How should a theravada centre approach the lay people for support?

I was planning to visit a centre, so first I checked their webpage, I thought they are a lit too pushy when it comes to donations, asking for money in a very explicit way to pay their bills. OK, let me be fair, they have bills to pay and utilities can be expensive sometimes. I have more experience with Mahayana (eventhough I follow Theravada now) and in the two centres I have been to, I have never seen similar thing, so it makes me wonder, why? Maybe their funding structures are different, more robust, I dont know... Is there anything in the Vinaya that can help? What are the limits when it comes to asking for money?