Philips NA551/00 Steam & Split Capacity Explained

The Philips NA551/00 is a steam iron with a split water tank that lets you switch between a large 300 ml main tank and a smaller 100 ml quick-fill tank. It delivers a continuous steam output of 25 g/min and a steam shot of 150 g/min, making it suitable for everyday ironing of cotton, linen, and denim. This article explains how the split tank works, what the steam numbers mean, and how to get the best results from this specific model.

Formula

The calculator estimates total steam output and water consumption based on your ironing time and how often you press the steam shot button. The formula is:

Total steam (g) = (25 × t) + (150 × s × (t / 60))

• t = total ironing time in minutes
• s = number of steam shots per minute (0 to 5 typical)
• 25 g/min = continuous steam rate of the NA551/00
• 150 g = steam shot burst per press

Total water needed in ml equals total steam in grams because 1 g of water produces about 1 g of steam. The refills output divides that by the 300 ml main tank capacity and rounds up.

Worked Example

Using the default values from the calculator: 30 minutes of ironing with 3 steam shots per minute.

1. Continuous steam: 25 g/min × 30 min = 750 g
2. Steam shots: 150 g × 3 per min × 30 min = 13,500 g
3. Total steam: 750 + 13,500 = 14,250 g
4. Water needed: 14,250 ml (about 14.25 liters)
5. Refills of 300 ml tank: 14,250 / 300 = 47.5 → 48 refills

The calculator shows 48 refills for the default values. That high number assumes you press the steam shot every 20 seconds for the entire session – in practice, most people use the shot button sparingly, so actual water use is much lower.

How the Split Tank Works

The NA551/00 has two separate water chambers. The main tank holds 300 ml and sits at the back of the iron. A smaller 100 ml tank is integrated into the handle area. You fill the small tank directly from the tap without opening the main tank. When the small tank empties, you simply refill it – the main tank remains sealed and keeps supplying water through an internal valve.

This design addresses a common annoyance: stopping mid-iron to unscrew a cap and fill a large tank. With the split system, you can top up the small tank quickly, which is handy for touch-ups or when you only need to iron a few items. The main tank still provides the bulk of the water for longer sessions.

Steam Output: What the Numbers Mean

The 25 g/min continuous steam is the amount of steam produced steadily while you glide the iron over fabric. This is moderate – enough for most cotton and linen wrinkles but not for heavy denim or thick curtains. The 150 g steam shot is a burst of high-pressure steam released when you press the shot button. That burst helps with stubborn creases, vertical steaming (holding the iron upright), and thick fabrics.

For comparison, many basic irons offer 15–20 g/min continuous steam and 100–130 g shots. The NA551/00 sits in the mid-range. It is not a professional steam station (those often exceed 100 g/min), but it is above entry-level. The 150 g shot is the more useful spec for tough wrinkles.

Choosing the Right Water

Like most steam irons, the NA551/00 works best with distilled or demineralised water. Tap water contains minerals that can build up inside the steam chamber over time, leading to spitting, reduced steam, or brown stains on clothes. If your tap water is hard, mixing 50% tap with 50% distilled reduces scale. Do not use perfumed water, vinegar, or starch – these can damage the internal seals and void the warranty.

The small tank makes it easy to use distilled water for the quick-fill, but the main tank also needs the same treatment. Empty both tanks after each session to prevent standing water from growing bacteria or leaving deposits.

Common Problems and Fixes

• Iron spits water – Usually the soleplate is too cool. Set the temperature to at least 2 dots (cotton) before using steam. Also check that the tanks are not overfilled.
• Steam stops after a few minutes – The anti-calc filter may be clogged. Run the self-clean function (if available) or rinse the tanks with distilled water.
• Brown spots on clothes – Mineral deposits. Use distilled water and run a cleaning cycle. Do not iron over the spots; they can permanently set.
• Small tank leaks when filling – Make sure the cap is fully closed and you are not overfilling past the MAX line.

Cost and Energy Use

The NA551/00 uses about 2000–2400 watts when heating. That is typical for a steam iron. Running it for 30 minutes costs roughly the same as any other 2000 W appliance – you can check your electricity bill for the per-kWh rate. The split tank does not affect energy use; the heating element is the same as in single-tank models. The main cost over time is water treatment (distilled water) and occasional descaling solution.

Safety and Maintenance

• Always unplug the iron before filling the tanks.
• Never immerse the iron in water.
• Empty both tanks after use and store the iron upright.
• Use the self-clean function every 10–15 fills to remove scale.
• If the power cord is damaged, stop using the iron and have it repaired by a qualified technician.

Do not point the steam shot at people or pets – the steam is hot enough to cause burns.

Frequently Asked Questions

Can I use the small tank alone without filling the main tank?

Yes, the small 100 ml tank works independently. If you only need to iron one shirt, fill only the small tank. The iron will draw from it until empty, then you refill. The main tank only supplies water when the small tank is empty.

How long does the 300 ml tank last?

At continuous steam of 25 g/min, the main tank lasts about 12 minutes of steady steaming. If you use the steam shot frequently, that drops to 5–8 minutes. For typical ironing (not pressing the shot button constantly), expect 10–15 minutes per full main tank.

Is the NA551/00 good for vertical steaming?

Yes, the 150 g steam shot works for vertical use – hold the iron upright and press the shot button to remove wrinkles from hanging garments or curtains. The continuous steam is less effective vertically, so rely on the shot burst for that purpose.

Does the split tank make the iron heavier?

No, the total water capacity is 400 ml (300 + 100), which is similar to a standard single-tank iron. The weight when empty is about 1.2–1.4 kg, typical for a mid-range steam iron. The small tank adds negligible weight.

What fabrics can I iron with this model?

It handles cotton, linen, polyester blends, and denim. For silk and synthetics, use the lowest temperature setting and minimal steam. The soleplate is non-stick, so it glides smoothly over most fabrics. Always check the garment label first.

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in t | Total ironing time | min | 30 | 0
in s | Steam shots per minute | - | 3 | 0
out steam | Total steam used | g | (25 * t) + (150 * s * (t / 60)) | 0
out water | Water needed | ml | (25 * t) + (150 * s * (t / 60)) | 0
out refills | Refills of 300 ml tank | - | ceil(((25 * t) + (150 * s * (t / 60))) / 300) | 0