Dega / Onga / De-gas gas spa heaters were one of the best, long-running gas heaters around. These were a fairly efficient bypass style heater, with built-in timer that controlled the pump, and also an air switch. They were well ahead of their time.
The most common 100mJ and 200mJ gas spa heaters. Note that these aren't truly that rating, as they were restricted by use of a regulator on the incoming gas line.
Unfortunately Dega heaters are no longer serviced due to their age, and lack of available spare parts.
Very common Dega Skid-pack included gas heater, pump, cartridge filter, and blower.
It might be best to consider a replacement heater, given the Dega heaters are now all 20-plus years old.
We are now the sole Authorized Service agent for all Dega / De-gas products. New Dega heaters are not available, and have been superseded.
Less-common Dega 200mJ spa heater. All De-gas / Onga heaters finished being built in the mid 1990s, but some were sold as New/Old stock up until the late 1990s.
Dega heaters were made obsolete in the late 1990s. The last of the heaters still used older parts. They were an Australian heater, with many Japanese parts.
They were different in that many of the components ran on 110v, rather than 240v.