The sisters-in-law have been named as Sharon Dodd-Archibald, 46, and Mary Archibald, 51, both from Glasgow.
They were found at the flat in Dalserf Court in the Gallowgate area on Sunday.
Their deaths are not being treated as suspicious. Police are awaiting the results of toxicology tests and post mortem examinations.
Following the discovery of the women's bodies at about 12:00 on Sunday, police said that one line of inquiry was possible carbon monoxide poisoning.
Although police will not formally rule that out until a cause of death has been established, it has emerged that no faults were found with the boiler during tests carried out by the Health and Safety Executive and Scottish Gas.
There are no other gas appliances within the flat.
The deaths of two women at a flat in Glasgow may not be due to gas poisoning after a boiler was found to be in working order with no faults.