1 - values may be “fixed-point” numbers, so the value will be 2^n times larger than you expected. A quick way to find the number of places after the “binary blob”, or bits for the fractional part, keep dividing by two (right shifting) until the number seems to be rounded down version of what you see on the display. The numbers in the transfer could be 2, 4, 8, 16 etc times bigger than expected.
2 - Values may be decicelcius/centicelsius, so 10 or 100 times what you expect.
3 - values might be BCD - binary coded decimal, each 4 bit chunk mapping to a digit. This used to be common in RTCs (real time clocks) and maybe numeric displays, but is probably not used in this case.
4 - the system will always communicate in F or C, probably C. The communications units will probably not change, even if you change how it is displayed.
5 - The values reported on the UI may be smoothed/averaged over time, so may differ from what you see in the protocol.
6 - I see your display is showing water temperature, house target temperature, actual house temperature. The house temperature and house target temperature are probaby local to the UI thremostat controller, not the boiler. The 78.8 and 33.9 look like number from the central heating system, boiler output water temperature, and return water temperature. There is also the 37.1c number that seems to be the temperature for the hot water to you sink and bath.
None are obvious in the decimal values you are looking at. I think you will be looking at the data for each of these to be scaled (multiplied) and spread over 2 bytes each.
I had a look. Assuming that your photos do not perfectly align with current system telemetry, I looked for pairing and scalings that made sense. Looks like they are 16 bit values, with 12 bits for the integer, and 4 bits for fractional part.
This is the sort of thing you should be looking at.
I picked 4 values that were on the display and looked for close matches in the data.
You will need to look at such values over time. If this is really RS485, you can get a cheap USB to RS485 interface, and log a days worth of data on your PC, then try various scripts to parse the packets.
Since this forum is about Saleae, I think we have taken you as far as we can. It really looks like you are getting quality data from your Saleae now, and just need to decode the data.