He accompanied James, 28, to the base camp at 4,230 metres before suffering from altitude sickness.
Mechanical problems meant a helicopter was unable to airlift him off the mountain for treatment and he had to endure a day-long ride on a mule.
James continued up the mountain with another Danish climber and their Argentinian guide. But the Dane was also taken ill and had to make his way back down.
Eventually, James carried the ironing board to 6,400 metres but then, feeling weak himself, he abandoned it before climbing the final 162 metres to the summit where he hoisted the Welsh flag.
Growing up on Anglesey, the brothers spent much of their leisure time climbing in Snowdonia.
Last year the brothers, along with their father Peter and James's girlfriend Sarah, climbed Kilimanjaro, at 5,859 metres the highest peak in Africa, and raised the Welsh flag at the summit.
They decided to climb Aconcagua to raise money for the British Red Cross. "We then decided to have a go at the Extreme Ironing because it would help raise the profile of the appeal," said James. "It certainly did that, and we have raised about £2,000."
