Another lockout this morning, 10 minutes after I got in the shower. DSH is off. System ran most of the night in stage 2 and was in stage 2 when it locked out. EWT at lockout looks to have been 31.3F, LWT at 25.7F (based on my monitor).

What is your well/city water temp? I have always thought that the way DSH's are plumbed the cold water can enter the buffer tank through the DSH rather then into the cold connection w/ dip tube.

Could the cold water in the DSH affect the refrigerant temp? enough to set off the lock-out. I believe the pro's have said the sensor that sets off a lockout is attached to the cold side of the refrigerant circuit.

(Just a homeowner)

Chris

What is your well/city water temp?

I have a well, and while I don't have a temp sensory (yet) on the incoming water temp there, I assume (yeah, yeah, I know) it is in the 50-ish range. Ground temp at 5 ft has been right around 40F.

The IOM for the system says this:

"LT1 Thermistor provides low temperature protection for WATER. When using ANTIFRREEZE solutions, cut JW3 jumper"

Could it be a bad thermistor?

I think we have put the DSH thing to bed. Causes of LT1 lockout are low EWT (cold ground loops), low LWT (perhaps slow circulation), low refrigerant, sticking TXV. So we would want to know flow (gpm) and temps. We presume when they introduced the ReNu that they checked the pressures so it is not likely a pressure thing. If the TXV is still being interfered with, some times you can clear it up by reversing the flow (put unit in cooling) and trap whatever in the filter drier.
If it is a TXV problem it is easy to detect with gauges on even when it's not locking out.

I'll put the system in cooling mode for a bit later today when I get home. Any suggestion on how long it should run or how many times I should reverse it before it is enough?

I am waiting to hear from the installer on replacement of the TXV valve. They were scheduled to do this tomorrow but I had to reschedule. It seems they only have one guy on their staff that is "qualified" to do this so getting him scheduled has been a headache. If I can clear it up through other means, I'd like to, rather than having someone start cutting into the system, unless this is something that should be fairly routine in the business and nothing to worry about.

Turned off heat and switched over to cooling. System started up and then locked out within a few minutes, giving an LT2 fault (5 blinks/clicks on the red light). Reset the system. Started up in cooling again. Ran for a few minutes then locked out with LT2 again. Switched back over to heat. DSH still off.

1) Have you checked your antifreeze concentrations?

Posted By docjenser on 23 Feb 2015 04:43 PM
1) Have you checked your antifreeze concentrations?

I have not done that personally. When the installer was here and they injected the additive they said they "checked everything" and it all looked good. What exactly "everything" meant, I do not know. After reviewing the troubleshooting steps for LT1 lockouts, this was going to be one of the questions I asked them. I even looked into buying a hydrometer so I could test myself.

Your units symptoms would be spot on with a low antifreeze

Posted By docjenser on 24 Feb 2015 01:53 AM


Your units symptoms would be spot on with a low antifreeze

Thanks for the info. I was thinking this myself based on what I have been reading here and elsewhere. I spoke to the installer. He is telling me that the specific gravity of the methanol in my loop was .84 when they checked it. Now, I have not read up on needed antifreeze levels to much detail, but when I look in the IOM at the antifreeze charts that Climatemaster provides, the SG of methanol with a +10F Low Protection Level should be between .975 and .98. Which way does the number swing when you add or remove methanol in the loop? Am I reading the chart right that I need to be around .98?

I suspect that he meant .984, which is not enough methanol.
The lower the number the higher the methanol concentration.
I specify now .978, which indicates 10F, .982 is supposed to protect you down to 15F. I also seen the hydrometers not to be ultimately precise, or installers not reading it correctly.

Keep in mind that the coldest part is the end of the heat exchanger, and in order to extract heat from the water, the wall of that heat exchanger has to be significantly colder. Then ice forms on the inside wall, obstructing the flow. The mean thing is that this increases the pressure drop, actually indicating a higher flow, when in fact the flow is less..

Methanol is not like glycol which freezes "slowly, first forming a slush. With methanol, the hammer falls.

Can someone tell me how long it 'should' take to circulate a 5 ton loop enough to ensure that the antifreeze is mixed well enough to get an accurate SG reading after adding 4 gallons of methanol? I'm looking for a ballpark here. Nothing fancy. An hour? 12 hours? A day?

Installer was here today. I managed to get my hands on the service tool to look through the LT1 Fault Lockout readings that were stored. Here is the data from the last lockout:

Heat 2 (Stage)
LT1 Temp: 9.9
LT2 Temp: 75.3
Hot Water EWT: 55.6
Comp Discharge: 188.7
Leaving Air: 85.7
Leaving Water: 26.0
Entering Water: 31.6
Control Voltage 25.3

They checked SG of the methanol and adjusted. They want it to circulate 24 hours and they will stop back tomorrow afternoon to take a reading. IIRC, it was at .981

Reversing to cool for just a minute or two was enough to see if that worked. Your symptoms are still consistent with a fouled TXV, but you are correct that changing the TXV is intrusive and good to avoid if possible.

Posted By joe.ami on 27 Feb 2015 09:43 AM
Reversing to cool for just a minute or two was enough to see if that worked. Your symptoms are still consistent with a fouled TXV, but you are correct that changing the TXV is intrusive and good to avoid if possible.

Thanks for following up. The installer was out on Wednesday and checked the methanol levels in the loop. They added some to get the freeze protection down to 10F. They continued to check and put gauges on the system and from the readings they got and after speaking with climatemaster, CM told them to replace the TXV. They are coming back out Monday to do that.

Any more lockouts so far? Mixing should take a couple to a few hours... If there have not been any more lockout since they added the antifreeze, I would think twice touching the TXV.

We have not had any lockouts lately, but the DSH has been turned off. The installer resolved to replace the TXV but showed up with the wrong part, so I am still waiting.

Turn on the DSH, and watch the unit. Again, turning on the DSH unlikely causes any lockouts!
Without any new lockout, do not touch the TXV. Chances are that your problem might be solved now.

Again, low antifreeze can fool skilled techs, and CM tech support!

Turned on the DSH the other day. We have not had any lockouts thus far since they added more methanol to the loop. They came out on Saturday to replace the TXV but had the wrong TXV with them. I am waiting for them to get the right part. When they were last here, they had gauges on the system and they said the TXV is faulty. I don't know what readings they got on the gauges so I can't really comment.

I did some checking of things on my system. Looking at loop pressures and such, trying to figure out HE for my loop. I took loop pressures at the schrader valve ports on the front of the unit and I get EWP at 32 and LWP at 27, for a Delta P of 5. What I can't find is the data on conversion to flow rate. Also, when I read the procedure for charging the loop, it says loop pressure should be 50-75 PSI, but I'm not sure if I would see that at these ports or if there is some other condition needed when taking these measurements. Can someone give me some advice here?

So on a similar note, I want to know why this system is costing me so much money to run. My electric last month ran me $650. I am pretty certain $250-300 is non-geo related. This month the bill is over $900. That just seems insanely high. Certainly not the savings I expected. Now, the house had oil heat before. We didn't use it much last winter so I don't have any fuel cost info. I wanna say that the geo is cheaper than the oil would have been. But It's hard when the bills are so high. I see people talking about their geo costing them far less per month this winter. I know every house is different, it is just not what I was expecting to see.

Thanks for all the help thus far.

ET, if the system is locking out often then you are using too much auxiliry thus the high bill, still less than oil and all is better if the antifreeze adjustment fixes it.
j