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.

 

[woody]

LD1 I am not an expert but sounds like you may have some thing restricting the air moving through the t-stat causing it to not read the house temp real time. then the 18v on y1 is a different problem.

 

[fitter1]

Please describe exact location you are reading 18v.ie. r-y1, c-y1, grnd.-y1? Lack of info. Btw. who did the start-up reports for warranty issues. All thermostats have anticipator settings for heating and cooling. Cooling are usually fixed. These help to minimize over and under shooting setpoint. Call the installing contractor back for this.

 

[LD1]

Lack of info? Y1 to common and y1 to ground both show 18v. How else would one measure y1 voltage. I thought that was a given.

I am the installer/contractor. Not sure what anticipator setting is. Didn't see that anywhere in the program or user manual. I linked the exact t-stat. Perhaps there are some hidden functions that only "experts" are aware of?

 

[BrokeFarmerJohn]

Never set it up but I can see that being problematic if it's not completely consistent

So it fools the Tstat into thinking it's satisfied so it shuts off early

Btw your correct on checking voltage and I understood it was checked correctly, if someone knows how to work a meter and says they installed the system, it's clear they know how to check voltage correctly lol.

I will stick to the if you isolated it to the stat than its a stat issue, change the stat and I believe that will solve the problem.

If it's not a issue with the performance of the system or a voltage issue into or out of the transformer to the Tstat than it can only be a Tstat issue.

Another test would be is disconnect the R wire, the hot 24v wire and see if you still have voltage on Y1, if you do I would be looking for breaks in the insulation of the wires.

 

[BrokeFarmerJohn]

If I met you in person I would pick the crap (****) out of your brain on installing a geothermal heatpump and how much it set you back doing it yourself, I have never seen it done before.

A regular heatpump system is nothing to install just time, if I knew how to install a geothermal I would, I'm going to convert my house to natural gas in the spring, a geo unit would be awesome. I heard there like $10k-15k or better to have installed.

 

[dadster4]

I would start by disconnecting the low-voltage wiring from the heat pump terminals and see if the voltage at Y1 to C is present... If yes, then the problem is within the heat pump itself. If not, then the problem is further downstream. Reconnect at the heat pump and check at the "base module" backplate terminals and check for Y1 to C there. If yes, be sure the base module is not shorted on the backside, and that the wiring to the heat pump is not damaged. If not, mount the base module to it's backplate and check for Y1 to C at the heat pump terminals. If yes, then the problem is with the base module.

 

[LD1]

I would start by disconnecting the low-voltage wiring from the heat pump terminals and see if the voltage at Y1 to C is present... If yes, then the problem is within the heat pump itself. If not, then the problem is further downstream. Reconnect at the heat pump and check at the "base module" backplate terminals and check for Y1 to C there. If yes, be sure the base module is not shorted on the backside, and that the wiring to the heat pump is not damaged. If not, mount the base module to it's backplate and check for Y1 to C at the heat pump terminals. If yes, then the problem is with the base module.

Pretty much what I did. I disconnected y1 from the heat pump. No voltage at heat pump on y1. 18v on t-stat wire y1. So something, either in the base module (wireless receiver), or the t-stat itself is causing the 18v.

Nothing at all to do with the HP

 

[LD1]

Well, did some more troubleshooting. Seems things may be getting worse. And I am thinking this can all be traced back to a faulty transformer. The transformer is putting out 32vac at idle. With the unit running, it drops to a more reasonable 26v.

Here is what the T-stat looks like


With the base module popped off, this is what we look like


And here is the voltage reading on the Y1 terminal of the control board in the furnace


And here is the voltage of Y1 coming off the t-stat. The yellow wire goes ONLY to the t-stat and is hooked to nothing else


And here is the same reading, only with the base module pulled out as pictured in pic 2. This leaves all the wiring attached. So this confirms there is no shorted wires. There are no wires at all in the base module or t-stat that are separated. Only circuitry


Now here is why I think things seem to be getting worse. The whole issue started with the Bard DSH pump circulating my hot water......would continue to cycle. Its method of operation is simple. Its plugged into a 120v source. Gets a 24v and common from the heatpump to power its circuitry. And a third low voltage wire, spliced into Y1 off t-stat as per bards instructions. Anytime Y1 is energized, it circulates water through the DSH, and moniters temps. If more than 2 degrees, it keeps running. If no, it shuts off for 10 minutes and tries again.

So, it is ONLY supposed to run if Y1 is energized. It seems to think Y1 is always energized because it cycles on and off every 10 min, wasting energy, and cooling off my hot water. So hopefully everyone has a clear understanding of how this unit is supposed to work, and what its doing wrong.

Now the bad. I was informed that this furnace has an "A" terminal for accessories such as this. So I unspliced from Y1 and hooked this circulating pump direct to it. Since it isnt being falsely energized by the t-stat. Well, bad news, it continues to cycle every 10 min. And measuring voltage on the bard unit, where the t-stat wire is supposed to signal it, is now showing 18v. And its not coming from the A terminal at the furnace either. Simply with control voltage present at the bard unit, and NO signal wire even hooked to it, it cycles every 10 minutes.

Here is the bard. Furnace is running. Currently measuring 28v being supplied to the bard, and getting 15v on the t-stat terminal. Causing it to cycle even with the t-stat wire unhooked.


So I am thinking that maybe the 32v coming out of the transformer toasted something?? In both the bard and t-stat?

 

[techman]

BrokeFarmerJohn:

This might give you some idea: http://www.tractorbynet.com/forums/rural-living/74680-geothermal-heat-pump-project.html?highlight=

paul

 

[LD1]

Here was my thread on doing the ground loops and manifolds. http://www.tractorbynet.com/forums/...geothermal-plumbing.html?highlight=geothermal

Never did do any follow ups with the unit install. But its pretty straight forward. Set the unit in the basement. Got 3 things to plumb, manifolds, furnace, and flow center. Plumb them all together and some wiring and its done. I went a little above and beyond with the DSH and bard unit. Contracted all the duct work out.