Minnesota Humidity and chilled water

Discussion in 'Maintenance and Troubleshooting' started by Timothy Pellizzer, Aug 2, 2015.

  1. Timothy Pellizzer

    Timothy Pellizzer New Member

    Hello! I have had a Geo system since 2010. The equipment is as follows: 3 6 Ton Econar Water to Water units connected to in floor heat as well as to 5 air handlers. The house foundation is 3900' and another 1000' garage. Current heated/cooled space is about 7500'. The system is able to warm and cool the home. But in the summer months humidity control in a problem. It is almost impossible to get below 63% humidity without running portable dehumidifiers. I understand that induct or in line dehumidifiers are available but I hope to solve the problem without them. I have never realized a cost saving from the Geo system, perhaps the exact opposite. It seems like a very costly system to operate. All of my cooling is performed via the water to water in the air handlers. I was told from other than my original installer(now out of business) that water to air would have been a much better solution considering that they are more efficient at heating/cooling and the removal of humidity. Is this true or is it just another Geo myth? Also what is the optimal temperature for the chilled water to maximize the removal of humidity? Any help would be greatly appreciated.
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The further you chill down the coil, the more humidity you remove.
    W-W can be as efficient as forced air, if designed for low supply water temperature. Econar was not the pride of the geo industry, they are out of business now. Chances are that your design is not very efficient, some of the installers/designers are not very evolved. Those are usually the ones going out of business soon or later, like yours.
     
  3. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Make sure you are chilling the water to as low a temp as you can without locking equipment out. Also make sure you are not running your fan when the chilled water is not circulated.
    The design does sound un-evolved (18 tons for 7500SF in a modern build).
    Cooler temps if possible, lower fan speeds to slow temp difference/run each air handler longer or more coil surface is the fix.
    Cheapest is to try lower fan speeds or lower water temp (if possible). If you can't lower water temp without lockout, see if you have a multispeed pump that you can speed up. If not and if lower fan speed doesn't work larger air handlers or a larger pump would be next.
    Whole house dehumidifiers work well and may be less expensive to operate than 18 tons or compressor.
    If there's any chance you leave near one of the contributing pros here you would likely benefit from a system evaluation to determine that you have optimized pump energy conservation, have an outdoor reset etc.
     
  4. Timothy Pellizzer

    Timothy Pellizzer New Member

    I think the chilled water is currently set to 48-50 F. I see a stat inside one of my larger control boxes that appears to be set to 48 F. Is it possible to go lower? I like the suggestion of using lower fan speed and no fan when the pumps are off. Should I consider replacing my Econar equipment with a different brand and then should I use water to air? i understand I have a little over a year to make changes prior to the tax credit removal. I am in the Mpls./St. Paul area if there is any one out there that may have an interest in working on the system. Also I just purchased a book on Geo called
    Modern Geothermal HVAC Engineering and Control Applications. I hope to educate myself a bit about a very complex system. Thanks to all for the help.
     
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Before replacing the equipment start with the lower fan speeds and cycle them off between calls for cooling.
     
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Why do you say it is a very complex system?

    Mark
     
  7. Timothy Pellizzer

    Timothy Pellizzer New Member

    My definition is probably different than yours. I will describe the system in its entirety. Starting from the outside of the house, I have three 350'Length x12'Wide x8'Deep troughs for the black poly piping that is spaced 1' apart in each trough. I live on a wet land so these are adjacent to the wetland. Generally wet. Inside I have three 2010 model year Econar 6 ton water to water units w/desuperheaters. I have perhaps a 150-200 gallon holding tank for hot water in winter and cool water in the summer. System was designed with only one holding tank. I have 6 air handlers w/dc motors and coils for the heating/cooling functions. I have a 250,000 btu backup wall mounted boiler. This boiler is also connected to a tank for internal hot water use. The desuperheaters are all connected to a electric water heater used as a storage vessel that then feeds into the other hot water vessel. I have inflow heat throughout first floor and basement areas with air only heating/cooling on second floor and over the garage. I think I have 40+ Grunfos pumps throughout the basement with one main pump that I believe operates 24/7. This massive pump(maybe 1+hp, about the size of a basketball sits on what I consider a main line that runs throughout the basement to supply all the other pumps used for the air handlers or the infloor heat. My guess is that I am way over pumped compared to other systems that I have recently seen. I have Honeywell thermostats for the air handlers and Teckmar controls for the in floor. The heating portion of the system works best with the cooling portion having a difficult time removing humidity. Here is a sample of the electric bills: Aug 2014 $377, Sept. 2014 $346, Oct. 2014 $367, Nov. 2014 $552, Dec. 2014 $765, Jan. 2015 $887, Feb. 2015 $822, March 2015 $605, April 2015 $505, May 2015 $425, June 2015 $368, July 2015 $452. These numbers include other electricity used in the house which I estimate to be $150.00/month. I am on the dual fuel rate for Xcel energy.
     
  8. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I would say that done correctly yours would be a sophisticated system.
     
  9. Timothy Pellizzer

    Timothy Pellizzer New Member

    Do you have any one to recommend in the Mpls/St. Paul area for repairs?
     
  10. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I could make the system be all that it can be. You may be a bit out of range for me while the bad foot heals.

    Mark
     
  11. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Sounds like a typical old fashion boiler design. Chances are that you are using more energy for pumping than for anything else.

    Feeding air handlers for heating is relatively inefficient. So are Desuperheaters for domestic hot water when you have 3 geo units making hot water. In most cases, modern designed geo systems would only need 3 pumps, one for the source (loop field), 2 for the load.
     
  12. Timothy Pellizzer

    Timothy Pellizzer New Member

    Wow! I just counted the number of pumps on my system. I have 28 separate pumps. All of them are Grunfos brand. I wonder why so many were installed on my system?
     
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I wonder that too. You pay for the pumps, but more importantly, for the electricity to run the pumps....
     
  14. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Tim:

    Do not panic, Doc, at times, over reacts, I doubt the pumps all run at once.

    I would be happy to look at the control ideas that you have and how to move what you have to what you want.

    I am not a well known member here. I just work here to help folks do what they want to do.

    Mark
     
  15. Timothy Pellizzer

    Timothy Pellizzer New Member

    Thanks Mark. I am about a third through the Egg Geo Thermal book. Sure wish I had read up prior to contracting for my system. Just the first chapter would have saved me a ton of money (he lists five or six things a good home system should have in his opinion) of which most are missing from my system.
    Tim
     
  16. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I am calm...;)
    There are pretty much 2 things which kill the efficiency of a water to water geo system:

    1) High load temperatures, increasing the lift and thus the compressor amperage drawn, as well as the compressor runtime.
    2) Large amounts of inefficient constant speed circulators.

    Keep in mind that hydronic geo system have much higher runtimes due to lower water temperatures. It is all about high flow and low temperature to be mostly efficient, thus the circulator runtime will be much longer with geo systems.
    Are they always all run at the same time? No.
    But chances are that even if a single zone is calling, a lot of pumps are running.
     
  17. Timothy Pellizzer

    Timothy Pellizzer New Member

    Hello
    I understand issue #2, large number of inefficient speed circulators. These I definitely have and perhaps they even are fighting or pumping against each other. The #1 I do not understand. Is the high load temperatures the difference between the inside set point and the outside temp? Or is it the difference in water temp of incoming and out going water? Is the lift how far away the outside and how low the field is?
     
  18. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    The lift Doc is talking about is the temperature change through the machine.
     
  19. Timothy Pellizzer

    Timothy Pellizzer New Member

    I took some pictures today on my day off.
    Tim
     

    Attached Files:

  20. Timothy Pellizzer

    Timothy Pellizzer New Member

    Here is the rest of them. I tried to get a shot of every piece of equipment.
    Tim
     

    Attached Files:

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