I'm not sure I understand why you don't want to start the loop pump and the compressor at the same time. If you look at the wiring diagram I'm sure they show an optional pump package connected to the compressor contactor. This means the pump starts whenever the compressor starts. I know you have a little different setup but the factory clearly shows it is okay to start the pump and compressor at the same time.
So I would forget about the time delay and continue your work to have any of the 3 units start the pump.

funny

I saw that on the circuit diagram in the manual and wondered about that too. Econar makes a PumPak accessory that is a box that contains loop pumps and valves - that you can attach to the heat pump. They show it triggered off the same contactor as the one that starts the compressor - all driven off the M1 signal out of the controller.

The question is would that work with the large loop field that I have. It appears that the Econar solution is designed for the case when you have a loop field (or section of one) dedicated to each heat pump - so a smaller amount of fluid to move. In my case, all of the heat pumps share one field - all connected. It's a lot of fluid that has to be moved and the worry is that during the winter, if the compressor turns on and there was insufficient warm water in the line to cause gas in the compressor line to vaporize, would that damage the compressor, cause it to freeze up, or create a low or high pressure alarm (which would shut down the unit since these conditions are sensed by the controller).

I just don't know enough about the delay in the movement of the loop fluid from a dead start and how GT heat pumps work. I do know that the loop field consists of 12 loops made from 1 inch inside diamter plastic pipe, and each loop is 110 feet long but coiled, so the length of each loop is a lot longer than 110 feet. The pump is a 1.5 HP Gould and has a flow rate of 150 GPM at 3600 RPM.

see http://www.goulds.com/pdf/BRGLNPE.pdf for the spec sheet

I also believe the loop field has about 300 gallons of fluid in it.

The thought is that if you delay the compressor start for 1 minute, by that time there is enough fluid moving through the pipes to avoid any possibility of damage to the compressor. I like this idea since it seems safest and would like to make it work if possible. But if someone can provide me info to convince me otherwise, I would love to hear about it since that hook up is very easy to implement (just eliminate Relay 1 altogether.)

It seems like the Approach 1 wiring I described works as I wish: I can get the 1 minute delay (or longer if needed) on the compressor start while immediately starting the loop pump when there is a Y call from the Tstat - all without blowing the controller fuse as occured in Approach 2. The only issue with Approach 1 is the Aux Heat call is coming on after 30 seconds of a Y call, which is 30 seconds before the compressor starts - and I think that is probably workable. It might be as simple as the way I am testing the circuit, or perhaps I need to think about delaying the W2 call from the Tstat (if that is wher it comes from) making the W2 delay longer than the delay of the Y input. I could also leave it alone and let the Aux heat come on for 30 seconds until the heat pump compressor starts, but I am not fond of that approach.

Thanks

As soon as the pump gets power the impeller starts and water starts to move. It is typical for the pump to start when the compressor starts. I can not think of any situation where doing this will cause damage to the compressor.

One suggestion I got from a friend at work was to set the delay of Relay 1 to 25 seconds or so, which is within the time before the Aux Heat call comes on. That would be easy to do and I would at least have some water movement within 25 seconds after the loop pump started.

I also just downloaded the documentation of my Honeywell TH3210D thermostat and found that there are some functions that are programmable (the operator manual I have at home does not mention this). There is a function for the Aux Heat Cycle Rate - and they recommend in the manual to set this for electric furnaces to 9 CPH, which I presume is 9 cycles per hour. Note that for gas/oil heat with less than 90% efficiency, the manual recommends a setting of 5 CPH, while for oil/fas furnaces above 90% efficiency they recommend a setting of 3 CPH. The programmable range for this setting is 2,3,4,5,6,7,8,9,10,11,or 12 CPH. What does this setting do? Specifically, what does a setting of 9 CPH setting mean. Can it be used to increase the time before the Aux Heat call comes on fatre the call for heat comes on? If I wanted to increase the time before teh Aux Heat call comes on, would that mean a setting lower than 9 CPH in my case?

There are also adjustments for Emergcency Heat Cycle Rate (9 CPH recommended setting for electric heat) and a Compressor Cycle Rate (3 CPH recommended for most compressors). What do these parameters control? Can anyone help me here?

In theory these parameters control how long the on & off cycles are for the heat or cool call. For electric heat the number is higher because more or less as soon as you call for heat you get heat output. For a hot water system you would want a lower cph because it takes time for the boiler to fire, the hot water to circulate, etc. With a lower cph the tstat will let the room temperature droop a little and then let it run a little longer. With a high cph the tstat turns the heat on and off more frequently.
You can play with it to see if it makes a difference.
Are you sure you need aux heat? I often tell people to turn it off (at the unit or the breaker) and see if you need it. If on the coldest days you need it then turn it on because that's what it's there for. Often times the ground loop is adequate that it can take care of all the heating needs.

funny

I watched the tstats like a hawk last year to see if the Aux Heat was coming on because of an issue we had early on when the GT system was first fired up - when we were in what I called "Toaster Mode" quite a bit.

Once the issue was fixed, I kept checking to make sure Aux Heat was not on and very rarely did I see it on. However, there were a few occasions on really cold days when the Aux Heat would come on for a few minutes to give the Heat Pump a boost. I was told by the HVAC company that this was normal, and have read the same thing on other posts on this forum. I guess I could flip the breaker for the heat pack off - but I would prefer to not do this since there are times when the heat pump might need a boost - probably when I am sleeping and not able to flip the breaker on.

The CPH adjustment might explain why my 2nd floor heat pump was cycling more than my downstairs units. The second floor is zoned - and each of 3 bedrooms has it's own tstat. I am guessing that I need to adjust each of those tstats to a lower CPH to reduce the number of on/off cycles. I will play around with that - but this won't solve my Aux Heat On issue with the loop contoller relays.

Can you explain to me how the tstat actually decides to flip the Aux Heat On? I had heard that the tstat has a timer in it, and after a set number of seconds of Heat On, and if the temperture in the room does not rise, then the tstat will flip on Aux Heat. I have also heard that the tstat will turn on Aux Heat when the differential between room temp and temp setting is >4 degrees. Is this correct? I never understood how the tstat decides that Aux Heat is no longer needed - any ideas on that?

If the only ways that the tstat can engage Aux Heat on is with a timer or a differential tempertaure, then it is quite possible that I caused Aux Heat to come on while I was I testing my circuit by jacking up the temp setting on the tstat too high.

Do you know if there is some feedback to the tstat from the heat pump contoller telling the tstat that the heat is ON a feedback that would be used to cause Aux Heat to come on? If so - what wire would that be? Can the Heat pump contoller itself force Aux Heat On - or is this function only driven by the tstat?

If I knew the internal workings of the tstat for how it contolled Aux Heat On and Off, I know I could design around it.

Thanks

That is a good question. In older tstats aux heat would be used when the room temp dropped x° (often 2) below setpoint. With prog tstats that didn't work too good because aux heat would be used each time it came out of setback. Now the tstats are programmed to use time and temperature difference to determine when to call for aux heat. How exactly that fuzzy math works is a question I would like to know the answer to. The higher end honeywell tstats have a setup number to adjust less agressive and more aggressive. Since you have a basic honeywell model I don't think you have that option.
I would try to email honeywell and see if they have an answer.

With some heatpumps they have a fault circuit which when connected to the correct tstat will cause a LED to light on the tstat. This informs the homeowner they have a problem. This is the only feedback circuit possible from the unit to the tstat. I don't think you have this setup.

The only feedback I have is the L line which is used when the compressor is locked out. Other than that - there is no feedback from the contoller to the tstat.

I am going to test the Approach 1 configuration again - but this time I will observe it at night when the heat is coming on by itself instead of by me adjusting the tstat. Since the outside temp is still relatively mild, I would not expect Aux Heat to come on. Let's see if that works.

I tested the Approach 1 wiring again and had the same result. The delay of the Y input to the heat pump controller is still somehow causing the Aux Heat to come on (but I have the breaker for the heater pack off so no toaster mode). It has to be something in the tstat casuing this to occur, but I just can't figure out what it could be.

I did find a great explanation of the CPH settings for the tstat which I provided below. It looks like I could play with the Aux Heat Cycle rate - lowering the setting a bit - to see if that would clear up the problem. Currently the setting is at 9 (per the manual recommendation) so the tstat will allow a lot of Aux heat cycles per hour.

The good news is that the Approach 1 wiring is not blowing the protection fuses to the heat pump contoller and the timing is working just as I want. So this will be the wiring I use for the loop controller and I have some options for what to do with the Aux heat issue. Last resort will be to turn off the breaker and only allow Aux heat in emergencies or extreme cold.

CPH specifies the maximum number of times the system will run per hour. The system will not run more than the CPH no matter what the temp does. It may run less if temp doesn't drop below the set point. Left to little or no limit, a digital thermostat will attempt to maintain a setting with little variance from the set point. A drop of half a degree might trigger it to kick on. Most people don't notice a 2 degree drop let alone a half so this is too much and exactly what the CPH setting is designed to prevent.

Set the CPH as low as you can and still feel comfortable between cycles.

Changing the temp on the thermostat may override the CPH, or reset the CPH clock. The hour starts as of the moment the temp. is changed.

I don't think this is the problem but I think you should look at the L terminal wiring. In the econar manual it states:
A lockout condition is indicated by the L terminal, which lights a red light on the thermostat (depending on the thermostat). This lockout condition means that the unit has shut itself down on a low or high-pressure switch to protect itself, and will not come back on until power has been reset to the heat pump. If a lockout condition exists, the heat pump should not be reset more than once. A service technician should be called immediately.

I don't think your tstat has a fault indicator but I also think you don't want to hook a wire to the L terminal of the tstat. In the honeywell manual it says that L is energized continuously when switched to em heat. I am not familar with any unit that uses this function but it must be out there. So the L terminal on the unit is an output and the L terminal on the tstat is an output. So you do not want to connect the two.

This morning I caught the system just as it turned on (my ears are now trained to listen for the click of the tstat and the fan coming on.) This time, when the tstat started heat all by itself, the Aux Heat call did not come on. I have a feeling that anytime I try to force the heat on myself, the tstat is seeing a large enough delta between set and actual temp that it is kicking AH on. I will have to watch the operations over the next few days to see if it consistently works without AH. In the mean time, the breaker to the heater pack is off to avoid the toaster.

I have decided to send an email to Honeywell tech support on the CPH setting for my tstat. Now that I understand what the CPH setting does, I need to know how the logic is implemented. For example, my tstat setting for Compressor Cycle Rate is set to 3. Does the tstat bleed these 3 cycles per hour (max) uniformly over an hour of time - or does it simply allow 3 on/off cycles in rapid succession, and then no more for the rest of the hour. If the allocation is uniform across an hour, then the Aux heat setting (which is currently 9 CPH) could be adjusted lower to keep Aux Heat from popping on so quickly - like when I increase the tstat setting by 2 degrees. Again - if it is a uniform distrubution of on/off cycles the tstat would permit Aux Heat to come on every 3 minutes with a 9 CPH setting and that is too frequent. So the CPH adjustment may in fact be part of the solution.

I have also discovered a nagging issue with my second story heat pump. That unit is actually zoned - where 3 bedrooms each have their own tstat. My guess is that the CPH setting for each tstat is set to the recommended default (3 CPH) which means that there are actually a total of 9 CPH allowed (3 for each tstat). That explains why that unit kept cycling so frequnectly on me last winter. I believe that a CPH reduction is probably warranted in each of those tstats and that would reduce the number of total HVAC cycles upstairs. The downside is that some rooms way have a wider tempertaure swing and then a longer run to get up to the set temp. But I would rather have a reduction in cycles as long as the swings are not too big (which could cause Aux Heat to pop on). Imagine Room 1 calling for heat and getting serviced - then shutting off. Then a few minutes later, Room 2 does the same thing, then Room 3. If I stretch out the ON/OFF times in all rooms, I will increase the probability that heat calls will overlap.

I will check on the L line. I believe that my tstat does not use L becasue I get no alarm lights when the compressor locks out - and I would like to have that. There have been cases where the compressor has locked out and the only way I knew it is when it got very cold in the room and I opened up the heat pump cover to see the red light on the contoller.

I configured all 3 of my heat pumps with the Appoach 1 wiring and have been observing the heat on/off cycles, with the 1 minute delay from the time the tstat calls for Heat (Y line high) to the time the compressors kick on.

So far there have been No Aux Heat calls on any of the tstats with the 1 minute delay of Y into the heat pump contoller. This confirms that I was causing the issue by touching the tstat Set To temp to get the heat to come on during testing.

I still have the Geothermal loop pump running continuously with a jumper on the dry contact RIB relay that provides power to the pump. This week I will be cutting over so that the loop pump will be activated by any of the Relay 2 inputs and that should be the end of this project.

I hope to see a significant reduction in my electric bills with this pump activation circuit. Thanks to all for the help.

Regarding the zone system, you are missing one component. The 3 tstats should tie into a control panel which then ties into the unit. this control panel has logic to determine what the unit does. I don't know what brand you have but I doubt it has a cph setting. It may have a min on and min off timer. You would have to look into how the zone panel operates to figure our why it short cycles.

funny

Thanks - that is a good point. I do have such a box that takes all 3 tstat cables in and has 1 set of control cables out. I have no idea what brand it is but I am going to look into that as soon as I get time.

In the mean time, I figured out that by setting the tstats upstairs back a few degrees (in heat mode: 62 deg vs the normal 65 deg setting downstairs), the 2nd floor heat pump almost never turns on - even prior to adjusting the CPH settings. Since nobody lives up there (except when we have guests), that has worked at solving the short cycling problem - for now. It may pop up again when we get to much colder temps, so knowing what the zone contoller is doing is key to getting the adjustments just right.

I fired up my loop control circuit last night and the loop field pump is now driven off the demand for heat. It seems to be working exactly as planned with no aux heat calls coming on.

I ran a test last night with a change to the CPH settings for both heat pumps servicing the main level. I first recorded the ON and OFF cycles with the Compressor CPH setting at 3 (the Honeywelll manual recommended setting for heat pumps). I then changed both tstats to a CPH of 2 and recored the results. Last night's outdoor temp when I started the test was about 35 and this morning it was 27.

With a setting of CPH =3, the main heat pump cycled on and off 3 times per hour with an average ON time of about 10 minutes. The cycles were evenly spread across the hour. The temperature that I measured with a standalone hydrometer/thermometer that was within inches of the wall tstat stayed between 65.2 and 65.8 degrees. The tstat was set at 65, and the displayed temp never moved off 65. Outside air temp was about 35. No Aux Heat calls from the tstat.

With a CPH setting = 2, the main heat pump cycled on and off 2 times per hour with an average on time of about 15 minutes. Again - cycles were spread evenly across the hour. The measured tempertaure varied from 64.2 to 67.8. The tstat was set at 65, and still did not move off 65 (what is happening here?). Outside air temp was about 27. No Aux Heat calls from the tstat.

So it looks like the CPH works just as funny described. I now wonder what CPH setting is better? Is one less cycle per hour worth the larger variance in temp range? Should I consider setting the CPH to 1? I am concerned that if I use a CPH of 1, the variance will get too big for a geothermal heat pump and I may see the dreaded Aux Heat.

Why did the tstat displayed temp not change when I was measuring a wider range during the CPH 2 testing? I found that very odd.

I would stay with the 3 cph. Honeywell tstats always match the room temperature and the setpoint until you are several degrees off. I'm a little surprised that with a 67.8 actual temp that the tstat still displayed 65 but not shocked. I guess they want people to think the tstat is working really well.

funny

Thanks - I will set it back tonight. I am impressed at how well the Honeywell tstat worked with the recommended settings in the manual. When I have it set to CPH=3, you can't notice any difference when moving from room to room, and there is very little variability that I measure from room to room. The tstat always maintains the room at the Set To temp to within 1 deg, and that is what I measure within a good portable thermometer located right next to the tstat.

When I set the CPH=2, I could feel the difference in the room temperature as I walked around and the variability I measured in the rooms was larger. If I was saving more than 1 cycle per hour I might be inclined to leave it at 2. But for only 1 cycle per hour , it doesn't seem worth it.

Thanks for the help.