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NSPS Fireplace Applicability/Definition Proposal June 3, 2011 

Prepared for HPBA by David Menotti and Bob Ferguson

Fireplaces 

1(a) A fireplace is a wood-burning appliance intended to be used primarily for aesthetic 

enjoyment and not as a room heater. A fireplace is not an affected facility. An appliance is a 

fireplace if it is in a model line that satisfies the requirements in subsections (b), (c), (d) or (e). 

(b) The model line is qualified under the EPA Wood-burning fireplace program, or, if that 

program has been terminated, was qualified at the time of termination, 

(c) The model line includes a safety listing under recognized American or Canadian safety 

standards, as documented by a permanent label from a nationally recognized certification body 

affixed on each unit sold, and that said safety listing only allows operation of the fireplace with 

doors fully open. Operation with any required safety screen satisfies this requirement. 

(d) (1)The model line has a safety listing that allows operation with doors closed, has no useroperated controls other than flue or outside air dampers that can only be adjusted to either a fully 

closed or fully opened position, and the requirements in either (d)(2) or (d)(3) are satisfied. 

(d)(2) Appliances are sold with tempered glass panel doors only (either as standard or 

optional equipment), or; 

(d)(3) The fire viewing area is equal to or greater than 500 square inches. 

(e)(1) A model line that is clearly positioned in the marketplace as intended to be used primarily 

for aesthetic enjoyment and not as a room heater, as demonstrated by product literature 

(including owner’s manuals), advertising targeted at the trade or public (including web-based 

promotional materials), or training materials is presumptively a fireplace model line. 

(e)(2) The presumption in subsection (e)(1) can only be rebutted by test data from a test 

laboratory accredited by a nationally recognized accreditation body, that were generated in 

substantial reliance on ASTM E2558 when operating the appliance with the door(s) closed, and 

that demonstrate an average stack gas carbon dioxide (CO2) concentration over the duration of 

the test run equal to or less than 5.00% and a ratio of the average stack gas CO2 to the average 

stack gas carbon monoxide (CO) equal to or greater than 15:1. The stack gas average CO2 and 

CO concentrations for the test run shall be determined in accordance with the requirements in 

CSA B415.1-2010, clause 6.3 using a sampling interval no greater than one minute. The average 

stack gas CO2 and CO concentrations for purposes of this applicability determination shall be the 

average of the stack gas concentrations from all sampling intervals over the full test run. 
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Background Information 

Fireplaces 

In order to draw the brightest lines possible to differentiate fireplaces from heaters, an 

applicability algorithm has been created with the intent of identifying criteria that will exclude 

fireplaces from the NSPS, without creating loopholes allowing appliances that are intended for 

use as space heaters to avoid regulation under the revised NSPS. Paragraph 1(a) sets the stage. 

The first criterion pursuant to paragraph 1(b) is qualification of the fireplace under the EPA 

wood-burning fireplace program, whether that program remains in effect or not. The logic is that 

these products have been accepted for inclusion in an EPA program for fireplaces and this should 

be a first order delineator. 

Exclusion under 1(c) requires a safety listing that only permits open door operation. This will 

allow both built-in and free-standing fireplaces to be excluded. Any product limited only to open 

door operation must be considered as an aesthetic product and not a heating product. 

If a model has a safety listing that allows open door or closed door operation or only closed door 

operation, paragraph 1(d) requires that the closed door operating mode must be further examined 

to determine whether it should be classified as a heater. The first test (1(d)(1)) is whether the 

appliance includes any user operated controls (other than flue or outside air dampers that have 

only fully-open or fully-closed positions). If user operated controls that adjust burn rate in 

anyway are included, the model is a heater. 

If paragraph 1(d)(1) is satisfied, the model must also satisfy either 1(d)(2) or 1(d)(3) to be 

classified as a fireplace under this tier in the definition scheme. Under paragraph 1(d)(2), the 

model must use only tempered glass in any standard or optional doors. It is well accepted that 

tempered glass can only be used in fireplaces, where large amounts of excess air, even in closed 

door mode, keep the glass temperature at a level where tempered glass can function. Heaters 

will cause tempered glass to fail due to elevated firebox temperatures. For models that don’t 

employ tempered glass, paragraph 1(d)(3) focuses on whether the fire viewing area is large 

enough to demonstrate that the intent of the product is to provide a very large, aesthetics-driven 

view of the fire. The minimum fire viewing area picked was based on a survey of major 

manufacturers. One manufacturer had one fireplace model with a fire-viewing area less than 500 

sq. in. but that product would have been defined as a fireplace based on other proposed criteria. 

Only one product employing ceramic glass with a fire-viewing area of 500 sq. in. was identified 

but that fireplace-like, built-in-the-wall product is an EPA certified heater. 

In recognition that a true fireplace product, including consideration for entirely new designs, may 

not be excluded from regulation by the preceding criteria, paragraph 1(e)(1) creates a 

presumption that a product is a fireplace if it clearly and unequivocally has been positioned in the 

marketplace and sold as a fireplace. To prevent abuse of this final criterion, a challenge test 

procedure is included in paragraph 1(e)(2). This test procedure could be applied prophylactically 

by the manufacturer (perhaps as insurance for a product whose appearance strays too far from 
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the traditional fireplace design paradigm) or required after the fact by EPA if evidence of 

potential abuse surfaces. 

The average CO2 level specified is based on the examination of limited available data, including 

a test of a currently exempt heater burning ASTM E2558 fuel. All available closed door 

fireplace data showed average CO2 levels below 5% and generally below 2%. The exempt 

heater had an average CO2 level of above 9% using the E2558 fueling protocol with door closed. 

The second qualifier addresses concerns about a product that might simply include dilution air 

introduction downstream of the firebox as a way of reducing the average CO2 concentration. By 

adding a cut-off threshold for the ratio of average CO2 to average CO, the impact of separate 

dilution air introduction is mitigated. Fireplaces typically operate with an air-rich combustion 

environment which results in relatively good combustion efficiency within their fireboxes. This 

in turn results in low CO concentrations relative to CO2. Heaters generally operate with more 

restricted air within the firebox. The combustion environment in uncontrolled heaters typically 

results in higher CO2 concentrations than a fireplace but also in CO concentrations that are 

disproportionally higher than fireplaces due to poor combustion efficiency. This difference in 

operating characteristics is the basis of the ratio requirement. The proposed ratio is based on the 

examination of limited uncontrolled fireplace data and voluntary program qualified fireplace data 

(ASTM E2558 fuel with the doors closed) and all ratios were above 15:1. Data for one currently 

exempt heater product with an average CO2 concentration below 2% was provided. The CO2 

/CO ratio for this product was around 5:1 which means that it would not be considered a 

fireplace by the 1(e)(2) criteria. The average CO2 concentration criterion by itself would not have 

excluded this product from the fireplace category.