HVAC/Thermostat (Y1 voltage) Help!!!!!!!!!

[LD1]

I know we have alot of HVAC experts on here, so I figured I'd run my issues by you all while I am waiting on hold for tech support.

This is the geothermal pump I have 4 Ton 2 Stage GeoCool Geothermal Heat Pump

this is the T-stat Pro1 Thermostats | T955WH - Wireless Universal Thermostat

Not really a fan of this t-stat for starters. It seems there is quite a bit of lag built into its temp sensors. IE: I have swing set for 0.7 degrees. So if I have t-stat set for 68......It will turn on the furnace once it gets down to 67.3, and off again once it hits 68.7......or its supposed to. I dont so much have a problem with the on time, as the house cools off slowly, the t-stat is fairly accurate in that regard.

The issue is once the furnace kicks on, the temp in the house climbs fairly quickly. Quite a bit faster than the t-stat registers. the result is....by the time the t-stat "thinks" its at 68.7 and shuts the furnace off, its actually at ~72-73 degrees. Has nothing to do with t-stat calibration, just timing. Cause after the furnace has kicked off, 20-30 minutes later the t-stat has finally caught up to reality and shows its 72 in the house. This causes alot larger temp swings than I would like. So wondering if all digital t-stats are like that ?


But that isnt even my real issue. My issue is a lingering ~18v on wire Y1 coming from the t-stat.....EVEN when the T-stat is off and not calling for heat.

This lingering 18v is NOT enough that it is telling the compressor to run, however it is enough to trick my desuperheater DHW pump into running. Which is one of these:
http://www.bardhvac.com/digcat/volume_3_cd/install_pdf_file/2100-517.pdf

Probably been doing it since I installed the unit back in the spring, but didnt notice it until just now. Was doing some basement remodeling and kept hearing the bard cycling. Reading the description of how it operates, it is only supposed to come on when there is a 24v signal on Y1 (telling the compressor to run). From that point, it will run for 1.5 minutes. At that point it will check the thermistors on the incoming water and outgoing water. If it aint seeing a 2+ degree difference, it shuts off. It moniters the incoming and outgoing water to be sure there is enough temp difference, if not, it shuts off. If signal is lost from Y1, it shuts off.

Well, with Y1 having a lingering 18v on it, every 10 minutes it kicks on and circulates hot water through my desuperheater. EVEN IF the furnace IS NOT running. After 1.5 minutes it shuts off because there is no temp difference (or a negative difference.) 10 minutes later, rinse and repeat.

Any idea why the t-stat is leaving 18v linger on the Y1 wire?

 

[LD1]

Here is an example of the t-stat lag.

Pic 1 is right when the unit shut off. The t-stat wasnt reading the actual temp....too much lag.

Pic 2 is ~30 minutes later when the t-stat finally caught up to reality.



Just got off the phone with tech support too. He agree that the t-stat shouldnt have that much lag.

Also agreed that there shouldnt be any voltage on Y1. But this unit as an A1 terminal as well on the board, that is for accessories. So I switched the bard (hot water circulator pump) over to that terminal. As its not tied to the t-stat and thus, doesnt have any lingering voltage causing it to want to run when the furnace itself isnt running. The 18v on Y1 still aint right, but at least I am not wasting energy circulating my hot water through the DSH now.

They are sending me a new t-stat with the temp lag being what it is, and the 18v on Y1 even with the unit off, something just aint right.

 

[BrokeFarmerJohn]

I know we have alot of HVAC experts on here, so I figured I'd run my issues by you all while I am waiting on hold for tech support.

This is the geothermal pump I have 4 Ton 2 Stage GeoCool Geothermal Heat Pump

this is the T-stat Pro1 Thermostats | T955WH - Wireless Universal Thermostat

Not really a fan of this t-stat for starters. It seems there is quite a bit of lag built into its temp sensors. IE: I have swing set for 0.7 degrees. So if I have t-stat set for 68......It will turn on the furnace once it gets down to 67.3, and off again once it hits 68.7......or its supposed to. I dont so much have a problem with the on time, as the house cools off slowly, the t-stat is fairly accurate in that regard.

The issue is once the furnace kicks on, the temp in the house climbs fairly quickly. Quite a bit faster than the t-stat registers. the result is....by the time the t-stat "thinks" its at 68.7 and shuts the furnace off, its actually at ~72-73 degrees. Has nothing to do with t-stat calibration, just timing. Cause after the furnace has kicked off, 20-30 minutes later the t-stat has finally caught up to reality and shows its 72 in the house. This causes alot larger temp swings than I would like. So wondering if all digital t-stats are like that ?


But that isnt even my real issue. My issue is a lingering ~18v on wire Y1 coming from the t-stat.....EVEN when the T-stat is off and not calling for heat.

This lingering 18v is NOT enough that it is telling the compressor to run, however it is enough to trick my desuperheater DHW pump into running. Which is one of these:
http://www.bardhvac.com/digcat/volume_3_cd/install_pdf_file/2100-517.pdf

Probably been doing it since I installed the unit back in the spring, but didnt notice it until just now. Was doing some basement remodeling and kept hearing the bard cycling. Reading the description of how it operates, it is only supposed to come on when there is a 24v signal on Y1 (telling the compressor to run). From that point, it will run for 1.5 minutes. At that point it will check the thermistors on the incoming water and outgoing water. If it aint seeing a 2+ degree difference, it shuts off. It moniters the incoming and outgoing water to be sure there is enough temp difference, if not, it shuts off. If signal is lost from Y1, it shuts off.

Well, with Y1 having a lingering 18v on it, every 10 minutes it kicks on and circulates hot water through my desuperheater. EVEN IF the furnace IS NOT running. After 1.5 minutes it shuts off because there is no temp difference (or a negative difference.) 10 minutes later, rinse and repeat.

Any idea why the t-stat is leaving 18v linger on the Y1 wire?

First off I would like to say I don't have experience with geo thermal units but the idea is the same as your basic HVAC system.

My first question regarding the temp swing on the T stat is the location of the stat, is the stat mounted on a interior wall away from any supplies? Is the wall sealed from other spaces like a attic or crawlspace? I have had issues with stats reading wrong because attic air was traveling down the inside of a wall, so the stat was being tricked by that temp difference, the wall was hotter or colder than the conditioned air in the living space. Also you can set the stat to have more or less of a swing before it turns on or shuts off the system, that would be in the programming of the stat which you would find in your installation manual.

The lingering voltage on Y1 (first stage of cooling) could be as simple as wire insulation failure, if the yellow and red wires touch anywhere in the run you will see voltage on that wire. I have had blower motors run and all kinds of crazy stuff from that, that's were I would begin, check all your connections on the low voltage side and look for ANY breaks in the insulation, if there's any cut it out and restrip the wire.

Another question that comes to mind of the furnace running away (72degrees when it reads 67 ext) is where is that degree swing? If that's at the stat I would say there is something making that stat think it's a different temp like I said before, if it's a issue of hot and cold spots in the house it's a lack of air circulation which you would need to look into balancing your air more, cutting back registers in hot zones ext.

 

[LD1]

Not a wiring issue. It's a wireless t-stat. I can isolate the wiring, and still get the lingering voltage on the wireless base module. I'm confident that it has to be something in the circuitry of the t-stat.

As to location, the t-stat normally resides in the hallway. Which is an interior wall, and supply's even close. But again, it's a wireless unit and I can move it around, side by side, with my hand held meter. Still the same end result. It's just slow to respond to temp changes.

The pictures taken of my handheld temp meter, and the wireless t-stat, were both in the basement. It's just slow to respond, then about 30 minutes later it has finally caught up and is reading the correct temp. No issues for when the unit is called upon for heat, as the hose cools off slowly. A slow cool over a period of 3 hours, down to the setpoint to call for heat, the t-stat can keep up with. Once on though, warming the house up several degrees in 30 minutes, it cannot keep up with.

Swing is also set pretty low IMO. Only +/- 0.7*F from setpoint.

 

[BrokeFarmerJohn]

Sounds like I'm not any help to you than lol.

It deff sounds like a controls issue, the only wireless stat I'm familiar with and than only a little is the old carrier edge stat, the way it was set up was, the low voltage was wired into a computer in the furnace which controlled the unit and all the Tstat did was see the room temp and was able to manually change the temp ext, other than that it was basically a monitor. Sounds like the refresh time on your stat is lagging, if it read the correct temp and the signal to the furnace was delayed it would suggest a network issue but it sounds like more of a local issue at the stat your dealing with. If the brain can't see the correct temp it's gonna keep running to satisfy the space.

 

[LD1]

Sounds like a similar stats.

There is a receiver hardwired to the furnace. The receiver is where the c,r,y,o,b,etc wires from the furnace all hook. Then the t-stat communicates to it wirelessly. The wireless portion is where all the changes and programming occur. And decisions are made (based off temp, swing, setpoint, etc) to energize the different wires.

It works just like a regular programmable wireless t-stat. Just keep the wires local at the furnace, and be able to move the brains of the unit wherever you want.

 

[BrokeFarmerJohn]

Sounds like a similar stats.

There is a receiver hardwired to the furnace. The receiver is where the c,r,y,o,b,etc wires from the furnace all hook. Then the t-stat communicates to it wirelessly. The wireless portion is where all the changes and programming occur. And decisions are made (based off temp, swing, setpoint, etc) to energize the different wires.

It works just like a regular programmable wireless t-stat. Just keep the wires local at the furnace, and be able to move the brains of the unit wherever you want.

I haven't herd too many things about the edge stat but as far as a lot of those stats go, I like my old wired stats lol, there not nearly as complicated and easier to troubleshoot, my preferred set up is the one I have, which is a Honeywell 8000 series stat with a wired outdoor sensor, I have a regular heatpump which is set to run emergency heat only under 32 degrees outside temp. The manufacturers are saying run the heat pumps down to 0 degrees but at that temp I think personally your just trading dollars for wear on the equipment, what you gain in energy savings your losing in equipment wear.

A geothermal unit is a totally different animal because it's below the frost line and exposed to a hotter temp than one above ground.

Is yours a ground to air geo thermal heatpump? Meaning the coils underground in your back yard? There's also water to air heat pumps using a river or pond, some sort of body of water, than there's that idea but vertical vs horizontal coils, that's used in commercial buildings mainly where land is a issue, they bore a bunch of holes below ground straight down.

I'm sorry I'm not more help to you, I'm sure if I was there I might be able to figure out what's going one by isolating different things and following the sequence of operations. I learned about geothermal when I went to school for HVAC but found in the real world there about as rare as a fuel oil furnace so I haven't really gotten my hands on one or had the opportunity to set one up, nobody wants to shell out the upfront cost to install one.

 

[BrokeFarmerJohn]

I was hoping by talking about it more someone that knows more info than I do on geothermal would chime in and say they have seen this issue before with one and guess accurately what the problem is and how to fix it.

I used to get on yahoo answers and help people with a lot of there HVAC issues or decipher what a technician told them about there systems and I'm usually pretty accurate and can tell them what to look for and or how to fix it themselves.

 

[LD1]

It's a closed loop geo system with the loops in my back yard.

Don't really thing it's a geo related issue, just a t-stat issue. Y1 shouldn't have voltage on it when the t-stat isn't calling for it.

If it weren't for the bard dhw circulator unit, I think this unit could run like this for 20 years and no one would ever know. The lingering 18v isn't enough to make the furnace run, but the bard must use some more sensitive circuitry, or, cause it's sure fooling it.

 

[BrokeFarmerJohn]

It's a closed loop geo system with the loops in my back yard.

Don't really thing it's a geo related issue, just a t-stat issue. Y1 shouldn't have voltage on it when the t-stat isn't calling for it.

If it weren't for the bard dhw circulator unit, I think this unit could run like this for 20 years and no one would ever know. The lingering 18v isn't enough to make the furnace run, but the bard must use some more sensitive circuitry, or, cause it's sure fooling it.

The only way that Y1 could have voltage on it is if a wire is touching the hot wire or the stat controller is misdirecting voltage, only two reasons I can think of.

Way to tell would be just following the power back, high (120v or 208-240v) voltage in to the 24v transformer, 24v coming out of the transformer, 24v going into the stat controller, if it's all good to the stat board and you still have 18v on Y1 than the stat board in the furnace is bad. Just make sure all voltages to the board is correct.

You can diagnose any problem with the sequence of operation, voltage flows just like a river, you just have to follow it back to the source.