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Fully automatic radiator de-aeration valves



Aladdin Autovents automatically bleed air and improve efficiency of radiators, heating systems and underfloor heating networks.

  • No need to manually bleed radiators
  • Keeps radiators and heating systems fully heat generating and efficient
  • Drains air from underfloor heating networks
  • Reduces heating costs
  • Avoids tenants calling out service engineers just to vent radiators

Aladdin Autovents are loved by homeowners and landlords.
More than 10 models of Autovents are available to suit different types of radiators and heating systems. They also include high quality designer Autovents and bespoke versions for specialist applications. They offer a stylish and efficient alternative to having to manually expel air from radiators.
Aladdin Autovents improve overall heating system efficiency. A standard radiator with just 2” of air can be up to 75% inefficient.

Fully automatic radiator de-aeration valves
Loved by landlords and homeowners

  • • no more manual venting
  • • keeps the radiators hot to the top
  • • no gas = reduced corrosion = extended component life
  • • avoids cost of tenants calling out services engineers just to purge radiators
  • • Save heating and energy costs by optimising radiator efficiency
  • • Radiator manufacturers now offering as optional extra

Sizes to fit –
1/2”, 1/4”, 1/8”, 6mm and 6mm Barlo type,
for radiators, towel rails and UFH,
Operating pressure 16 bar @ 120 °C.
Lifetime leakfree guarantee,
5yr operating guarantee.

Aladdin Autovent technical data


Aladdin Autovents save energy, keeps radiators hot to top,reduce corrosion and system noise, and dispense with the need for radiator keys.


Landlords like them:

As they reduce the risk of damage caused to systems by tenants failing to bleed air from radiators, as well as the cost of call-outs from those tenants who call out service engineers when air builds in a radiator.


For installed “problem” radiators:

Often systems have a problem radiator in which air collects; most often the towel rail. The symptoms are a cold top bar and the noise of bubbling water. The correct Aladdin product (check the thread size of the radiator) can be installed without draining the system. Just shut off the two water valves, release the pressure in the radiator via the existing manual vent, and use a spanner to take out either the manual vent or the blanking plug before installing the Aladdin valve. Open the water valves and the radiator will then bleed itself.


For new installations:

An increasing number of professionals believe Aladdin’s Hygroseal™ products more than pay for themselves in time-saved in new installations. The installation of new or replacement radiators traditionally has required the time consuming task of running from radiator to radiator to bleed air out as the system refills. Further, water out of the tap contains about 17% air by volume which separates naturally within the system over time and, in a system without Aladdin’s valves, would necessitate the regular bleeding of radiators for the first two weeks of operation at least. Some installers now fit Aladdin’s products on every radiator they fit to save time and money.

Although a perfectly designed and engineered central heating system should not collect air from outside the closed system:

  • New water out of the tap contains about 17% absorbed air by volume, which must be drained off from a closed central heating system as and when it separates;
  • Not all systems were perfectly designed in the first place, and many systems have been adapted with, e.g. new radiators fitted;
  • Many plumbers think that some compression and press-fit plastic fittings can suck in air on the suction side of the pump;
  • Corrosion in the system, e.g. inside pressed steel radiators, can result in the formation of gasses.

Fitting Aladdin Autovents helps by automatically eliminating gas and air from radiators which increases the efficiency of central heating systems from two perspectives:

Fitting Autovents extends the effective life of systems components: Autovents automatically bleed air and gasses from radiators which reduces corrosion and its consequence, the formation of sludge, which in turn extend the life of pumps, automatic valves, etc.

Because fitting Autovents reduces the volume of air/gas in radiators it helps maintain their thermal efficiency, therefore reducing the fuel requirement.

Technical Spec

The Standard mechanism that operates all of Aladdin’s Autovent range is identical, with the only variation from Standard being the Low Temperature mechanism that was developed for under-floor heating manifolds.

All Aladdin valves have exactly the same operating characteristics. The only operational difference between the Standard and the Low Temperature models is the temperature that the valve will start to operate at: about 30°c for the Standard, and 20°c for the Low Temperature mechanism.

How the Standard mechanism works:

On the first fill, gas (air) passes quickly through the valve until water hits the mechanism. The water causes the special hygroscopic washers in the valve to expand which forces the plastic washer and its EPDM seal to seal against the bottom, shutting the valve off.

On the first fill only, it is usual to see a drop of water on the cap of the valve.
When the radiator turns on, the temperature of the Autovent raises, the water absorbed in the hygroscopic washers evaporates through the 6 holes in the cap (see table below for vent times). If in the meantime gas has built up in the radiator, the gas will slowly and silently seep through the valve mechanism until water again touches the bottom of the hygroscopic washers which will expand and shut the valve immediately. This action NLB guarantees to operate for 5 years.

The speed of vent cycle varies with temperature and pressure; at higher temperatures and pressures the vent cycle is faster.

These tables relate to a 1 bar pressure cycle.

Standard Autovent
Temperature °C 40 50 60 70 80 90
Vent Time (hrs) 6 5 3 1.5 1 0.5

Low Temperature Autovent

Standard Autovent
Temperature °C 20 30 40 50
Vent Time (hrs) 13 4.5 2.5 2


After 5 years the radiator may again collect air in which case the cartridge has come to the end of its operating life and requires replacement. Autovents have a 5 year operating guarantee*, and a lifetime leakfree guarantee
*HV30 UFH version has 3 year operating guarantee, and a lifetime leakfree guarantee

Autovents are guaranteed for 5 years.

  • The valves are fully automatic, requiring no manual adjustment, and will not leak in the unlikely event of failure as a Patented backup failure safety mechanism is incorporated.
  • They work when fitted at any angle.
  • Their one–way valve makes them suitable for use with radiators which can cycle into negative pressure, typically loft conversion radiators or on the suction side of the pump.
  • The innovative Hygroseal™ technology (Patent protected) utilises a ‘dual-seal positive valve closure’ which provides an extended, leak-free life.
  • Installing the valves is a simple DIY job that doesn’t require system draining, a ‘less than one minute’ operation.
  • Seals: The ½” BSP versions have EPDM O-ring seals which are sufficient, though some fitters prefer to use some plumbers tape. Micro versions generally require some plumbers tape to fit.
  • Operating pressure: to 10 bar.
  • Operating temperature: to 120°C.


How do I find out the size of my radiator tapping?

With a 1/2″ BSP thread, the threaded hole in the tapping at the top of the radiator is approximately 20mm diameter – you should be able to fit your index finger in the tapping. The plug screwed in to the tapping will either be a chrome hexagonal valve, or a ‘plug’ with a square cavity in it. If you are uncertain or for smaller tappings please contact your radiator’s manufacturer.

Can I fit Autovents to a new system?

Yes, on newly installed closed systems there will be a small pressure drop over the first 2 weeks or so as dissolved air separates from the fresh water (around 17% by volume), but any further pressure drop would be due to loss of system water (leaks). Some installers are priming a newly installed system to about 10% more than its operating pressure to compensate on a system fitted with Autovents.


What if the Hygroscopic™ Autovent is not venting?

The first time radiators fitted with these Hygroscopic™ Autovents are filled the air hisses out until water hits the hygroscopic washers and then they seal (you will often see a small ‘bubble’ of water after the first fill). If more air/gas builds up in the radiator, it will not escape until the hygroscopic washers have dried a little and have shrunk enough for gas/air to escape. The time it takes for the hygroscopic washers to dry and shrink varies according to ambient temperature and humidity: see the table in the Technical Details on the Product Page. So please, give this valve time to dry, before contacting us.

Can I vent the Hygroscopic™ Autovent manually?

Yes. Cartridge version: by loosening the cartridge slowly until you can hear gas/air escaping.
Cartridge-free version: by using a spanner to loosen the whole valve slowly until you can hear gas/air escaping.

Air collecting in a radiator can be an early indication of a leak in the central heating system. Should I be worried that fitting an Autovent will mean that I spot a leak later?

On a pressurised system:

Air can enter the system through micro-gaps in joints etc., without a leak, but in some cases a leak could lead to air collecting in one radiator, and in those cases fitting an Autovent might delay the identification of a leak. On such systems, NLB recommends that Autovents should be fitted to installed radiators that have a history of collecting air, and only after a careful inspection of the system has not identified any leak.

On a header-tank system:

After the air absorbed in the water has separated, the best early indicator of a leak is a drop in pressure of the system, and an Autovent should, if anything, lead to a faster drop in pressure so an even earlier indication of a leak.

When do I know when to replace my Hygroseal cartridge?

If after a minimum of 5 years, the radiator starts getting cold at the top, the cartridge may require replacing in order to continue venting automatically. It is worth manually venting in case it is simply a case of the radiator running cool for a long period, and then seeing if the valve starts venting automatically again.

Can I fit the valve to a piping ‘spur’ at a system high – point?

Yes, provided the temperature of the piping allows the valve to operate at 35°C for the Hygroseal vent.

Does the Autovent work on Closed and Open systems?

Yes, on newly installed closed systems there will be a small pressure drop over the first 2 weeks or so as dissolved air separates from the fresh water (around 17% by volume) , but any further pressure drop would be due to loss of system water (leaks). Some installers are priming a newly installed system to about 10% more than its operating pressure to compensate on a system fitted with Autovents.

On a Closed system will fitting automatic vents cause the pressure to drop to zero and the boiler stop operating?

The answer is linked to the above – continual venting will be due to new air entering the system (through micro-gaps in joints etc.). Once the fresh water has vented its 17% of absorbed air the volume of water cannot further reduce in size – so if you still experience pressure drop it’s due to water loss, i.e. a leak, which will require to be cured.

Can the valves work on negative pressure systems?

On about 1 in 400 systems air may be drawn in to the system where either (a) there is a radiator close to the suction side of the pump or, (b) where a radiator is higher than the water tank, in which case when the pump stops running a vacuum forms (e.g. in loft conversions).
The Hygroseal valve has a semi-one way valve fitted already as standard, and will work on negative pressure systems.

Don’t all automatic de-aeration valves leak?

No. Aladdin Autovents do not leak. They are guaranteed to operate for 3 years, and guaranteed leak-free for life. They contain a patented mechanical valve that positively closes when water gets to the internal mechanism of the valve. The Hygroseal™ range has a 5 year replacement guarantee.

Can corrosion inhibitors be used with an Autovent?

Yes. Fitting the Autovent should reduce the need for corrosion inhibitors as all your radiators will be free of air, but we do recommend their use because corrosion leads to further gas collecting in the radiators. To allow inhibitors to be used ensure at least one radiator still has a manual vent plug fitted at the opposite end to an Autovent, as this will allow the inhibitor to be injected.

Can leak-stop products be used with the Autovent?

Leak-stop products can jam valves in certain circumstances.
We do not recommend their use.

Product Range

Product NLB Code Pack Qty Outer EAN
Aladdin Autovent 1/2″ BSP Chrome – 1 Pack HV30-1 HV30C-1 Each 5 5060123340044
Aladdin Autovent 1/2″ BSP Chrome – 2 Pack HV30C-2 HV30C-2 2 5 5060123340204
Aladdin Autovent 1/2″ BSP Chrome – 10 Pack HV30C-10 HV30C-10 10 5 5060123340211
Aladdin Autovent 1/2″ BSP Chrome, Plus 1/2″ BSP Blanking Plug HV30C+BP HV30C+BP 2 5 5060123340082
Aladdin Autovent Replacement Cartridge for HV30C HV30C-CART HV30C-CART Each 5 5060123340358
Aladdin Autovent 1/2″ BSP Chrome – 1 Pack (Non replaceable Cartridge) HV30-1 HV30-1 Each 5 5060123340273
Aladdin Autovent 1/2″ BSP Chrome – 2 Pack (Non replaceable Cartridge) HV30-2 HV30-2 2 5 5060123340280
Aladdin Autovent 1/2″ BSP Brass Finish – Fits into UFH Manifold (Non replaceable Cartridge) HV30-1 UFH HV30-1 UFH Each 5 5060123340860
Aladdin Autovent Micro 1/8 – 1/4″ ” BSP Chrome – 1 Pack (1 Micro plus 1 Bush) MICRO 1-8- 1-4 MICRO 1/8-1/4 Each 5 5060123340648
Aladdin Autovent Micro 6mm Chrome – 1 Pack MICRO 6MM MICRO 6MM Each 5 5060123340679
Aladdin Autovent Micro Barlo 6mm Chrome – 1 Pack (Fits Barlo/Quinn radiators) MICRO BARLO MICRO BARLO Each 5 5060123340808