Changing out the Alde fluid.

ScottG · April 2021

@ChanW, I expected issues with trapped air, especially since my pump seemed to push a lot of it in along with the glycol. However, once I fired up the circulator pump (set to it's highest speed) the air burped out via the reservoir within less than thirty seconds.

While I lack the x-ray vision that would allow me to look inside the unit, I can say the heat was reaching both convectors, the level in the reservoir was stable, and--once I turned the pump speed back down--everything ran very quietly. That was good enough for me.

I don't know what role the automatic air bleeder played (if any). I'll keep an eye on the reservoir with the assumption that if any more air finds its way out it will be reflected by a drop in fluid level.

Excellent diagram, BTW. I tried to describe that in words several pages back, but the picture really speaks volumes.

@Tampakayaker, pulling the drain plug will drain only the reservoir, the boiler chamber itself, and the hose in between. If you trace the glycol loop in ChanW's diagram you will see that both ends of it are high points--one at the reservoir and one at the top of the Alde.

And yes, if you remove the hose from the reservoir you will need to plug the port in the tank.

In my case, the boiler wouldn't drain until I pulled off the outflow hose, presumably breaking some sort of vacuum that was preventing flow. I'm not sure what was going on as this hadn't been mentioned before, but pulling off the hose was easy enough--and it worked--so I didn't try any other measures.

ChanW's 2014 is the only T@B I am aware of with the third convector under the driver's bench.

ChanW · April 2021

I think the check-valve in the system prevents half the system from draining.

Ach! I neglected to show the check-valve.

ScottG · April 2021

Between my own experience and what others have contributed here, I think the issue of removing the old glycol from the convector loop (if you choose to do so) can be approached multiple ways:

Blow it out with air.
Force it out with new glycol.
Suck it out with a wet-dry vac.
Drain it by removing a hose from the lower right (passenger side) convector.

Each of these strategies could in turn be approached multiple ways, depending on whether you wanted to work from within the reservoirs, or open the system at one of many possible points. The important thing is they all work, so whichever methods trips your trigger, that's the best on for you. ;-)

The only thing it seems you can't do is force glycol backward though the system. @BrianZ pursued this approach several pages back and found there is a check valve near the Alde that would prevent this.

ScottG · April 2021

ChanW said:

I think the check-valve in the system prevents half the system from draining.

Ach! I neglected to show the check-valve.

Maybe, but I'm not sure it makes a difference as you are still dealing with those high points. Perhaps without the check valve the act of draining the boiler would in effect syphon out the glycol tapped in the convector loop. Moot point, regardless.

Denny16 · April 2021

Yes, the check valve (or non-return valve) is between the circulation pump and first convector, which would also keep he boiler from completely draining. That is why you need to pump the fluid around to replace it. Just draining the system from the low point drain, only gets part of the fluid out, about 1/3 to 1/2.

Cheers

ChanW · April 2021

Hmmm! Trying to understand what @Denny16 was saying made me wonder, why not use the Alde pump to pump out the old glycol, flush, and pump in the new?

Using one of @ScottG's tubes stuck into the reservoir tank and into the inlet port, and have a hose coming off of the tube, going into a bucket, to collect the waste.

Then fill the reservoir with clean fluid (distilled water to flush, or new glycol to fill). Turn on the Alde pump, and keep adding glycol as it gets pumped out. And make sure the bucket doesn't overfill.

Or would the pump suck it down too quickly to keep up with?

I'm also wondering if the pump would just blow the tube out of the inlet port.

@Denny16 Is this along the lines of what you were saying??

ScottG · April 2021

I think what @Denny16 suggested would work just fine, so long as you keep the reservoir topped up to avoid sucking air. Even then it might still work so long as the air keeps moving it's way through the system and out the other end. After all, this is the most basic way of refilling the system after a simple partial gravity drain.

Ultimately, this is one of the reasons I was drawn to the hand pump. Force and speed are slow and controlled, and you can stop anytime and make adjustments as needed.

ChanW · April 2021

Yeah, I'd want some sort of remote switch to be able to shut the pump off easily.

Denny16 said:

............ You could get a 3-gallon bucket, add a hose barb fitting to the bottom of it and connect this hose to replace the connection from the reservoir. Then you have 3-gallons to allow the Alde pump, set on high and continuous, to pump from the 3-gallon bucket of new fluid into the system. with the return line to the reservoir connected to an empty bucket to collect the old fluid. This would be a one person setup.
cheers

ReenieG · April 2021

@Denny16 in that case, why not remove the drain plug with a pan underneath and run the Alde heater pump? This "should" push more out, no? Then, when you get what appears to be more drained out, simply fill the reservoir and run the pump again on 5 which several people have suggested to get the air out.

ScottG · April 2021

@ReenieG, I'm not sure how well the circulator pump can push air to pressurize the system, nor am I certain if it is okay to run it dry. However, I'd love to hear the results if anyone wants to give it a try!

ChanW · April 2021

My suggestion of using the Alde pump to pump it out through @ScottG's 3/8 in chrome tube sounds like it would be hard on the pump too. I doubt the pump is designed to take that kind of resistance.

ReenieG · April 2021

@ScottG it certainly wouldn't be "run(ning) it dry" since the whole point is to push more of the trapped glycol out. I doubt with this technique it would ever get down to dry. I suppose IF that would be the case, the question would be how the pump works. Is it simply pushing the glycol around or is it actually needing the glycol to lubricate it as it functions.

ChanW · April 2021

I think what @Denny16 is suggesting could be the simplest answer, if there were an easy way to disconnect the reservoir's inlet hose.

Or better yet, a way to get a larger diameter tube like @ScottG's to stick into the port inside the tank.

Denny16 · April 2021

Rennie, just opening the low point drain (see the previously posted diagram) would continue to drain the reservoir, not the system. You could also suck air into the Alde from the low pint drain, which is also connected to the input side of the boiler. You need to isolate the boiler from the drain, and the reservoir return line to keep old fluid from returning to the reservoir.

You need to get new fluid going into the input side of the boiler (from reservoir with low point drain closed) and collect old fluid coming from the reservoir return hose, which you just disconnect from the reservoir and put into a bucket, preferably with some fluid in it to keep the end of the hose submerged (think bleeding a car hydraulic brake system) to collect the old fluid. You need to break the loop and the reservoir, which is what the Alde glycol service pump system does.

Bayliss · April 2021

@Denny16, can you point us to something (e.g., an Alde diagram or other reference) that identifies where the glycol line check valve is located? If not, how did you conclude/determine that it is between the circulation pump and first convector, and where, specifically?

ScottG · April 2021

ReenieG said:

@ScottG it certainly wouldn't be "run(ning) it dry" since the whole point is to push more of the trapped glycol out. I doubt with this technique it would ever get down to dry. I suppose IF that would be the case, the question would be how the pump works. Is it simply pushing the glycol around or is it actually needing the glycol to lubricate it as it functions.

@ReenieG, to clarify, the circulator pump draws from the reservoir and pumps away from the low point drain. If the drain were open and the pump were running, you would indeed be sucking air into the pump and trying to push that air through the entire system in order to push the trapped glycol out via the reservoir.

I'm not certain the circulator pump is up to that task.

ReenieG · April 2021

@ScottG I need a visual aide. I'm not good at this without a diagram, lol.

ScottG · April 2021

Regarding the check valve (a.k.a., non-return valve), see @BrianZ's comments about halfway down Page 6.

I know there is a looong discussion with a lot of comments to slog through, but we are starting to revisit questions that have been asked and answered. I'm glad more owners are taking in interest in this topic and want to tackle their own Alde maintenance. There is an absolute wealth of information here--If you really want to know what is going on, I humbly suggest grabbing a cup of coffee (or three) and starting back at the beginning! :-)

ScottG · April 2021

ReenieG said:

@ScottG I need a visual aide. I'm not good at this without a diagram, lol.

@ReenieG, look at the plumbing schematic posted here. There are a few errant labels that need to be corrected, but it will show you the direction of glycol flow in the heating system.

For that matter, the graphic @ChanW posted on the previous page of this discussion also shows the flow of glycol. Just remember your 2018 will not have the left convector. Otherwise everything else is the same.

Bayliss · April 2021

Thanks @ScottG. I have been following this discussion since its inception, but totally missed the post you directed me to, which clearly answers my question.

ScottG · April 2021

Bayliss said:

Thanks @ScottG. I have been following this discussion since its inception, but totally missed the post you directed me to, which clearly answers my question.

I here ya', @Bayliss, there is a lot here and I also sometimes have trouble locating specifics. My comment wasn't directed at you (or anyone else) in particular. I am glad to see this old tome generating some new interest.

That said, it's almost happy hour so I think I'll tap out for tonight! :-)

ReenieG · April 2021

@ScottG thank you for the link and info!

Bayliss · April 2021

No problem, @ScottG. I appreciate you directing me to the info. However, after looking at the Alde diagram posted by @BrianZ, it depicts the system with the Alde Flow. Since I do not have the Alde Flow, I am still not clear where the "non-return valve" is physically located on the Alde 3020 without the "Flow" system. I do not see it in any of the photos I have of my Alde/plumbing compartment, so I will need to take a closer look at that area next time I visit my trailer.

Below is the best photo I have of that specific area. The "non-return valve" may be the section of aluminum tubing between rubber glycol line that is to the left of the Automatic Air-bleeder in the photo, but that is inconsistent with it being located between the circulation pump and the first convector. I just can't tell (from my photos) where it is located within the configuration of my Alde 3020 system. There isn't anything like it close to my circulation pump, even when viewing photos of the entire Alde compartment, which is why I posed the question.

Image: https://us.v-cdn.net/5021717/uploads/editor/zr/v1qgv41oqwyk.jpg

pak · April 2021

I'm thinking the check valve is in the pump itself as that is the (cold) return line. Please correct me if my assumption is flawed. The drain spout/plug is between the pump and the reservoir tank. If it is, this would explain the limited amount recovered from removing the plug. I think too this is the line to which the fill line is attached in the r tank. My r tank is in the wall behind the toilet. I can see the return line into the tank but not the drain(return) to the pump. I think I will be adding a joint in a more convient location to ease connecting the new glycol pump line.

pak · April 2021

ScottG: how much pressure was required to fill the system. Did the back pressure, if any, pop the stopper out of the reservoir hole?

Sharon_is_SAM · April 2021

I think Alde mentions not to use the boiler/furnace unless you have glycol in the system. I think you can run the circulation pump without activating the heater. Also, do you really want to be dealing with heated glycol?

ChanW · April 2021

@bayliss, I'd guess that you're right, the check-valve is that aluminum fitting just left of the automatic bleeder in your photo. Not much else it could be.

It's the same on ours...

Horigan · April 2021

I found using the shop vac method was very quick and easy and it clearly got all the fluid out. I don't know exactly where the check valve is, but it doesn't matter with this method. Refilling the system was also easy just using the Alde pump(s) at max setting. I didn't have to do any tilting or jacking of the T@b to get the system bled. Just filling the reservoir, running the pump briefly, and repeating until the reservoir level stabilized. I had very little air left to bleed from the bleed valve in the shower. I think I got it all done in less than half an hour.

ChanW · April 2021

I have a '320’...

With the shop-vac method, where do you suck?.... er, where do you put the "suction point" of the vacuum? (Ok, there's no way to say it so it sounds 'polite'...)

I sucked from the inlet port inside the tank, and it didn't get all the glycol, I drained two cups more from the drain tube. Still only about 1¾ gallons total.

Makes sense. Once the hose has an 'air path', the fluid will lie on the bottom of the hose and just sit there.

Denny16 · April 2021

Bayliss said:

@Denny16, can you point us to something (e.g., an Alde diagram or other reference) that identifies where the glycol line check valve is located? If not, how did you conclude/determine that it is between the circulation pump and first convector, and where, specifically?

Here you go @Byliss, the check valve is labeled non return valve in lower right hand corner. Without the Flo tanks, the valve is on the main boiler pump outlet. The next bit connected here is the heat conductor ( rear one for a TaB400):

Changing out the Alde fluid.

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