Charging $6.43 for a "customer" charge takes a lot of guts considering you get your bills electronically. Sounds like they have found a way to skirt what I assume is regulated charges. I'd complain to them and whoever they file rate increases with.

jpespisa

 FLOW RATES

The diagram above is for a 6 ton SCW system. It would flow 8gpm in 1st stage. In 2nd stage both valves will be on and it would flow 8+4=12 gpm. These are safe numbers for 46*F to 53*F EWT's. The bleed should not let temps below that.

Thanks for the suggestions. I'm going to implement these one at time and see how the system reacts. I'm going to hold off for a couple of days as the temperature is going to drop down into teens over the next few nights. Don’t want too many variables to deal with.

- Try reducing CPH to 2
- Try reducing gpm to 8
- Check differential setting for Honeywell thermostat

Very smart to not change too many things at one time. A person would be guessing as to which changes helped and which ones did not.

If you can't find a differential, try the Less Aggressive setting if you want. Please keep us updated. 

Geome,

Just checked both, the user and installation thermostat manuals. I don't see any option for setting the differential or aggressive mode. I was wrong on the default CPH, it is set to 3 which explains why I never observed the HP cycling more then 3 times an hour. BTW the thermostat I'm using is the Honeywell VisionPRO TH8320U.

A quick web search showed Visionpro does not have adjustable temp differential.

Regards,

Masoud

jpespisa,

I'm looking at the VisionPRO 8000 manual that includes the TH8320. Check to see if you have installer setup number 680. That's the setting for "Temperature Control in Heat" where you can (if you have this setting) set it to Less Aggressive. It's on page number 19 of the manual that I downloaded earlier this year.

I just looked it up on the Honeywell web site at:
http://customer.honeywell.com/Honeywell/ProductInfo.aspx/TH8320U1008
It looks like the "U" is some sort of packaging option.
It does list: "Differential Temperature (F) ± 1 F"
Whether this is the setting that I am referring to above, or something to do with thermostat accuracy, or something else, I don't know. I do know that this setting delayed 2nd stage engagement for us.  It may be a several days before I get back online to follow up on your post. Good luck!

Thanks geome, the manual on the Honeywells WEB page has much more detail then the one that came with the thermostat. I do have setup number 680. This gives one other option to try.

You're welcome. Hope you like it. I actually use the 8000 manual as a reference to explain in more detail some of the features on my Prestige. The Prestige manual doesn't explain nearly as much about inner thermostat workings of a Honeywell as the 8000 manual does. I know there may be differences between models with similarly titled settings, but I just keep that in mind. Let us know how you make out!

I thought I would provide an update on my observations over the last two days. As I mentioned previously in the thread, I’m holding making any changes until the cold spell passes.

 

The low temp over the last couple of days was 19.6*F. The HP seems to have performed well. I don’t set back the thermostats and maintain the house at a constant temp 68*F. Even with the low outdoor temps the HP never entered the second stage which I think is good sign as it will get colder in the coming months.

 

The cycle time increased to ~20 minutes from the previous 10-12 minute cycles. This greatly improved my HWG performance. EWT to the HP from HWH was over 100*F.

 

This only issue of concern was the drop in the HP EWT from the well. It dropped as low as 43.5*F. I didn’t observe any noticeable performance issues with the HP at the lower EWT. The well temp has recovered partially as its back up to 45*F. I’m wondering if I should increase the bleed rate to help prevent the EWT from dropping so low. I’m currently bleeding at 1.5gpm. Before the cold spell the 1.5gpm was working and maintained the well temp above 46*F. But it looks like I need to increase the rate as the colder weather approaches. Any recommendations on the bleed rate? I guess I can keep bumping it up until I find the rate that works with the coldest outside air temps.

 

This is my first full winter season with the HP so I’m monitoring the system closely. I’m expecting I will need to tweak the system for optimal performance.

Geome,

Today I tested the ‘Temperature control in heat” (680) on my Honeywell thermostat. In the default mode (setting 2), when I raise the thermostat 1 degree the HP starts in stage 1 and after two minutes enters stage 2. That seems way to short. Would like to know why Honeywell only runs stage 1 for two minutes before entering stage 2.

When I changed the setting to 1, the less aggressive mode, the HP never entered stage 2. The cycle time was still short and the HP had no problem raising the room temperature 1 degree. Unfortunately I don’t know how long stage 1 will run in this mode. Would be nice if it was documented somewhere. I think this setting is a keeper. I’ve changed both thermostats to setting 1.

I’ll change the cycle time next. I’m not sure how much benefit I’m going to get from this setting. It’s starting to look like I’m only going to observe longer cycle times when the outside air temp is less the 25*F. Now that we are back in the 30’s my cycle time is back to the 10-12 minutes. At these temps the HP just doesn’t need to work as hard to maintain the temperature.

I haven’t decreased gpm rate yet. Probably give the 8gpm a try in the next few days. I did bump up the bleed rate to 2gpm. Hopefully the will help prevent the well temp from dropping so low.

With any of these settings it is difficult to tell exactly at what temperature differential the thermostat is engaging different stages because the thermostat doesn't provide tenths of a degree display. However, your results are the same as mine with the Less Aggressive (or "1") setting in that second stage doesn't seem to be running as much compared to the normal "2" setting.

Our geothermal units run in 1st stage for 1 minute before second stage engages, so the 2 minute switch over to 2nd stage that you are experiencing may be a function of your geothermal system and not the thermostat.

According to Honeywell, for VisionPRO TH8000 thermostats, 1st stage will run until it gets to 90% capacity, then 2nd stage will engage. If someone can explain what running at "90% capacity" means, please let me know. I don't understand how this is calculated.

I agree that setting fewer cycle times will make more of a difference at more extreme outdoor temperatures since that's when the system will run more. It will also be affected by how tight the house is, insulation value, etc. I like the longer run times.

I have no clue on flow rates since my system is closed loop and I don't monitor it.

geome

I changed the CPH setting to 2 yesterday. So far I like the results. I didn't expect a benefit with moderate outside temps so I’m pleasantly surprised. My run time has increased about 5-6 minutes per cycle. This improved my HWG substantially. No complaints yet from the family regarding the temp swings.

It looks like at one point last night the second stage kicked in. It only occurred once and only after the HP was running for ~20 minutes. So 20 minutes might be the length of time the HP will run in stage one before switching to stage 2 two with the current thermostats settings.

These where great suggestions BTW. Very happy with the results to date.

I’ll reduce gpm in the near future.

Glad you like the settings.

* Generally speaking, and assuming everything is equal, in 1 hour:
If 1 CPH (cycle per hour) is 30 minutes on and 30 minutes off, then
2 CPH would be 15 on, 15 off, 15 on, 15 off, and
3 CPH would be 10 on, 10 off, 10 on, 10 off, 10 on, 10 off, and
4 CPH would be 7.5 on, 7.5 off, 7.5 on, 7.5 off, 7.5 on, 7.5 off, 7.5 on, 7.5 off.

Note: run times will be a longer than I listed above with greater CPH due to more on/off cycles being less efficient than fewer on/off cycles.

The above is just an illustration of how CPH works. Actually, when the thermostat turns on, the unit will remain on until the thermostat is satisfied. If there are the same or fewer thermostat calls than the CPH setting, no problem. If there are more thermostat calls than the CPH setting, the thermostat needs to wait until the hour is up. Then the system would just run longer for the first "on" time the next hour to make up the temperature difference.

Not sure on this, but I think if you change the CPH settings, the CPH counter will reset, so you can have more CPH than the thermostat is set for in that particular hour. I also believe changing the thermostat temperature may reset the CPH too since homeowners would be upset if they increased the temperature and nothing happened because the CPH was used up for that hour. 

* Maybe the 90% capacity is calculated using the 1st stage run time (like your 20 minutes run time) compared to anticipated run time for the selected CPH setting (based on something similar to what I have above perhaps).

What a useful thread, folks.  Thank you very much! 

My GSHPs (with SCWs) seem to cycle quite a bit.  In a year, I have never gotten any meaningful hot water.  About the best I have ever gotten is 90F.  Most of the time I see 68F (which is better than nothing, but far less than I was expecting).  With 68F water, I was starting to wonder how much of the temp increase was due to absorbing heat from the conditioned basement (water comes in at ~50). 

I also have Honeywell 8000 series thermostats.  I changed the CPH to 1 (from 3) to see what happens.  My house is superinsulated, so I can't imagine the temperature falling too much in 30 minutes.  I have high hopes the desuperheaters will be more useful than I have experienced to date.  If this works, I will shout it from the rooftops. 

I am also betting my water flow rates are way high.  While the pumps are variable speed, water through the GSHPs is either on or off.  Unfortunately, I do not have a good (and inexpensive) way to determine the flow rates.

Thanks again,
Ed
Mr Green Dreams
www.GouinGreen.com  

Let us know how this works for you Ed.

Just thinking some more about this. For people with 2 stage compressors, if the inside temperature drops too much between cycles (due to less CPH), then 2nd stage might engage resulting in a shorter 2nd stage run time compared to 1st stage.

There should be more of a temperature difference with 2nd stage hot water production, but if it doesn't run long enough it may not help. If 2nd stage engages due to CPH reduction, a person can experiment with different CPH to find out what works best for them. They could also experiment with delaying 2nd stage engagement by various methods. Consult your installer to make sure changes are ok with them.

In general, for fewer CPH there should be some benefit to domestic hot water production, running efficiency, and better dehumidification in AC mode. Every house is different and results will vary I'm sure. I really like not hearing our system go on and off as much (I changed our CPH from 3 to 2) and I would think that less wear and tear on the system due to less cycles would be good in general. But, I am not a pro and know nothing about open loop, zoned systems, radiant, etc. So check with your installer to make sure they think these changes are ok given your particular situation.

Our settings are now 2,2,1 for 1st stage, 2nd stage, and aux. I may experiment with 2,1,1 later this winter.

Ed,
I too have a variable speed (constant pressure) well pump and open loop system.

I measure flow with a 1" diamter variable area flow meter from dwyer... it was about $100 and I installed it right above the expansion tank and well mainfold in the main supply line. I have two TACO EBV valves in parallel (one for each stage) and a manual ball valve on each parallel for flow control. To adjust flow you manually open the TACO valve and adjust your branch ball valve as needed. This has worked great so far.

For a low budget method of flow control...depending on how you discharge the water, you might be able to direct the discharge water temporarily into a bucket and measure the time it takes to fill up to a known quantity. To get accuracy you'd want to do it several times and use a larger bucket ! This would be pretty tough to do on a two stage unit. Because after any change you make, you have to again check both stage flows to ensure they are sufficient.

My day job is commercial HVAC, we reguarly sell "water regulating valves" that automatically modulate to minimize water flow on larger commercial chillers and heat pumps, but ClimateMaster and I think others are dead set against them on residential units as they tap into the refrigerant circuit and if they go bad the unit could experience high head. pressure. ..

I did some extensive low cost "meter count" testing to get a pump curve that shows flow rate through my unit vs. power consumption in kW. I found that my pump takes more energy than I thought, and I promptly reduced my flows to 1.5 gpm per ton to help maximize my "total system" energy efficiency.

For my 3 ton unit on 2nd stage @ 4.5 gpm (min recommended for 50 deg or above water).... my well pump takes 900 watts. Does anyone know what a typicall 3 closed loop system pump draws for power ??

Jokin,

I like your idea of using ball valves instead of flow regulators. I was concerned about committing to a fixed flow rate for each stage. The only issue I have with ball valves is the noise. I am adding backpressure with another ball valve further down the line which significantly reduces the noise but it’s not as quiet as the flow regulator. How do you manage the noise generated by the ball valves?

One other question; I just reduced my stage one flow rate to 10gpm. This puts me below the 2gpm rate recommendation for EWT under 50*F. I don’t think I’m going to see 50*F well temperatures until the spring. What’s the risk of running the HP at less then 2gpm with well temperatures between 44 and 47*F? And should I take that risk?

So I went back and looked at the manual for my units (Climate Master Tranquility 27 - 038). The performance chart provides data for flows from 4.5 to 9.0 GPM at different EWT. I am fairly certain that well pump energy usage is NOT factored into their data (although closed loop circulators might be). Now if I only had two 1" flow meters and some current monitoring equipment, I could find that performance sweet spot.

Ed