Stainless Steel Unpressurized Solar Water Heater 100L with Vacuum Tube

A 100L unpressurized solar water heater with vacuum tubes is the most popular entry-level SKU for residential solar thermal systems. It uses 10 high-boron silicate glass vacuum tubes (Φ58×1800mm) to absorb solar energy. The SUS304 food-grade stainless steel inner tank stores 100 litres of water, with a 50mm polyurethane insulation layer keeping water hot for up to 72 hours. The whole system operates on natural thermosyphon circulation—no pump, no controller, no electricity required for the primary circuit.

This guide consolidates verified manufacturer specifications, FOB pricing, export terms, and a buyer FAQ to help distributors, importers, and brand owners source with confidence.

How the Unpressurized Vacuum Tube System Works

The operation follows the natural thermosyphon principle:

1. Ten Φ58×1800mm borosilicate glass vacuum tubes with three-target CU/SS/AL coating absorb sunlight and convert it to heat.

2. Cold water from the bottom of the tank flows down into the tubes; as it heats, it becomes less dense and rises back into the tank.

3. This continuous natural circulation requires no pump, no controller, and no electrical input.

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

5. Hot water exits under gravity pressure, determined by the height difference between tank and outlet.

Critical installation rule: the tank must be installed above the collectors for thermosyphon to occur. Non-pressure systems rely on gravity pressure, so the tank should be positioned on the roof or at least 3–4 metres higher than the hot water tap.

Standard 100L Technical Specifications

Based on verified manufacturer data from Seven SS Stars, Sunrise, VISION, Haier, and Jiaxing Carrefour:

Specifications compiled from Seven SS Stars, Sunrise, VISION, Haier, Jiaxing Carrefour, and Linuo Ritter factory listings.

Tube Count and Capacity Mapping

It is important to clarify the tube-count relationship, as different manufacturers map tubes to capacity slightly differently:

Data from VISION VNS-SA series. Note: Sunrise SR-NC/NS-12 maps 12 tubes to 100L capacity, demonstrating manufacturer variation.

For the 100L capacity, 10 vacuum tubes​ is the most common configuration in the VISION, Seven SS Stars, and Linuo Ritter product lines.

FOB Price Reference

Based on verified manufacturer quotations from multiple sources:

• Ensun ENSUN-CNP100:​ US$66.70–87.00/set

• VISION VNS-SA100 (100L, SUS304 inner + outer):​ US$80–100/set

• Haining Yinuo 10-tube 100L:​ Starting at US$80/set FOB

• Jiaxing Carrefour 100L:​ US$69–199/set

• Haier GV100REMB (100L, brand name):​ US$130/setat100+piecesvolume;US$230/set at 2–19 pieces

• China-sups 100L compact (SUS304 inner + outer, 55mm insulation):​ US$160–200/set

Note: Final FOB pricing depends on inner tank thickness (0.31–0.58 mm), outer tank material (full SUS304 vs. colour-coated galvanized), bracket material, insulation thickness, certification package, and order volume. Full all-stainless-steel construction commands premium pricing within these ranges.

Why This Configuration Wins in Emerging Markets

The 100L unpressurized vacuum tube unit with SUS304 stainless steel 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

• Lowest landed cost per litre​ — FOB prices start at US$66.70/set

• SUS304 corrosion resistance​ ensures 10–15 year lifespan even in coastal humidity

• Thermosyphon reliability​ — no moving parts means minimal warranty claims

• Ideal household size​ — 100L suits 1–3 people, the dominant demographic in emerging residential markets

Suitable Markets and Applications

Export Terms Summary

• MOQ:​ 1 set for samples; volume pricing from 5–20+ sets

• Payment:​ T/T, L/C, Western Union, D/P, PayPal

• Incoterms:​ FOB, CIF, CFR, EXW

• Nearest ports:​ Shanghai, Ningbo, Qingdao, Tianjin

• Lead time:​ 7 days (sample); 7–15 days (full container)

• Production capacity:​ 3,000–9,000 sets/month per factory

• Spare parts:​ 1% free with bulk orders

• Warranty:​ 3–5 years comprehensive; 15 years on vacuum tubes

• 40HQ loading:​ 170 sets (VISION VNS-SA100)

Optional Accessories

• Assistant tank​ (3L/5L/8L) — automatic cold-water feed

• Electric backup heater​ (1500W/220V or 110V) — cloudy-day backup

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

• Intelligent controller​ — temperature and water level display

• Aluminium reflectors​ — boost winter performance

FAQ for International Buyers

1. What is the FOB price for a 100L unpressurized SUS304 unit?

US$66.70–100/setfromShanghai/Ningbodependingonconfiguration.All-stainless-steelconstruction(inner+outer+bracket)commandspremiumpricing.Sampleordersatthehigherend;containerordersatthelowerend.HaierbrandedunitsstartatUS$130/set for 100+ piece orders.

2. Is the unit truly "stainless steel"?

The inner tank is always SUS304-2B food-grade stainless steel. For a fully stainless steel unit, specify SUS304 outer tank in your inquiry. Many economical configurations pair SUS304 inner tank with colour-coated galvanized steel outer tank and bracket to optimize cost.

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

Most manufacturers (VISION, Seven SS Stars, Linuo Ritter) use 10 × Φ58×1800mm vacuum tubes for 100L capacity. However, Sunrise maps 12 tubes to 100L. Confirm the exact tube count with your supplier.

4. How many units fit in a container?

VISION VNS-SA100: 70 sets per 20GP, 170 sets per 40HQ. Exact numbers vary by packaging configuration.

5. Does it work in cloudy weather?

Yes. The high-efficiency vacuum tubes capture diffuse radiation. An optional 1500W electric backup heater ensures continuous hot water supply on overcast days.

6. 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.

7. What certifications are available for my market?

Baseline: CE, ISO9001, CCC. Market-specific: Solar Keymark (Europe), SRCC (North America), INMETRO (Brazil), SABS (South Africa). Mexican market requires NOM-027-ENER and NOM-001-SCFI compliance.

8. How long does the system last?

Quality SUS304 inner tanks deliver 10–15 years of service life. Vacuum tubes carry 15-year warranties. The galvanized steel bracket provides decades of corrosion protection.

9. Is installation complicated?

No. The compact integrated design enables simple plug-in installation on both flat and pitched roofs. No pump, no controller, no electrical work for the primary circuit. A qualified plumber can complete installation in 2–4 hours.

10. What is the optimal bracket angle?

20°/25°/27°/30°/38°/45° are standard options. Choose the angle closest to your local latitude for optimal annual solar capture.

Why Source This SKU from China

The 100L unpressurized vacuum tube solar water heater with SUS304 stainless steel represents the optimal convergence of simplicity, material quality, and market fit. Chinese manufacturers have refined this product line for over 20 years, with automated argon arc welding, high-pressure polyurethane foaming, and systematic OEM services ensuring consistent quality at scale.

For distributors, this SKU offers four compelling advantages:

1. Market-proven demand​ — 100L non-pressure units are the #1 volume seller in emerging markets

2. Differentiated quality​ — SUS304 construction commands premium margins over mixed-material competitors

3. Simplest after-sales​ — No pump, no controller, no electrical components in the primary circuit means minimal warranty claims

4. Competitive pricing​ — FOB prices starting at US$66.70/set enable distributors to achieve 50–70% gross margins in target markets