In 2000 we moved into an apartment in Tokyo run by the semi-public housing corporation UR. It was new and had a natural-gas heating system. Unlike other gas systems we'd used in the past, however, this one heated water that was then circulated to outlets in different rooms in the apartment. Direct gas ignition devices we'd bought for previous apartments were useless in our new one so we had to get rid of them and buy special stand-alone devices from Tokyo Gas that connected to these outlets. When we moved out of the UR apartment several years ago we also had to throw those away because our new apartment, also run by UR, had a different heating system and Tokyo Gas has no buy-back program.