摘要 |
An electric heater unit is manufactured so as to form a base in a supporting dish by compacting powdered microporous insulation into the base. At least one electrical resistance heating element is supported on or adjacent to the base and a peripheral wall is formed in the supporting dish and integral with the base by compacting further microporous insulation material into the dish to a controlled compaction density. The compaction density of the peripheral wall may be different from that of the base, for example higher.
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