Our house was built in 1975 and we have Heatform fireplaces both upstairs and in the basement. The blowers still work and the liners are in good condition. There are gas lighter wells (?) In the bottom of each insert. The upstairs has an ash dump with an external door, but oddly, downstairs does not. I would like to install gas logs in both (not a fan of dealing with wood and ash). Can I install ventless or should they be vented, or should I have both? And can the current gas lighter be converted?