Thanks for having this forum as its proving to be invaluable ! We purchased a new to us home back in Aug. It has a closed loop Geothermal Heat Pump system that is approximately 10 years old. During the switch over from Cool to Heat we noticed that the unit would not switch from cool to heat unless the entire system was powered down and then Heat was called for. We found out that the EWC NCm-300 zone board was bad.. So I got myself a new board and was ready to install it, then I started to dig into the system and can't figure out why its wired(SET-UP) the way it is... hopefully everyone here can help me figure it out !! Its a Climatemaster Tranquility 27 5 Ton Air Handler ( TAH064AGSMCS), Climatemaster TTS064BGC00CNNS 5 Ton Split R410A Copper Coil no HWG Heat Pump Climatemaster AGL15C 15KW Electric Heater EWC NCM300 Zone Control Board with two zones set up 14'' Barometric Bypass Damper Zonex TREC 20 x 8 Single blade Damper Zonex, TREC 22x12 Rectangular Damper. Based on the wiring at the thermostat / zone board / and heat pump, it looks to be configured as a single stage Heat pump with AUX electric heat. Based on what I can find out this unit , it should be a two stage unit with a variable speed fan.. I can't figure out why it would be set up as a single stage unit ? Could it be thermostat or zone board limitation ? or just an easier install ? Im a total novice but can pick stuff up pretty quickly. Just trying to decide if I should upgrade the zone board and get the wiring correct to take advantage of the dual stage efficiencies ? Any thoughts or help is appreciated !!
I can't help directly with your issue but it wouldn't be the first system to have been "rigged" to "work" by a homeowner or technician that is too cheap to do fix something correctly and/or isn't familiar with the equipment they are working on. Fortunately for you, there are a ton of experts on this board who will advise appropriately. I have a new to me house too and I can't fathom how some of the stuff got to its current "working" condition by the prior owners. Fortunately, the geo system was the first thing I did so that is good to go! Good luck
Thanks for the reply, I’m beginning to think they either didn’t understand the unit or just used a cheaper zone board that wasn’t able to handle the multiple stages, and made it work. good luck to us both !
Are you actually using seperate zones? The reason that I ask is that I have the same model, minus the zone boards that you are referring to - I can look at mine and compare if you aren't getting anywhere. For a GEO system to be only using a portion of its functionality is a shame. Let us know,
Yup, it is set up for two zones through the board. Everything is functioning, Correctly (as wired) except that the aux electric heat is coming on far too often. That’s what got me looking to see why? Seems they have jumped the y1 and y everywhere from the heat pump through the Air handler wiring. No idea why. Is your unit set up with multiple staging through your thermostat? Separate y and y1 ? Thanks for the reply.
According to the EWC NCM300 Zone Control Board technical bulletin below, "Will control 1 stage Heat Pumps with Electric auxiliary heat." https://www.ewccontrols.com/acrobat/090375a0226.pdf Aux heat coming on too frequently is often due to the thermostat differential temperature being set too low or manual changes in the thermostat setpoint causing Aux heat to engage to raise room temperature. Per the bulletin above (see snip below), the zone control board also has a second stage heating timer with and adjustable range of OFF and 7 to 42 minutes. If this is set to anything other than OFF, and your heat pump is only running in first stage, then Aux heat will kick in after the number of minutes set on the dial regardless of the difference between the actual room temperature and the setting on the thermostat.
Thanks for getting that info. They originally had Honeywell Vision Pro 8000 series thermostat. I replaced with the Honeywell WiFi version but they do not give you a setting to set thresholds for staging. So the board was controlling. It was set to 28 minutes. I have since replaced the board (that might have had something to do with the aux heat running) and also had ecobee 3 thermostats that I can now see the staging and control the aux heat much more closely. I guess my main question is why would this system have the y1/y jumped everywhere when it’s a 3H/2C unit ? Two stage compressor with aux electric heat. How much efficiency’s am I missing out on ? thanks for your info !
