What SEER would an 18 year old unit be?

[Maikerum]

I am trying to do a rough calculation of how much I would save replacing 18 year old heat pumps.

A sample would be a 3.5 ton split system heat pump. A basic new one would be 13 SEER. What would the old one from 1994 likely be? 8 SEER?

I know how much I save would depend on how much load (and therefore how much they run) but is a 13 SEER 50% more energy efficient than an 8 SEER?

Is there a rule of thumb on energy savings from a higher SEER?

Thanks very much

[ar_hvac_man]

Post a model number and someone can identify the seer.

8 SEER would probably be close for that year. My customers rave about how much lower their electric bills are when I change one that old out. There is a calculator I believe but I dont have it.

[beenthere]

94 should be 10 SEER.

[R123]

Emerson has a calculator. It is advertised on this site.

[Maikerum]

Thanks for all the answers. I appreciate the help.