Open loop Geo system not cooling as normal
Last Post 17 May 2015 10:13 AM by joe.ami. 30 Replies.
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lawtoolguyUser is Offline
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04 Jul 2014 12:15 AM
Hello, I have question on recommended solvents for flushing a open loop heat ex-changer. My system has ran fine for 3 years but is starting to show signs that the heat ex-changer is fouled. after flushing I see no sign of any contaminants and the solution I used phosphoric acid shows no color change at all. My clear flow meter is as clear as the day I installed it. Here's all info I have on my system. Florida install used for Cooling only since I haven't needed the heat for three years. Tetco ESII 4 ton R-22 system with Cooper Nickle ex changer Clean filter and coil Open loop with 76 degree in and dumping 86 degrees out at 6 GPM presently. 40 PSI before heat ex-changer 37 PSI after. While running at the 6 GPM my high side pressure stays very high at 350 PSI and low side is around 50 PSI. I have had multiple high side trips over past two weeks. If I open up flow to 8 GPM High side does drop down to 330 - 340 but still to high. My return air is at 80 and supply is at 70. When I pulled the water in and out lines off unit I attempted to inspect inside of plumbing on water side and found a grayish black film that began to flake off the inside of the heat ex-changer pipes which I believe maybe Manganese. Has anyone had any luck with cleaning this type of scale by back flushing? RydLyme? Nickle Safe? This system has been in use for 3 years now working fine. It is still cooling just not efficiently. When I first setup the system I had 22 degree difference from supply and return. High side always around 225-250 Low side 70 - 75 PSI. 15 - 20 Degree difference from inlet and outlet depending on flow rate. Any input would be appreciated. Thanks in advance
joe.amiUser is Offline
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04 Jul 2014 10:02 AM
Do you know your super heat and sub cool? Do you know what the entering and leaving water temp was when you first put it in (EWT/LWT)? Is the fan coil and filter clean?
Joe Hardin
www.amicontracting.com
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lawtoolguyUser is Offline
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04 Jul 2014 12:48 PM
Hi Joe, Thanks for any input you have. Filter and coil are clean. EWT when installed was 78 degrees and LWT 91 - 96 based on what flow was set at between 6 to 8 GPM. Today with Flow at 8 GPM EWT 76 LWT 86. These were my readings. Low pressure side gauge 49 psi 25 degrees. Line temp 78 Degrees. 78 - 25 = 53 super heat High Pressure side gauge 350 PSI 140 degrees Line Temp 171 Degrees 140 - 171 no sub cooling Not able to get high side pressure down below 340 and this was with flow at 12 GPM. Low side will not get any higher then 50 PSI. I will definitely be installing wired temp gauges soon.
joe.amiUser is Offline
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04 Jul 2014 01:08 PM
Sounds like a TXV problem. Who put it in?
Joe Hardin
www.amicontracting.com
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lawtoolguyUser is Offline
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04 Jul 2014 01:23 PM
TXV was installed in the unit. I installed unit and had A/C purged and virgin R-22 installed 3 years ago to factory 4 lbs by HVAC installer.

Has worked fine since then till now. I just got out of shower and noticed that hot water is real hot. Tank heater is turned off while DSH is on and its heating water extremely hot. I just turned down the on temp for my circulate pump to keep it from circulating to much heat to tank.
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04 Jul 2014 01:43 PM
Might need another txv
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
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lawtoolguyUser is Offline
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04 Jul 2014 01:50 PM
I was thinking that I didn't have heat transfer I needed with the black film that formed on the inside of my exchanger. TXV could be starving I guess by reading symptoms I'll look for frost spots at TXV. Also look at pressures while in heat to see any change.
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04 Jul 2014 03:25 PM
Three lines going into TXV have light frost on them. Three lines come from DX coil and are frosted lightly from point them leave DX until they hit the TXV. Line out to filter dryer has light sweat no frost.
lawtoolguyUser is Offline
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04 Jul 2014 03:52 PM
When changed to Heat mode flow starts and compressor runs for 10 seconds and I get Low side trip.
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17 Jul 2014 05:48 PM
Finally got back from vacation and had system drained. Charge was at 5.2 lbs which was a little high. We turned off A/C while gone for a week. Removed TXV and pulled it apart but did not see any garbage to speak off. Only thing I am noticing is it looks like it was installed backwards and it's been like that for 3 years. The ports have no labeling but look identical to my replacement TXV which does have the IN port labeled. The old TXV had the filter dryer Installed on the lower port side and the higher port going to the evaporator coil. Looking at the install instructions for new Emerson TXV it shows the 1/2'" IN port going to the filter dryer side and the 3/8" unlabeled out side to the evaporate coil side. This puts the 1/4 " by pass tube on the complete opposite side then the original install. If someone could chime in I'm dry fitting and getting ready to start running nitrogen soon.
engineerUser is Offline
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18 Jul 2014 08:00 AM
R22 pressures above 300 high side and below 60 low side are completely inappropriate for a water source system with 76 EWT. 76 in 86 out at 6 GPM is just 30 kBtuh rejected into the ground; net cooling effect likely barely over 1.5 tons after factoring out system electrical power.

Glad to read you are running N2 before brazing...
Curt Kinder <br><br>

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
lawtoolguyUser is Offline
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20 Jul 2014 04:10 PM
New TXV has been installed along with moisture indicator and filter dryer. 5 LBS R-22 returned back into system

New readings are better but still not getting super heat and sub cooling where they need to be.

Low side 75 PSI 44*
suction temp 74*
30* super heat

High side 265 PSI 121*
Liquid Line 99*
22* Sub Cooling

Supply 72*
Return 83*

EWT 76* AT 15 PSI
LWT 88* AT 18 PSI

6 GPM

88* outside

TXV is now working. I can adjust setting now and see adjustment reflected in the pressures but not able to get High side down to 225 PSI which it should be. I also picked up some nickle-safe and flushed heat exchanger again for another hour but still did not help.
engineerUser is Offline
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20 Jul 2014 10:08 PM
If the heat exchanger is heavily scaled, Nickel-safe may not suffice.
Too much superheat
too much subcooling
airside delta-T piss-poor
Low side pressure a tad high but consistent with elevated return and supply air temps
Rejection slightly improved to 12x6x500 = 36kBtuh, but still just 2 tons or so net cooling.
Is your report of 6 GPM based on an external flowmeter (or 5 gallon bucket test) or are you inferring from Delta-P across heat exchanger? If fouled, value is suspect.
What's it do if you goose flow up to 8-9 GPM?

Where in Florida are you? 76*F EWT implies south...at or below State Route 60.
Curt Kinder <br><br>

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
lawtoolguyUser is Offline
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21 Jul 2014 08:39 AM
I'm thinking I have multiple issues. The TXV replacement
Has resolved some of the pressure issues.

When inspecting water side exchanger I don't see any iron
Fouling at all in pipes or my Flowmeter but I do see what
I believe is manganese. It's a thin layer of blackish grey
That after it dries out it flakes off the inside walls of heat
Exchanger plumbing. If I bump up GPM to 8 to 10 I drop my
High side pressure to around 250 PSI but l loose Transfer. EWT 76 LWT 83 I'm 30 minutes west if Orlando I'm guessing still have fouling in exchanger but haven't found A product that can clean the manganese from the inner walls Of exchanger. Thank you for your input Curt.
joe.amiUser is Offline
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21 Jul 2014 09:07 AM
Let the thing run in heat for awhile then jerk the "O" wire. That will often break up a build up.
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
lawtoolguyUser is Offline
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21 Jul 2014 09:20 AM
Hey Joe
After looking at the TXV after removing it
I think it was damaged at install and was
Always stuck open. I could not get the valve apart
Once removed and I applied air pressure
It was far from free flowing as the new valve was.

One thing I forgot to test was heat mode as we were
So happy to have a/c again. I switch it over to
Heat tonight and confirm no more low side trips then
Pull the O wire.
lawtoolguyUser is Offline
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21 Jul 2014 10:16 AM
Heat mode is working fine no low side trips. Fuse to toaster has been removed since day I installed unit. 75 outside EWT 76 LWT 69 Return 80* Supply 102* High side 215 psi LIQUID 82* Low Side 75 PSI Suction 72* Pulling orange wire did not shock system at all. Reversing valve did not change until until cooling kicked in then you could here the swoosh. Checked voltage while in heat mode and had 27 VAC. no voltage in cooling mode
lawtoolguyUser is Offline
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24 Dec 2014 05:41 PM
Well electric Bill was high for the remainder of the summer but we stayed cool. We have had unit off for past 2 months while temps have finally cooled off. I ran Reydlym through system for 4 days and fired it up today to see if it made any difference. Return air 80* Supply air 73* low side 67 psi high side 230 psi suction 75* Liquid 95* 5 GPM 75* EWT 87* LWT Guessing I have three choices at this point. 1.Try to find a replacement waterside ex-changer and replace this one. Time consuming and not sure this is the fix. If it fixes problem plan for vertical bores and closed loop system. 2.Buy a R410 4 ton Outdoor condenser and new evaperator and plumb in to existing geothrmal unit converting to conventional system and forget about geothermal. 3.Fork out cash and buy completely new system and forget about Geothermal Any input?
joe.amiUser is Offline
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25 Dec 2014 08:24 AM
What are the pressures supposed to be?
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
jonrUser is Offline
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25 Dec 2014 11:23 AM
You could take a small sample of the HX deposits and test various acids against it in a glass. Take the best and use it liberally (you have little to lose at this point).

I haven't looked into it, but perhaps sulfamic or hydrochloric, both with an inhibitor.
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