The heat exchanger on my Father's Hayward heater gave way, and now I'm in the market for a new natural gas heater for the hot tub only.
The last 2 or 3 have been Hayward H100iD1 type with mixed success. Sometimes they last 5 years, sometimes they start failing parts quickly into the second year.
It's the cheapest and easiest option.
An alternate is the Raypak Rheem 106A which I have no experience with.
Outdoor tankless water heaters are in the same price range and seem to have significantly higher grade components and warranties.
Flow rate is less and connections are standard for indoor plumbing, so we'd have to divert lower flow through the heater but I imagine it would still work, although the heating rate would be less.
Interested in the communities thoughts...
Thanks.
