I have a motorhome with a wet heating system and the only place to actually hang wet/damp things is a small (400mm X 700mm) conventional wet ladder wall hung radiator. I'd like to fit a heating element to the rad to avoid the need to have the full heating system on when all I want is just the small radiator. Will I be able to close the valve to stop the flow of fluid while I remove the blank from the top of the rad and insert the element? Apparently this system needs a pump to bleed it - I don't have the pump. Will any air that's introduced to the system be limited to just that rad? What size element should I fit? Watts or length of element would be good to know. I tried to upload a pic of the valve but it was rejected. I understand the valve is called a dual control domestic type. This link might work! https://photos.app.goo.gl/HMktUCZTq49vGRbp9 Thanks folks.