Changing out the Alde fluid.

Good morning, fellow aspiring amateur Alde technicians! 

@Bayliss, et. al., there appears to be some variation regarding the non-return valve. On mine, it was a small piece incorporated into the "flow assembly" itself--I could feel it and (when the system was apart) see it right under the black zip ties just downstream from the air bleeder in this photo. 

 

It was clearly not the larger component BrianZ pictured on Page 6 of this discussion (though it presumably serves the same function):


The aluminum component under the metal spring clamps was just a hollow connector:



I'm thinking (guessing) that at some point the small integrated check valve I have was replaced with more robust version, at that in turn replaced the simple connector between the flow assembly and the hose to the first convector.

It's an academic discussion. Regardless of the specific configuration, the check/non-return valve on the 320 is located in the hose carrying glycol away from the boiler, just downstream from the automatic air bleeder. (In the 400, it appears to be at the outflow of the Alde Flow--same idea.)

If you think about the flow of glycol, this location is--technically--between the circulator pump and the first convector. However, describing it that way is unnecessarily misleading.

ReenieG said:

@ScottG thank you for the link and info!

You are welcome, @ReenieG--I agree a picture tells the story so much better.

After pondering it a bit, I'm sticking with my opinion that the circulator pump will not push air. I tried this--albeit accidentally--while I was changing my glycol...

As I mentioned previously, after pulling the plug and successfully draining only the reservoir, I was scratching my head as to why the boiler wasn't draining as well. In an attempt to shake things loose, I activated the circulator pump. Doing so did not help the boiler drain. It also did not push any more fluid into the reservoir at the other end (where it could exit though the open drain). Maybe if I had tried longer and with a higher pump speed I might have had some success, but wasn't my priority at the moment so I moved on to a more successful approach.

Bayliss said:

@ChanW and @ScottG, thank you both for the further analysis of the location of the non-return valve on Alde systems without the Alde Flow.  I imagine you (and others on this forum) find it much easier to troubleshoot issues once you know how everything is constructed and the location/purpose of each component, so this entire discussion thread has been very informative.

You make a good point, @Bayliss --when you understand how something is assembled and how it works, it makes maintenance, modifications, and repairs a whole lot easier.

After changing my glycol and realizing how easy it was, I felt in hindsight this 400 comment discussion was a bad case of analysis paralysis. However, viewed from the opposite perspective, maybe all the analysis was exactly why it was so easy!  :-)

@ChanW, if you took the Alde glycol out line,  curved it up at the point of the arrow, and stuck it into the Alde on the same side as the pump (along with the air vent and check valve), you'd have a pretty good rendition of the post-2014 320 systems.

So many demands...  ;-)

Nice, @fstop32. That was what I mentioned seeing in my flow assembly when I had it off, but neglected to take a photo prior to reassembly.

Mine seemed like it was installed a little deeper, but I'm not 100% certain. The hose itself was soft except for a 1/4" or so solid section under the arrow sticker. It was definitely not the long aluminum fitting I pictured above, so Alde must have changed something post 2015.  

The end of the hose in your photo looks a little rough, like it might be cracked in several places. Am I seeing that correctly?

FWIW, after completing my glycol exchange, I ran tests on the old original (2015) glycol and new glycol from a sealed container.

Appearance: No difference, both looked clear, bright yellow-green, with no evident debris or sediment.

Aroma: The new glycol smelled, well, faintly like antifreeze. The old glycol had an additional note of rubber, similar to that of the Alde glycol hoses.

Concentration/Freeze Protection: Measured with refractometer. Old: 46%/~-15F; New: 47%/~-17F

pH: Both looked about 9+ with litmus paper; tested to 9.7 with a benchtop pH meter.

Just for giggles, I also tested the new glycol in the system, once it had been thoroughly circulated. It's concentration/freeze protection was 45%/~-13F, and its pH (with meter) was 9.5.

Because I had flushed the system previously, I suspect the slightly lower values may have to do a bit of dilution from residual distilled water. I probably should have pushed a little more new glycol through when refilling, but I'm not losing any sleep over this miniscule difference.

To be clear, I'm not offering interpretations or conclusions, just information. By currently accepted standards, my six-year-glycol was virtually identical to the brand new stuff.

@N7SHG_Ham,  I agree 100%. However, to date those official (though limited) word from Alde and nuCamp has been that pH is your indicator of sustained corrosion protection. The current situation suggests that there may be other factors at play...