Air gap definitely required to avoid possible cross-connection.

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Best Regards,
Dennis J Sunday
Home Inspection Systems
Www.homeinspectionsystems.com

"Pat" "pblomquist at "@ yahoo dot . com wrote in message
hlink.net...
I'm installing an undersink 4.5 gal. water heater and need a good way
to connect the 3/4" pressure relief valve to a 1-1/4" drain line.
The only fittings I've found that come close to this is a
dishwasher connection for 1-1/2" pipe. This would require re-plumbing
the sink with pop-up stopper for 1-1/2" pipe.

Other possibilities would be to run it through a brick wall or just
drain it into a container.

Any ideas? Do I need an air gap?

Thanks
pb