That is the issue in this case. I had heat this morning. I did not the other day. I don't think thermostats are intermittent. They work or they don't. Also, I doubt I have an air bubble because I have not flushed and filled this car since I got it - almost a year now.
Intermittent behavior screams either monovalve or an electrical fault. And if the venting is going wrong it's not the monovalve. (Not by itself, anyhow.) -- Jim
