Hi,
this scrubber could likley use a reqular scheduled blowdown, a surface continuous blowdown and/or addition of an anti foaming agent similar to those employed to prevent the same actions in boiler water.
This is a residential unit the cord is probably attached to a safety valve release handle. The "ventilation shafts" the combustion air inlet, or the flue, should be free and clear of debris or product of combustion buildup. Ensure the area that the boiler is in has enough fresh air...
