Function or macro to convert string with weeks, days, hours, minutes to Hours

Hi,

I would like some help coming up with a function or macro that will enable me to convert the below estimates stored as strings in excel into hours. I also want to avoid using text to columns.

Original Estimate
1 week, 6 hours
1 week, 1 day, 6 hours
2 hours, 35 minutes
2 weeks
1 hour, 1 minute

The results should be:
Hours
174
198
2.58
336
1.02

I'm really stumped and would appreciate any help.

Thanks!