Initial H content mass after CE, M_H, as a function of WD mass. The dashed red line marks the value of M_H above which H burning releases sufficient energy to cause the envelope to expand beyond 1 R_⊙. Models with larger M_H are excluded from our sequences. The solid blue line separates sequences that undergo or avoid H-shell flashes. The green dashed line indicates the M_H threshold below which residual H burning contributes less than 50% to the WD luminosity. The hatched green region shows the range of M_H values excluded from our study.