My review on the T-REB CCR is based on about 30 hrs on it. I have only used it as a stand-alone main sidemount rebreather and not as a bail out unit to a backmounted rebreather.
This unit is built by www.othergravity.com exclusively as a sidemount rebreather, therefore it has several particularities that clearly differentiate it from a backmount rebreather.
Pros:
·Compactness – The whole unit assembled is approximately the same as an 80 CF / 11 Lt Aluminium tank, having the oxygen tank (2 liters steel) on board.
·CE certification – One of the few non-backmount CCR units on the European market, besides the Triton and Liberty, to hold this stringent rating in respect with work-of-breathing parameters in all positions.
·eCCR – This is a fully electronic rebreather being able to maintain a constant setpoint of ppO2 by the use of the classic voting logic based on 3 oxygen sensors. There is a proprietary oxygen injection system named eCOIS (electronic Control of Oxygen Injection System) which commands the solenoid valve in order to inject the oxygen in a series of rather very short bursts, as opposed to the classic system, which injects a single short burst of oxygen once in a while. It appears to me the logic is set up to maintain an actual ppO2 ¨not less than¨ the Set Point on 1st instance, though this is not detailed in the manual.
·Oxygen sensors and electronics head are located mid-body and well protected - in between the unit’s upper half (containing the counterlungs & oxygen tank) and the lower half (containing the scrubber canister). The sensors can be very easily accessed for drying-out after the dive and can also be easily detached off the head.
·Robustness – The unit, once fully and correctly assembled, is rock-solid and meets the ¨expedition-grade¨ standards. The body is made of solid anodized aluminum and there is an option of Delrin body.
·Two counterlungs – The unit’s upper half part contains the two 3D counterlungs made of a solid balistic-nylon fabric, while the oxygen tank is located in between them. The unit is designed to be donned on the right side, lined up with the chest plane. The exhaust counterlung is located on the outer side and is fitted with an OPV, therefore any water ingress may be cleared with relative ease. The flood tolerance is high, up to 1 liter of water may be taken on board without producing a caustic cocktail and still allowing breathing, though the WOB is obviously much higher.
·Radial scrubber – This is a standard fitting, allowing great flexibility.
Cons:
·Electronics reliability – In my particular case this appears to be the weakest point. After about 15 hrs total time I started to encounter a systematic “voting out” of the sensor no. 3 whilst in immersion only, which could not be cleared by diluent flushing or any other operation, The the unit had previously passed all calibration tests at surface. The sensor returned to normal values once the dive ended. This behavior of sensor no. 3 occurred irrespective of the sensor lifetime itself (brand new or several hours used) or if the sensors had been swapped between them. The sensor no. 3 has the lowest position in normal operation with the unit horizontal, thus the highest chances to get flooded or affected by the moisture, yet in all my cases it was dry. The unit was sent back once to the manufacturer for service on this matter, without avail.
·Battery management – There is a single head-integrated battery feeding both the head electronics and the handset controller and it is not user-serviceable. An erratic behavior on the integrated battery was encountered after about 10 hrs total time, culminating with a total power shut down, whilst the unit was idling at the surface, after having already passed all the pre-dive tests and checks. Since specific troubleshooting was not mentioned anywhere in the manual, there were multiple attempts to sort out the issue remotely along with the manufacturer, all without avail. Eventually the entire electronics head was renewed, the new head having a newer firmware version. There had been several emails exchanged on this topic between the manufacturer and a selected group of instructor trainers and instructors, however nothing was raised officially, no service bulletin or announcement was ever disseminated within the community.
·Firmware management – The official website does not mention the latest firmware version for the head and the handset, nor this information is disseminated within the community. There is no Bluetooth module integrated in the unit, hence the firmware can only be updated by the manufacturer only – this requires the electronics head to be forwarded back to their premises in Poland.
·Electronics assembly – The entire design of the unit requires the head (containing the single battery) to be connected to the upper part of the unit in order to power up the handset controller, hence a quick check on battery status is not otherwise possible.
·Mouthpiece – It is supplied by iQsub and the internal schematics is not available officially. The rotating knob must be internally greased quite frequently, since it has the tendency to get stuck over the day. Greasing requires dismantling, which in turn is not straight forward. If the knob is not turned fully open 90° during the dive, the water will ingress through, completely flooding the unit in just seconds.
·Accessories – The unit package is supplied out of the box ready-to-dive with various accessories, however there would be needed for more. The supplied LP quick connector to the off-board diluent is made by Mares and of poor quality, the connection being difficult even on land and without pressure on the hoses. The Swagelok connector is the preferred choice, however it needs to be purchased separately from the market at a high cost. The manufacturer does not offer this as a later add-on. Other useful accessories such as a LP hose male/female for oxygen calibration, carrying handle, NERD holder can also be procured from third parties but not from the manufacturer.
·Quality control – The canister bottom has a single O-ring which is of poor quality, in my case allowing the water to slowly ingress into the canister during the dive after about 20 hrs total time of unit use. The leak does not appear during the positive / negative test and requires a very careful eye to spot. This is a recurrent situation, since there is at least one other unit I know having the same issue.
The OPV on the exhale counterlung is set up to release the pressure at a very low setting, most probably below 20 mBar, rendering the positive test almost useless. The release setting is not available in the manual.
·The counterlungs anti-colapse system does not work as an ADV (automatic diluent valve) underwater, the release pressure setting appears very high and is not available in the manual.
·Troubleshooting info – Both the operations manual and the official website lack detailed troubleshooting info. In fact the website lacks even basic info such as the downloadable version of the operations manual and any retail price range. The manual is forwarded on demand through the peer network of instructors and instructor trainers.
·eCOIS oxygen management– While switching the controller from a low setpoint 0.7 bar to a high setpoint 1.1 – 1.3 bar at depth (20 M or alike) the eCOIS would systematically inject excessive quantities of oxygen into the loop, raising the ppO2 to alarming levels of 1.7 – 1.9 bars. The only way to control this appears to be very slowly breathing during the switch and at least 30 seconds after.
·Handset controller ergonomics – It has a small LCD screen with a low resolution, making it difficult to read if looking from aside. There is no dive log function available, let alone deco info. The ppO2 info and setpoint is big enough, but anything else is small and difficult to read. The proper info can be supplied via a Fischer connection by a third party Shearwater computer, which in my opinion is a must.
My Conclusion:
The idea behind the design of this unit is great and it has indeed some strong points against other available units on the market. There are however several issues on the electronic part which, combined with some quality control issues, put this unit behind other similar rebreathers. A better approach would have been perhaps to design it as a simpler constant-mass-flow mCCR. As an eCCR, a better option would have been to integrate a proven Shearwater DiveCan controller, similarly to JJ or SF2, instead of an in-house controller. There is a lot of room for improvement on the official website as well, where basic relevant information is lacking.
The learning curve might be fragmented and slown down by various failures but, once all sorted out, the unit performs well and provides a great flexibility and comfort underwater to a dedicated sidemount diver. A non-sidemount diver choosing this unit as his 1st rebreather will need to master 1st the sidemounting in OC and then to have nerves of steel in dealing with potential issues on 1st instance.
Due to multiple electronic failures and inconsistent manufacturer support, the T-Reb concept did not work out for me, so I am still in the process to find a suitable non-backmount rebreather, as an alternative to my well-proven JJ-CCR.
This unit is built by www.othergravity.com exclusively as a sidemount rebreather, therefore it has several particularities that clearly differentiate it from a backmount rebreather.
Pros:
·Compactness – The whole unit assembled is approximately the same as an 80 CF / 11 Lt Aluminium tank, having the oxygen tank (2 liters steel) on board.
·CE certification – One of the few non-backmount CCR units on the European market, besides the Triton and Liberty, to hold this stringent rating in respect with work-of-breathing parameters in all positions.
·eCCR – This is a fully electronic rebreather being able to maintain a constant setpoint of ppO2 by the use of the classic voting logic based on 3 oxygen sensors. There is a proprietary oxygen injection system named eCOIS (electronic Control of Oxygen Injection System) which commands the solenoid valve in order to inject the oxygen in a series of rather very short bursts, as opposed to the classic system, which injects a single short burst of oxygen once in a while. It appears to me the logic is set up to maintain an actual ppO2 ¨not less than¨ the Set Point on 1st instance, though this is not detailed in the manual.
·Oxygen sensors and electronics head are located mid-body and well protected - in between the unit’s upper half (containing the counterlungs & oxygen tank) and the lower half (containing the scrubber canister). The sensors can be very easily accessed for drying-out after the dive and can also be easily detached off the head.
·Robustness – The unit, once fully and correctly assembled, is rock-solid and meets the ¨expedition-grade¨ standards. The body is made of solid anodized aluminum and there is an option of Delrin body.
·Two counterlungs – The unit’s upper half part contains the two 3D counterlungs made of a solid balistic-nylon fabric, while the oxygen tank is located in between them. The unit is designed to be donned on the right side, lined up with the chest plane. The exhaust counterlung is located on the outer side and is fitted with an OPV, therefore any water ingress may be cleared with relative ease. The flood tolerance is high, up to 1 liter of water may be taken on board without producing a caustic cocktail and still allowing breathing, though the WOB is obviously much higher.
·Radial scrubber – This is a standard fitting, allowing great flexibility.
Cons:
·Electronics reliability – In my particular case this appears to be the weakest point. After about 15 hrs total time I started to encounter a systematic “voting out” of the sensor no. 3 whilst in immersion only, which could not be cleared by diluent flushing or any other operation, The the unit had previously passed all calibration tests at surface. The sensor returned to normal values once the dive ended. This behavior of sensor no. 3 occurred irrespective of the sensor lifetime itself (brand new or several hours used) or if the sensors had been swapped between them. The sensor no. 3 has the lowest position in normal operation with the unit horizontal, thus the highest chances to get flooded or affected by the moisture, yet in all my cases it was dry. The unit was sent back once to the manufacturer for service on this matter, without avail.
·Battery management – There is a single head-integrated battery feeding both the head electronics and the handset controller and it is not user-serviceable. An erratic behavior on the integrated battery was encountered after about 10 hrs total time, culminating with a total power shut down, whilst the unit was idling at the surface, after having already passed all the pre-dive tests and checks. Since specific troubleshooting was not mentioned anywhere in the manual, there were multiple attempts to sort out the issue remotely along with the manufacturer, all without avail. Eventually the entire electronics head was renewed, the new head having a newer firmware version. There had been several emails exchanged on this topic between the manufacturer and a selected group of instructor trainers and instructors, however nothing was raised officially, no service bulletin or announcement was ever disseminated within the community.
·Firmware management – The official website does not mention the latest firmware version for the head and the handset, nor this information is disseminated within the community. There is no Bluetooth module integrated in the unit, hence the firmware can only be updated by the manufacturer only – this requires the electronics head to be forwarded back to their premises in Poland.
·Electronics assembly – The entire design of the unit requires the head (containing the single battery) to be connected to the upper part of the unit in order to power up the handset controller, hence a quick check on battery status is not otherwise possible.
·Mouthpiece – It is supplied by iQsub and the internal schematics is not available officially. The rotating knob must be internally greased quite frequently, since it has the tendency to get stuck over the day. Greasing requires dismantling, which in turn is not straight forward. If the knob is not turned fully open 90° during the dive, the water will ingress through, completely flooding the unit in just seconds.
·Accessories – The unit package is supplied out of the box ready-to-dive with various accessories, however there would be needed for more. The supplied LP quick connector to the off-board diluent is made by Mares and of poor quality, the connection being difficult even on land and without pressure on the hoses. The Swagelok connector is the preferred choice, however it needs to be purchased separately from the market at a high cost. The manufacturer does not offer this as a later add-on. Other useful accessories such as a LP hose male/female for oxygen calibration, carrying handle, NERD holder can also be procured from third parties but not from the manufacturer.
·Quality control – The canister bottom has a single O-ring which is of poor quality, in my case allowing the water to slowly ingress into the canister during the dive after about 20 hrs total time of unit use. The leak does not appear during the positive / negative test and requires a very careful eye to spot. This is a recurrent situation, since there is at least one other unit I know having the same issue.
The OPV on the exhale counterlung is set up to release the pressure at a very low setting, most probably below 20 mBar, rendering the positive test almost useless. The release setting is not available in the manual.
·The counterlungs anti-colapse system does not work as an ADV (automatic diluent valve) underwater, the release pressure setting appears very high and is not available in the manual.
·Troubleshooting info – Both the operations manual and the official website lack detailed troubleshooting info. In fact the website lacks even basic info such as the downloadable version of the operations manual and any retail price range. The manual is forwarded on demand through the peer network of instructors and instructor trainers.
·eCOIS oxygen management– While switching the controller from a low setpoint 0.7 bar to a high setpoint 1.1 – 1.3 bar at depth (20 M or alike) the eCOIS would systematically inject excessive quantities of oxygen into the loop, raising the ppO2 to alarming levels of 1.7 – 1.9 bars. The only way to control this appears to be very slowly breathing during the switch and at least 30 seconds after.
·Handset controller ergonomics – It has a small LCD screen with a low resolution, making it difficult to read if looking from aside. There is no dive log function available, let alone deco info. The ppO2 info and setpoint is big enough, but anything else is small and difficult to read. The proper info can be supplied via a Fischer connection by a third party Shearwater computer, which in my opinion is a must.
My Conclusion:
The idea behind the design of this unit is great and it has indeed some strong points against other available units on the market. There are however several issues on the electronic part which, combined with some quality control issues, put this unit behind other similar rebreathers. A better approach would have been perhaps to design it as a simpler constant-mass-flow mCCR. As an eCCR, a better option would have been to integrate a proven Shearwater DiveCan controller, similarly to JJ or SF2, instead of an in-house controller. There is a lot of room for improvement on the official website as well, where basic relevant information is lacking.
The learning curve might be fragmented and slown down by various failures but, once all sorted out, the unit performs well and provides a great flexibility and comfort underwater to a dedicated sidemount diver. A non-sidemount diver choosing this unit as his 1st rebreather will need to master 1st the sidemounting in OC and then to have nerves of steel in dealing with potential issues on 1st instance.
Due to multiple electronic failures and inconsistent manufacturer support, the T-Reb concept did not work out for me, so I am still in the process to find a suitable non-backmount rebreather, as an alternative to my well-proven JJ-CCR.
