Actually I use the G2 with the heart rate belt a little bit longer than this discussion thread exists - and sorry to say it never worked to my satisfaction, at least not compared to the previous Polar belt with my old Galileo Sol. I reported problems, both with the G2 and with the belt, to Scubapro, several times. But I better do not comment on the reactions. Nevertheless my observations might be useful and help to destroy any hope except of they develop a new version of the product:
I used my Galileo SOL for about 9 years and about 900 dives together with the original Polar belt, without any battery replacement on the belt (yes, many replacements on the Galileo, none for the belt). And it still works. So I know how to use such a belt.
For the G2 with the Scubapro HRM belt my experience from more than 260 dives is that you have to replace the battery of the belt after 80 to 100 dives or at least after a year. Moreover, even above water you should not expect that the combination of belt and G2 works properly, i. e. both the belt and the G2 (hardware or software) could be the culprit. So this does not seem to depend on pressure (except that the belt is not qualified beyond 60 m). In some cases the HRM display of the G2 disappeared after a while or it showed absolutely implausible values, in particular for the heart rate (such as above 200 while you do not do anything special). Above water this disappearance is a rare case, underwater it seems to be a frequent case, both for heart rate and temperature. The displayed heart rate is often implausible for a short while, in particular when the display stops and comes back again. This looks like there is a communication problem and/or a problem with the decoding of the transmission protocol. The temperature is usually plausible, if it is displayed, alternating with the heart rate. I saw deviations from expected values of more that 2 degrees Celsius (2 degrees would probably be within the technical spec, although unbelievably high) in very rare cases only. So the major problem seems to be with the continuity and the correctness of the heart rate.
To make the situation even more confusing: I observed more problems in sea water than in fresh water. In many cases the signal disappeared as soon as I had my head below the surface in sea water. And the signal comes and disappears in all depths. And it distracts you from what you should watch and thus is a safety risk (apart from influencing the calculation of the dive in a questionable way). Yes. sometimes no problems can be observed. And the old Galileo/Polar had some problems, too.
So to conclude: the usability of the HRM-G2-combination is far from what you might expect from a world-leading company like Scubapro. Let us hope for the next version of this (in principle) nice thing. The Galileo Sol and the Polar belt were able to do it (without body temperature).
What I suggest? Dive without HRM. Or be ready to be part of an ever-lasting experiment, if you like such challenges.
. Now that we got the pairing issue sorted hopefully the process of replacing the battery sorts out the depth issue. @giannis k . I'm curious, why did you purchase two heart rate monitors? Could you not get one replaced under warranty? @montage , have you tried replacing the battery? The reason why I ask is because with all the HR monitors I have owned, when they start acting funny, a simple battery change usually solves the problem. The computer may be able to pick up the signal in optimal conditions (the surface or close to it) with a weak battery but fail as you dive deeper. And who knows how long the original battery has been sitting in the unit slowly draining.
One more tip, you should start wearing the heart rate belt BEFORE you start the G2 computer.
