72 Pa. Stat. § 5911
It shall be the duty of the purchasers at treasurers' sales, as soon as any deed or deeds shall have been tendered, after the deeds are acknowledged in the court of common pleas of the proper county, by the treasurer who made the sale, or his successor, as the case may be, to pay to the treasurer the amount of the purchase money, or such part thereof as shall be necessary to pay off the taxes and costs, and also to pay, in addition, the sum of one dollar for the use of the prothonotary for entering the acknowledgment of the deed; and in case the amount is not forthwith paid, it is hereby declared to be the duty of the treasurer to bring an action of debt, in the name of the proper county, for the same, in such courts as debts of equal amount are by law recoverable, and when judgment is obtained there shall be no stay of execution, nor shall it be competent for the defendant in such suit, to give, in evidence, any irregularity in the assessments or proceedings of the commissioners or treasurer, touching any sale made in pursuance of this act.
72 P.S. § 5911