Hello there, @JackieDeFabio. Yes, it's possible to do an ACH payment when paying your vendor bills through Online Bill Pay in QuickBooks Online (QBO). Let me show you how.

You can pay your bills online for a faster transaction in QBO. We work together with Online Bill Pay to let you pay your vendor bills directly from within the system with ACH (bank transfer). 

To do this, you'll first have to sign up for Bill Pay. You can either use a direct link or the Bill Pay App. If you'll sign up using a direct link, here's how:

1. Log in to QuickBooks Online.
2. Go to Online Bill Pay Learn More page, then select Get Started. 
3. Accept the updated Terms of Service agreement by clicking the I agree to the General Terms of Service box. Then click Continue.
4. Enter your company information, then select Next.
5. Follow the prompts to connect your bank account.
6. Select Next.
7. Enter in your personal information, then select Next.
8. Finally, answer a few identity check questions. If you have issues with this process or are declined during the identity check process, contact Intuit's Care Support.

If you opt to sign up using the Bill Pay App, please see this article for the detailed steps: Sign up for Online Bill Pay.

Once you're done, go ahead and make a payment to your vendor in Online Bill Pay. For the step-by-step guide, you can refer to this article: Pay a vendor.

Also, You may want to check out these articles as your reference in case you need to find answers to the frequently asked questions about Online Bill Pay and managing your bills through it in QBO: 

• What is Online Bill Pay?
• Pay bills on Online Bill Pay

Let me know in the comments if there's anything else you need or concerns about paying vendors online and managing expenses in QBO. I'll gladly help. Take care, and have a great day, @JackieDeFabio.