I acquired a 5T Tranquility 27 with the copper coil and HWG.  It is 5 yrs old and was previous run as open loop water source on hard water.  I have read a few concerns already with the exchangers on these units and hoping they are not actually much concern. I am however concerned about the water exchanger because it was run on hard water for 5 yrs, notably Manganese. The system was only removed because the well developed issues and the user did not want to hassle with any more geo stuff. 

When I install, I am pretty firm that I want to use a closed loop system to improve reliability assuming the coil in the unit is OK.  I guess my first reach would be Propylene Glycol since it can be friendly on coils and plastics.  I am not sure what to think about Methanol.  My experience with it is in racing and it will eat metals up!  But I was also thinking along the lines of improved thermal conduction in the fluid to optimize the system. 

Regarding the loops, this system will be on a very large rural property so space limitations are nill.  There will be a pond approx 300-400ft away.  It will be a 1 acre, 15ft deep pond.  The thought came to mind to add some tubing in the bottom of it but still not sure what that temp will look like on the bottom year round.  My calculations show that with the 4M gallons in that pond, the temp would not change more than about 1*F per month either way and that does not consider any thermal conduction to the earth. 

I am trying to determine the most efficient system here as well as most reliable.  I would rather spend an extra 20/mo and have no problems..


So, I am looking for any good/bad info in the TT27 units as well as thoughts on a loop system and fluid fill.  I have read where people have lost exchangers and compressors in only a few years which worries me but I also have a 20yo heat pump system right now that runs like a top.  I tend to think those Copeland scrolls are pretty darn tough.. 

Oh, before I depart, one of the MOST concerning things and questions I have is if the water exchanger on these can be easily replaced or if the whole system has to be taken down? 

If you have ice on the pond, the bottom should be around 39F. I'd clean the heat exchanger with acid and go ahead with the pond bottom heat exchange loop.

Make sure that it ok to clean a copper coil with the acid, tho!!!

How 'bout we start with the btu requirement and the duct capacity of your home.
j

Manual J indicates 5T max. duct capacity will be 2000cfm (new home). Because the 27 is two stage, it offers a little flexibility in the installation. Mostly just want to learn about the units. I am NOT building a multi-zone system. I have heard of short cycle issues and scroll failures as a result (probably poorly engineered though). In any case, the unit can be centrally placed and do well in the 4000sf space.

Joe's point is well taken - just because a 5T unit fell off a truck in your driveway doesn't mean it is appropriate to your home.

Fears of multizone systems causing shortcycle issues and scroll failures are nonsense.

I suggest using mild cleaners such as Nickel safe or vinegar if heat exchanger fouling concerns are substantiated.

Methanol wins out over Glycol since it does not thicken with decreasing temperature.

I am most concerned of the Methanol reacting with the Copper exchanger coil and causing more damage over time. Do you have direct experience of and time duration to confirm Methanol as a viable option?

I should note that the 5T was confiscated by me only because it was the right size for my loads. Max load at 55k btu. The unit is rated at 64K btu but stage one runs at 38k btu. Should run like a charm.

On the short cycle, I too kind of have to take some stuff I read on the Inet with a grain a salt. My experience with scrolls is they are damn reliable if the system is built even half way right.

Do you have any experience with the TT27 to have any pos/neg feedback on them?

For acid cleaning, do something like this: http://www.waterfurnace.ca/Engineer/Misc%20References/Cleaning%20Heat%20Exchangers.pdf

I know of no corrosion issues with methanol in loops, but I'm a Floridian - we need not concern ourselves with frozen loops - all ours are straight water.

I can't speak to the CM TT27 since I deal in WF, but my understanding is that the two are quite similar since they share the same line of compressors (Copeland Ultratech)

Methanol at a 20% solution is "as typical". I would be more concerned with the quality of the make up water than the methanol if you have a copper coil.
Eric

Fair point.

CM probably has a doc similar to WF as to max allowed minerals and other characteristics of loop water

I don' think I would reach for anything less than distilled BUT RO water is cheap and might be just fine. Problem I think is most commercial drinking water has additional minerals added for "taste". I don't plan to taste my loop water anytime real soon. For the qty needed, I think it would be worth getting HQ water for an install.

If you are worried about corrosion, corrosion inhibitors are very effective.

Well, I have not heard any dirt on the Climatemaster TT series so I guess I will have to assume they are a decent piece of equipment. I am most concerned with the exchangers at this point

My kneck of the woods a 5 ton would be oversized for that application, any chance we can still "confiscate" a 4 ton? It will likely be cheaper to operate. Throw in a little envelope improvements and 3 tons would be even better depending on your cost/kwh.
j

Wow, 3T for 4000sf? I think my load calc is already pretty conservative. The unit operates at a higher eff in stage one which would be 3T.

Posted By fastline on 31 Jul 2011 11:35 AM
Wow, 3T for 4000sf? I think my load calc is already pretty conservative. The unit operates at a higher eff in stage one which would be 3T.

I don't know what you mean when you say load calc is "pretty conservative" sounds like gigo.

I'll tell ya what I mean:

Properly designed geo meets 92-98% of the heating requirements (not the loss) and 100% of the cooling.
So if 95% of the days where you live are above 18* for instance then you use auxiliary for any weather that's colder.
I have to pull numbers out of a hat here so bear with.....let's imagine now your heat loss down to 18* is 42,000 btu's, now you need a 4 ton at most but if some extra insulation brings that number to 38kbtus, now you are right sized with a 3 ton.

You are correct that operation in stage one is more efficient.....but.......only for properly sized equipment. Over sized equipment runs a larger compressor all the time often costing more to operate than right sized equipment with auxiliary contribution. If we follow the "first stage is more efficient" theory to it's logical conclusion, then we size heat pumps large enough that 2nd stage is never employed (and we "invent" single stage heat pumps).

Oversized equipment requires a larger generator to run in power outages, a larger loop field (with greater pumping costs) more antifreeze, larger duct systems.......oh and used equipment doesn't have warranties or qualify you for a tax credit.

So your "free" equipment will cost you more to install, possibly cost you more to operate and disqualify you for the tax credit.  

You can keep asking about acid flushing (personally I prefer to shock a coax to clean it by changing the reversing valve during a cycle to get a large temp swing knocking build up off the walls) or design your system based on best fitting heat pump not what's "free" (at which point I think you'll find you don't need to worry about cleaning a coax).

J