We will be closed this Friday, April 18, in observance of Good Friday. We will reopen as usual on Monday, April 21, 2025.
Please send us a message at sales@onco-tx.com and we will get back to you as soon as we can. We look forward to working with you soon!

Oslin Nation Co.: An HTS Company logo

McDonnell & Miller – the industry leader. Delivering reliable performance and safety in boiler and level control products for over 90 years. Whether it’s ease of serviceability, continuous improvement, product enhancements or interchangeability, McDonnell & Miller is continually doing more to give you the best performing residential, commercial and industrial liquid level and flow control products found anywhere.

McDonnell & Miller Products We Carry:

Flow Switches

Low Water Cut-off’s

Level Controls

Boiler Controls

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Need help with your project? Have questions about a product? We would love to help. Reach out to us so we can put our experience and knowledge to work for you.