do they make something for gas driers to add heat in the house but not the gas?
I assume you mean that you want to use the heat exhaust from your dryer in the house instead of venting it outside. Unfortunately that exhaust has tiny bits of lint that comes off the clothes. You see it in your lint tray. It is HIGHLY flammable and if it was allowed to build up in your house any small spark could ignite it and cause a fire. That's why all dryers are set up to exhaust outside. In order to 'reuse' the heat in the house it would require a filtering system that would be prohibitive, demand constant maintenance and probably not make that much of a difference anyway. It makes more sense to try and preserve the heat you already have by insulating windows and doors.
You can do this with an electric dryer however gas dryers MUST be vented outside because of the fumes. there used to be a heat exchanger you could put in the vent pipe it had copper fin tube and a small fan but after use it was found that you spent more on electricity for the fan than you saved in heat. For those of you that have electric dryers see link below.
