Stainless Steel Low Pressure Solar Water Heater with All Accessories

A stainless steel low pressure solar water heater is a compact, non-pressurized thermosyphon system that uses a food-grade SUS304 stainless steel tank, high-borosilicate vacuum tubes, and a stainless steel bracket to deliver reliable domestic hot water with no pump, no controller, and no electricity required for the primary circuit. When supplied as a complete package with all accessories — assistant tank, electric backup heater, magnesium rod, controller, silicone seals, stainless bolts, and ventilation caps — it becomes a truly plug-and-play solution for distributors, importers, and brand owners targeting residential and light commercial markets.

This guide consolidates verified manufacturer specifications, the all-accessories package, FOB pricing, and a buyer FAQ to help you source with confidence.

How a Low Pressure Solar Water Heater Works

The system operates on the natural thermosyphon principle:

1. Borosilicate glass vacuum tubes (Φ58 × 1800 mm) with three-target CU/SS/ALN selective coating absorb sunlight and convert it to heat.

2. Water inside the tubes heats up, becomes less dense, and naturally rises into the storage tank above.

3. Cooler, denser water from the bottom of the tank flows down into the tubes, creating a continuous natural circulation loop.

4. The SUS304 stainless steel tank with 50–55 mm polyurethane insulation retains heat for 72 hours.

5. Hot water exits under gravity pressure, determined by the height difference between tank and outlet — approximately 0.1 bar per meter of elevation.

Critical installation rule: the tank must be installed above the collectors for thermosyphon to occur. Pressure is gravity-fed only (max 0.06 MPa / 0.5–1 bar), making these systems ideal for rooftop installations where the tank sits 3–10 meters above the taps.

What "All Accessories" Actually Includes

A truly complete low pressure solar water heater package from a verified Chinese manufacturer includes:

Standard (Always Included):

• SUS304-2B stainless steel inner tank (0.4–0.6 mm)

• SUS304 or SUS201 stainless steel outer tank (0.4 mm)

• 50–55 mm high-density polyurethane foam insulation

• Φ58 × 1800 mm three-target vacuum tubes (quantity by capacity)

• Stainless steel SUS201 bracket (1.2 mm) or galvanized steel (1.5 mm)

• Stainless steel bolts and nuts (SUS304)

• Water-proof silicone rubber seals

• Anti-aging dustproof rubber seals

• Plastic pipe holders

• Ventilating cap (air vent)

• 3/4" or 1/2" SUS304 inlet/outlet connections

• Stabilized high-temperature silicon seal material

Optional Devices (Configure Per Market):

• Assistant tank (3L / 5L / 8L / 12L / 30L) — automatic cold water feed

• Electric backup heater (1500W / 220V or 110V / 50–60Hz)

• Intelligent controller (TK-7 / TK-8A) — water level and temperature display

• Magnesium anode rod — anti-corrosion for hard water regions

• Booster pump — for areas with unstable water supply or insufficient height differential

• Reflector — aluminum component for enhanced winter performance

• Thermostatic mixing valve — temperature regulation at outlet

• T/P (temperature & pressure) relief valve — safety at 4 bar / 90°C

• Non-return valve and ball valve — system isolation

Standard Technical Specifications

Based on verified manufacturer data from ImpoSol, INLIGHT, Qirui, Volchi Solar, and Sunseason:

Capacity, Tube Count, and Container Loading

Based on ImpoSol IPJG-SS series verified data:

FOB Price Reference

Based on verified manufacturer quotations from INLIGHT, Sunseason, Volchi, TradeWheel, and ImpoSol:

• All stainless steel low pressure evacuated tube system (INLIGHT ILND series):​ FOB US$138–330/set

• 20-tube low pressure stainless steel system (Sunseason YJ-20SS1.8-H58):​ FOB US$190–200/set

• 16-tube low pressure stainless steel (Sunseason YJ-16SS1.8-H58):​ FOB US$145–160/set at 5+ sets

• Compact low pressure galvanized steel (INLIGHT):​ FOB US$117–130/set at 50+ sets

• Non-pressure stainless steel solar water heater (TradeWheel/Haining Sanneng):​ FOB US$78.8–198/set

• Rooftop low pressure stainless steel (Jiangsu Audary):​ FOB US$70–198/set

Final FOB pricing depends on inner tank thickness, outer tank material (full SUS304 vs. SUS201 vs. galvanized), bracket material, insulation thickness, accessory package, certification requirements, and order volume. Full all-stainless-steel construction with complete accessory package commands premium pricing within these ranges.

Why Low Pressure Systems Win in Emerging Markets

The low pressure non-pressurized unit is the volume leader for several reasons:

• No freezing concerns in most populated regions of Africa, Middle East, Latin America, South Asia, and Southeast Asia

• Simplest installation — compact integrated design, no pump, no controller, no electrical connection

• SUS304 corrosion resistance ensures 15+ year lifespan even in coastal humidity

• Thermosyphon reliability — no moving parts means minimal warranty claims

• Significant energy savings — 70–90% solar fraction in sunny climates; 50–70% in moderate climates

• Long service life — 20–25 years typical for complete system

• Continued operation during water supply interruption (stored water reserve)

• All-accessories package enables immediate installation without separate procurement

Advantages and Limitations

Advantages

• Continued operation during water supply interruption

• High efficiency: peak 70–75%, annual 55–65%

• Long service life: 20–25 years typical

• Significant energy savings: 70–90% solar fraction in sunny climates

• Lower initial cost compared to pressurized systems

• "Install and forget" — SUS304 tank requires no anode rod replacement

• All accessories included for a complete turnkey package

Limitations

• Low water pressure, especially on upper floors (gravity-fed only)

• No freeze protection — not suitable for sub-zero climates without draining

• Variable water temperature during draw

• Rooftop installation creates pressure issues in multi-story buildings

For multi-story buildings or applications requiring mains pressure, consider a pressurized heat pipe system or copper coil pre-heating system instead. A booster pump ($500–1,300) can solve pressure issues but adds cost and complexity.

Suitable Markets and Applications

FAQ for International Buyers

1. What is the FOB price for a low pressure all-stainless-steel 200L unit with all accessories?

FOB pricing ranges from US$78.8–330/setdependingonconfiguration.A200Lall-SUS304systemwithfullaccessorypackagetypicallyfallsintheUS$190–200/set range at volume (Sunseason YJ-20SS1.8-H58). Sample orders at the higher end; container orders at the lower end.

2. What exactly does "all accessories" include?

Standard accessories included: stainless steel bolts and nuts, waterproof silicone rubber seals, dustproof rubber seals, plastic pipe holders, and ventilating cap. Optional accessories available: assistant tank (3–30L), electric backup heater (1500W/220V or 110V), intelligent controller, magnesium anode rod, booster pump, reflector, thermostatic mixing valve, T/P relief valve, non-return valve.

3. Is the whole system stainless steel?

The inner tank is always food-grade SUS304-2B stainless steel. For a fully stainless steel unit, specify SUS304 or SUS201 outer tank and SUS201 bracket in your inquiry. Many configurations pair SUS304 inner tank with SUS201 outer/bracket or galvanized steel to optimize cost. Full SUS304 construction delivers maximum corrosion resistance for coastal environments.

4. How many vacuum tubes does a 100L unit have?

10 × Φ58×1800mm vacuum tubes for 100L capacity. The tube count scales with capacity: 15 tubes for 150L, 20 tubes for 200L, 30 tubes for 300L, 36 tubes for 360L.

5. How many units fit in a container?

ImpoSol IPJG-SS series 40HQ loading: 80L = 194 sets, 100L = 172 sets, 120L = 150 sets, 150L = 125 sets, 200L = 96 sets, 240L = 82 sets, 300L = 68 sets, 360L = 57 sets.

6. Does it work in cloudy weather?

Yes. The high-efficiency vacuum tubes capture diffuse radiation. On clear sunny days: 100% abundant hot water; partly cloudy: 50–70% adequate with backup; overcast: 20–40% requires electric backup. The optional 1500W electric heater ensures continuous supply.

7. Can it handle hard water?

SUS304 stainless steel resists calcium scaling well. For hard-water regions, specify a magnesium anode rod and schedule periodic descaling every 3–5 years. The anode rod prevents corrosion and scale buildup on tank walls.

8. What certifications are available for my market?

Baseline: CE, ISO9001, CCC. Market-specific: Solar Keymark (Europe, EN12976), SRCC (North America), INMETRO (Brazil), SABS (South Africa). Qirui offers full Solar Keymark EN12976 certification.

9. How long does the system last?

Quality SUS304 inner tanks deliver 15+ years of service life. Vacuum tubes carry 15-year warranties. The stainless steel bracket provides decades of corrosion protection. Overall system lifespan: 20–25 years.

10. Is installation complicated?

No. The compact integrated design with all accessories enables simple plug-in installation on both flat and pitched roofs. No pump, no controller, no electrical work for the primary circuit (unless electric backup is specified). A qualified plumber can complete installation in 2–4 hours. The assistant tank automates water filling; the controller automates water level and temperature management.

11. What is the optimal bracket angle?

20°–50° adjustable. Choose the angle closest to your local latitude for optimal annual solar capture. Standard options: 25° / 38° / 45°.

12. Can the system integrate with existing solar PV?

Yes. The optional electric backup heater (1500W/220V) can be powered by surplus PV electricity, creating a hybrid solar thermal + PV system.

Why Source Low Pressure All-Accessory Systems from China

The stainless steel low pressure solar water heater with all accessories represents the optimal convergence of simplicity, material quality, and turnkey convenience. Chinese manufacturers have refined this product line for over 20 years:

1. Material expertise​ — Automated argon arc welding achieves consistent 0.4–0.6 mm SUS304 wall thickness with leak-free seams. Full SUS304 or SUS316L construction ensures 15+ years of corrosion-free operation.

2. Complete accessory integration​ — Unlike commodity suppliers who ship bare systems, verified Chinese factories include all necessary hardware: stainless bolts, silicone seals, dustproof rings, pipe holders, ventilating caps, and offer the full optional device menu (assistant tank, electric heater, controller, magnesium rod, booster pump, reflector).

3. Configuration flexibility​ — One factory can produce the full 50L–500L capacity ladder with 6–50 vacuum tubes, enabling distributors to build a complete product range under a single supplier relationship.

4. Certification readiness​ — CE, ISO9001, Solar Keymark EN12976, and CCC certifications are standard on production lines, eliminating 6–12 month certification timelines.

5. Scale economics​ — Production capacities of 5,000–8,000 sets/month drive FOB prices from US$78.8/set, enabling distributors to achieve 50–70% gross margins in target markets.

6. Export infrastructure​ — Established relationships with freight forwarders, familiarity with HS code 8419.12.0000 / 8419.19.10, and 12-day delivery after deposit.