A review of the posts seems to strongly indicate that having a system run most of the time in 1st stage is advantageous, how so?

It seems to me that running a long time in 1st stage should be similarly efficient as running less time in 2nd stage?  Where is my thinking wrong?

Thanks

jambsi,

1st stage operates at a higher efficiency. The cost of adding (heating) or removing (cooling) heat per BTU is less in terms of the amount of electricity used. In other words the decrease in running time in 2nd stage is less than proportional to the increased energy use.

From a system dynamics point of view, I am not so clear about the impact of various run times and GPMs (if variable) on the performance of a horizontal ground loop, and the long-term effects on EWT.

Regards, Masoud

Should also add:
Longer run times may result in longer equipment life and a better desuperheater hot water output. Fewer compressor on cycles saves energy.

Regards, Masoud

How would you characterize the efficiency advantage of staying in 1st stage vs going to 2nd stage for the same heat gain?  Is it 10% more efficient, 50% more efficient?

If the hardware makes a difference in your answer I'm talking Climatemaster 049 4 ton with EWT of 31F (its a river loop)

Thanks

Tranquility 27 049 in heating is rated as: 1st stage cop = 4.6 and 2nd stage cop = 4 @ EWT = 32 degrees F. It indicates 1st stage is 15% more efficient than the 2nd stage.
Coefficient of performance for heating is the energy output (BTU's) divided by energy input (BTU's). 1 KWH= 3413 BTU's.

Regards, Masoud

long 1st stage operation vs shorter bursts of 2nd stage increase comfort by both distributing heat more evenly and reducing blower noise.

On my own personal system ComfortAire 049. I have broken my Y2 stage with an normally open, adjustable outdoor temp sensor set at 20 degrees f. In other words second stage can only come on if tstat calls for stage 2 and the temp is below 20. Allows me to stay in stage one and use programmable tsat to drop temp during the day when at work and bedtime without stage 2 coming on from the large temp difference between set and room.

That sounds like a great idea, a similar (same?) control exists on my system for the aux resistance heat.  Is this something a homeowner could do?

Could you post the part number of the normally open temp sensor?

Please consult with installing contractor before altering system operation. Capacity of loops is finite and designs are often tight for more economic installation. Sabotaging designed in 2nd and 3rd stage heat cycles may decrease satisfaction not enhance performance.
Good luck,
Joe

So are you saying Geothermalman's idea is self-sabotage?  With all due respect the wording sounds like one of those cover-you-ass statements made so often by manufacturers?  I'd really find it useful if you could elaborate on what the risk is?  Why is it better for 2nd stage to kick in after x minutes, vs only if outside temp warrants it?

Thanks

Joe is correct. I should have stated that I have an open loop system w/ a constant supply of 55 degree f. ground water. If staying in stage 1 cannot keep up w/ your homes heat load or your personal comfort than second stage heat pump or third stage aux heat may be needed.

Perhaps "altering" would have been a better choice of words than "sabotage", however my point is the same. As I do not know how the system is designed, I can't encourage you to change the installer's set-up.
To answer your question about consequence, leaving unit in stage one when 2 is called for could cause short comings in desired temp. Decideding much later that it is insufficient and creating a larger than designed demand on ground loops could take heat from the ground faster than it can migrate back to the loops. Compound that by not turning on a designed in aux. coil until much later than required could cause low ground temps and low btu outputs that take some time to recover. As G-man points out, open loop systems do not suffer the same slow recovery (the heat moves as fast as the water vs slow as dirt).
I have customer's ask me about these things (many of whom visit this site) and we simply discuss the possible consequences. The more interesting question though is can you turn off the aux coil (which takes way more to operate than stage 2). I've had two customers this week who didn't reach desired setting. In both cases the electrician had left the breakers off for the aux. coil. Both homes were still in the 60's so if they are okay with that the can leave the coil off with the understanding that prolonged sub-zero weather with out the aux. coil will slowly reduce the geo btu's available.
Good Luck,
Joe

Beg to differ

The Btu requirment for the home in a hour lets say is the same if acheived though 50 min of stage 1 or 30 min of stage 1 and 2
the ground will have to recover the same heat and will do so at the same rate
Use of Out door temp sensors to controll staging ( if set up correctly using estimated balance points of each stage ) is the most eff way to operate a system
Would you say on a 50 degree day a cust goes to work for 8 hours , lowers the temp 5 degrees comes home turns it up 5 degrees and aux heat comes on is a comfort issue , a design issue , or a lazy installer issue?

Respectfully GF,
Your scenario is all true if you acheive desired temp. without continuous operation. However if system loses ground while running continuously then you could exceed the capacity of ground loop or earth to transfer heat quickly enough to catch up........depending on design and job conditions.
I wouldn't recommend a 5 degree set back nor expect a unit not to employ 2nd or 3rd stage to get there.
I do not disagree that there is room to tweek performance. But while we argue btu capacities of a ground loop the broad point of consulting with your installer before changing the system set-up isn't such a bad idea.
J

Agreed about the installer and 2nd stage in my opinion should by timer controlled , aux is my real sticking point because a system with excessive use of aux will give you high electric bills which gives geo a bad name , On set backs The adage dont do them with geo should be modified ( if aux is controlled by either number of zones plus out door temp , or out door temp plus time delay ) to dont set back to 50 degrees when its below 30 , because of the time it will take to recover , when cust compare costs of old systems to geo the fact that they have maintained 70 24/7 often escapes them or they think its actually more eff . because the installer warned them about adjusting the temp and triggering an upstage . they dont get a fair comparison

It would be interesting for one of our friends with a WEL to monitor unit with 5 degree set-back/recovery.
J

I set ours back every night. What would you like to know?

Now the temperature here in NJ is in the teens, our auxilliary heat is kicking in more often (10 min. off aux. then 2 min. auxilliary heat on). We have 2 zone. Upstairs thermostat's auxilliary heat doesn't kick in at all. We have single stage compressor. Is this normal? We have 3 ton.

conniepangan ~ mine is running like yours and I have a 3 ton. But mine is 2 stage. Also, in the design specs (before we bought the system from our hvac guy) told us that when it got below 30 Aux would start to be used and the geo system would run 100% of the time.