Geo w/radiant infloor issues

Discussion in 'Maintenance and Troubleshooting' started by JWS73, Dec 29, 2010.

  1. JWS73

    JWS73 New Member

    Hello, new to the forum. I'll keep this as to the point as I can.

    Have a two story farm house completely remodeled and reinsulated. True 2x4 with blown in cellulose. Box sills foamed. Double pane replacement windows thoughout.

    Have added a 42x30 garage with bonus room--2x6 blown in cellulose.

    Our geo of choice was a Geocomfort system with both a split and combo unit. The split is for the 1st floor of the house and infloor heat in garage. 2nd floor unit has two zones, one 2nd floor of house and other bonus room serviced by geo in basement pumping refrig to attic air handler. Infloor is supposed to be fed by geo 100% with no supplement.....

    System was fired in mid-Feb with dip switches incorrectly set to infloor as priority over 1st floor of house. Floor worked great but house couldn't keep up. 2nd floor unit worked fine. By the time the contractor would listen to concerns March was here. Dip switches corrected.

    Issue is that we started the house and infloor in early November--abnormally warm fall here with 65-75deg days still. When 1st floor began to call for heat infloor wouldn't function. Complained and they said we didn't start it soon enough and would have to give it time (65deg daytime at this time)

    Now the situation is that the 1st floor has a high duty cycle with occasional strip to top off. The infloor tank never gets heated. We have looked for drafts and can't find any. Carpenter friend has been there a couple of times and compliments tightness of house.

    Contractor has kept saying that "you're just calling for too much heat on the 1st floor" as of last week. I had the 1st floor set at 62 and second at 64. (we are not living there yet)

    I now have bumped temps to 68 and 70 resp to see if we can hold them--no problem other than infloor still doesn't work. Yesterday morning man working in house turned heat down to 62 on first floor--said it was too hot. Took 3 hours to loose 6 deg and water only heated to 70deg from 55deg in tank (no zones activated in infloor)

    After heated exchange with contractor I decided to wire up water heater serving as storage tank to try to get some heat pumping. Only one element was hooked up as contractor had unhooked bottom. I was hesitant to rewire bottom with fear that current might back feed to geo thru thermostat. With one element we heated all three concrete zones within 12 hours. Biggest is 30'x30' parking that went from 49 to 55. Bumped it on up to 60 by this morning. Amazing.

    Contractor called this pm wanting to come and reset priorities and duty cycles to get concrete warm--already did that but go ahead, and shut off my water heater circuit. They have the 1st floor geo set to run forced air 10min, then off 10min with infloor getting odd period. I observed the system for 2 hours and it is actually building heat in the buffer tank. This evening we were maintaining 68deg with no strip with a little heat build in the tank--up to 90deg. No wind, 24deg outside.

    Stats per admin list:
    1. Location Deland Illinois
    2. Heat Load: 86491Btu/hr Indoor design temp 70deg Outdoor 2deg
    3. Geocomfort 2x3T 1st floor/infloor unit GT036B13LT1CB
    2nd floor unit GT036B10CB

    4. 6 Vertical wells 150' deep 3/4pvc
    5. Ave Cost/KWh $.109
    6. EAT:73.5deg LAT--forgot to get it, will repost tomorrow
    7. EWT: 39 LWT: 28
    8. % load by geo 98.7% of heating Balance point 12deg
    9. Installers assessment---it's working just fine, we just need to tweak a few things.
    10. Projected op costs $1611/yr $1047 heat $397 cooling $166 hot water

    Few stats from this evening
    a. Water leaving geo to tank 73deg
    b. Water returning to geo 64deg
    c. temp at infloor manifold 88deg
    d. returning water temp 64deg
    e. compressor never shut off in 2hours of observation

    All temps taken with a infared gun--all I had. Thanks for any input as my wife and I are a bit frustrated. Please point out other info needed as this is still new to me.
  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    With all of the radiant

    floors or wall panels I have designed and built slow and steady wins the race. Radiant hydronic systems do not care how the water gets warm and due to the relitivlly low delivery tempuratures are a good fit with geothermal equipment

    I do not have enough information to be of much help. What type of "in floor" heating system is it. If the floors in the home are staple-up they will need warmer water than the garage floor if it uses tubing in the concrete slab.

    More information on the plumbing and control stratigies is needed. A few pictures of the piping could be useful.

    I am not familiar with the equipement you describe.

    Just home from a trip east to visit family, and almost visit Waterpirate, so I have some catching up to do. I will be happy to do what I can to get your issues resolved, as will the rest of the group here.

    Last edited: Jan 4, 2011
  3. JWS73

    JWS73 New Member

    Update to original thread

    It's been several days since original post but have more data to share.

    For clarification the infloor portion is heating a single slab of 4" concrete divided into three zones, which are seperate rooms. Office, entry, and garage parking which is all new construction added to the side of the original old house. These areas are controlled by ambient air stats which in turn run seperate valves on a manifold. The contractor used red pex tubing as a loop field, which feeds thru the old outer foundation wall of the house to the manifold

    The office and entry are supplemented with forced air from the first floor of the house with the stat being in two rooms away and above these areas, ie. first floor of house is about 3 feet above ground level as we have a basement.

    In the living area of the original house there is no radiant heat, just forced air from the geo.

    The first floor of the house and radiant heated areas are using the combo unit. Second floor is where the split unit is running an air handler with two zones.

    Since posting the contractor returned, said they just reset combo unit to give the garage infloor priority and, wala, we magically have heat being fed to the buffer tank via the geo and floor is keeping up as well as 1st floor of house. The next morning after original post the 10min on 10min off was gone and we were back to on call demand (never told if something was changed to alter this pattern). 1st floor was keeping up with less effort (time and frequency) than before with little use of strips.

    Problem: Now our electrical usage is unreal. Duty cycle for the combo unit compressor has been close to 100% as stated in original post. I took another couple of hours on the late afternoon of 12/30 to log system activity (18hrs into short warm weather burst that lasted until NY eve night--50 day 40 night) and found an 80% duty cycle. For period from 12/28 @ 7:00pm to 1/2 at 9:30 pm or 122.5 hours we burned 1142kWh. Haven't figured out how to post average temps, nor easy site to find them.

    I decided to ask another Geocomfort dealer to come run a diagnostic. Made for an interesting day. He studied for some time as he was not familiar with this combo unit. His first inclination was that the buffer tank temp was not hot enough at approx 94 and raised it to 118. He then spoke with tech support and they both agreed on this action as well as increasing flow rate thru floor. Felt that this should get system fully on top of floor heat and lower run times of the compressor. This was done at 11:00 am and the geo responded by raising buffer tank temp to above. His other temp data is below. His only action aside from adjusting temps/flow was to add a little water to the loops. Don't know what original psi was but he felt it a good idea to top it off--felt no more than 8oz added to get 4psi differential in EWT&LWT.

    I returned at 3:30 to find the buffer tank back to 75. Geo was cycling to house heat then off--didn't seem to be attempting to heat tank. Whole first floor of house felt colder as did duct air. There was no call from the radiant side as all zones were at temp or above. Will see in the morning if any heating was done or if we are going to loose concrete heat. Technician from dealer #2 did nothing at control panel inside unit other than check some voltages, etc. No manipulation of dip switches.

    His observations of the system with proper equipment:
    EWT: 31.5 @ 44psi
    LWT: 26.8 @ 48psi
    Duct temp
    return: 67.4
    heated: 77.5
    Water temps:
    as above raised to 118 to floor
    found a 91 return temp-with smallest zone running to function system, others satisfied. Widest delta I've seen. Most of the time its 10-20.

    Contractor #1 coming back tomorrow. Should be interesting.

    Any ideas would be appreciated. We don't feel like anyone really has a full grasp on what is going on here. Again, location is DeLand Illinois zip 61839 Champaign 20 miles away if that helps for climatic data. I have found a weather station at Weldon which is 5 miles away.
    Thank you.
  4. JWS73

    JWS73 New Member

    Addition to update

    It seems to me that the combo unit compressor is running louder than it has before. When it finally does shut off it sounds like an abrupt mechanical clunk and then a hissing that sounds like pressure being bled off. Technican today didn't seem concerned with it.
  5. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I'm not familiar with the specific model, but making 118 *F water is likely near the top of capability. The result is that the compressor is near or above rated current, and refrigerant pressures are very high. Efficiency and longevity will suffer. The clunk may be the reversing valve if it changes mode or the compressor coming to a halt with high Delta-P. The hissing is the rfrigerant equalizing after shutdown and that sound will be more pronounced at higher loads.

    Power consumption of 9+ kW (1142 / 122) suggests 24/7 operation by all 3 units or much resistance heating going on.

    If I read the OP correctly you have 9 nominal tons feeding an 86.5 kBtuh design load...there ought to be plenty of spare capacity unless outdoor temps have been well below zero...I can't find Deland, IL on a map to check recent weather.

    Something must be way way there subslab insulation?
  6. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

  7. JWS73

    JWS73 New Member

    The system is made up of two 3 ton units for total capy of 6ton---6 vertical 150' closed circuit wells.

    The combo unit started making the hard shutdown noise w/pressure backfeed sound after one of the visits from original contractor. Is it possible to adjust refrigerant/compressor operating pressure for some desired outcome? I have not been told what, if anything, has been adjusted by original contractor in the last couple of weeks--after a couple of visits to my knowledge.

    Regarding the slab there is insulation under it b/t concrete and reclaimed concrete fill. There was no thermal barrier or expansion joints installed b/t zones........ At this time all zones have been set to the same temp. Call frequency to any of the three infloor zones has dropped dramatically.

    But, power usage is still 10kW/h ballpark. When we are there we seldom see strip heat come on according to the stats readouts. Two of the three forced air zones were on alot today. The infloor again was very sporatic. Today has been very cold and windy (20deg & 15-20mph wind) and while working there I did notice strip on once this morning on the 1st floor zone.

    We are not living there yet and there is no other electrical powered items running. Going to have electrician come back and check panel for any loads that might be on that we don't know about. He's done it once and found nothing but try again.

    We have been told by geo contractor to talk with insulator--it's their fault. Will get records from insulator next week. Spoke with general contractor (straight up guy who tells it like it is) and he calmly said "That is a tight house. I've been to many jobs w/geo as heat and you have plenty and then some of insulation to make that thing run right." (I know he's not a geo tech but it's another viewpoint)

    At this point we are going to explore a door test/themal camera to double check insulation.

    Thank you for the responses and any other input/thoughts would be greatly appreciated.
    Last edited: Jan 8, 2011
  8. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    What does b/t mean?

    No thermal barrier or vapor barrier? If not you could be trying to heat from your place to Cleveland.

    The shut down noise sounds to me like a very high pressure sut down.

    How do you know if the floors are running or not?

    Has the contractor ever done in slab radiant before this job?

    What is the EWT to the floors if they are running?

    I control radiant floors with air temp sensing stats all the time so I have no issue with that part. I want to know the total length of each loop in the floor. It sounds as if each zone is its own loop without any regard for FLOW or Head.
  9. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Ah - De Land - two words.

    "High pressure shutdown" sums up what I was getting at.
  10. JWS73

    JWS73 New Member

    There is a thermal/vapor barrier under the slab. But, it does not wrap the slab between the slab and footing walls. Nor is there th/vpr barrier between zones in the slab.

    I cannot answer the question regarding the contractor/dealer's infloor experience. It is a large multi-location dealership and presented their design for the floor and it seemed logical--I didn't research much to double check them at the time of discussion and installation as I was working 12hr+ days harvesting my crops. (Not an excuse in hind site) To clarify, this install was done by the geo dealer, not the home insulator.

    The infloor system is comprised of three zones:
    1. Zone 1 Entry/foyer 100sqft approx
    2. Zone 2 Office 204 sqft
    3. Zone 3 Parking 1000 sq ft approx

    Zone 1 is heated by (1) loop, zone 2 (1) loop, and zone 3 (4) loops. All exit and return into a 7 position manifold (1 blank). The control valves are on the EW side and flow meters on the LW side. I do not know the length of each run. Will investigate.

    The control valves are activated by a control box with lights indicating when a call for each zone is present. That's how I know a zone is flowing & there are indicators that rise out of the top of the valves when they are open.

    The circulation motor has been set at medium by the dealer and flow out of the loops at roughly .3GPM each. Technician from dealer #2 raised motor speed to high and recalibrated loop flow to .6GPM. Dealer #2 tech's actions were advised by tech support at the manufacturer of the geo system. Tech support really wanted .7GPM but it wouldn't support that much flow. Dealer #1 reset pump to medium when coming back to "reassess" the situation late in the week.

    Tech support also advised to set all zones at same temp. Since that action infloor calls for water have been drastically reduced. So much so that the heated water sitting idle in the EWT side pipe coming out of the buffer tank cools to almost ambient air temp--I have not seen it do that until now. Usually gauge and pipe remain hot (when system is functioning)

    Originally EWT to the manifold was about 94 with usually about a 20deg Delta T. When tech #2 came, he raised thermostat on buffer tank to about 120 giving about a 118ish EWT into the manifold. He had a high Delta T at about 27 deg, which is the highest I've seen. Since the return of dealer #1, I have not seen the temp gauge on the EWT side of the buffer tank rise above 105deg. I will measure again tomorrow.

    A high pressure shut down doesn't sound good--literally on site or by the comments posted. The dealer seems to care not. When dealing with high pressure shut down situations on farm solution pumps it usually ends bad.

    So how is this adjusted or addressed? Could this be contributing to high energy usage? Is it something that has been adjusted to current state for a desired result? i.e. more heat?

    From comments on here and people I have spoken with looking for advise I am told we have enough capacity, just something badly amiss. Is it possible that a component is not serving to put enough btu's into heated air, but sending it somewhere else?

    Thanks again for comments.
    Last edited: Jan 8, 2011
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Lets review

    Heat goes to cold every time, so It is too bad there is no insulation between the slab and grade. The objective is to nudge the heat out of the slab and into the space. We still may be able to create a work around.

    I am surprised that the vapour barrier does not extend up the walls of the addition or the older section of the foundation. My guess is there is not a tough inspection system happening in De Land

    Nothing to be done about ether point short of busting up the concrete and starting over.

    I am going to jump ahead to the high pressure issue. In heating mode the condenser side of the system is in the home not in the yard. So to have an issue with high pressure means we are not getting rid of the heat, but you knew that. Not knowing how the combination system is piped internally to provide warm air and warm water limits Internet corrections. My first guess is you are not moving enough water through the floor.

    A concrete slab makes a great heat sink storage tank, but you have to spend the time it takes to fill it up. Once full it will heat the space, and unfortunately with out some sort of thermal break it is going to try and heat up some of De Land. Using low temperature water it will take awhile to store the available heat. It may not catch up all this winter,

    If I were to design a system for your space I might not have zoned the areas due to the high mass floor. We have not looked at the loops as to size and length. De Land can not be much different than Cleveland, so here is how I would have laid out the loops. I start using 1/2 pex with the first few passes on the out side walls at 6" OC, then about to or three feet into the space go to 9" OC and then to 12" OC for the balance. I tend to pack the pipe in doorways as I know I will have more heat loss in these areas.

    Using 1/2" pipe there is a sweet spot when it comes to length, and that is 300' per cicuit If you go longer than that the pumping power required increases logrithmicaly. Your system is cast in stone so we do not care what is in the slab because we can not easily change it.

    What can we do? Move more water. I am used to seeing way more than a 20* delta T on starting a cold slab. If we can increase the delta T your high pressure shut down should go away.
    Last edited: Apr 20, 2011
  12. JWS73

    JWS73 New Member

    Thanks for your thoughts Mark and others.

    Another question: We were asked to set the 1st floor house stat 2deg minimum under the second floor zones to lower load on 1st floor. Is there logic to this? We might have a comfort issue doing this.

    Currently have the 1st floor set at 68 and second at 70. As a side note: The staircase to the second floor goes up thru the center of the house to end of upstairs hallway. Tech that ran ducts set up a return to the second floor unit at the top of the stairs to evacuate warm air naturally rising and pooling there. Sounded logical. Then master tech came along and set second floor of house stat right at top of stairs and under the above mentioned return. We questioned this placement and got no response other than "it's where we want it" during install. Now there is a comfort difference from stat area to far end of 2nd floor (far end happens to be north) and master tech said as much in his report of the house last week. Well no kidding Shurlock. Most days the second floor house zone hardly runs.

    Just a few thoughts as the wife and I have been brainstorming about this.

  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    The thinking is that return air when collected represents the average air temp of the zone. That's clearly not the case in the space you describe. I'd have picked an interior hall near the north occupied rooms.

    As to setpoints, why have a stat if you can't set it how you want it? No zoning system would be able to give you 60*F upstairs and 80*F downstairs, but aside from such extremes, you should be able to adjust for comfort.

    I ask clients their desired setpoints and try to design a system to meet them. I tell them we can't make it 60 / 80 without zoned returns and exterior doors between zones, but aside from that I want their needs to drive the system, not the other way 'round.
  14. JWS73

    JWS73 New Member

    New question:

    How should the maximum heating capacity of the geo unit compare to the design load? We have found that both of our units together add up to 60K btu/hr without strip heat included. Calculated load for the structure is 86K btu/hr.

    Thank you for your post Engineer.
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    We are cooling dominated so design for 100% cooling load.

    Up north it is typical to design for 90-95% of the heating load and figure on strip operation on a few cold nights - much cheaper up front than supplying 100% with geo.

    Your system design sounds a bit light but I'm hesitant to condemn someone whose thinking I haven't received.
  16. geome

    geome Member Forum Leader

    We have 2 water to air units with 2 separate thermostats. We keep our upstairs doors closed and have a remote thermostat sensor in one of the bedrooms.

    In the winter, this helps keep the warm air from the 2nd floor unit (not the warm air rising from the 1st floor unit) in the bedrooms. In the summer, this helps keep more cool air in the bedrooms instead of the air "falling" down the stairs to the first floor.
  17. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    At first glance your balance point would appear to be in the teens and the geo handling ~97% of load ( I do not have all the design data available to me of course). I don't think you are undersized.
    I've never been able to articulate this very well, but when we say 92-98% of the load, we don't mean 98% of your 86kbtu peak load, we mean that with geo running aux coil is only going to provide 2-8% of your annual btu's used.
  18. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    % Design

    Building on Joe's comment.

    Generally for our area, based on my designs, 85% of peak heating load satisfies 98% of run time conditions; thus, supplemental heat is required for 2% of the year.

Share This Page