https://customer.honeywell.com/en-US/Pages/Product.aspx?cat=HonECC%20Catalog&pid=L7248L1070/B&catpath=AllCategories

Thank you for replying. I have been to that web page several weeks ago. I have scrutinized the install manual very carefully and have not found an answer to the questions I posed on this forum. If you actually can answer them then I would much appreciate hearing from you.

The answers are there in the instructions, they have to be used and enabled. if you arent using DHW inputs, duu, tPL, and tPt wont show unless function is turn on, see page 5.
The intent of thermal purge is to insure usable residual heat in the boiler is circulated until it is sufficiently
depleted from the system before the burner is allowed to fire. Nothing to do with outdoor reset.

Its all there if you fully understand what your reading and comprehend heating functions.

Thank you for following up. I admit maybe I'm just dense, but if duu does not appear in the list of settings, I do not understand how to enable ZR for DHW. Perhaps the controller senses whether there is a wire attached to its ZR terminal and shows duu only under those conditions.

As for thermal purge, the instructions on p. 5 say "tPL** Thermal Purging Limit Temperature (�F or �C), "OFF" if disabled." The way I read that is, to turn on thermal purge, adjust tPL to something other than OFF. If tPL is not in list of settings I am baffled how to enable it. And yes, I think I do understand the purpose and operation of thermal purge.

I had asked whether you could setup the L7248L to do BOTH thermal purge and outdoor reset. Pages 5 seems to say, NO:

**Settings available for adjustment only when the
W8735S1000 AquaReset Outdoor Reset Kit is NOT
installed.

Sorry if I just don't understand. I really appreciate your effort to help.

Well, now I can answer my own question. Sometimes a letter to the CEO gets you the cooperation you need - I spoke to a Honeywell product manager in their Environmental & Combustion Controls division.

The reason I don't see the settings I expected, is that my aquastat (date code 0829), while only 4 years old, has neither of the features that interest me. Although this basic (electronic) design was introduced in 2004, it was not until 2010 that Honeywell added Outdoor Reset capability, in spite of the fact that residential O.R. has been available for over half a century. Go figure.

As for Thermal Purge, it made its appearance only this year (2012) and not voluntarily. Federal energy efficiency regulations mandated this feature.

So, for my purposes, unfortunately my aquastat has all the features of Honeywell's analog design from 25 years ago, and if I want Reset I will have to buy a current-production L7248L.