How about Anyang Yuxin boiler? Their boilers are of good quality. Are they good after sale?

We have used Yuxin boiler for 4 years, and the effect is very good. The boiler they used in the third phase is not bad. As for after-sales service, they pay the maintenance fee in advance before the company sends technicians to repair it. It is said that there will be no charge after repairing it for users before! Forgot to adopt! thank you