Thetford parts reference
Thetford 639857
Thermostat
639857 is the Thetford part number for the thermostat. It is printed in Thetford’s own parts documentation, which we hold a copy of and link below.
Thetford says to use 639866 instead
Thetford marks this number with “USE 639866” on its own parts list, which is the manufacturer telling you 639866 is what to order now. That instruction comes from the document, not from us, and not from what sellers happen to call the part.
Current number: 639866
What this number replaces
If you were looking for 634786 and 639018, this is the number those parts point to. Thetford marks them with “USE 639857”, so 639857 is the one to order.
Which parts lists carry this number
It appears on the parts lists for 2 different models: DE0041 Series and DE0061 Series. A number shared across several models usually means the component was carried over between them, which is useful when the exact list for your model is not the one you can find.
Where this comes from
- Published by
- Thetford
- Retrieved
- 2026-08-28
- File checksum (SHA-1)
3050b13ebea5a432a9698848631a2f59dc537f22
What we have not checked
We can show you that 639857 is a real Thetford number, what Thetford calls it, and which parts lists carry it. We have not verified that it fits your camper. That depends on your model year, build date and what is actually installed, and we do not publish a fitment claim until we can show it in the manufacturer’s own document.
Current marketplace inventory
Listings from eBay
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