lp-364 Rev. 000 Rel. 007 Date 2.12.18
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1. Open Loop Systems
Open loop systems have a check valve/non-return valve on the cold
main. Expanded water is released via the PTRV, which is mounted
on the tank or solar collector loop. To prevent wasteful dumping
of water, it is required to install a potable water expansion tank on
open loop systems.
2. Closed Loop Systems
Closed loop systems should always be installed with a solar
expansion tank. Refer to the solar expansion tank manufacturer’s
guidelines regarding correct sizing.
3. Drain Back Systems
Expansion tanks are not required in drain back system design.
L. Lightning Protection
To avoid lightning related damage or electrical safety issues, it is
advisable to earth/ground the frame and copper circulation loop of
the collector.
M. Pipe Sizing and Connections
HTP solar collectors are provided as standard with 1” copper pipe
ports. For domestic heating applications with 1 or 2 collectors,
nominal 1/2” piping is suitable. For applications using 2 - 4 solar
collectors in series, it is advised to use nominal 3/4” piping. For 5 – 8
collectors, use 1” pipe. For drain back systems, use 3/4” pipe for 1 – 4
collectors and 1” pipe for 5 – 8 collectors. In connections of banks of
collectors, larger pipe sizes should be used as required for the given
application, with consideration given to flow rates, pressure drops,
and pump sizing.
The material used for the solar loop must be able to withstand the
operating temperatures and pressures to which the system may
be exposed due to normal or extraordinary conditions (e.g. pump
failure or power outage). Copper or stainless steel pipe is the most
widely used piping material for solar applications.
N. Connection of Multiple Collectors
The maximum number of collectors that can be connected in
series is 8. If the entire installation requires more than 8 collectors,
use parallel strings of an even number. If even numbers cannot be
achieved on parallel strings, flow balancing valves must be installed
to ensure each collector has the same flow.
In drain back systems, supply and return connections to the collector
must use eccentric fittings or a fitting arrangement that allows full
draining of header pipes. The collector or array should be mounted
with a 1/4” pitch towards the supply port to facilitate the drain back
process. In addition, collector plumbing should slope toward the
drain back reservoir at 1/4” per foot minimum to allow the system
to drain. If continual slope is not achievable, consider a pressurized
closed loop system.
O. Potable Water
If the system is open loop direct flow, meaning that potable water is
flowing through the collector, any components used in the system
must meet potable water requirements.
P. Mounting Frame
Four mounting choices are available for HTP solar collectors: Tilt
mounts or 2/3 mounts, flush mounts, or rack mounts (see Part
4). Feet are supplied to fasten the panel securely to the roof. It is
important that frame attachment points and externally supplied
fasteners are of suitable structural strength and corrosion resistance.
Be sure to tighten all hardware securely.
Q. Galvanic Reaction
Zinc galvanized components should NOT be installed in direct
contact with stainless steel or aluminum, as galvanic reaction
between metals can cause premature oxidation of the zinc coating,
as well as the steel and aluminum underneath, leading to premature
solar system failure and property damage. Such damages ARE NOT
covered by product warranty.
Avoid using galvanized steel bolts. Use stainless steel components
instead. If galvanized components ARE used, avoid direct contact
between two metals by using rubber/plastic separators.
If roof surface is galvanized steel, refer to manufacturer’s corrugated
roof installation guidelines.
Part 4 - Mounting Installation
A. Mount Types
HTP offers three types of mounting assemblies.
1. Tilt Mount (Part # 8600P-002) or 2/3 Mount (8600P-691)
Tilt or 2/3 mounts are most commonly used on flat roofs. These
mounts can be adjusted to an angle to maximize collector efficiency.
HTP’s tilt or 2/3 mounts consist of four hinged triangle feet that, when
combined with a rear strut (Part # FP-ST), can create a panel tilt or
inclination of up to 60
o
. The rear strut determines the degree of tilt,
and can be cut to the appropriate size.
2. Flush Mount (Part # 8600P-012)
Often called direct mounts, flush mounts are often used on a sloped
roof that is within 15
o
of latitude. Flush mount feet raise the collector
3” from the mounting surface. If roof pitch is insufficient, a tilt mount
may be necessary.
3. Rack Mount (Part # 8600P-014)
Rack mounts are used to attach collectors to a metal frame (such as
Uni-Strut). These mounts can also be used to attach collectors directly
to the roof. However, this is unadvisable, as rack mounts install close to
the roof surface and allow collectors to collect leaves, snow, and other
debris.
B. General Mounting Information
Mounts should be attached to collectors as close to symmetrically
as possible. Mounting clamps should be attached to the collector
between 4” and 10” from corners if installed vertically, and 4” and 16” if
installed horizontally. See below for detail.
Figure 3 - Solar Collector with Acceptable Mounting Locations
Ensure the roof surface is solid and able to withstand in excess of
330 lbs of pull force that may be encountered during high winds.
Consult a structural engineer if in doubt. Failure to do so could result
in property damage, severe personal injury, or death.
