Appraisal contingency how many days?

[Michael Plante]

We usually do owner finance so I have little experience with this. 

Received an offer we would like to accept but appraisal contingency is for 24 days 

I really don’t want to tie the house up for that long if the appraisal comes back lower than selling price. Which I think it may as house prices have simply exploded in the past 3 months. 

Is 24 days too long to allow for an appraisal in your opinion?

Any other words of advice are appreciated.  Thank you