7 What are we going to cover? Basic components of a water-water & combo geothermal heat pump system.Tips on proper installation of a hydronic geothermal systemLimitations of a hydronic geothermal systemSome design considerations of the systemPiping options for the load sideControl options for the hydronic system
8 What have the problems been? Design water temp won’t heat space.Insulation generally is the culpritHeat pump is locking out on HP.Waterflow, Waterflow, Waterflow!To much load side antifreeze?Controls, Controls, Controls!High bill complaints.Low loop temps, could be a multitude of reasons!Running system at max 120F temps all season.Design of the system must meet the expectations of the customer, and it is your job to install and verify your system will do the job!
9 Questions to ask yourself? What will be my design max water temp?What will be my design min water temp?Will I have a supplemental or backup system?If so, how will it be piped and controlled?What is the heat distribution system?High mass floors - concreteLow mass floors – staple upRadiation – high or low tempAm I doing chilled water for cooling?Do I have areas that need antifreeze?Who is doing the insulation? What is it?What type of floor coverings do I have?
10 Proper design starts with Loads! Doing an accurate load calculation is priority number 1 including radiant design!This will dictate your supply water temp and flow rates of the system.Knowing the building materials, insulation values, floor coverings, etc. is critical.Jobsite verification of building materials and insulation practices (pictures, pictures)This all goes into a successful installation and a happy customer with low energy costs!
17 Staple up tubing with no underneath insulation and carpet for floor covering.
18 Staple up tubing with R-10 underneath insulation and carpet for floor covering.
19 Staple up tubing w/ HE plates, with R-19 underneath insulation, and low R-value carpet & pad for floor covering.
20 Other Recommendations Radiant floor tube spacing at 9” o.c. min.Do not mix more than 25% glycol antifreeze on load side of heat pump (preferably 0%)Flow rate through each radiant floor loop to be between .50gpm and .75gpmPipe sizing is critical; flow = BTU’sVariable Speed pumps & zone valves!Insulation values, floor coverings, flow rates, tube sizes, etc. all factor in to calculating system design!
21 Water-to-Water Heat Pumps Energy obtained from or rejected to a ground-coupled source (closed-loop)Utilized to make domestic hot waterUtilized for hot water hydronic systemsUtilized for chilled water hydronic systemsOptional desuperheatersWho do you see as fitting in these three categories?21
22 Combination Heat Pump (Triple Function) Energy obtained from or rejected to a ground-coupled source (closed-loop)Utilized for hydronic heating applications (no chilled water )Utilized to heat or cool air in forced air applicationsPackaged systemOptional DesuperheaterWho do you see as fitting in these three categories?22
23 Typical Water-Water System Source SideW2W UnitLoad SideWe are going to focus on the Load Side of the System!
24 Load-side “Guidelines” ALL heat pump hydronic systems require a buffer tank (well almost ALL).“Decouples” floor pumping and unit flow requirements.Usually 1 gallon per 1,000 BtuhIn most cases, controls are the most difficult part of the installation.Know what you’re getting into!Design systems for max. water temps of 120F or less for compressor life and efficiency!
25 Buffer Tank Sizing V = T x (Qhp – Qload)/Delta T x 500 V = VolumeT = Desired minimum run time (minutes)Qhp = HP CapacityQload = Heat flow to load when HP is onDelta T = Differential set point (10F)Example = 5 x (52, )/10 x 500 = 52
26 Buffer Tank SizingThe capacity of the heat pump and depending on the control strategy will determine the amount of storage needed.Hot tank – single set pointUsually 10 gallons/ton or 1gal/1000btu’sDemand controlled – single set pointUsually 6 gallons/ton or 1gal/1500btu’sCombo units buffer should be smaller!Example = 5-ton (52MBH + hot tank)5-tons x 10gal/ton = 50gal or 52,000btu/1000= 52gal
27 Load-side “Guidelines” Both Source Side and Load Side Coaxial heat exchangers are typically identicalPressure drop ratings are the sameFlow rates on the load side should be roughly the same as the source side2.5-3 gpm per tonConnection size doesn’t always mean pipe size (unit or pump flange)
28 Loop Field Sizing “Guidelines” Hydronic radiant systems depend on supplemental heat source:No supplemental heat – up size loopDirect supplemental heat – same as W/AIndirect supplemental heat – up size loopCombo unit systems:100% radiant – size as you normally would depending on supplemental heat sourceSome radiant & some F/A – up size loopHydronic systems will need more loop based on the mass of the system vs. heating air!
29 GSHP Max Load Side TempGround Source Heat Pumps using R-410a refrigerant typically can only achieve a maximum load side temperature of 120F ELT. This prohibits the use of this technology with other forms or hydronic heating such as radiators and/or sometimes baseboard radiation.There are new low temp baseboard radiators available that will heat at lower than 120F!
31 Design the GSHP system to utilize the lowest water temps possible for proper space heating and highest system efficiency! Things to consider: - Tube spacing/sizing - Flow rates - Insulation - Floor coverings
32 Outdoor reset controls With the COP of the HP going up as the load water design temp goes down, outdoor reset makes sense as a recommended control strategy.Outdoor reset control will vary the design load temperature based on outdoor temperature. The colder the outside temp, the warmer the load temp.This maximizes the COP of the system.
33 Glycol on Load SideWater quality is also very important!!!
35 Pipe sizing guidelines Pipe sizeFlow(gpm)Max P.D.(FT/100 FT)Max. Vel(FPS)1/2"0-25.02.23/4"2-44.42.41"4-84.83.011/4"8-154.03.311/2"15-243.72"24-452-1/2"45-723"72-1305.7Notes: Use with hot water and chilled water closed piping systems Based on schedule 40 BI or Copper pipe
36 Heating only Hydronic Systems Water-Water Unit ApplicationsPressurized piping systemsControlsCombo Unit Applications
37 Components of a Water-Water System Water-Water Heat PumpBuffer Tank (Pressurized or HSS)Load Side PumpControls (Aquastat)Air PadFlow CenterPressurizedNon-PressurizedHose kit
38 Additional Components of System TubingFastenersManifoldsFittingsZone pumps/Zone ValvesFlanges (w/ pumps)Hydronic AccessoriesAir EliminatorExpansion TankControlsZone ControlPump RelayThermostats
39 Heat Only – W2W Unit & HSS Tubing Manifolds PT Ports Aqua-stat Load Side PumpZone PumpsGW UnitBuffer Tank
40 Heat Only – W2W Unit W2W Unit Aqua-stat Tubing Zone Pumps Load Side PumpFlow CenterBuffer TankManifolds
49 Components of a Packaged Combo System Combo Heat PumpThermostat (Forced Air)Electric auxiliary heater (Optional)Air PadBuffer Tank (Pressurized or HSS)Load Side PumpAquastat (hydronic control)Flow CenterPressurizedNon-PressurizedHose kit
50 Additional Components of System TubingFastenersManifoldsFittingsZone pumps/Zone ValvesFlanges (w/ pumps)Hydronic AccessoriesAir EliminatorExpansion TankControlsZone ControlPump RelayThermostats
51 Heating Only - Combo Unit GT UnitAqua-statPT PortsLoad Side PumpBuffer Tank
57 Chilled Water vs. DX Cooling W2W units have lower EER’s than Water-Air heat pumpsBe careful of sensible cooling capacities of the air handler or water coils – do not size strictly based on tonnageAll piping with chilled water needs to be insulated including pumpsBuffer tank must be insulated and have an air seal to prevent condensationAdvantage – one unit vs. two units
69 Back up Boilers What is the boiler’s primary function: Back up source onlySupplemental heat – same output tempIncrease supply temp to provide additional btu’s to high load areasWhat source of energy is the backup boilerGasElectricWood
72 Other Applications Pool & spa heating Domestic water heating Snow melt Process water chillingIce storage or Ice arena’sWaste heat recoverySimultaneously heating & cooling
73 So, the Keys to Success Are; Design the system properly, not using Btu’s per sqft, but rather good design practices.Insulation is a huge factor along with thermal breaks, if you aren’t doing it, verify it is done right!Select the proper control strategy for the application, buy off the shelf vs. build your own so anyone can service and troubleshoot!Size your piping and pumps for proper flow.Select your piping strategy for the application as well as the supplemental heat source.