Radiant heating heats people and objects first by applying the technology of long wave electromagnetic energy. After the people and objects are warmed they release the warmth into the air which then heats the ambient clean air.
I ask the homeowner if employ the hot tube often and I learn that they often in order to several times a week, even over the winter. I visit many homes where the hot tub is kept warm and circulating all of the time, yet never included.
The battery should be serviced. The posts and terminal ends should be investigated by a reputable and any water should be added in if possible. The battery should also be load-tested and how it can hold an electric power charge should be monitored.