How do i use drain out bathroom in a regular bathtub, sink or shower drain? English boiler manufacturers industrial watertube boilers in: ds-type, d-type, o-type, a-type, & tsgu-type. Let us service your heating system, deliver your fuel and keep your water flowing! Learn more about using your vaillant product. You’ll want to plug the drain at this point because there’s going to be a chemical reaction that you don’t want overflowing.