Energy Kinetics Gurus... Odd Energy Manager Issue

NEMatt

Been looking at an odd issue with my EK1 today (may have been going on a while longer but I was only in the basement today and saw it).

PROBLEM:
Early in a heating call, particularly when the return water temp is low, the lights on the return temp indicator will extinguish except for POWER.  Sometimes 100 will flash beforehand.  Sometimes it will just go blank.  MONITOR light never illuminates.

The zone valve(s) close because they don't think the boiler is at 140 yet.  Burner continues running as normal.

After a number of seconds have elapsed the return temp on the monitor will come back on (sometimes preceded by the 100 blinking a tad).  If hot enough, zone valves open etc.  Most I have seen this happen in a single heating call is twice.


PERTINENT FACTS (maybe?):
- This never happens later in a heat call

- This never happens during the energy recovery phase as the zone is being circulated after the call ends.
- It happens on any zone. 
- 3 zones... 2 ecobees one conventional tstat
- Everything else about boiler operation is nominal

- Jiggling wires into the energy manager doesn't cause it to happen

- The Carlin primary it has stops ignition 15 seconds after flame is sensed so I don't think this is some weird arcing issue wigging the energy manager out

Per Energy Kinetics, if the 100 degree light blinks and MONITOR is on, the temp sensor or wiring is shot.  However monitor never comes on, and their troubleshooting info does not mention anything about all the lights going on except POWER.

Any EK gurus have thoughts? @Roger

Roger

Thank you for your question, @NEMatt .

The 100 degree error light will only stay lit if the sensor does not communicate properly for five minutes continuously, so the condition you’re seeing sounds like the communication is not working for periods of time that are less than that. 

The first things that come to mind are checking the sensor wiring (as you wiggled the wires; that’s part of the test), also check the screw tightness and then the contact from the quick connector to the circuit board edge of the manager. It could just be a sensor that needs to be replaced, or it could be aggravated by the Ecobee thermostats if they are power stealing and don’t have their own common wire. It could be an issue with the ignitor arcing to ground that is enough to interrupt the communication on the sensor, but not enough to cause further intermittent operational issues with the microprocessor on the digital manager. So the ignitor and electrodes should also be checked as it may take a little while for the sensor to recover after the ignitor turns off.
Replacing the sensor is the easiest to check, although if you don’t have one available certainly check these other things first.

Best,

Roger

NEMatt

@Roger thanks very much for the reply.

I looked at it more today and thought on it a bit more. It's almost as if the problem occurs most frequently when the return is cold and the zone valve(s) are still cycling.  Once it is steadily above 130 or 140 it'll run the remaining cycle without any issues including the energy recovery period.

I also have now witnessed twice where it thought it detected a freeze condition, flashed 120, and then recovered later.  This too happened early in a heat call.  Makes me think the sensor is on the fritz.  No reason it should  read <40 degrees.

One of the Ecobees is wired with a common to the transformer, one is wired with a FastStat Common Maker as I am pretty sure this entire house was built around that original two-conductor thermostat wire!  One has been wired for a couple years, the other one since December or so.

I don't think it's the ignitor since this phenomenon can happen for a few minutes depending how many zones are open and how cold the boiler/return water is.  Ignitor should be off.

Probably going to replace the sensor and then see what happens.

Roger

That sounds like a good course of action, @NEMatt .  Seeing a 120° flash (freeze condition) when the boiler is warm is usually a good indication that the sensor is no longer communicating properly.

NEMatt

@Roger is this sensor a proprietary EK unit or something I can find locally at a supply house?  No PNs are readily identifiable on it.

szwedj

@NEMatt The system manager on your boiler uses a digital sensor. That sensor is one of the few parts unique to EK and is only available from the factory. The trade professional who services your system will be able to provide a replacement and correct this for you.

NEMatt

@szwedj thanks.  I usually have one of your factory installers come out.  Figured I'd save him the trip for something this simple if possible. I'm sure he has better stuff to do

exqheat

Take a resistance measurement of the sensor. Most are 10 or 20K. You can get them on the internet.

NEMatt

@exqheat I was sifting through some EK tech documents and found a resistance reading but it was at 75F.  I don't think the boiler is getting that cold between calls.  I might test it after removal.

jringel

That sensor is not a thermistor as it has a chip built into the probe. It cant be ordered on the internet and needs to be ordered through the factory.

szwedj

@exqheat the digital sensor (copper bulb) which is used with digital managers is not a thermistor, so the only way to test a digital sensor is by connecting to the manager itself.

@NEMatt The newer managers with the lcd display come with a dual thermistor (silver bulb) and those can be tested. At room temp (approx. 77F) it should read ~10K Ohms between the black and red wires and between the white and red wires

NEMatt

Yup, got it.  Have one of your installers coming Friday with one.

NEMatt

Resolution:  New return temp sensor has solved the issue for the time being as expected.