FAQs Aladdin Autovent


Fitting Aladdin Autovents to radiators helps increase efficiency by eliminating gas and air from radiators automatically.
Aladdin Autovents reduce the volume of air/gas in radiators and helps to maintain their thermal efficiency, thereby reducing the fuel and energy usage.

This guide should answer most questions asked regarding the Aladdin Autovents.

1)   How do I find the correct sized Aladdin Autovent valve for my radiator? 

Thread ½” BSP (20.8mm outside diameter approximately)
The standard radiator tapping size for Panel Radiators and Towel Radiators (80% of market) is the ½” BSP tapping.

½” BSP (British Standard Pipe) plumbing thread allows a ½” tube to pass inside the thread which approximately has a 20.8 mm outside thread on it. The inside is around 18.6 mm and inside that size a ½” 12.7mm pipe will pass.

Aladdin Products now make a few ½” BSP models of Autovent.

The first model, the HV30C, is designed as the top of range model that has a cartridge system. This provides for the cartridge to be removed at the end of the cartridge’s life. This alleviates having to remove the entire valve and change it after 5 years. However, you just need to change the lower cost cartridge.

The cartridge also provides for manual override. If you want to drain the system or need to manually vent, then using the U key you can open the vent approximately ‘one and a quarter turn’ and the valve will vent.

The HV30 model or OEM model (Original Equipment Manufacturer) is a lower cost ½” BSP version with exactly the same mechanism inside, lasting the same amount of time.

For this model and all other models to manually vent, you need to unscrew the entire valve half a turn. At the end of life, you switch off the radiator valves and remove the valve.

There is also a circular ½” BSP valve (Antrax) which has 3 side ports that allow a U key to be used to rotate the valve and screw in/unscrew from a radiator.

Thread 1/8” BSP –  9.8mm approx (outside diameter)
This is the 1/8” BSP model. We provide a 1/8” Micro model that will fit cast Iron ‘School Type’ radiators (made in cast iron or aluminium section).

Our 1/8” BSP comes with a ¼” chromed adaptor which is 1/8” BSP on the inside and ¼” BSP on the outside.

¼” BSP is approximately 14.5mm. If you use the ¼” BSP thread for your radiator, then it will need PTFE tape fitted on the outside of the bush.

Thread 6mm approx (outside diameter)
We have two 6mm models. One is called the Micro Barlo which has an extended length thread and a conical tip. The other is the Micro 6mm which has a short 6mm thread.

The Micro Barlo fits ‘Roll-Top’ radiators. These have a rolled over steel smooth top to the radiator panel. The left and right edges are welded seams. One model has the bleed pin facing to the wall and on a double panel a second bleed pin also faces outwards.

A CenterRad Centerbrand radiator has a little well on the end of the roll top radiator facing end out from the radiator. This also uses the Micro Barlo. This valve needs no oring seal but seals on the cone end of the valve stem.

The Micro 6mm with the short thread fits towel radiators that have a 6mm nut welded to the top at the back. The valve uses an oring (provided) that seals onto the nut.

Thread 5mm approx (outside diameter)
We have a Micro Barlo 5mm which has an extended length thread and a conical tip.

The Micro Barlo 5mm fits the Cotswold Classic type of panel in tubular bathroom radiators. These valves are fitted in an upward direction deep into the horizontal tube. There are other bathroom thick tube radiator that it fits to.

Thread 5mm approx (outside diameter)
We have a Micro Barlo 5mm which has an extended length thread and a 60° conical tip.

The Micro Barlo 5mm fits the Cotswold Classic type of panel in tubular bathroom radiators. These valves are fitted in an upward direction, deep into the horizontal tube. There are other bathroom (thick tube) radiators that it fits.

This model also fits the old Myson radiator that is 4.8mm and was 1/16” BSP.

Thread 7mm approx (outside diameter)
We have a Micro 7mm which has a short thread that fits the CenterRad radiator where the tapping is at 45° to the radiator.

2)   How do the Autovents work?

Click here to view how the HV30 Autovent works

3)   How long do the Autovents Last?

Aladdin Autovents are guaranteed for 5 years but usually last considerably longer.  

4)   How do I know when my Autovent needs to be replaced?

Once your radiator begins to feel cold at the top, air has begun to build and the Autovent needs to be replaced. Our Autovents have a unique patented design which means at the end of the product life they will seal shut.

5)   Don’t all Automatic De-aeration valves leak?

No. Aladdin Autovents do not leak. The Hygroseal™ range is guaranteed to operate for 5 years and guaranteed leak-free for life.  All Aladdin Autovents contain a patented mechanical valve that closes to a water-proof seal when water gets to the internal mechanism of the valve.

6)   Can I fit Autovents to a new system?

Yes. Further, there will be significant time saved on installation by eliminating the need to visit each radiator as the valves close automatically when the radiator is full of water.  NLB recommends a final visual inspection to check for system joint leaks, but next-day, or next-week visits to bleed the radiators will be unnecessary.

7)   Do Autovents 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 100% more than its operating pressure to compensate on a system fitted with Autovents.

8)   On a closed system, will fitting automatic vents cause the pressure to drop to zero and the boiler stop operating?

No. Hygroseal™ incorporates as standard a semi-one way valve (patented) which shuts the valve and does not allow water to egress.  This functionality is tested up to 10 bar pressure (with domestic heating systems operating at c. 1.6 bar).  Once the fresh water has vented its absorbed air, the volume of water cannot further reduce in size.

If a system continues to lose pressure after the first 2 weeks or so of being filled, this can only be due to water loss, i.e a leak.

9)   On a Closed system, can a radiator continue to collect air without there being a water leak?

Yes, this is possible.  Some plumbers suggest that on the suction side of the pump micro-gaps in joints could allow air ingress, yet when the pump is off (and the pressure equalises to the c. 1.6 bar of normal operation) the micro-gaps are too small to allow water egress.

10)   Can corrosion inhibitors be used with an Autovent?

Yes.  Fitting the Autovent should reduce the need for corrosion inhibitors, but we do recommend their use because corrosion leads to further gas collecting in the radiators.

11)   Can leak-stop products be used with the Autovent?

Leak-stop products can jam valves, so NLB does not recommend them.

What if the Autovent is not venting? (see also Troubleshooting Autovents)
The first time radiators fitted with Hygroseal™ 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 washers to dry and shrink varies according to system pressure, temperature and humidity.

12)   Can I vent the Autovent manually?

Yes.  Cartridge version: by loosening the cartridge a little & slowly until you can hear gas/air escaping.  For non cartridge versions, unscrew the Autovent.

13)   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™ Autovents.

14)   Can the valves work on negative pressure systems?

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).

Yes, The Hygroseal™ Autovents has a semi-one way valve fitted as standard and will work on negative pressure systems.

15)   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 as in Q10 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. The autovent can also be re-set by gently pressing a straightened paper clip into the hole on the reverse of the valves.

16)   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 the leak later?

On a Closed, pressurised 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. An Autovent should, if anything, lead to a faster drop in pressure so an even earlier indication of a leak.

On a header-tank 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. 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 if no leak in the system has been identified.

17)   Is the Autovent guaranteed?

Yes, the Autovent is guaranteed.
The guarantee is subject to proof of purchase being supplied. This guarantee does not affect any statutory rights the consumer may have in law. For further information regarding the terms and conditions of the Autovent guarantee please Click Here.