Hi @Erikbeeren ,
The standards gem has some online documentation but, in my experience, it is not the most helpful resource since it usually does not include info about specific HVAC templates.
I know most of the assumptions about the HVAC equipment efficiencies come from the DoE Commercial reference buildings and the sample IDF files that are associated with them. So those might be a good resource to check to see if the values in those match values that you get from the templates with Honeybee.
If they don’t match, then you have most likely found a bug in the openstudio-stanadrds gem and you should open an issue on the repo that I linked to. Matt Dahlhausen (one of the primary maintainers of that repo) is usually pretty good about fixing bugs as long as you are specific about the issue that you think is a bug (I know he also gets a lot of generic “it’s not working” bug reports that are far less helpful).
Maybe it’s also worth noting that the openstudio-standards gem is not yet at version 1.0 and, while you can see that it’s good enough for us to use right now, it’s still under heavier development than the other more stable parts of OpenStudio, like the core OpenStudio SDK. So I would not be completely surprised if this hard-sized heating coil issue is a bug. Matt is the person who could tell you if it is, though.