2 Stage Bryant HP ?

[behrend]

Hi all, this is my first post here. We built a new home and choose a Bryant 2 Stage HP (ANA286) with a Steffes ETS. After the contractor got the bugs worked out this summer, the cooling worked very well. However, in the winter I notice the following problem: The majority of the time, the HP runs on the low stage which produces very little heat when temps are dropping (20-30F). Once the temp sensor in the ETS sees this decrease in temperature, the ETS begins supplying heat to make up for it. The ETS seems to charge about the same amount wheather the HP is running or not. I am using about 4,500 - 5kWH during months where the average high is about 40F and low of 20F. However, if I crank up the thermostat a degree or 2, then the HP makes all kind of heat. I currently have a Honeywell thermostat that does not appear to let me force the HP into the 2nd stage. The current draw seems minimal between the high and low stage (5.5A to ~8A) so it would seem like the thing to do would be to force it into the high stage all the time when heating? I am fairly green at this and know just enough to be dangerous. Thanks for your opinions.

[Evolutionizer]

The 286ANA is the next down from top of the line in heat pump models. It is Evolution control compatable which is the interface (thermostat) of the system.
I would talk to your contractor about it. I think you will be very satisfied with upgrading to it. Its easy to use and with a few peramitter settings your contractor sets you shouldn't have the low and high stage issues. Go to
http://www.bryant.com/interactive/evolution.shtmland check it out.
Which air handler do you have?
Is it variable speed?

[tigerdunes]

behrend

Purchasing an Evolution Bryant 2 stg heat pump without the Evolution controller is a big mistake. This may be at the heart of your problem.

IMO

[nubbin]

When you bump up the temperate setting, are the strip heaters coming on? This will increase the heating rate and raise the electric usage.
If you have a Infinity type control, the contractor may have not set the outdoor temp level that causes the heat pump to switch to high speed.
It has taken us a while to convert the classes into field experience. Computer Controls!!!! argh!

[mwjhvac]

The bryant evolution control will not work with steffes. What model do you have. These units are very complex in setup. Was the unit ordered correctly to match the 2 stage hp with a ecm motor. If you are concerned if the installer is qualified or not go-to www.heatforlessnow.com or www.steffes.com only reason I ask is that the power co's were giving these to there customers and just anybody would in stall them. My profile has my Email if you need help finding a local steffes dealer.

[behrend]

Thats for the input, just for clarification the unit in question is not a strip heater, it is a Steffes 3120 electric thermal storage unit. The thermostat we are using is a honeywell 3H/2C programmable unit. I have attempted to change the settings on the Steffes to lower the charge rate however am still burning upwards of 200kWH on a colder day (10-20F) to heat a 2000ft^2 house with R-19 walls and R-38 ceilings. I do not see much of a difference in energy consumption with the heatpump on or off.

MWJHVAC - It sounds as if you are familiar with the Steffes. Yes, the unit has the ECM controlled blower and that part seems to work correctly. The blower drops to low speed when the HP is running in low and kicks up to high when the blower is running on high. The thermostat very rearly goes into AUX mode but if I understand the steffes correctly, it automatically started mixing stored heat when the outlet temp drops below the setting (90F in this case). Like I mentioned, the cooling works fabulous and I think the heating would work well also if I could get it to perform on high stage.

Thanks again as I have been mucking with this for almost a year now.

[mwjhvac]

I am very familiar with the steffes. I are you asking how to force 2nd stage and never have 1st stage?

[skippedover]

I'm no expert on the Steffes but it sounds like the 2-stage HP is not the cat's meow in this case. Normal 2-stage operation is for the t-stat to sense a need for heat and trip on 1st stage HP. When the 1st stage can no longer keep the thermostat satisfied (the temp begins to drop) then 2nd stage is called on. The problem in this situation is that the Steffes control is programmed to intercept the inability of the HP to satisfy on 1st stage the to supplement the HP 1st stage heating because the LAT from the HP indoor coil is less than 90. So with the added heat from the ETS, the stat never gets to drop enough to trip 2nd stage. Obvisouly the Evolution/Infinity control can't be used because it needs an Evolutution air handler to communicate with and with the Steffes unit, you don't have that option. Again, I don't know the Steffes but it seems that a control/relay or something is needed to keep the ETS from supplying heat until the HP has exhausted both 1st & 2nd stage. In other words, the ETC should be a 3rd stage of heat when the HP can no longer supply 90-degree LAT off the indoor coil on 2nd stage. I don't know what that control is but that's the order things need to happen in to make it work properly.

[mwjhvac]

There is a config setting (C010 Minimum Discharge Air Temperature - Sets the minimum discharge air temperature the system targets during a Stage 1 heat call.} You will have to do this in the conig settings.

[behrend]

Skippedover, I completely agree with what you are saying. I sent an email to the HVAC guy with more or less the same thoughts. Is what concerns me, is that we were the first 2 stage HP they mated with the Steffes. I have not contacted Steffes yet, but perhaps they have some insite on this as well.

MWJHVAC, the C010 CONF is set to 90F. That is what the electric company recommended as their default setting. Also, they recommended a charge factor of 20 instead of the factory default 30. This brings me to another question. The C006 is set to 34 for the 3100 series. Shouldn't this be set to the 130 (2+128) since this is used with a hp with reverser valve? I have left it at 34 for now.

[mwjhvac]

Okay I talked to steffes today tech said to go a head and start dropping config C010 5 degrees at a time and see if 2 stage will go. C006 should stay at 34 this is set by the electric co. The only draw back to dropping the dat settling will be comfort. It may or may not trigger second stage depending on run time and temp drop. Is your rate for storage different than you daily rate. For example in Minnesota we get 3.4 cents kw storage and 3.9 cents kw dual fuel. The reason I ask is if your hp satisfies the t-stat with out ever hitting 2 nd stage and using some of core temp and then recharging at a different rate this would be alright. But the 2nd stage would be more used in cooling. Thanks for bringing this to my attention I want to keep this thought for future suggestions when selling this system. Good luck with this.

[behrend]

MWJHVAC, Thanks for the proactive help. I will try the C010 modification tonight. I'll drop it to 85 and see what happens. Also, with our electric company, they supply in bucket rates. 0-1000kWH is ~10 cents, 1001-4000kWH is about 6.3 cents, 4001+ kHW is~10 cents. I also fired an email to Steffes, I was hoping they had some firmware updates that may help with this. Have you sold a 2 stage HP or just a single stage with these units? So far, the HVAC installer has not called me back about this. Again, thank you so much for all of your help and I will post what the results are with the C010 change.

[mwjhvac]

I have only sold single stage hp. But this brings up a good point about 2 stage other than cooling it really would not be needed. I am a Carrier dealer so I sell the exact same heat pump with gas heat. I will be doing some research to see if it is worth it, because in Minnesota we use a/c maybe 3 months a year. From what I learned in this case here it would not be the right hp. So my research continues.

[behrend]

Here is NW Pennsylvania, many people don't even have A/C because it is fairly cool in the summers here. I am regretting now the extra expense of the 2 stage at this point. From what I calculated in energy, there is a negligable difference in the summer for having the 2nd stage. Anyhow, I lower C010 to 85 last night but haven't been home to see how it is doing. I'll keep you updated. Also, I sent an email to Steffes a few days back and haven't heard anything. Do you have a tech contact email that I could bounce some thoughts off of in the future? Thanks again.

[behrend]

So I have been experimenting with the C010 settings. At 85, I did not see a big change in the amount of Steffes modulation. At 80, I did see a significant decrease in daily energy consumption, the HP is running on the high stage quite a bit. As anticipated, the house now feels 'drafty' with 80F air exiting the registers. I sent an email to Steffes tech support but have not heard back. It would seem the Steffes unit could make some of these decisions and override the thermostat for the high/low stage calls? As of right now, my daily kWH consumption is down from about 150-180kWH/day to about 90-100kWH per day. This is good news for now.