We still seem to be having some issues with our Geo install that was done last summer. Primarily, we are still seeing LT1 lockouts for low loop temp. The system is a Climatemaster Tranquility 30 Digital, 5 ton, feeding two zones. The loop is a closed loop horizontal slinky burried at 6 feet. We also have a desuperheater feeding a 50 gal buffer tank, feeding a 75 gal HWH. We are located West of Philadelphia, PA.

Throughout December and January we were experiencing lockouts daily, several each day sometimes. I have a monitoring system installed and EWT was showing at right around 32.0F when the lockouts would occur. I did confirm that the antifreeze jumper is cut, and the loop is filled with a methanol mix. LWT is usually around 26F making for a delta of around 6F, which seems normal. The EWT would never get much below 32F, if at all.

Over the past two weeks, the installers came out twice and looked at things. The first time, they checked temps, flow, pressure, etc. Changed the filter. After describing more of the symptoms to their lead tech he told me about the bulletin for the compressor oil sticking/TXV valve problem. They added the requested additive to the system and I was immediately seeing an improvement in the operation of the system. We are now seeing much longer run times without lockouts and EWT that goes down to about 31.5F.

However, for the past 3 days since the additive was added, the system locks out right after I get a shower in the morning and start using hot water, forcing the DSH to do it's thing. I go and reset the lockout, the system comes on and runs all day.

So I have two main topics that I would like to pose:

1. Should the TXV valve be replaced as well? Is it possible that it was damaged or gummed up enough that it is still faulty, given the amount of time the system had been running before the additive was added to correct the compressor issue? Is there some other readings that will help to better diagnose the problem here?

2. My ground temperature at 5FT is 40F (away from the loop). Is it reasonable to expect that at this time of the year, with such a temp, that a loop would simply be out of heat? With the antifreeze jumper cut, how low should I be able to expect the EWT and LWT to go? If antifreeze protection is supposed to go as low as 10F, why do i never get anywhere near that? Could there be a problem with the loop itself and how do I determine that?

Thanks in advance for any assistance. If more info is needed about the system, please ask and I'll provide whatever I can.

The additive has been successful in avoiding TXV replacement most of the time. First I would temporarily disable the DSH to make sure that is the actual precipitous vs coincidence.

Posted By joe.ami on 13 Feb 2015 08:55 AM
The additive has been successful in avoiding TXV replacement most of the time. First I would temporarily disable the DSH to make sure that is the actual precipitous vs coincidence.

Thanks for replying. It has been pretty clear that the only lockouts we have seen since the additive was put into the system are immediately following a large draw of hot water from the system. I am fairly certain that turning off the DSH would end the lockouts that we do see. Given that type of behavior, is there a simple explanation as to what could still be wrong or where I should look?

And my other question was why, if my loop has methanol and the jumper is cut to allow lower temps, do I still never see my EWT go any lower than 31.5F. LWT is never below 25F. Is this normal or should I be seeing temps going lower than that?

Thanks.

Sorry, this might not be useful to know, but what kind of monitoring system do you have? How are the sensors attached to/reading the loop temperatures? Is it possible the loop is actually way colder, but the sensors are giving incorrect information?

Posted By decafdrinker on 19 Feb 2015 06:43 AM
Sorry, this might not be useful to know, but what kind of monitoring system do you have? How are the sensors attached to/reading the loop temperatures? Is it possible the loop is actually way colder, but the sensors are giving incorrect information?

I had considered that, but I don't think there is that much difference in the calibration. The system is by my-ewise. The sensors are strapped to the EWT/LWT lines inside the unit and insulation wrapped, so I think there is a good reading of the line temps.

If anyone wants to review the data, you can see it here: http://myewise.net/site.php?id=3213

Posted By EvilTwin on 19 Feb 2015 06:16 AM



And my other question was why, if my loop has methanol and the jumper is cut to allow lower temps, do I still never see my EWT go any lower than 31.5F. LWT is never below 25F. Is this normal or should I be seeing temps going lower than that?

Thanks.

It is not uncommon for loops  to reach a "steady state"  temperature somewhere around 30°

"I am fairly certain that turning off the DSH would end the lockouts that we do see. Given that type of behavior, is there a simple explanation as to what could still be wrong or where I should look?"

Why be fairly certain when you can be completely certain? I can't think of a simple explanation I'm still guessing coincidence i.e. you are using night time set backs and showers are accompanied by long run times.

Posted By joe.ami on 19 Feb 2015 09:38 AM
"I am fairly certain that turning off the DSH would end the lockouts that we do see. Given that type of behavior, is there a simple explanation as to what could still be wrong or where I should look?"

Why be fairly certain when you can be completely certain? I can't think of a simple explanation I'm still guessing coincidence i.e. you are using night time set backs and showers are accompanied by long run times.

Thanks for the replies, Joe. Honestly, I'm trying to find some simple theories without having to resort to shutting off my DSH for a few days and heating my hot water with the tank heater for a few days, costing me more $$$ in electricity expense.

My expectations with this system are such that I would never expect that my system would be locking out like it is, unless something is wrong. My experience thus far since the additive was put in to correct for the oil/rust inhibitor coagulation on the TXV valve is that the system locks out immediately following a large hot water draw, namely a shower. I have experienced this in the early morning (no nighttime setbacks on the stats) and I have seen this happen in the evening. With the deep cold we are seeing in the past weeks the system is running nearly 24/7, especially all night long with AUX heat pulsing on/off to keep up.

I ask these question here because I thought that this is what this forum is for, to ask questions of knowledgeable professionals that may be able to help me. My installer is somewhat responsive but I think they are more worried about how much their service calls for this sort of thing are costing them. I feel I need to constantly continue to educate myself on all things GEO/HVAC in order to get them to continue to troubleshoot the problem. As a consumer I shouldn't have to go to extreme lengths to be knowledgable about such things and maybe that means I need to go find a different contractor to service my system. I do technical troubleshooting for a living and 'what-if' questions and scenarios are a big part of that. That's really what I am looking for here...some 'what-if's, so that I can better understand what is going on and maybe help me to know whether my installer is feeding me a line of crap because he honestly doesn't know what's wrong. I am not afraid to roll up my sleeves and get my hands dirty checking various aspects and settings in the system. I just want to get things working the way they should. $700+ per month electric bills really don't seem right for a geo system that is working properly, does it?

Sorry for the rant.

EvilTwin,
I think the DSH thing is a red herring but would like to be sure, so in troubleshooting one thing knowledgeable pros do is rule things out vs work on the premise that we are reasonably certain something is the problem and attack from there.

Why would you have to leave the DSH off for a few days if system only faults during showers?

Posted By joe.ami on 20 Feb 2015 06:04 AM
EvilTwin,
I think the DSH thing is a red herring but would like to be sure, so in troubleshooting one thing knowledgeable pros do is rule things out vs work on the premise that we are reasonably certain something is the problem and attack from there.

Why would you have to leave the DSH off for a few days if system only faults during showers?

Well, I could turn off the DSH, go take a shower and see if it locks out, but it is not 100% lockouts after every shower. What I do know is that when it does lockout, it always happens after a shower.

So my question is this...If the problem only happens after a large hot water draw, i.e. Shower, and does not happen when the DSH is off, what could be a possible source of the problem? What measurements or readings could I take to further troubleshoot the problem?

This is becoming circular. You did not indicate whether or not you are using night time set backs which is one of the potential problems. For that matter are we sure the lock out is the same (LT1)? You haven't indicated that.
I ask because I don't see a scenario in which DSH causes LT1 by itself. So I think it's a red herring. You don't wish to rule it out so....stalemate.
Good Luck.

Posted By joe.ami on 21 Feb 2015 07:47 AM
This is becoming circular. You did not indicate whether or not you are using night time set backs which is one of the potential problems. For that matter are we sure the lock out is the same (LT1)? You haven't indicated that.
I ask because I don't see a scenario in which DSH causes LT1 by itself. So I think it's a red herring. You don't wish to rule it out so....stalemate.
Good Luck.

Actually, I did indicate that I do not do nighttime setbacks in my comments on 2/19.

On several occasions, when the system has locked out, I push the test button on the system board and get four flashes/clicks. It has never been anything different.

Why is it hard to speculate on the possibility that

A. The loop is already about as cold as it is going to get before it will lockout
B. The DSH kicks in after a shower, drawing more heat from the loop than normal
Causing the LT1 to trip? Now, if you are going to tell me that it just doesn't work that way, then fine. Please educate me. Meanwhile, I'll shut off the DSH for today and see what happens. I am 99.99% certain that I will not get a lockout.

Thanks.

Sorry I missed the comment about set backs amidst the lengthy paragraphs.
I'm not trying to be contrary. If you want to trouble shoot then lets do so. If you think it's the DSH, step one prove it's the DSH.
Good to know you confirmed the fault is the same.

"B. The DSH kicks in after a shower, drawing more heat from the loop than normal
Causing the LT1 to trip? Now, if you are going to tell me that it just doesn't work that way, then fine. Please educate me."

Okay, it doesn't work that way. Your unit draws a fixed number of btus (mostly) taking 10ish% from heating to make hot water when DSH is employed, not drawing more btus. It also kicks in when you wash dishes or draw a bath or anytime buffer tank (if you have one) drops below temp.

Now I said mostly because lower entering air or water temperatures can raise the efficiency of the unit slightly which slightly raises the btus collected. I wouldn't call that more than normal anymore than peak heating load in the middle of the night.

Why do I ask you to support your premise? A rookie (who thinks hes a seasoned vet) in my firm was having a terrible time trying to figure out why a unit kept shutting off on limit. I asked a variety of questions including did you check the air filter to which he answered yes.
As it turned out he checked the filter by asking the homeowner who said it was 2 weeks old. During those 2 weeks, the homeowner had jack hammered a basement floor to add a Lav. Concrete dust does a fine job of plugging a filter.
Rookie was fixated on the ice near the exhaust/inlet (gas furnace) which typically wouldn't cause a furnace to run hot..........When poor operation continued I went to have a look. New filter-no problem.

So there is an order to things in troubleshooting. Some things are more likely than others. DSH is not impossible, but not as likely a cause (vs coincidence), once you isolate it then we go down the road. That starts with how is your DSH piped?

You might also consider whether anything else happens simultaneously (flapping doors from people heading to school/work)....garage door open.... And you might find it useful to monitor EWT/LWT before and after you start the water demand and get DSH running.

BTW you told me it doesn't happen everytime so I don't think a one day test is conclusive.

glad to go on the journey with you, but if you'd like the benefit of my experience, then let's employ it.

Alright. So here's what just happened. I went down the basement to go turn off the DSH. As I get there, I feel the exposed area of the DSH input and it is cold. Immediately, I think oh crap, wife just got in the shower. Missing my chance. So I open up the unit, locate the proper DIP switch and turn off the DSH. Within seconds, the unit goes into lockout, right in front of me. What does that mean? Probably nothing. My knee jerk reaction is that the cold water already started flowing and kicked off a HWG cycle. I reset the system. For now, the DSH is off.

The DSH is piped properly, from what I read in the IOM, at least in terms of pipes going from point A-B. They used a flexible piping from the DSH to the buffer tank, not all copper like the IOM recommends. I suspect it was done because the HWH tanks are 10 feet away.

The monitoring system that I have is keeping track of a lot of things, including EWT/LWT and DSH potable water temps. I am still on the fence for buying a digital stat that will give me all of the internal readings.

Thanks for helping. It is appreciated.

"My knee jerk reaction is that the cold water already started flowing and kicked off a HWG cycle." I don't think that cold water in the DSH input will turn on your heat pump. With most systems, the thermostat turns on the heat pump. The DSH only runs when there is a call from the thermostat.

There is really not much in the operational control system that a DSH can cause a lockdown. The DSH is nothing but a heat exchanger on the discharge pipe of the compressor, and heat is "stolen" from the heat going to the air coils. The DSH is not turned on or of, it is only a small pump turning on which pumps tank water through that heat exchanger.
Thus the amount of heat extracted from the water is the same, there is just a few percent less heat going into the air. Your compressor or refrigerant circuit would not even know that wether the DSH is running or not. Thus any high pressure lockdown you are describing is unlikely DSH related.

Perhaps I misstated what I was trying to say. The DSH input line has a temp sensor on it that the system uses to sense incoming water temp. If the temp is low, the DSH pump turns on and moves water from the buffer tank through the DSH and back out to the tank. I didn't mean to imply that cold water would turn on my heatpump. And, according to the IOM, when the DSH water temp gets to the high limit, the DSH pump shuts off and

"Once the HWG has satisfied the water heating demand during a heat pump run cycle, the controller will cycle the pump at regular Intervals to determine if an additional HWG cycle can be utilized".

Doc, thanks for the extra explanation . I gathered that from what Joe said earlier. I guess I was thinking the DSH was robbing the loop of more heat, but it is, in fact, robbing the heating coils of that heat (for lack of a better term). As I said before, since the additive was put in, the only time I get lockouts now is immediately during/after a large draw of hot water. I guess that's why I was focused on something related to the DSH. To me, logic dictates that if that is when the lockouts occur, then the DSH is somehow a catalyst in those lockouts. For now, the DSH is off.

So if I go a few days without any lockouts, I turn the DSH back on and we see the same lockout patterns, what does that tell us? What would be the next thing to look at?

OK, so over 24 hours and several showers later, DSH off, no lockouts. The system is actually off right now because the temps are above 40 outside. The odd thing is that when I look at my data, it looks like the DSH is still making hot water. Do I need to do a full shutdown on the heatpump in order to shut off the DSH? I know I flipped the right dip switch to shut it off.

Sure, the DSH is still making hot water, just the circulation pump is off, not pumping the water through it. You might get thermal siphoning which affects your readings.