I know it sounds weird. Even on the hottest days, my geomax 2 (4 vertical loops) is grossly oversized.....it runs 50% of the day on stage 1 even on the hottest days. I have to keep the thermos at 74 otherwise it runs even less and then the house feels humid. I,d be happy with 76 or 77, but the system won,t run long enough to dry the air. Is there any way to "reduce" anything in order to force longer run times at the higher temp?

Fewer cycles per hour will result in longer run times at the expense of greater temperature swings.

Water Furnace Envision has a switch to lower the cooling mode fan speed 10% (maybe it's 15% - I'd have to look it up) for better dehumidification, if desired. Not sure if you can (or should) manually accomplish this on your system.

Hope everything else is good with you!

As Geome suggests, I believe there is a way to reduce fan speed. You should run the numbers on down sizing. It's DIY kind of work and tax credits still apply.

Thanks joe and geome.
I don't want to downsize the system because it's well sized for heating....possibly slightly undersized.
I'll look into reducing the fan speed with the dip switches....maybe a more gentle continuous flow of dry air..
CPh is set to 3 for both stage 1 and stage 2
Edit: just checked...I'm on the lowest fan speed now....800 cfm. My dats is 46 when the system runs (eat is 73) any slower and my coil will ice up!

Your 3/3 (1st/2nd stage) CPH settings sound typical. We didn't care for our system frequently turning on and off, so we reduced our CPH to 1/1. I've observed that 1/1 still allows 2 CPH in first stage with our Honeywell thermostats. We barely notice the temperature swing, but we'd rather have that than have more cycles. With reduced CPH we noticed better dehumidification due to longer run times. Of course, there are setting between 3/3 and 1/1. It's worth trying some different combinations.

I assume your fan is set to Auto and not Circulate or On.

Posted By decafdrinker on 09 Jul 2014 10:11 AM
Edit: just checked...I'm on the lowest fan speed now....800 cfm. My dats is 46 when the system runs (eat is 73) any slower and my coil will ice up!

How many DIP switches for fan CFM do you have?  The reason I ask is because in our Envision system, the lowest fan cfm dip switch (of three) is for fan only with no compressor (and fan startup and shutdown before the compressor starts and stops.)  For us, it's the middle dip switch (of three) that is for 1st stage.  800 CFM sounds right for 1st stage, but though it best to confirm that your 800 CFM switch is indeed for 1st stage.

"I don't want to downsize the system because it's well sized for heating....possibly slightly undersized."

It's clear your system is grossly oversized which means it probably costs more for heating than a right sized unit. What was the load on your house and where are you located?

Thanks Joe. I'm not sure anymore of the heat load. I'm located in Pa, just north of Philly. The original house was a Cape Cod 1 1/2 story. Two different companies gave me estimates. One said 3.5 ton, one said 4. The 4 ton guy gave me a heat and cool load sheet that indicates heat loss of 38,000. But since then, a new full second story was constructed, adding about 300 sq feet total, but higher ceilings (full 8 ft instead of 6.5 ft).

Most winters, according to my WEL, Stage 1 heat 50% of the time, Stage 2 kicks in on top of that 40-50%, and stage 3 aux is required a few percent (WEL0487, 3rd graph down).
Most summers, though, Stage 1 cooling is on between 20 and 50% of the time, Stage 2 rarely kicks in.

My heating is set to 70 in winter, and 76 in summer. No setbacks. I went with the 4 ton geo.

Ok. Definately oversized. Not as bad as I imagined. I presume your weather is similar to ours. Which is only demanding in short spurts particularly with a set point as high as yours. You will have to dial down or dehumidify with a different appliance.

Thanks. Changing the CPh to 2'seems to have helped a bit....unless it's my imagination. I don't want a lower set point coz it gets really cold.

I'm grossly oversized  at 8 tons of cooling for 3400 sf of single story residential structure in hot Dallas climate.  Two WaterFurnace units, 5 and 3 ton, 2 stage, variable speed, no heat coils, common borehole field, with WEL monitor (at http://www.welserver.com/WEL0043/ ).

Inside RH runs between 40 - 43% during the Summer.  See WEL chart: http://www.welserver.com/perl/plot/WEL0043/Humidity.png .  This is accomplished by:

1. Running tstats (Ecobee) with widest possible control bands (results in fewest cycles per hour and longest average run time per cycle).

2. Setting WF ECM2 blower fans at lowest possible speeds, while keeping Leaving Air Temp no colder than 47 degrees (have WEL monitor set to notify me if LAT gets colder).  See WEL chart:
http://www.welserver.com/perl/plot/...rTemps.png .

3. Setting WF DIP switch setting for 10% slower fan speeds for dehumidification emphasis.

We're satisfied with 40 - 43% inside RH during the Summer.  If we were not, we would:

4. Add a duct to the supply side to allow for air to blow into the attic.  We'd have a manual damper control, for this duct at the plenum.  Using this manual damper plus ECM blower fan speed controls, I'd figure out how much to open the damper to lower inside RH.  I'd keep the 47 degree coldest limit on LAT, and gradually open the damper, a little each week, until inside RH is down to whatever is desired.  I'd use the WEL to measure and analyze everything.

It sounds to me like you've done the first 3 noted above, and that it's time now to consider number 4.  Not a big expense item (assuming you have plenum with enough surface area for installing a small duct to it).

Hope this helps.

Best regards,

Bill

Posted By Bill Neukranz on 12 Jul 2014 04:24 PM

...

We're satisfied with 40 - 43% inside RH during the Summer.  If we were not, we would:

4. Add a duct to the supply side to allow for air to blow into the attic.  We'd have a manual damper control, for this duct at the plenum.  Using this manual damper plus ECM blower fan speed controls, I'd figure out how much to open the damper to lower inside RH.  I'd keep the 47 degree coldest limit on LAT, and gradually open the damper, a little each week, until inside RH is down to whatever is desired.  I'd use the WEL to measure and analyze everything.

...

One of my many WEL-using colleagues recently pointed out to me that this won't work.

The air that gets dumped into the attic has to come from somewhere.  More than likely being sucked in from outside.

I forgot to keep in mind that where ever you put (dump) air, there's got to be a return path for it, or, the return is going to be from outside.

Bringing in air from the outside to dump air into the attic isn't going to accomplish anything.  I should have thought of this.

Best regards,

Bill

Bringing outside air in certainly would increase runtimes.

Posted By joe.ami on 11 Aug 2014 11:13 AM
Bringing outside air in certainly would increase runtimes.

I'm no expert....my first thought was "open some windows"......