Hopefully so you don’t end up
with something like this!
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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
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Design water temp won’t heat space.
◦ Insulation generally is the culprit
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Heat pump is locking out on HP.
◦ Waterflow, Waterflow, Waterflow!
◦ To much load side antifreeze?
◦ Controls, Controls, Controls!
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High bill complaints.
◦ Low loop temps, could be a multitude of reasons!
◦ Running system at max 120F temps all season.
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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!
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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?
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What is the heat distribution system?
◦ High mass floors - concrete
◦ Low mass floors – staple up
◦ Radiation – high or low temp
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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?
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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!
Concrete slab with R-5 edge and horizontal.
Concrete slab with R-10 edge and horizontal.
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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!
• 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
• Energy obtained from or
rejected to a groundcoupled source (closedloop)
• Utilized for hydronic
heating applications (no
chilled water )
• Utilized to heat or cool air
in forced air applications
• Packaged system
• Optional Desuperheater
Source Side
W2W Unit
Load Side
We are going to focus on the Load Side of the System!
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ALL heat pump hydronic systems require
a buffer tank (well almost ALL).
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“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!
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
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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
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Demand controlled – single set point
◦ Usually 6 gallons/ton or 1gal/1500btu’s
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Combo units buffer should be smaller!
Example = 5-ton (52MBH + hot tank)
◦ 5-tons x 10gal/ton = 50gal or 52,000btu/1000=
52gal
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Both Source Side and Load Side Coaxial
heat exchangers are typically identical
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Pressure drop ratings are the same
Flow rates on the load side should be roughly the
same as the source side
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2.5-3 gpm per ton
Connection size doesn’t always mean
pipe size (unit or pump flange)
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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
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Combo unit systems:
◦ 100% radiant – size as you normally would
depending on supplemental heat source
◦ Some radiant & some F/A – up size loop
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Hydronic systems will need more loop based
on the mass of the system vs. heating air!
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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!
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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.
The Effect of Glycol on Microbial Activity
% of samples found with > 1000 CFU/mL
Probability of
Contamination
100%
80%
60%
40%
20%
0%
0% to 10%
10% to 20%
20% to 25%
above 25%
Concentration of Glycol (vol%)
Water quality is also very important!!!
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
4.0
3.7
2"
24-45
4.0
4.4
2-1/2"
45-72
4.0
5.0
3"
72-130
4.0
5.7
•Notes:
Use with hot water and chilled water closed piping systems
Based on schedule 40 BI or Copper pipe
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Water-Water Unit Applications
• Pressurized piping systems
• Controls
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Combo Unit Applications
• Pressurized piping systems
• Controls
 Water-Water
Heat Pump
◦ Buffer Tank (Pressurized or HSS)
◦ Load Side Pump
◦ Controls (Aquastat)
◦ Air Pad
◦ Flow Center
 Pressurized
 Non-Pressurized
 Hose kit
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Tubing
◦ Fasteners
◦ Manifolds
◦ Fittings
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Zone pumps/Zone Valves
◦ Flanges (w/ pumps)
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Hydronic Accessories
◦ Air Eliminator
◦ Expansion Tank
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Controls
◦ Zone Control
◦ Pump Relay
◦ Thermostats
Tubing
Manifolds
PT Ports
Aqua-stat
Load Side Pump
Zone Pumps
GW Unit
Buffer Tank
W2W Unit
Aqua-stat
Tubing
Zone Pumps
Load Side Pump
Flow Center
Buffer Tank
Manifolds
Sensor in tank
115F
T1
24V AQUASTAT WITH
N/O DRY CONTACTS
THAT WILL CLOSE ON
FALL IN TEMP!
T2
HEATING ONLY CONTROLS!
W2W Unit
Aqua-stat
Load Side Pump
Buffer Tank
Flow Center
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Combo Heat Pump
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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
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Tubing
◦ Fasteners
◦ Manifolds
◦ Fittings
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Zone pumps/Zone Valves
◦ Flanges (w/ pumps)
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Hydronic Accessories
◦ Air Eliminator
◦ Expansion Tank
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Controls
◦ Zone Control
◦ Pump Relay
◦ Thermostats
GT Unit
Aqua-stat
PT Ports
Load Side Pump
Buffer Tank
On Demand Control Strategy!
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Water-Water Unit Applications
• Pressurized piping systems
• HSS non-pressurized piping systems
• Controls (heating & cooling)
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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)
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HSS
HBX
Tekmar
Johnson Controls
Honeywell
Ranco
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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
HBX ECO-1000 Wiring Diagram (2stg)
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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
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Pool & spa heating
Domestic water heating
Snow melt
Process water chilling
Ice storage or Ice arena’s
Waste heat recovery
Simultaneously heating & cooling
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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.
Thank You!!!