HTP Drain Back, Installation, Start-Up, Maintenance, Parts, Warranty

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lp-585 Rev. 000 Rel. 001 Date 9.10.18
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solar hot water heaters provide a backup when solar contribution is
limited due to adverse weather conditions.
Do not introduce HTF into any fittings on the heater except those
clearly marked for that purpose.
B. System Design
System design should be completed prior to installation. Solar
collectors need to be installed correctly to ensure high efficiency and,
most importantly, safe and reliable operation. Please seek professional
advice for the design and installation of your solar heating system.
NOTE:
Only authorized licensed contractors are permitted to install
the solar collector.
C. Solar Collector Installation
NOTE: These solar collector instructions are general in nature.
Reference the solar collector manufacturer’s instructions for more
specific and detailed installation information.
The solar collector installation contractor shall obtain all required
permits and approvals when installing the solar system. The installation
shall conform to all federal, state and local regulations governing
solar water heating system installations. The contractor shall adhere
to sound building safety and trade practices. Special consideration
must be given to building code requirements for the penetration of
structural members and fire rated assemblies.
All persons working on roofs should have completed a fall safety
course and must be properly outfitted with appropriate safety
equipment. Failure to follow this information could result in property
damage, severe personal injury, or death.
Before installation, the contractor shall inspect the condition of
the roof and notify the homeowner of any existing roof damage or
necessary repairs. The most important structural consideration is to
securely anchor the solar collector and solar strut mounting hardware
to the structural members of the roof with stainless steel hanger or lag
bolts. Consult with the collector manufacturer installation manual for
proper guidelines in your application.
Solar collectors should be covered at all times until installation is
complete. Failure to follow this information could result in severe
personal injury or death.
Preserving the integrity of the roof membrane is the most important
roofing consideration. Ensure that all roof penetrations required to
plumb and mount the solar collector are properly flashed and sealed
in accordance with standard roofing practices. The recommended
elastomer for sealing roof penetrations is Tremco “POLYroof”.
D. Collector Angle, Plane, and Direction
1. Collector Direction
The collector should face the equator. In the northern hemisphere,
this is due south, and in the southern hemisphere, due north. Facing
the collector in the correct direction and angle is important to ensure
optimal heat output. A deviation of up to 15
o
from due south is
acceptable, and will have minimal effect on heat output.
Figure 1 - Suggested Solar Collector Mounting Designs
2. Collector Angle (Tilt)
It is common for collectors to be installed at an angle that corresponds
to the installation latitude. While adhering to this guideline, an angle of
la/- 10
o
is acceptable, and will not greatly reduce solar output.
The solar collector should be installed at an angle between 20 – 80
o
to
ensure optimal operation.
For year-round domestic hot water, the collector should be tilted to
an angle of equal to the latitude of the installation site. Add 15
o
to
3. Collector Plane (Horizontal or Vertical)
The collector could be installed vertically, but may be installed at an
angle, such as sideways on a pitched roof. It is not recommended
to install a drain back system in the horizontal or landscape style.
In vertical installations, collectors may be installed with 1/4” pitch
towards the supply port to facilitate the drain back process.
E. Collector Piping
Collector piping in drain back systems may be constructed of
copper and brass fittings, or PEX.
Systems Piped in Copper
To avoid leaks and fluid loss, copper and brass ground joint unions
should be used to join the collectors. Use only lead-free solder.
Engelhard Silvabrite 100 or equivalent is the required soldering
material. Use of 50/50 lead solder is expressly prohibited. Use of
galvanized steel, CPVC, PVC or any other nonrated plastic pipe is
prohibited.
Systems Piped in PEX
• The PEX shall not be exposed to sunlight.
• Drain back systems employing PEX shall be non-pressurized
(capped at atmospheric on the day of installation) or the
system shall be vented to the atmosphere.
• At the inlet and outlet of the collector(s), a length of
uninsulated copper tube of no less than ¾” nominal
diameter shall be used for a distance of no less than three
feet before the conversion to PEX for the return line is made.
• Connections in the PEX piping runs to and from the collectors
shall use only those fittings supplied and/or approved by
the PEX manufacturer for potable water piping.
• The systems shall have a pressure-only relief valve installed
at the drain back tank location or the tank shall be vented to
the atmosphere. The pressure rating for this valve shall be
no less than 25 psi and no more than 50 psi.
Never use dielectric unions or galvanized steel fittings in the
collector loop. Doing so will lead to corrosion, property damage,
and possible early water heater failure. Such damage IS NOT
covered by warranty. Use only copper and brass fittings.
the latitude to optimize for winter performance (space heating).
Subtract 15
o
from the latitude to optimize for summer performance
(indirect pool heating).
Given the formula above, a solar collector installed at 30
o
N latitude
should face due south at an angle of 45
o
for wintertime advantage,
and 15
o
for summertime heating.