Confusion of AutoSizing

[Megan]

To size radiators, you have to make some changes in the spreadsheet generated by the Room Loads step. On the Room-Htg Loads tab, change the heating load percentage to be addressed by the radiators to something greater than 0%. Because this defaults to 0%, the radiators get autosized to zero capacity (they see no load).

Note - this is different than the process used for Prototype System 9's. All system 9 radiators are sized on the Sys 9 tab and require that you do NOT make changes to the Room-Htg and -Clg Loads tabs.

[macleodd]

The comment above re System sizing of room units may be misleading, I should clarify.

A room unit's temperatures (air and radiant) are autosized by both System sizing and Zone sizing.
But a room unit's *load* can only be autosized by Zone sizing, and only from a Prototype system (i.e. with grey top bar, from Library). If you have a simpler system to model, you could perhaps start from a Prototype System 1 and cut it down.

Apologies that this is not yet documented in the ApacheHVAC user manual, this is expected for v2015.

Regards, Donald

[JohnLloyd]

Sorry Donald, just to make sure I'm completely clear, you're saying that is not possible to autosize radiators without using a system derived from one of the prototypes?

So Megan's method of manually modifying the calc spreadsheet will not work?

Thanks,
John

[gloriatorios]

Is there a simple tutorial anywhere that walks you through the Autosizing feature? It would be a useful thing to get my head around but at the moment I'm scared!

[macleodd]

John

Megan's instructions re increasing the load percentages from 0% apply specifically to Prototype system types 1 - 8, and also to any systems derived from them (while retaining the grey container).

You may be interested, or even pleased, to hear that the entire spreadsheet approach is scheduled to be replaced by fully integrated system management at some point in 2015

Regards Donald