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XCCR vs. HH part 2 - does the better always have to be the enemy of the good?

In the first part of this article, in which I described the genesis of the X-CCR, I declared to describe the differences and similarities between the X-CCR and the HH. Why describe the differences and similarities and why in relation to HH? Here the answer is simple. I encounter many opinions about X-CCR, but generally
Published: September 2, 2015 - 15:48
Updated: July 22, 2023 - 11:32
XCCR vs. HH part 2 – does the better always have to be the enemy of the good?

In the first part of this article, in which I described the genesis of the X-CCR, I declared to describe the differences and similarities between the X-CCR and the HH. Why describe the differences and similarities and why in relation to HH? Here the answer is simple. I encounter many opinions about X-CCR, but generally all these opinions can be combined into two groups: the first group says “it is the same as HH”, or even “it is a copy of HH” and the second group says “it is something completely different than HH”. And to be honest they are all a little bit right.

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Let me refer here to a completely different market, namely the car market. Let’s take BMW as an example (the choice of the brand is accidental, maybe it was decided that BMW has models with “X” in their name;)). The factory decides to launch a new car model and withdraw one of the already produced ones. Naturally, both these models will be similar, and it may even happen that some of the parts will be practically identical. After all, production takes place in the same factory, so it is not surprising. On the other hand, so many changes have been made and the product has been upgraded that it differs significantly from its predecessor. To emphasize this, it gets a new name. Always in such cases arise all sorts of controversies and doubts such as whether these new solutions will work, because the old ones worked, whether it will be as reliable, etc.

And that is natural. You could say that this is the cost of progress. One thing is certain, that if any reputable company with experience introduces a new model, you can expect that it will keep all its previous quality standards and will not allow itself to release a “junk” on the market. Although history knows cases of minor slip-ups. But he who does not move forward, goes backwards.

I am convinced that the X-CCR is a milestone in iQSub’s history, and this is only its first small step towards becoming a world leader in the rebreather market. More to come soon, but about that another time.

Now let’s address those similarities and differences between the X-CCR and the HH. So, one by one:

1. Quality policy

Here at X-CCR, iQSub sets the bar very high. Starting with the materials for production, the manufacturing process, quality control, selection and training of instructors, to the training of end users and warranty and after-warranty service. The entire process from the selection of materials to the training of the end user and the issue of the unit to him and its subsequent service is to be under the full supervision of the factory.

The X-CCR has been designed and manufactured in accordance with all requirements of CE standards. The certification process is currently underway. All documentation has already been accepted by the certification body and the certification process will be officially completed in the next few months.

Only complete “ready to dive” units will “come out of the factory”. Each X-CCR has its own serial number (serial numbers also apply to key components). Each unit is “assigned” to a specific user and its history will be known at all times. The X-CCR will only be sent to people with the appropriate training. In the case of people who have just signed up for a course, the unit will be sent either to the instructor or directly to the student, but locked. Only the instructor during the course will be able to unlock it.

Sales will only be made through authorised distributors and instructors. Each instructor must be approved by the iQSub factory.

iQSub provides ongoing warranty and post-warranty service. All repairs will be carried out directly at the factory and of course with warranty.

How it was with HH is what most people involved know, and it was not always rosy. One of the things HH was very often accused of was the lack of CE. There were a lot of different parts on the market, all sorts of “assemblies” started to appear. Different people took care of the service (to paraphrase Stuhr’s song: everyone can repair something, a little better or a little worse). Various types of units assembled on HH parts and sold as HH started to reach people without training. But I have already written about that in the first part of the article.

I would like to reassure all HH owners here that iQSub has implemented a programme of action in this area too. iQSub declares full warranty and post-warranty support for customers who have so far purchased their HH units from authorised dealers or instructors. At the same time, a solution is being prepared for all those who have bought various types of compilations on HH items. All this support and service will be available through HH dealers and instructors, and performed directly at the iQSub factory with the factory guarantee.

2. external appearance

At first glance, the X-CCR and HH look almost the same. Because the construction of the tube with scrubber and bottles attached to it is common. However, when you take a closer look, the first differences appear. The first one is the design, where in case of X-CCR there appears very characteristic “X” and other milling of the case.

A less noticeable difference is the size. Namely, the X-CCR is a few centimetres smaller than the HH with the same scrubber parameters (length, width and bed weight). This reduction was achieved by reducing the unnecessary dead volume in the tube (the outer container of the scrubber). This provided two benefits. The first, and less important, is logistics. When transported for example by air, the X-CCR takes up less space and can be put into a smaller suitcase. And the second is already much more important in my opinion. By eliminating unnecessary dead volume in the scrubber’s container the breathing resistance is further reduced and definitely less ballast is needed. And the obvious thing for CCR divers – less gas in the loop and smaller volume means easier buoyancy and less diluent consumption.

Another external difference is the head. And here, when you take both heads in your hand, you can see clear differences between X-CCR and HH. The first thing is that the X-CCR head houses the electronics and power in the form of 2 batteries – in HH all electronics and power are in the handset. The second thing is the cable passages. In the X-CCR Primary, HUD and Secondary are connected with detachable, airtight and watertight connectors that prevent water or gas from getting into the cables and electronics – in HH they are fixed connectors, through which gas and moisture from the rebreather gets into the cables and can get into the electronics. I will describe the differences in electronics in more detail in the next section devoted just to electronics. Another difference in the head appearance is the shape of the ring closing the head on the tube. The X-CCR has this ring designed in such a way that access to the o-rings sealing the head is very easy – in the HH these o-rings are hidden under the ring and access to them without a “specialist” tool is practically impossible, which makes it very difficult to lubricate these o-rings or replace them.

The undoubtedly noticeable external difference is the handsets. In X-CCR they are much, much smaller than in HH. Those who had a chance to see HH handsets know that their size is not the smallest one. This difference is due to the fact that in HH handset all electronics and power supply for the rebreather must fit, while in X-CCR in primary there is “only” display and buttons.

There is also a visual difference in the displays themselves and the way they display and inform the diver of problems. In the X-CCR, the display is much larger (although the handset itself is much smaller) than in the HH, and is in colour. In underwater mode, one screen displays all the information necessary for the diver at once: ppo2, depth, dive time, battery status, amount of gas in cylinders (diluent and o2), CO2 and remaining canister time. In HH, the screen is narrow and changes from time to time, so it doesn’t always display what the diver is interested in at the time. In HH, to get to some of the information, e.g. remaining canister time, you have to enter the OPT menu. The X-CCR also has a very clear and readable system of informing the diver about “problems”. If everything is OK all the information on the handset is displayed in green. If any value starts to deviate from the norm, this particular information (value) is displayed in yellow, and if the deviation from the norm is significant it is displayed in red. You only have to look at the display with the corner of your eye to know whether everything is ok or not. In HH in such a case the word “ALERT” appears, but in the same colour as the other information and alternating with them.

Related to the handset is another visual difference, namely the cables. The handset cables in the X-CCR are much thinner and much more flexible than in the HH. This has also been achieved by fitting electronics and power into the headsets. Information to and from the handset is transmitted digitally. In the HH there are thick and rigid multi-core cables that transmit electrical voltage.

An important external difference is the absence of classic pressure gauges on the X-CCR. Cylinder pressure is measured using electronic sensors in the head, and the result is displayed on the handset. Those who swim on the CCR know how troublesome classical pressure gauges can be and how much effort is needed to hide them in such a way that the configuration is streamline, but at the same time access to them and their reading is relatively easy.

There are also minor differences in the counter lungs (CL), but these are rather cosmetic differences related to design. At the moment work is being completed on CL 3D as well as on new back mounted CLs. In X-CCR there is a new type of ADV integrated with T-piece, in HH ADV is compressed and mounted in counter lung, although in recent HH units this new solution started to appear.

Many small components have also been designed or redesigned specifically for the X-CCR. Such as the diluent and oxygen separation bars. They are much smaller, yet the diluent strip has one more port, which was always missing in HH and you had to combine in order to connect an additional hose e.g. from QC6 to an offboard cylinder or anything else.

What the X-CCR and HH have visually the same, apart from the scrubber tube plus cylinders design, is the scrubber itself is virtually identical, the bayonet-type connections ensuring the unit is easy to assemble and disassemble, the quality of materials and the precision of construction.

3. electronics

And here there are most differences, but also some similarities. Whatever we say, it is quite different electronics, even quite different approach to electronics in rebreather. Is it better? This question is obvious and justified. But the answer is not so simple. Of course it is the easiest to write “yes it is a better solution” but we have to justify it. The matter is doubly difficult, because firstly this electronics is new, and secondly the old solution worked. So in fact you need to answer two questions. One: ‘can the new electronics be unreliable and therefore dangerous? The second: “if the old solution works, does that mean it is reliable?” So I will first focus on answering these two questions and then try to show more differences and possible similarities between the electronics in X-CCR and HH.

PPO2 measurement

The most important thing in rebreather diving is to know the PPO2 in the breathing loop, in short the diver must have some information about what he is breathing. In the X-CCR the PPO2 measurement is done by three oxygen sensors (galvanic cells) exactly the same as in HH and practically in all rebreathers and analysers. So the measurement itself and its accuracy are identical.

The principle of operation of galvanic cells is quite simple and in very short and “peasant” language (I apologise to all physicists, mathematicians and chemists for the simplifications used and the “unprofessional” vocabulary, but I want it to be communicated as simply as possible and understandable for everyone) it looks as follows: each sensor has two electrodes (cathode and anode) separated by a thin layer of electrolyte. In the environment of the gas to be measured, the electron exchange created by the reaction causes potential differences at the electrodes. The resulting voltage is proportional to the partial pressure of oxygen and its function is linear. This means that if the sensor generates a voltage equal to “x” at ppo2 equal to “y”, it is known in advance exactly what ppo2 is at voltage “z”. In short, you don’t need complex electronics or a complicated algorithm to “convert” sensor measurements into concrete reliable data. You might as well do it in excel. In fact, the ppo2 measurement in a rebreather is nothing more than an analyser, the same as you can find in many diving bases or centres making nitrox, only instead of one sensor it has three, so the measurement can be verified on the fly.

In X-CCR and HH the sensors are located in a special chamber in the rebreather head. And now comes the most important differences. In the case of X-CCR the electronics are located in the rebreather head, right next to the sensor chamber, each sensor is electrically separated and the voltage generated by each sensor separately goes to the nearby electronics, which using a very simple algorithm (like in any analyzer) converts the voltage to PPO2 and already in digital form passes it to the display informing the diver about PPO2 in the loop. In fact with the X-CCR we have 3 independent electronics and 3 PPO2 “displays”: Primary, HUD and Secondary. So this is done via three quite independent routes. In case of HH the voltage generated by sensors in the sensor chamber of the rebreather’s head has to be transmitted via cables to the handset, where the electronics are located. In HH it is solved very simply, each sensor has a “+” and “-” so each, “+” as a separate wire is led to the electronics in the handset, and all “-” are connected together in the head and as a single wire are also led to the electronics in the handset. And here a serious problem arises, that is the total loss of PPO2 measurement in case of a short circuit on the 02 sensor or if the cable to the handset is damaged or cut. This reading is lost on all instruments (unless you have installed the 4th sensor connected to independent electronics). In HH you can read PPO2 in 3 places, but there are only two electronics: Primary and Secondary. Diva (HUD) is connected to one of the electronics and only shows PPO2 calculated by the electronics to which it is connected, i.e. it is simply a second display of the respective electronics. Because of this unfortunate common “-” these two electronics are not so independent.


In the case of the X-CCR, the Primary electronics were designed specifically for this rebreather. Besides the PPO2 reading it has the following functions: CO2 control, solenoid control, logbook, scrubber run time, sensor change time control, battery status, cylinder pressure, depth, dive time, etc. The handset is connected to the electronics with a very flexible cable through a hermetic connector in the head. This connector is detachable and completely prevents any possibility of moisture or gas from the head from getting into the cable and the handset. The handset itself has a large, very clear and colour display. The communication and warning system is very simple and clear. Under water, all information should be displayed in green. In case any value starts to deviate from the established norm, this information is displayed in yellow. And if any of the values exceeds the acceptable range, this information is displayed in red. Since the electronics and the handset communicate digitally, damage to the cable or the handset itself does not affect the PPO2 reading or the operation of the electronics itself.

In HH Primary it is the Juergensen Marine electronics designed many years ago. Depending on the version, apart from PPO2 readout it is responsible for solenoid control, decompression counting, battery state in case when only Primary is from Juergensen Marine and secondary is SW Petrel, it is also responsible for DIVA control. Since in HH the electronics and power supply are located in the handset, the handset is connected to the head with a rather thick and stiff multicore cable. The cable to the head is connected by means of inseparable cable grommets. The connection is designed in such a way that moisture and gas from the rebreather can get into the cable and into the handset, which can again cause damage. Through this cable flows the voltage generated by the sensors to the electronics as well as in the opposite direction the current needed to open and close the solenoid. If the cable or the hanset is damaged, the whole electronics including the PPO2 reading and the solenoid is lost. In case of short circuit, we can lose the whole PPO2 reading also on the other electronics.


In the X-CCR, these electronics can operate in 2 modes: PPO2 or ALARMS. In PPO2 mode the diver is informed only of the most important thing for him, the PPO2 in the loop. In ALARMS mode, the primary electronics settings are monitored and the diver is informed whether all parameters are within normal limits. As soon as one of the rebreather parameters (PPO2, CO2, pressure in the oxygen and diluent cylinder, scrubber time, etc.) starts to deviate from the norm, an alarm with vibration is displayed. Here, as in Primary, the HUD is connected to the head with the same type of hermetic connector.

In HH, the DIVA (HUD) is linked to one of the electronics and relays information read by that electronics to the diver. DIVA also has 2 modes of operation: PPO2 or USER MODE. In PPO2 mode, the diver is informed of the PPO2 in the loop. In USER MODE the diver is informed if the PPO2 remains within the range set by the diver on this electronics. In both modes, the diver is informed if the PPO2 is too low or too high, if the sensor fails, if the scrubber’s protection time has expired, (but only in the event of inspection by a secondary Juergensen Marine).


The X-CCR in series as Secondary has electronics produced by the German company Heinrichs-Weikamp which has been producing advanced dive computers and PPO2 controllers for years. And it is an OSTC cR specifically developed to meet the needs of CCRs. You can read more about this solution on the manufacturer’s website Thanks to easily replaceable cables (we can order in the factory a cable with a connector for any computer), we can connect any computer that monitors 3 sensors. And here it is identical as in Primary, the cable connecting the computer with the head is connected via a hermetic and detachable connector. Since in this case the computer must be supplied with voltage generated by the sensors, there is an additional protection in the head, so that even if the cable is damaged and there is a short circuit, it will not affect the PPO2 reading from the other electronics (Primary and HUD).

In the case of HH we have two options. The first is the Juergensen Marine electronics and in this case the Secondary controls the DIVE (HUD) in addition to the PPO2 reading. The second possibility is the Shearwater Petrel. Here, as in the Primary HH, the cable is connected via a non-separable conduit through which moisture and gas can enter the cable. As with the Primary, damage to the cable and a short circuit can lead to complete loss of measurement and PPO2 reading.

As I already mentioned Primary electronics and HUD in X-CCR are located in the head in a special hermetic chamber. The chamber with electronics is additionally filled with special gel, which protects electronics from water in case of chamber leakage. Additionally, in the electronics chamber, a pressure sensor is mounted, which monitors the pressure in this chamber and informs the diver about possible leaks. Upgrading the software in the X-CCR is very easy to do and each user can do it themselves after receiving a software update email from the factory. The power supply for the electronics in X-CCR is located in the head and is fully redundant. This is solved by giving two batteries in separate hermetic and isolated chambers. Which power all the electronics. If one battery fails, the other automatically supplies power to all the electronics.

The HH electronics located in the handset and each have their own power supply. If one battery fails we lose the electronics that were powered by that battery. And so in an extreme case we can lose Primary with solenoid and HUD (DIVA) at the same time. In case of HH and Juergensen Marine electronics there is no software update option at all.

I am convinced that already at this stage attentive readers are able to answer for themselves the two basic questions posed at the beginning. But let me try to sum it up:

“Can new electronics be unreliable and therefore dangerous?”

Electronics can always fail. Regardless of whether it is new or old. Of course, the probability with a new one is much higher than with an old and proven one. It is so “obvious”;) Therefore, always in the case of key elements on which depends the operation of the device, and in this case the life of the diver, appropriate protection is used. In the case of the X-CCR we have full protection in the form of a second (actually third) proven and independent electronics. There is not much to say here. It is quite simple, even if there are any problems with the new electronics, their operation, reading, etc. the diver has full control over what he breathes, and this is the most important thing in rebreather electronics.

“If an old solution works does that mean it is reliable?”

As far as the Juergensen Marine electronics are concerned, they do indeed work. However, it is not reliable or without quite key “points of failure”. The most important problem is the possibility of a complete loss of PPO2 measurement and reading, in which case the rebreather under water becomes practically useless and even dangerous. For me this problem was always important, that is why in all my HHs I always had a 4th sensor mounted and an independent computer connected to it. Another important problem is the power supply, where if one battery fails you lose all the electronics powered by it.

In terms of direct safety and reliability of the electronics, I think that’s it. Below I present in a telegraphic shortcut “additions” to the X-CCR electronics, which, as any additions for some will be cool for others unnecessary. But they have two things in common: the first that they are in the standard and the second that if you do not want them, you can simply turn them off and do not use them.

CO2 control

The X-CCR is fitted with a CO2 sensor as standard, which monitors PPCO2 throughout the dive, alerting the diver to any increasing amount in the breathing loop.

Cylinder pressure monitoring

The X-CCR also comes as standard with electronic pressure control of the oxygen and diluent cylinders. The handset displays information on the quantity of each gas.

Control of O2 sensor replacement time

When replacing the sensor with a new one, its timer is reset. The Rebreather will remind itself when its replacement time is approaching due to its age. Or the diver can check in the menu when, which sensor was replaced, that is, how old they are. Of course, the diver is still responsible for checking its operational status. But it no longer requires scribbling the date on each sensor with a marker to keep track of their replacement date.

Calibration memory

The diver can easily see when the last calibration was performed. In case the diver has not calibrated since the appointed time, the rebreather will remind him.

Scrubber memory

The X-CCR counts and remembers the number of scrubber changes, in addition to counting the canister’s protective time and warning the diver when the scrubber is about to run out.

Service information

In the menu you can see information such as production date, last service date, etc.


The X-CCR memory stores information about the date, time, depth and dive time, but also provides graphical graphs of the dive profile, temperature and PPO2. All alarms are also stored.


Owner information is stored in the electronics and the handset displays owner data in surface mode.

Black box

All information about the rebreather and dives are stored here. So that the history of dives, services, failures etc. can be retrieved at any time in the factory.


The X-CCR is equipped with an electronic compass with directional memory.


In X-CCR there are 6 setpoints available. 4 are programmable by use and the other 2 are the “M” setpoint, i.e. manual, where the electronics only make sure that the PPO2 in the loop does not drop below 0.4 and the diver is responsible for the rest. And the “FP” setpoint, which allows the diver to set the PPO2 in the loop to “steady state”. A very cool feature is that when you enter a setpoint change, it automatically sets to the nearest possible setpoint and the diver just has to approve it, or choose another if the one suggested doesn’t suit him. The setpoints that are not possible to reach are automatically excluded and so, for example, on the surface we will not turn on a setpoint greater than 1.00 (sometimes it is impossible to turn on even 1.00 if the atmospheric pressure is lower and/or oxygen is less than 100%).

The 3-move rule

The X-CCR electronics in underwater mode have a rule of thumb that any change the diver needs to make will be done in a maximum of 3 moves. Which, in the case of HH, sometimes requires quite a bit of “clicking around”.


The 2.8 inch colour screen with the “fllip screen” function, i.e. a rotating screen and the “revert” function giving the possibility to mount it on a second hand while keeping the logic that the most important information is always on the outer edge of the screen. The diver is clearly informed underwater about the rebreather’s condition in a three-colour system: green = OK, yellow – something is no longer OK, red – definitely not OK.

That’s probably enough of the important similarities and differences. I tried to present the subject in the simplest way possible and accessible not only to HH owners and rebreather divers. Therefore many simplifications may have appeared in the text, but they do not affect the facts or final conclusions. Anyone interested in more details or more technical knowledge, I encourage to see the X-CCR live.

About the author:

Marcin Bramson is a CCR HammerHead and X-CCR instructor. He has been involved with HH practically since the beginning of its production. One of the first HH users in the world. X-CCR test diver involved with this project from the very beginning. In everyday life he deals with diving and rebreather training.

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Nurek z blisko 20 letnim doświadczeniem. Od 2003 roku nurkuje technicznie, z czego 10 ostatnich lat z wykorzystaniem CCR. Zakochany w jaskiniach i wrakach. Nurkowanie jest jego pasją, którą dzięki zamiłowaniu do przekazywania wiedzy, udało mu się połączyć z pracą. Od 2012 prowadzi własną szkołę Deep Adventure specjalizującą się w szkoleniach rebreatherowych
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