Michael Travers, 59, managed to make a 999 call to report that Mary, 60, and Scott, 31, were unconscious before collapsing himself on Saturday night.
The mother and son, from Larkhall, Lanarkshire, were taken to Edinburgh Royal Infirmary in a critical condition just before midnight after the tragedy at their chalet at Soonhope Farm, Peebles.
Police and fire crews remained at the scene on Sunday as extensive safety checks were carried out.
Early indications were that the victims may have suffered carbon monoxide poisoning, dubbed “the silent killer” because it has no smell or taste, reports the Daily Record.
Stunned friends of Michael, the boss of an electrical services firm, took to social media to pay their respects.
Gary Aitchison wrote: “R.I.P Mick Travers – great times and great travel buddy - see you on the dark side of the moon.”
James Wolfie Smith wrote on a motorbiking club’s page: “R.I.P Mick Travers you are sadly missed by all and by Castle Mcc. Our thoughts go out to you and your family.”
Ecky Farmer posted a photo of him with Michael in France. He wrote: “Me and ma big pal Mick Travers up Val d`isere.... Rip big fella.”
The family would often escape to the borders for a relaxing break at their chalet.
In a Facebook post earlier this year, Michael wrote: “Off to the chalet in Peebles today for the weekend.
“It goes like this: Heater on, kettle on, place heated up, Mary and Scott into the PJ’s, back out of them on Sunday and up the road. They call it relaxing!”
The chalets, known locally as the Soonhope Huts, were built alongside the track by the Soonhope Burn on the west side of Kittlegairy Hill.
They are popular with holiday-makers and weekend visitors from Edinburgh.
A police spokeswoman said: “Officers were called to an address in the Soonhope area of Peebles at around 11.45pm on Saturday, where three people had taken unwell. Inquiries are ongoing.”
Just last month, it was revealed how one in 10 Scottish adults has suffered carbon monoxide poisoning in their home.
Research conducted with 2,000 UK homeowners as part of Dunfermline firm CORGI HomePlan’s campaign to keep homes safe and warm this winter showed a further one in 11 people knows someone who has been poisoned by the “silent killer”.