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SFD Preheating Solar Water Heater with Copper Coil

SFD is a domestic solar water heater that actively performs natural circulation by virtue of the thermosiphon principle.
The water tank itself is not under pressure, but through the built-in copper coil in the water tank, the tap water is exchanged immediately for the purpose of utilizing fresh high-pressure hot water
  • SFD

  • Stainless Steel, Copper (heat exchanger), Polyurethane, Vacuum Tube

  • Using solar energy to make hot water

  • High pressure hot water , Low pressure water tank

  • 3 years

  • 15  18  20  24  30 

  • 150L  180L  200L  240L  300L 


1. Product Description

1.1 Overview


  • SFD is a domestic solar water heater that actively performs natural circulation by virtue of the thermosiphon principle. The water tank itself is not bearing any pressure, but through the built-in copper coil in the water tank, the running water is exchanged immediately for purpose of fresh high-pressure hot water.

  • SFD mainly consists of 5 models, 150L, 180L, 200L, 250L and 300L, to meet the needs of families in different regions.
  • In areas with low latitudes and high temperatures, such as Puerto Rico, Jamaica, Indonesia, etc., people directly use SFD solar water heaters for shower. However, in high-latitude and low-temperature areas, such as South Korea, Denmark, Poland, etc., people often use SFD products as preheating equipment, combined with gas water heaters, to provide medium-temperature hot water for bath, kitchen or heating floor heating.

1.2 Structure

SFD mainly consists of a hot water storage tank, copper(heat exchanger), glass vacuum tubes and frames.


1.3 Working Principle

The glass vacuum tubes absorb light energy through the AL/N/AL/SS/CU coating and converts the light energy into heat energy stored in the insulated water tank. The running water (cold water) is heated while passing through the built-in copper coil (heat exchanger) of the water tank, then high pressure hot water is coming out from outlet.


2. Features and Specifications

2.1 Features

  • The water tank has a built-in copper coil (heat exchanger) for secondary instant heat exchange. The difference between the hot water outlet temperature and the tank temperature is less than 2 °C. The hot water outlet pressure is high and equal to the tap water pressure. The copper coil test pressure is 0.9Mpa, but the water tank itself does not bear any pressure. The water tank is only used as a heat storage medium, and fresh hot water in the copper coil is used for dometic hot water directly. 


  • The inner tank  is made of food grade stainless steel SUSU304 by fully automatic argon arc welding and double-sided argon gas protection to effectively prevent the surface from being oxidized. Strict welding process control is better to protect the crystal structure of SUS304 from damage. The inner tank can be used for more than 15 years.

    Soldering video check here:


  • The solar water tank is made of polyurethane insulation, good process and thickness of 55mm to ensure that the temperature drop of hot water within 12H is less than 2°C.

  • Double-layer solar vacuum collector tube with AL/N/AL/SS/CU coating, absorption rate >92%, reflectivity<8%. and service life 15 years.

  • It can be combined with gas, electricity and other energy sources and can automatically control automatic switching.

2.2 Specification

The SFD series mainly has models, 150L, 180L, 200L, 250L and 300L, to suit the needs of families in different regions.


2.3 Size


SFD size

2.4 Optional Accessories

Water Supplier

Automatically add water in the tank.

Electric Heater

Auxiliary heating equipment.


Magnesium Rod

Anode protection, protect the inner tank from corrosion.

Thermostatic Valve

Automatically control the outlet temperature according to the setting.

3. Product Installation and Cases

3.1 Installation

  • SFD can be installed on the ground, on a flat roof or on a sloping roof. The frames are fixed connected with base (ground or roof).

  • Installation and use steps: Select the installation location, assemble frames, place tank on the tank holder, install glass solar vacuum tube, connect hot and cold water pipe, supply water, make inspection, fix the screws, use in normal, make regular inspection and maintenance.

    Please check here for installation methods and steps:

3.2 Cases


4. Warranty and Certificate

  • 1st sunflower has passed certifications from different quality management systems and  product testing institutions. such as ISO9000, CE, Solarkeymark, SRCC, BV, SGS, Watermark etc.
  • Solar vacuum tubes and frame: 5 years.
  • Water tank: 3 years.

5. Packaging and Transportation

  • The solar vacuum tube with heat pipe is packed in carton, and the carton is equipped with anti-pressure foam. We will add plywood cases extraly for package of goods under LCL shipment.
  • The package design can be stacked and stored, but the base layer should be flat and evenly stressed. The maximum stacking level of the solar vacuum tube is 17 levels.

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