My geo servicer said we have Ethanol and recommended swapping it out for PG due to the possibility of premature pump failure (we've had some hi pressure warnings and the system shut down once, so we may or may not have an issue already - he will be out to investigate).

My question -
If we have pump failure due to ethanol, can we replace just the impeller that is work, or the whole pump?  We have the Flowcenter 236 with B&G PL-36 pumps)?

Does somebody know what a reasonable price is for just the pump?

I have installed hundreds of flowcenter 236,136,255 with the b&g pump assymbly's at a concentration as high as 30% methanol and not one single failure that was methanol related.  Please post more details about your symptoms and people here can help identify the real problem.  I doubt very seriously that it has anything to do with your freeze protection, unless your concentration is over 50%.  Has your glycol happy tech tested your % currently in system?
hope this helps

many installer switching from PG to alcohol based antifreeze for many reasons, we did this last year and I would never go back! If in the right concentration, there is no reason the pump should fail (what pump by the way, the circulation or the heat pump?).

Posted By ergnut on 27 May 2010 11:37 PM
...we've had some hi pressure warnings and the system shut down once ...

There's no way P-glycol can improve that situation; ethanol is a better
heat exchange medium than P-glycol (and methanol is better yet).

Switching to P-glycol WILL result in lower flow rate (GPM), less turbulence
(lower Reynolds Number), and reduced heat exchange capacity -- for any
given circulating pump, loop field, and level of freeze protection.

Suggest you check with Bell & Gosset regarding chemical compatibility;
there are at least two versions of the PL-36 pump (cast iron and bronze).
The B&G web site also has specs, parts lists, service manuals, etc.

Looby- is methanol widely in geo systems? (I'd think the toxicity & corrosive factors would have made it prohibited by regulation in some places.)

Posted By Dana1 on 28 May 2010 10:52 AM
Looby- is methanol widely in geo systems?

Yes, widely. The best thermal and flow properties of any common
antifreeze, inexpensive, no ATF entanglements (i.e., denaturing).
Low molecular weight = freeze protection at lower concentrations.

No corrosion problems with HDPE and appropriate pump materials;
moderately toxic, but biodegrades rapidly in soil/groundwater. If a
loop leaks, it won't get very far before the microbes take care of it.

There may be regulatory barriers in some places -- but not SE PA.

...it's a cryin' shame to squander EtOH as antifreeze,

Looby

ergnut,
You might want to find a new geo servicer.
Good Luck,
Joe

Or perhaps a more experienced tech with the same outfit, especially if the installer warranted the installation beyond the the manufacturers warranty.

The system has run w/o interruption for around a year until the "Hi Pressure" light on our WF Synergy three started flashing.  The tech will look at the system tomorrow, but I can tell you the loop pressure (its the field loop we're talking about) is in the high 20s and its making cool air and hot h2o, still.  The tech did the original install and he said it contains ethanol (I think) - but at the time he worked for a different company, less reputable and now OOB.  He said his current company doesn't use ethanol, they use PG, and they've seen numerous pump failures from ethanol.  I don't know the concentration in my system, but I do know the motors are not the brass models.

Its the field loop circ pumps.

So if I understand, ethanol and (perhaps methanol) have superior thermal properties relative to PG? How much of a difference would one expect to see due to this?

And we aren't seeing lots of ethanol (or methanol) pump failures (but the concentration is a critical factor here)?

I don't have direct experience with this issue - here in FL we don't have to concern ourselves with freeze protection beyond circulating straight water and leaving freeze-protection setting at 30 F or so.

That said I agree with Looby. The increased viscosity associated with Glycol at low temps will have adverse effect on both flow and turbulence; both will decrease heat transfer, further aggravating the situation. Alcohol / water mixtures don't exhibit anywhere near similar viscosity issues, or at least they didn't appear to the last time I took a bottle of Vodka out of a freezer...

Posted By ergnut on 01 Jun 2010 10:47 PM
So if I understand, ethanol and (perhaps methanol) have superior thermal properties
relative to PG? How much of a difference would one expect to see due to this?

Nothing wrong with PG, IF the system was designed for it. However,
PG is more viscous than lighter alcohols, so switching from ethanol
or methanol to PG will result in lower flow rate and reduced turbulence.

If the system had excess capacity, the difference could be minimal;
if it was running "on the edge" the difference could be very large.

And we aren't seeing lots of ethanol (or methanol) pump failures
(but the concentration is a critical factor here)?

My HVAC guy is a WaterFurnace "GeoPro" dealer, and he uses methanol
exclusively (along with Grundfoss pumps and WF flow centers). WF also
recommends/sells ethanol (Environol™) antifreeze; so, I must admit to
being extremely skeptical of "alcohol-induced pump failure" reports.

Anyhoo, freeze protection is highly dependent on molecular weight of
the antifreeze; so, methanol and ethanol give more freeze protection
per pound than higher molecular weight glycols. For example, 15F
protection requires about 20% methanol, or 25% ethanol, or 30% PG.

None of those concentrations should be a problem for HDPE, but
I seem to recall that methanol should be avoided in systems with
cast iron (or any ferrous metal?) parts.

Posted By engineer on 01 Jun 2010 10:56 PM
Alcohol / water mixtures don't exhibit anywhere near similar viscosity issues, or at least they didn't appear to the last time I took a bottle of Vodka out of a freezer...

A purely scientific experiment performed in the event this issue ever came up on this forum, right? 

ergnut,

We offer an ethanol alcohol mixture called Environol that is specifically formulated for WaterFurnace customers. We would recommend this over propylene glycol, as Environol has better heat transfer properties. We are not aware of the commonly used antifreeze solutions causing premature pump failure. Typically, poor water quality or air in the loop is the cause of pump failures. Could you be more specific in regards to the type of ethanol solution used in your system?

WaterFurnace International, Inc.

Just trying to be helpful...