My Tranquility 28 HP keeps registering a low-loop temperature alarm, even though I've clipped the jumper that should allow it to run well below 30 degrees. I have temp sensors on the entering and leaving loop connections and I never see the outgoing loop temp drop below 29.8, and yet the system goes into lock-out mode even when it's supposed to keep running down to ~10 degrees. Thoughts/ideas? Thanks D

My GeoMax (ClimateMaster) is doing the same thing, at about the same temperature. On my system, gradually we're tracing the problem to the wrong anti-freeze mix. Look for the thread about compressors being on but no flow in the loop.

If you are handy and comfortable in a system cabinet, locate the freeze protection sensor and attach another temperature probe near it. It may well be on the refrigerant (not water) line leaving the coax heat exchanger (WF Envisions have them there). That data may help sort things out.


Standard Disclaimer: Lethal voltages and dangerous pressures lurk within system cabinets...don't go there if you can't work safely and comfortably.

Check exactly which Jumper was cut. There was a typo in a CM/Heatcontroller installation manual which told the installer in one paragraph to cut jumper JW2 when it was supposed to be JW3 (FP1). They fixed the typo, and now they have a new control board.

First, thanks to the folks who replied.  Each suggestion sounds like a viable option for resolving the problem.  I'm going to start with suggestion one, the antifreeze ratio is off.  I'm using Cryo-tek-100, does anyone know what percent glycol it is?  Being a DIY idiot, I stupidly assumed the % was 100 when I added it to my loops.  I've read reports that it's either 60 or 60%, either one would raise my freezing pt. significantly.   Based on my calculations I'm thinking I was running with ~8.6% glycol when I thought I'd been running somewhere between 15 and 20%.   A 8.6% mix would be exactly in line with the cut off temps the HP is locking out at.

Tomorrow I'll add more.

If that doesn't work, on to suggestion two, measure temps internal to the unit.


Thanks again.

David

 

You NEED a minimum 25% glycol mix. Anything lower than 25% can allow a "slime" to grow inside the loops, hindering heat transfer.

Bergy

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/78070/afv/topic/Default.aspx


I explained everything in the above thread. Cyrotek-100 only contains about 60% glycol, at least it has the Freeze protection of 60% glycol. So if your installer thought he has mixed you up a solution containing about 25% glycol, which should be the rule of thumb, giving you 15F protection, you in reality only have 15% giving you 24F protection. Typical mistake from the supply house selling this as 100% not knowing better, installer not aware of it either. I lost count how many of those we have seen....Our local supply house caries cyrotek-100. Than around x-mas time the loops start to freeze up.
Yes, this will freeze your heat exchanger, the temps in there are lower than your LWT. That is why you are off. It will result in a freeze protection lockdown. Keep in mind that you need to account for the glycol you are draining out in order to refill it with 100% of whatever blend, which might still only has 60% glycol. And the amount which remains in your flush cart if you use one. You doing it yourself, I assume you have a non pressurized system. Do the math before you do anything. If you are not sure, get a refractometer. Still not sure, flush everything out and start over, possibly using methanol. If in doubt, you can do the fridge test by putting some of your antifreeze mix in the freezer.

I have had low press switches fail on these units.
Joe

Posted By docjenser on 28 Dec 2010 11:33 PM
Do the math before you do anything. ...

If you are not sure, get a refractometer.

If the original antifreeze was 60% glycol + 40% sumpin' else,
you can't trust a refractometer (or a hydrometer, or math).

If in doubt, you can do the fridge test by putting some of
your antifreeze mix in the freezer.

Yep. If you don't know what's in there, that's the only reliable way.

Actually, for cryotek-100, the freeze point when tested and the refractometer scale correlates exactly with a 60% glycol mixture, e.g. if you mix it down (25% Cryotek-75% water) it indicates a 15% glycol -85% water mixture (as if Cryotex-100 is a 60% PG blend), and it also has the freeze point of 15% glycol - 85% water (24F).

Posted By docjenser on 29 Dec 2010 09:55 PM
Actually, for cryotek-100 ...

That information is useful only if you KNOW that the installer
used cryotec-100 -- or something else that was 60% glycol
with the other 40% consisting mainly of water.

Anything you dissolve in water lowers the freezing point, and
(to a first approximation) the amount of change depends only
on the number of "foreign" molecules per liter of solution. So,
if the "other 40%" contained a significant amount of anything
besides water, the freezing point would be affected noticeably.

google: "colligative properties"

Posted By davewick on 28 Dec 2010 08:58 PM

 " I'm using Cryo-tek-100, does anyone know what percent glycol it is? "

...

Posted By docjenser on 30 Dec 2010 02:17 AM

Posted By davewick on 28 Dec 2010 08:58 PM

 " I'm using Cryo-tek-100, does anyone know what percent glycol it is? "

Sorry 'bout that. I had this thread confused with another where the
the owner didn't know which antifreeze product the installer used.

Problem solved. It's was the mixing ratio problem. I added the appropriate amount of antifreeze and the system is running reliably. Thanks for everyone who answered.

thanx for letting us know the outcome