Posted By geome on 31 Jan 2011 12:22 PM
I'm not familiar with refractometer operation. Will the information be useful if the loop was filled with softened water...

I don't understand why a refractometer would be the first choice.

A hydrometer is much cheaper, and I'm guessing that it would
be less prone to errors caused by small amounts of "other stuff"
in the brine. Brewers use hydrometers, as do auto mechanics --
and in both cases, the fluids they're dealing with can be highly
colored and quite "gunky." I don't think I'd have much faith in
a refractometer for those apps (but again, that's just a guess).

WF's Flow Center Installation Manual recommends hydrometers for
methanol and ethanol antifreezes (doesn't mention refractometers,
and doesn't say anything about p-glycol antifreeze measurements).

I don't see any reason why a (different) hydrometer wouldn't work
equally well for glycol. P-glycol is about 3% heavier than water,
while methanol is about 3% lighter (both at 15F protection level).

www.waterfurnace.ca/Engineer/Flow%20Centres/Flow%20Center%20Installation%20Manual%20-%20IM1961.pdf

Spirit hydrometers come cheap from Amazon and the like. I suppose one would have to compensate for any difference between density of meth vs ethanol - Mr Google says they are darned close.

The WF Flow Center Installation Manual has curves for both
methanol and ethanol. (Environol™ = ethanol with blue dye,
a popular Trekkie substitute for Blue Romulan Ale™.)

...of course, I only use it for medicinal purposes,

Looby

 (Environol™ = ethanol with blue dye,
a popular Trekkie substitute for Blue Romulan Ale™.)

...of course, I only use it for medicinal purposes,

Looby

Really?????
Are you sure that "recreational" should be added??

I bought the wf set up from a dealer we do business with and it cost a whopping 15.00.  Hydrometer, cool pvc case/floaty beaker, and the chart.
Eric

Posted By Dan CGD on 31 Jan 2011 08:20 AM 
The next question is what is the loop field doing longterm and are you getting enough heat from the loop field with the REHAU system. I am interested since we do have a supplier that is wanting us to install REHAU, though we've been reluctant since we have had such good luck with standard HDPE loops. Hope all goes well with the antifreeze correction.

Dan

www.cogeothermal.com

Dan,
I took a really hard look at the rehau system.  I am sure that the rehau pex will provide a exchange and should hold up well long term, however
I could not make it work in my application due to product cost.  The loops were more expensive, fittings. need for indoor manifold or vault outside for mechanical joints.  I just could not get the cost to work vs. standard hdpe even when reduced footage was included based on their chart when compared to hdpe.  The complete write up is on the other forum.  If you get this to work or find different results please let me know.
Eric

Thanks guys. I'll look for the hydrometer. I would only do the test once. Are there any pitfalls associated with drawing a sample large enough for testing?

Looby said "I don't understand why a refractometer would be the first choice." 

With Glycol systems, a Refractometer only requires a drop of liquid to check the level of protection.

Bergy

Posted By Bergy on 01 Feb 2011 08:43 AM
...a Refractometer only requires a drop of liquid ...

Good point.

Even with a tall/slender container, the hydrometer would likely
need 2-4 ounces of fluid. Inconsequential if you're mixing a
new batch of antifreeze -- but maybe more than you'd want to
bleed from a pressurized loop, on a regular basis.

...thanks, I hadn't thought of that,

Looby

I can set loop pressure, but it may be difficult to get the drawn methanol mix back in there. :-)
If I bleed off 2-4 ounces, and do this do this just once, I assume this will be fine to do?
Any thoughts on the softened water effecting results with a refractometer or a hydrometer? PM me if you want.

If I bleed off 2-4 ounces, and do this do this just once, I assume this will be fine to do?

No problem. Replacing a few ounces of AF with pure water will have no measurable
effect. I'm guessing your loop contains something in the neighborhood of 100 gal.

Any thoughts on the softened water effecting results with a refractometer or a hydrometer?

Absolutely no measurable effect on a hydrometer. An ion exchanger (softner) just
replaces calcium, iron, etc. with harmless sodium. If anything, a softener should
improve accuracy -- but the effect on specific gravity will be microscopic.

I don't know much about practical application of refractometers. I woulda guessed
that typical ppm-level impurities would have very little effect. OTOH, it seems that
refractometer users on the web spend a lot of time worrying about "calibration."

Thanks Looby for the detailed explanation.  Knew I could count on you!
Blushing yet? 

I thought you might all want to hear the end (I hope!) of this saga that I started 6 pages ago (!). 

Just before the new guy came to change the glycol concentration, I bled off a little bit more of the old antifreeze.  After he came and went, the system was working quite normally again.  At one point the loop was down to 26F on the LWT with a healthy flow of 12 gpm, a temperature never reached with the old antifreeze (exchanger froze instead and went into lockout). 

I ordered a refractometer (about $20 on Ebay) for propylene glycol.  It arrived today.  I checked the calibration (it was already perfect).  Then I tested a few drops of the old antifreeze and got a result of 28F Freeze protection.  Wiped that off and tried a few drops of the new antifreeze now in the loop.  Got a result of 10F Freeze protection.  Noticed also the taste of the glycol was a lot stronger (yeah, I taste stuff). 

A huge THANK YOU to everyone on this board.  You have taught me so much, and helped me troubleshoot this system of mine.  Your insights, encouragements, and suggestions have been invaluable, and I hope this thread helps others.
You've also made me buy several new gauges that I've never previously owned, but that's another thread.  (GRIN)

One last question, how do you put fluid back into the loop?  Geome asked about drawing off a little and was thinking about replacing it....how?  Hypodermic syringe or something?  How do you overcome the pressure and would you put the liquid back in through the p/t port?

Posted By decafdrinker on 02 Feb 2011 09:25 PM
You've also made me buy several new gauges that I've never previously owned, but that's another thread.  (GRIN)

One last question, how do you put fluid back into the loop?  Geome asked about drawing off a little and was thinking about replacing it....how?  Hypodermic syringe or something?  How do you overcome the pressure and would you put the liquid back in through the p/t port?

I enjoyed reading your post.    Yep, through the PT port.

GRIN some more - you need another tool (if you will be happy topping the loop off with water.)

http://www.flowcenterproducts.com/accessories.php

Scroll down to the RAM-1 item.  Was about $64 last summer.  You will also need a garden hose or you can buy a 6' short length hose called a "hose reel leader" from Lowes for about $8 and connect it to your drain valve of a water heater.  Flush the hose (and the sediment from the water heater) first, them connect the pressure ram and bleed all the air from it (or you will inject air into the loop), then you're ready to go (setting the loop to proper pressure.)  If any connections drip, tighten them and re-purge air from the setup I just described before beginning.

I still don't know of a "good" way to get the antifreeze back into the loop.

Posted By decafdrinker on 02 Feb 2011 09:25 PM
One last question, how do you put fluid back into the loop? 

... Hypodermic syringe or something? 

You might wanna think twice before sticking a syringe into a P/T port.
If the syringe is big enough to do any good, the pressure in the loop
could turn the syringe barrel into a great plunger-cannon.

Glad it worked...

Anyone used one of these to test methanol antifreeze loop protection?

http://www.ezred.com/Product_Pages/EZS104.htm

yep, not so good, repetitive readings give you different results everytime.

Thanks Doc. I found some nice, and reasonably priced, glass hydrometers (0.950 to 1.000 SG) but the 500ml (2" diameter) cylinder would take roughly 16 ounces to fill it (maybe 8-12 oz would work depending on the point at which the hydrometer floats.) I really don't want to draw that much from the loop.

Not much luck so far on refractometers with SG scale of less than 1.000 with good resolution. If anyone has a recommendation for one they have used for methanol, please let me know.

I'll find something eventually. Worst case, I can ask our installer to bring a tester over the next time we have a problem.

I have one of these.

The picture is lousy as it shows a case with about ten hydrometers.

It fits nicely in a piece of 3/4" PVC pipe

Posted By geodean on 03 Feb 2011 08:24 PM
I have one of these.

The picture is lousy as it shows a case with about ten hydrometers.

It fits nicely in a piece of 3/4" PVC pipe

How well do they work?