[Equest-users] Furnace AFUE, Et, HIR and furnace fuel auxiliary

[Bishop, Bill]

When selecting "furnace" for the heat source, eQUEST adds 800 Btu/h for
furnace fuel auxiliary (pilot light) as default. The default 800 Btu/h
adds 12% to my baseline heating energy, so it is not trivial.

ASHRAE Standard 90.1, Table 6.8.1E lists minimum furnace efficiency
requirements.

What should I enter for Furnace HIR and Furnace Fuel Auxiliary for
Baseline System 3 (PSZ-AC) and the new 90.1-2010 Baseline System 9
(Heating & Ventilation; Warm-air furnace, gas-fired)?

 

First, which equipment type applies? Table 6.8.1E has three gas-fired
equipment types - Warm Air Furnace, Warm Air Duct Furnace, and Warm Air
Unit Heaters. I think both Systems 3 and 9 would be Warm Air Furnace,
since packaged (System 3) and ventilation (System 9) systems would seem
to preclude duct furnaces and unit heaters.

 

Second, does the note, "Units must also include an interrupted or
intermittent ignition device (IID)" mean that no pilot light should be
modeled? This note to Table 6.8.1E does not apply to Warm Air Furnaces
<225,000 Btu/h in 90.1-2004 or 90.1-2007, but applies to all Warm Air
Furnaces in 90.1-2010. This is a LEED 2.2 project but the building is
currently under construction.

 

Third, Warm Air Furnace minimum efficiency is 78% AFUE or 80% Et .
Should I use HIR=1.282 (78%) or HIR=1.25?

 

Thanks for your thoughts,

Bill

 

 

 

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