Radiant Floor Systems Coupled with Geothermal Heat Pumps By Brian Urlaub, Enertech Global

Hopefully so you don’t end up with something like this! Why are you here? Hopefully so you don’t end up with something like this!

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 system Limitations of a hydronic geothermal system Some design considerations of the system Piping options for the load side Control options for the hydronic system

What have the problems been? Design water temp won’t heat space. Insulation generally is the culprit Heat 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!

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 - concrete Low mass floors – staple up Radiation – high or low temp Am 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?

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!

Insulation, Insulation, & Insulation

Floor Coverings & Design

Concrete slab with R-5 edge and horizontal.

Concrete slab with R-10 edge and horizontal.

Staple up tubing with no underneath insulation and carpet for floor covering.

Staple up tubing with R-10 underneath insulation and carpet for floor covering.

Staple up tubing w/ HE plates, with R-19 underneath insulation, and low R-value carpet & pad for floor covering.

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 .75gpm Pipe sizing is critical; flow = BTU’s Variable Speed pumps & zone valves! Insulation values, floor coverings, flow rates, tube sizes, etc. all factor in to calculating system design!

Water-to-Water Heat Pumps Energy obtained from or rejected to a ground-coupled source (closed-loop) Utilized to make domestic hot water Utilized for hot water hydronic systems Utilized for chilled water hydronic systems Optional desuperheaters Who do you see as fitting in these three categories? 21

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 applications Packaged system Optional Desuperheater Who do you see as fitting in these three categories? 22

Typical Water-Water System Source Side W2W Unit Load Side We are going to focus on the Load Side of the System!

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 Btuh In 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!

Buffer Tank Sizing V = T x (Qhp – Qload)/Delta T x 500 V = Volume T = Desired minimum run time (minutes) Qhp = HP Capacity Qload = Heat flow to load when HP is on Delta T = Differential set point (10F) Example = 5 x (52,000 - 0)/10 x 500 = 52

Buffer Tank Sizing The capacity of the heat pump and depending on the control strategy will determine the amount of storage needed. Hot tank – single set point Usually 10 gallons/ton or 1gal/1000btu’s Demand controlled – single set point Usually 6 gallons/ton or 1gal/1500btu’s Combo units buffer should be smaller! Example = 5-ton (52MBH + hot tank) 5-tons x 10gal/ton = 50gal or 52,000btu/1000= 52gal

Load-side “Guidelines” Both Source Side and Load Side Coaxial heat exchangers are typically identical Pressure drop ratings are the same Flow rates on the load side should be roughly the same as the source side 2.5-3 gpm per ton Connection size doesn’t always mean pipe size (unit or pump flange)

Loop Field Sizing “Guidelines” Hydronic radiant systems depend on supplemental heat source: No supplemental heat – up size loop Direct supplemental heat – same as W/A Indirect supplemental heat – up size loop Combo unit systems: 100% radiant – size as you normally would depending on supplemental heat source Some radiant & some F/A – up size loop Hydronic systems will need more loop based on the mass of the system vs. heating air!

GSHP Max Load Side Temp Ground 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!

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

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.

Glycol on Load Side Water quality is also very important!!!

Affects of Antifreeze in System

Pipe sizing guidelines Pipe size Flow (gpm) Max P.D. (FT/100 FT) Max. Vel (FPS) 1/2" 0-2 5.0 2.2 3/4" 2-4 4.4 2.4 1" 4-8 4.8 3.0 11/4" 8-15 4.0 3.3 11/2" 15-24 3.7 2" 24-45 2-1/2" 45-72 3" 72-130 5.7 Notes: Use with hot water and chilled water closed piping systems Based on schedule 40 BI or Copper pipe

Heating only Hydronic Systems Water-Water Unit Applications Pressurized piping systems Controls Combo Unit Applications

Components of a Water-Water System Water-Water Heat Pump Buffer Tank (Pressurized or HSS) Load Side Pump Controls (Aquastat) Air Pad Flow Center Pressurized Non-Pressurized Hose kit

Additional Components of System Tubing Fasteners Manifolds Fittings Zone pumps/Zone Valves Flanges (w/ pumps) Hydronic Accessories Air Eliminator Expansion Tank Controls Zone Control Pump Relay Thermostats

Heat Only – W2W Unit & HSS Tubing Manifolds PT Ports Aqua-stat Load Side Pump Zone Pumps GW Unit Buffer Tank

Heat Only – W2W Unit W2W Unit Aqua-stat Tubing Zone Pumps Load Side Pump Flow Center Buffer Tank Manifolds

Heat Only – W2W Unit

24V AQUASTAT WITH N/O DRY CONTACTS THAT WILL CLOSE ON FALL IN TEMP! Sensor in tank T1 T2 HEATING ONLY CONTROLS!

Heat Only – W2W Unit w/ HSS

Heat Only – 2stg W2W Unit W2W Unit Aqua-stat Load Side Pump Buffer Tank Flow Center

Heat Only – 2stg W2W Unit

Heat Only – 2stg W2W Unit

Components of a Packaged Combo System Combo Heat Pump Thermostat (Forced Air) Electric auxiliary heater (Optional) Air Pad Buffer Tank (Pressurized or HSS) Load Side Pump Aquastat (hydronic control) Flow Center Pressurized Non-Pressurized Hose kit

Additional Components of System Tubing Fasteners Manifolds Fittings Zone pumps/Zone Valves Flanges (w/ pumps) Hydronic Accessories Air Eliminator Expansion Tank Controls Zone Control Pump Relay Thermostats

Heating Only - Combo Unit GT Unit Aqua-stat PT Ports Load Side Pump Buffer Tank

Heating Only - Combo Unit

On Demand Control Strategy!

Hot/Chilled Water Hydronic Systems Water-Water Unit Applications Pressurized piping systems HSS non-pressurized piping systems Controls (heating & cooling) HSS System (on demand) HBX Controls (either or, plus Outdoor Reset) Geo-Tech (Don Schuster) (Set point) Terra-Therm Hydronic Controller (Set point) Do it yourself (who knows) Controls (Heating only) HSS HBX Tekmar Johnson Controls Honeywell Ranco

Chilled Water vs. DX Cooling W2W units have lower EER’s than Water-Air heat pumps Be careful of sensible cooling capacities of the air handler or water coils – do not size strictly based on tonnage All piping with chilled water needs to be insulated including pumps Buffer tank must be insulated and have an air seal to prevent condensation Advantage – one unit vs. two units

Sensible vs. Total Cooling

Heating & Cooling Hydronic Systems

Basic 2 Aqua-stat Wiring setup

Heating & Cooling Hydronic Systems

HBX ECO-1000 Wiring Diagram

HBX ECO-1000 Wiring Diagram (2stg)

Htg & Clg W2W unit w/ HSS

Htg & Clg W2W unit w/ HSS

Geo-Tech (Don Schuster)

Do It Yourself – Good Luck!

Back up Boilers What is the boiler’s primary function: Back up source only Supplemental heat – same output temp Increase supply temp to provide additional btu’s to high load areas What source of energy is the backup boiler Gas Electric Wood

W2W unit w/ Boiler - Supplemental

W2W unit w/ Boiler - High Temp

Other Applications Pool & spa heating Domestic water heating Snow melt Process water chilling Ice storage or Ice arena’s Waste heat recovery Simultaneously heating & cooling

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.

Questions or Comments??? Thank You!!!