to install a filling tee just downstream of the existing drain--is intended to duplicate the Alde pump as closely as possible while solving the problem of having to access and remove the return line to the reservoir. I am under the impression that with certain models of T@B getting at that part of the system may be difficult if not impossible.

As I've said before, I think there are probably multiple ways to successfully accomplish this task, including blowing the system out with air as you propose. However, if I were going to do this I would disconnect the heating loop just downstream of the auto-bleeder (incorrectly labelled the "Glycol Pressure Relief Drain" in my original schematic) and force the old glycol out at that point. If I had my druthers I'd rather not push all that residual glycol I'm tying to flush back into the Alde jacket and through the circulator pump. Once the system is completely empty you could fill the system (either by gravity or by an external pump) through the reservoir outflow just as is done with the Alde service pump.

BrianZ · February 2020

Thanks, @ScottG, for your reply.
That's what I thought you meant, and your main concern seems to be about glycol flowing "backwards" through the pump. However, here are a few points that might allay these concerns..

First, many have drained their glycol by simply removing the drain plug & collected a gallon or more of glycol, which we can presume comes mostly from the Alde "jacket" (I believe the specs say it holds 0.92G), plus what's in the expansion tank & its line to the drain. So, if most of this flows by gravity through the pump to the drain, then there cannot be much, if any, resistance to reverse flow of glycol through the pump (at least at low pressure).

Second, the reverse flow of draining the Alde glycol is indeed low pressure, because a column of liquid at only about a foot tall does not exert much. 12 inches of water, for example (about the height of the Alde), exerts only 0.43 psi at the bottom of the column (or 0.44 psi for glycol with a specific gravity of 1.026). Using only 1 or 2 psi of compressed air should be enough to push & lift glycol out of the heating loop & into the Alde to drain, while not posing any risk to the pump, however, more pressure may be needed to actually blow it all out if the water column collapses under gravity in a larger diameter tube. Using distilled water to displace the glycol may be required initially.

Third, there is at least one Alde circulation pump model I've seen where the brochure specifically states that "motor does not restrict circulation when not in use". I would conclude this is also true for our model on the 3010, if it can freely drain the tank when the pump is off (reverse flow). Circulation pumps are often built like a paddle wheel that has fan blades spinning in the liquid pushing it through the tube. If at rest, fluid could still circulate between the blades, such as by gravity.

UPDATE (2-28-20): THIS IDEA WILL NOT WORK due to a one-way valve inside the Alde output pipe that prevents backflow (see my later message)..
As for pushing glycol from the heating loop hoses back through the Alde to drain, unless Alde has some sort of check valves (I haven't heard of any), there should be no reason not to do this, as the glycol itself is all the same, because it normally circulates through the entire system. As long as minimal pressure is used, I see no reason for concern. IT DOES HAVE A CHECK VALVE.

The last thing I would want to do is disconnect a glycol hose inside the trailer if I can avoid it and any potential spill. I also can't see trying to disconnect the expansion tank if that can be avoided. I'd be curious to know what kind of psi levels are generated inside the system when using Alde's expensive service pump - I bet it's significantly more than a couple psi. The circulating pump itself shouldn't need to generate more than 1-2 psi just to move glycol through the system.

I think your idea for adding a filling port valve near the drain tee is a good one, or else just adding a temporary barbed valve stopcock into the drain (secured with a hose clamp) for pumping in fresh glycol slowly from the outside with a hand pump.
Or even just one of these, or a brass one..

ScottG · February 2020

All good points, @BrianZ.

My concern with pumping residual glycol back through the Alde and circulator pump had less to do with flow direction than it did with not wanting to force any sediment or other contamination that might have settled in the convector loop back into the guts of the unit. However, that is likely not an issue in most cases.

I were going to completely empty the system using compressed air as you suggest, I think I would skip the additional filling port and just fill from the reservoir relying on gravity and the circulator pump and bleed valves. If you do opt to add a fitting, be careful using brass (and certainly avoid copper) as corrosive galvanic reactions can occur via the glycol with the aluminum in the Alde. To be safe I would stick with aluminum, stainless, or PE.

I do think your idea would work, but personally I won't be testing anything for a few more months until the weather is a little more conducive to fiddling with the camper. :-)

BrianZ · February 2020

Agree, @ScottG, and neither am I planning on doing anything soon, but winter is a good time for thinking & planning. I may even wait another year if pH & specific gravity check out ok. We've only had 2-1/2 camping seasons so far since buying our T@B new in Aug 2017.

ScottG · February 2020

Yeah, interest in this discussion dropped off quickly once owners (including me) started reporting that their existing glycol was still testing fine. :-)

Thanks for weighing in and please report back on what you end up doing.

db_cooper · February 2020

Still interested, but waiting for you experts to figure out an easy way to do it.

I'll continue to replace 1/3rd of the fluid every year as I've been doing until then. We use our Alde a lot when plugged in at home and on propane when traveling. I'd like to do a complete flush and switch to long life fluid, but will just keep adding Sierra brand I can find locally, but more frequently.

ScottG · February 2020

Hey @db_cooper, as I recall it was you who resurrected this old discussion which ultimately led down the rabbit hole! :-)

Seriously, your report of your approach was important in figuring this all out. A simple drain and fill from the reservoir is likely to introduce quite a bit of air in to the system, but if I'm following your experience correctly you were able to bleed the system just fine with the circulator pump and built-in bleed valves. That was one of the big initial questions regarding the necessity of the special Alde service pump.

Based on recent calculations of the total system capacity, a simple drain and fill like you do probably swaps out over half the glycol.

db_cooper · February 2020

After my most recent drain and fill, I'm happy to report that it's never been quieter. No gurgling at all, I did the raise and lower tongue dance and the auto bleeder did the rest.

I really expect my once a year half replacements to keep the Alde protected.

BrianZ · February 2020

After further thought about my proposed idea for flushing out old glycol from the Alde by using compressed air at the tank air vent, and the "backwards" flow it would create, I now have further questions & concerns related to the Bleeder Valve (or "Flow Assembly" as Alde calls it) that would need to be answered before I would consider this a viable approach.

First, I realized that the small air bleeder hose would likely also need to be clamped closed, in order to help prevent the escape of glycol & possibly minimize issues with the air valve mechanism (some have had to replace it after it got stuck open during normal use & dumped glycol, and advice from Nucamp to try tapping on it to release the valve may not work). Not knowing how this valve is designed internally, I am uncertain about exactly how it operates, and have not found any design diagrams yet.

Second, Alde's own description of this Flow Assembly in their online literature and spare parts catalog seems to imply there is a one-way flow restriction, but it's not clear to me whether this refers to flow of air out of the bleeder valve or the flow of glycol through the main pipe..

Does the "non-return valve" refer to preventing backflow from the air tube or is there a check valve at the Alde outflow? If there is a check valve in the Flow Assembly that prevents backflow of glycol at the Alde outflow, that would void my idea for flushing the system. Further, if that were the case, then perhaps it might explain why most seem to only recover about a gallon from the drain.
So many questions, and not enough answers!

ScottG · February 2020

Good questions, @BrainZ, but getting a little out of my pay grade. ;-)

By attempting to duplicate the original Alde protocols as closely as possible, my hope is that these issues will not be a concern.

BrianZ · February 2020

Well, it appears that Alde's own part listing for the pipe that's included in the Flow Assembly confirms what I suspected - that there is a one-way valve preventing flow in the opposite direction..

And a closer view..

Image: https://us.v-cdn.net/5021717/uploads/editor/on/ewegw0kdjm88.jpg

The valve inside the output pipe would prevent back-flushing glycol from the system; so I'll be looking for another approach to empty & refill the system.

ScottG · February 2020

Good info, @BrianZ. Do you know where exactly that piece is installed in the Alde system?

Denny16 · February 2020

It goes on the output side if the Flow tank pump, which connects to the back radiator and flows around the system, pipe on the far right side, labeled “Non-return valve”
Updated graphic to English version.

ScottG · March 2020

Oui, oui. Ce'st tres bien. Merci, beaucoup, @Denny16!

BrianZ · March 2020

@ScottG, it appears to be at the output end of the flow assembly (bleeder valve) on the Alde output. See my previous post showing the flow assembly & its description which reads similarly (i.e., "non-return valve").

Denny16 · March 2020

Oui, yes, it is what Alde lists as a “non-return valve” which is the check valve you asked for it’s location on the system.

ScottG, de rien.

ScottG · March 2020

C'est ce bon. Mes yeux sont ouverts!

Makes sense. I need to update my plumbing schematic at some point to reflect the automatic air bleeder and check valve in the glycol loop.

BrianZ · March 2020

@Denny16, which T@B model has the extra red flow tank & pump? I haven't seen this before.

Denny16 · March 2020

The Alde Flow was added to the 2019 units I believe. I have a very late 2018, with the 3020 Alde, but no Flow. I am trying to get it added, which is why I downloaded the Alde connection sample. My dealer stated NuCamp said this was difficult to do. Looks like a basic plumbing job requiring some additional tubing, a drain valve and the connector metal tubes.
I am still trying to figure out what is so hard? Perhaps they think I need to shiftbthe main Alde unit to make room. Worst case, I would loose the sewer hose storage tube to make room door the Flow unit, like the 2021 install below:

cheers

gregndeb · April 2020

Here’s what I did to change my Alde fluid. It worked well with very little mess. I’ll break this post up in two sections: 1) How I created the tools and 2) The actual fluid change operation.

Overview

Previous discussions seemed to talk a bunch about draining all the fluid out with the possibility of using compressed air, removing hoses, air in the system, risk of breakage, etc. I set out to minimize the work, yet get a clean fluid change. Basically, I just pushed the old fluid out with new fluid. The amount of air introduced in the system was very minimal. I did not disconnect ANY fittings or drain plugs.

Section 1: The tools

I purchased a RV water pump to do the work. My dealer had a FlowMax unit. I think it cost me about $70-80. Advantages over the Sureflo pump (that is in the official Alde tool) in stock at my local dealer, price and fittings were included. The dealer also mentioned that many customers replace their Sureflo units with the FlowMax. I got a 12Volt model since I would be powering the unit from inside our T@B. I mounted the pump to a chunk of plywood, added a switch and about 10-12-feet of wire to a 12-Volt “cigarette lighter” plug. Note, the fuse in our T@B to the power plug is 15 Amps and the pump draws 7, worst case.

I had 2 leftover hoses from a washing machine. I left one end on each hose and attached the other to the fittings supplied by the pump. I took one of the removed ends and attached it to ½” OD vinyl tubing. The vinyl tubing was about 8-feet long with nothing on the other end.

I created 2 adapters to attach within the Alde reservoir. I used 3/8” OD tubing, typically used to supply water to toilets. I wanted low restriction, ability to bend, yet have some strength. Standard toilet pipe was a good choice. On one end of each I put a right-angle fitting (3/8” tubing to ½” Female Pipe Thread) then another adapter to standard garden hose thread. One piece of tubing is straight. The other has about a 2-1/2” offset.

The other end of the tubing was a little more involved. I got 2 neoprene stoppers (purchased at Lowes). The diameter was 27/32” at the large end and 21/32” at the small end. The overall length was 1”. (I apologize that I don’t remember the part number. These dimensions I measured were from my assembled adapters, so there may be some stretching of the stopper as they are installed on the tubing) To make the holes in the stoppers, I first drilled a ¾” hole in a scrap of wood, then inserted the stopper in the wood. That would hold the stopper so I could then drill out the center of the stopper with a 5/16” drill. I used a brad-point or forstner drill bit to make a clean hole in the neoprene. I then stretched each stopper over the end of each of the tubes. The neoprene fits tight enough that no clamps or gluing was necessary. (I might have used water to help when slicing on.)

That’s it for the special tool creation. Pictures below:

ChanW · April 2020

Excellent. Waiting with baited breath for part two!

gregndeb · April 2020

Part 2 – Actually flushing and changing the fluid

Part 1 had the special tool creation. This is what I did to change my Alde fluid. It worked well with very little mess

Overview

Previous discussions seemed to talk a bunch about draining all the fluid out with the possibility of using compressed air, removing hoses, air in the system, risk of breakage, etc. I set out to minimize the work, yet get a clean fluid change. Basically, I just pushed the old fluid out with new fluid. The amount of air introduced in the system was very minimal. I did not disconnect ANY fittings or drain plugs.

Items needed:

· Special items, covered in section 1:

o Adapters to go within Alde reserve tank (one straight, one with offset)

o Electric pump (used a good-quality RV water pump)

o Hoses to the pump (2)

o 8-foot ½” OD vinyl tubing with hose end

· Other items needed

o Flashlight

o 2 gallons of Alde fluid.

(I used about 2-1/2 gallons but I wanted to flush out everything)

o Drill-powered pump “el-cheapo”

o Drill (to run the cheap pump)

o Standard short garden hose (8-feet should be enough)

o 5-gallon bucket

Drain the excess fluid from the reservoir. I put the 8-feet of vinyl tubing INTO the reservoir inlet hose and slid the hose down the inside of the hose. I then inhaled to get most of the hose primed, attached the drill pump and pumped out the reservoir and the hose contents. Remove the hose when completed.

(Some previous discussion talked about using the drain plug under the trailer. Some said that it only cleans out the hose and not much really comes out of the Alde system. So I figured, why even use the drain? I just removed the fluid from the hose and reservoir.)

Attach the straight adapter to the standard garden hose. Put the other end of the hose in the bucket. Keep the adapter end near you for later.

Attach the pump inlet hose to the new bottle of fluid. Attach the pump outlet to the offset adapter. Hold the offset adapter in the bucket and briefly run the pump. This will prime the pump and remove any crud/lubricant from the pump. This will also remove all air from the new incoming fluid.

Insert the offset adapter in the Alde reservoir. The neoprene end should fit in the reservoir outlet. Now you insert the straight adapter to the reservoir inlet. It should be pretty easy to apply gentle pressure to both the adapters within the Alde reservoir to make a good seal.

SHOWTIME!

(It is advisable to have an assistant to help if something goes wrong. Mine checked the outflow to the bucket and passed the new bottles of fluid to me.)

Turn on the pump, while holding the adapters within the Alde reservoir. You should see the new fluid bottle drain and old fluid go to the bucket. It takes about 15-20 seconds to drain a 1-gallon bottle with a 3 GPM pump. Stop the pump before the bottle gets totally empty. That way you won’t introduce air in the system. I put in about 2 gallons of fluid in the system. The fluid to the bucket was pretty clear, so I pumped about another ½ gallon just to be sure I got rid of the old fluid.

The theory of having the inlet and outlet adapters sealed to the reservoir was that no fluid would leak in the reservoir, thus it would stay empty. That worked for me. If you did get some leakage, you may need to get the drill pump and hose and remove leaked fluid from the reservoir.

Remove the straight adapter from the Alde reservoir. Add new fluid to the reservoir. (I did a little above “Max”.) Leave the offset adapter in the reservoir.

Remove the pump inlet hose from the new fluid bottle and place inside and to the bottom of the Alde reservoir.

Ensure the offset adapter is held in the reservoir outlet and the pump inlet hose is below the fluid level. Run the pump about 10 minutes to purge any air from the system. I had a few spurts, but it appeared that I did not have any air in my system.

(The Alde tool uses 2 pumps working in parallel, to really pump the water fast. My one pump seemed to be enough.)

Remove all your tubing, pumps etc. To be sure, I ran the Alde circulator pump about another 10 minutes, then I turned on the heat and checked for operation. All seems good.

Let me know your thoughts. If someone wants to borrow this setup please let me know. I live in Lexington, KY.

Picture 1 shows the fluid being filled and the old being forced out. The new fluid is the bottle on the left. The pump inlet is on the right pump side. The old fluid is exiting diagonally, out the bottom right corner of the picture.