Review of Phase I Oilheat Chimney Venting Project Summary of Key Technical Issues Prepared by: Oilheat Manufacturers Association John E. Batey, PE Technical Director

Acknowledgements Oilheat Manufacturers Association (OMA) members supported this draft vent study. Oilheat Manufacturers Association (OMA) members supported this draft vent study. We also thank Jamie Pye and the Maine Oil Dealers Association for their valuable input and funding for this Phase I study. We also thank Jamie Pye and the Maine Oil Dealers Association for their valuable input and funding for this Phase I study. In additional, we recognize the important contributions made by Brookhaven National Laboratory for many years of oilheat venting research. In additional, we recognize the important contributions made by Brookhaven National Laboratory for many years of oilheat venting research.

Introduction Technical concerns with chimney venting of higher efficiency oilheat equipment have existed for the past 20 years. Technical concerns with chimney venting of higher efficiency oilheat equipment have existed for the past 20 years. Many of these remain unresolved. They need to be resolved so that consensus guidelines can be developed to assist oilheat equipment manufacturers, installers, and code officials. Many of these remain unresolved. They need to be resolved so that consensus guidelines can be developed to assist oilheat equipment manufacturers, installers, and code officials. This initial report summarizes key concerns and areas where additional research is needed. This initial report summarizes key concerns and areas where additional research is needed.

Overview Chimneys were required for early natural draft oilheat equipment to draw in the combustion air and to vent exhaust gases. Chimneys were required for early natural draft oilheat equipment to draw in the combustion air and to vent exhaust gases. In the 1970s the average flue gas temperature was In the 1970s the average flue gas temperature was ~ 650F to 700F. ~ 650F to 700F. After the 1970s, equipment efficiencies increased rapidly and flue gas temps dropped. After the 1970s, equipment efficiencies increased rapidly and flue gas temps dropped. This increases the possibility of chimney damage from flue gas condensation especially in older and larger chimneys. This increases the possibility of chimney damage from flue gas condensation especially in older and larger chimneys. Existing oilheat chimneys are both lined and unlined and code groups have begun to look into re-lining. Existing oilheat chimneys are both lined and unlined and code groups have begun to look into re-lining. The concerns are increasing as the efficiency of new heating equipment continues to rise. The concerns are increasing as the efficiency of new heating equipment continues to rise.

KEY QUESTIONS: KEY QUESTIONS: How high can new oilheat equipment combustion efficiencies go without incurring chimney damage? How high can new oilheat equipment combustion efficiencies go without incurring chimney damage? What is the current inventory of chimneys serving oilheat equipment? What is the current inventory of chimneys serving oilheat equipment?

Existing Technical Concerns and Past Research Past research on chimney venting of gas appliances identified a number of concerns related to flue gas condensation and chimney damage in mid- to high efficiency equipment. Chimney liners were recommended to increase flue gas temperatures and lower condensation rates. (Ref 1,2) Past research on chimney venting of gas appliances identified a number of concerns related to flue gas condensation and chimney damage in mid- to high efficiency equipment. Chimney liners were recommended to increase flue gas temperatures and lower condensation rates. (Ref 1,2) Older gas chimneys are oversized and can experience flue gas spillage and moisture condensation within the chimney leading to chimney damage and potential safety concerns Older gas chimneys are oversized and can experience flue gas spillage and moisture condensation within the chimney leading to chimney damage and potential safety concerns

Technical Concerns and Past Research Key points include: Chimney inspection is essential Chimney inspection is essential Sizing tables are needed for the new liners Sizing tables are needed for the new liners Periodic vent inspections are recommended Periodic vent inspections are recommended Causes of chimney damage must be understood before relining Causes of chimney damage must be understood before relining Appliance must be sized to the actual heating demand Appliance must be sized to the actual heating demand Masonry chimneys showing damage should be relined Masonry chimneys showing damage should be relined Vent table should be used to size the reliner when mid-efficiency gas appliances are installed in an older masonry chimneys Vent table should be used to size the reliner when mid-efficiency gas appliances are installed in an older masonry chimneys For oil to gas conversions, careful cleaning of the chimney liner and debris removal is essential For oil to gas conversions, careful cleaning of the chimney liner and debris removal is essential

Technical Concerns and Past Research Vent II computer model identifies when existing masonry chimneys are acceptable and when relining is needed. Unlined masonry chimneys deteriorated more rapidly than lined chimneys Unlined masonry chimneys deteriorated more rapidly than lined chimneys Chimney crown damage due to freeze-thaw cycling was the most common damage – the outdoor chimney crown was a good indicator of chimney condition Chimney crown damage due to freeze-thaw cycling was the most common damage – the outdoor chimney crown was a good indicator of chimney condition Tall chimneys and cold climates contribute to increased condensation Tall chimneys and cold climates contribute to increased condensation For gas appliances, water vapor can condense in chimneys lined with clay tile when exposed at outdoor air temperatures of 32F to 35F – (Note: oil is expected to condense at lower temperatures.) For gas appliances, water vapor can condense in chimneys lined with clay tile when exposed at outdoor air temperatures of 32F to 35F – (Note: oil is expected to condense at lower temperatures.) Dilution air is expected to reduce condensation rates in chimneys (Note: the difference in dilution rates between gas draft diverters and oil barometric dampers needs to be examined.) Dilution air is expected to reduce condensation rates in chimneys (Note: the difference in dilution rates between gas draft diverters and oil barometric dampers needs to be examined.) Vent “wet time” was examined as a measure of vent condensation Vent “wet time” was examined as a measure of vent condensation Dilution air decreases vent gas temperature, however, and the benefit of higher vent gas temperature needs to be compared the reduction in dew point from dilution air. Dilution air decreases vent gas temperature, however, and the benefit of higher vent gas temperature needs to be compared the reduction in dew point from dilution air.

Technical Concerns and Past Research The Vent II model’s ability to predict condensation rates was verified by field tests and was the basis for developing vent relining tables to guide installation of gas heating equipment. The Vent II model’s ability to predict condensation rates was verified by field tests and was the basis for developing vent relining tables to guide installation of gas heating equipment. Most clay tile lined chimneys that experiences problems had excessively long vent connectors, were high chimneys, or did not have dilution air. Most clay tile lined chimneys that experiences problems had excessively long vent connectors, were high chimneys, or did not have dilution air. Clay tile pieces, mortar, or other debris in the chimney clean-out are signs of chimney damage Clay tile pieces, mortar, or other debris in the chimney clean-out are signs of chimney damage Single gas-fired fan-assisted appliances should not be vented with unlined or clay tile lined masonry chimneys. Single gas-fired fan-assisted appliances should not be vented with unlined or clay tile lined masonry chimneys. Variability in chimney construction makes it difficult to determine dilution air rates Variability in chimney construction makes it difficult to determine dilution air rates Many existing masonry chimneys were not built to code. Many existing masonry chimneys were not built to code.

Technical Concerns and Past Research In 1994 local code officials in Oregon interpreted national fire codes in a way that prohibited the use of unlined chimneys for new oil heaters, even though many had been operating without incident for decades. This prevented the installation of new oil heating equipment unless the chimney was lined or rebuilt. (Ref 3) In 1994 local code officials in Oregon interpreted national fire codes in a way that prohibited the use of unlined chimneys for new oil heaters, even though many had been operating without incident for decades. This prevented the installation of new oil heating equipment unless the chimney was lined or rebuilt. (Ref 3) This incident underscores the need for chimney venting research and guidelines for oil heating equipment. This incident underscores the need for chimney venting research and guidelines for oil heating equipment.

Technical Concerns and Past Research This initiated an OMA project with the collaboration of state oil heat associations to supply input at the National Fire Protection Association technical committee meetings for installation of oil burning equipment. This initiated an OMA project with the collaboration of state oil heat associations to supply input at the National Fire Protection Association technical committee meetings for installation of oil burning equipment. OMA led a group of oil heat associations that recommended revisions to NFPA-31 to allow new oil heat equipment to be installed. The revised standard included provisions for a preliminary chimney inspection and draft tests when the new appliance was installed. (See Attachment A - Action Plan and OMA Tech Update) OMA led a group of oil heat associations that recommended revisions to NFPA-31 to allow new oil heat equipment to be installed. The revised standard included provisions for a preliminary chimney inspection and draft tests when the new appliance was installed. (See Attachment A - Action Plan and OMA Tech Update)

Technical Concerns and Past Research NFPA-31 was also revised to include oil heating equipment Venting Tables with relining recommendations developed by Brookhaven National Laboratory as Appendix E. NFPA-31 was also revised to include oil heating equipment Venting Tables with relining recommendations developed by Brookhaven National Laboratory as Appendix E. These tables are based on a vent model developed by BNL for oil heat equipment. The tables present recommendations for chimney liners but are not requirements as they are contained in the appendix of the standard. These tables are based on a vent model developed by BNL for oil heat equipment. The tables present recommendations for chimney liners but are not requirements as they are contained in the appendix of the standard.

Technical Concerns and Past Research

It is noted that for a steady state efficiency of 88%, a chimney height of 10 feet, and a flue connector 10 feet long, that the highest firing rate recommended is 0.75 gallons per hour. Four and five inch liners are not recommended. It is noted that for a steady state efficiency of 88%, a chimney height of 10 feet, and a flue connector 10 feet long, that the highest firing rate recommended is 0.75 gallons per hour. Four and five inch liners are not recommended.

Technical Concerns and Past Research Ref 4 was developed by engineers at Brookhaven National Laboratory and focuses on relining recommendations for masonry chimneys. It is recommended for existing masonry chimneys to improve draft and reduce flue gas condensation when new higher efficiency heating equipment is installed. Ref 4 was developed by engineers at Brookhaven National Laboratory and focuses on relining recommendations for masonry chimneys. It is recommended for existing masonry chimneys to improve draft and reduce flue gas condensation when new higher efficiency heating equipment is installed. Inspection of the existing chimney liner is recommended before installing a new appliance. Many existing chimneys are oversized for the new more efficient boilers and furnaces that operate with much lower exhaust gas temperatures than older equipment. Inspection of the existing chimney liner is recommended before installing a new appliance. Many existing chimneys are oversized for the new more efficient boilers and furnaces that operate with much lower exhaust gas temperatures than older equipment.

Technical Concerns and Past Research One of the key criteria implicit in the BNL recommendations is the need to maintain a minimum exhaust gas temperature (95F to 120F) at the top of the chimney to reduce condensation and chimney damage. One of the key criteria implicit in the BNL recommendations is the need to maintain a minimum exhaust gas temperature (95F to 120F) at the top of the chimney to reduce condensation and chimney damage. Laboratory and field testing to verify these minimum temperatures and validate the OHVAP model was never conducted. Laboratory and field testing is needed to validate the findings of the OHVAP model before it can be used with confidence. Laboratory and field testing to verify these minimum temperatures and validate the OHVAP model was never conducted. Laboratory and field testing is needed to validate the findings of the OHVAP model before it can be used with confidence.

Technical Concerns and Past Research 30 to 40 years ago flue gas temperatures of oil- powered boilers and furnaces ranged from 650F to 700 F. 30 to 40 years ago flue gas temperatures of oil- powered boilers and furnaces ranged from 650F to 700 F. Typical fuel oil firing rates were 1.25 to 1.50 gallon per hour range. Typical fuel oil firing rates were 1.25 to 1.50 gallon per hour range. Modern oil heating equipment has much lower flue gas temperatures (400 F to 450 F) and lower firing rates (0.75 to 0.85 gallons per hour) as equipment efficiencies rose and house heat loads reduced. Modern oil heating equipment has much lower flue gas temperatures (400 F to 450 F) and lower firing rates (0.75 to 0.85 gallons per hour) as equipment efficiencies rose and house heat loads reduced.

Technical Concerns and Past Research Exhaust temperatures decrease as efficiency rises. Chimney draft decreases as the flue gas temperature drops. Also, the flue gas temperature at the top of the chimney decreases as the inlet gas temperature drops. In this way, installing higher efficiency heating equipment increases the probability of flue gas condensation and related chimney concerns. Exhaust temperatures decrease as efficiency rises. Chimney draft decreases as the flue gas temperature drops. Also, the flue gas temperature at the top of the chimney decreases as the inlet gas temperature drops. In this way, installing higher efficiency heating equipment increases the probability of flue gas condensation and related chimney concerns. No specific guidelines now exist that are commonly acceptable for existing installations or for the installation of new higher efficiency oil heating equipment. No specific guidelines now exist that are commonly acceptable for existing installations or for the installation of new higher efficiency oil heating equipment.

Technical Concerns and Past Research The chimney has a fixed heat loss rate. If the firing rate is reduced, less heat flow enters the chimney, and therefore, (for the same chimney heat losses) the exit gas temperature is lower. This can contribute to condensation and chimney damage by using appliances with lower fuel firing rates. The chimney has a fixed heat loss rate. If the firing rate is reduced, less heat flow enters the chimney, and therefore, (for the same chimney heat losses) the exit gas temperature is lower. This can contribute to condensation and chimney damage by using appliances with lower fuel firing rates.

Technical Concerns and Past Research A venting report by Brookhaven National Laboratory presented at the 1995 Oilheat Technology Conference report contains chimney venting tables for oil-fired appliances in Appendix A. A venting report by Brookhaven National Laboratory presented at the 1995 Oilheat Technology Conference report contains chimney venting tables for oil-fired appliances in Appendix A. It is noted that as the efficiency increases from 84% to 86% to 88%, the number of Not Recommended (NR) cases increases indicating that exhaust gas temperatures at the top of chimney are considered to be too low. This occurs both for the lower firing rates and for the taller chimneys. (Ref 5) It is noted that as the efficiency increases from 84% to 86% to 88%, the number of Not Recommended (NR) cases increases indicating that exhaust gas temperatures at the top of chimney are considered to be too low. This occurs both for the lower firing rates and for the taller chimneys. (Ref 5)

Technical Concerns and Past Research Field testing and validation of the BNL OHVAP model is needed before it can be recommended for use. Field testing and validation of the BNL OHVAP model is needed before it can be recommended for use. However, the vent tables supply valuable insight into potential chimney venting concerns for high efficiency oil heating equipment in conventional masonry chimneys. Research is needed to fully evaluate chimney performance at lower flue temperatures and at lower firing rates. However, the vent tables supply valuable insight into potential chimney venting concerns for high efficiency oil heating equipment in conventional masonry chimneys. Research is needed to fully evaluate chimney performance at lower flue temperatures and at lower firing rates.

Technical Concerns and Past Research Smoke and Odors Smoke and Odors Reduction in smoke and combustion odors during oil burner start-up and shut-down is very important to enable side wall venting systems. Reduction in smoke and combustion odors during oil burner start-up and shut-down is very important to enable side wall venting systems. Research by Brookhaven has shown that approximately two-thirds of the smoke produced during cyclic operation is during burner starts and stops. Research by Brookhaven has shown that approximately two-thirds of the smoke produced during cyclic operation is during burner starts and stops. Also, recent research with low sulfur and biodiesel fuel blends suggests that these fuels produce a significant reduction in PM and fuel and combustion odors that could favor expanded use of sidewall vent applications. Also, recent research with low sulfur and biodiesel fuel blends suggests that these fuels produce a significant reduction in PM and fuel and combustion odors that could favor expanded use of sidewall vent applications.

Technical Concerns and Past Research

The Advance Oil Heat – “A Guide to Efficiency Improvement” that was written by Brookhaven National Laboratory and the Energy Research Center about ten years ago includes discussions on chimney venting. The Advance Oil Heat – “A Guide to Efficiency Improvement” that was written by Brookhaven National Laboratory and the Energy Research Center about ten years ago includes discussions on chimney venting. A basic chimney inspection check list is presented. Some of this information may be useful in establishing initial chimney venting guidelines. A basic chimney inspection check list is presented. Some of this information may be useful in establishing initial chimney venting guidelines.

Technical Concerns and Past Research An article entitled “Backdrafting Woes” in Progressive Builder provides a means for quantifying house depressurization and backdrafting concerns to multiple exhaust fans to with oil and gas powered heating equipment. An article entitled “Backdrafting Woes” in Progressive Builder provides a means for quantifying house depressurization and backdrafting concerns to multiple exhaust fans to with oil and gas powered heating equipment. In a tight house the exhaust fans compete with the chimney-vented appliance for air supply. In some cases the heating appliance can backdraft, if the negative pressure in the house is excessive. In a tight house the exhaust fans compete with the chimney-vented appliance for air supply. In some cases the heating appliance can backdraft, if the negative pressure in the house is excessive. This work is based on many years of research in Canada on house depressurization. This paper begins to quantify house “air-tightness” and exhaust fan air flow rates to house depressurization. This work is based on many years of research in Canada on house depressurization. This paper begins to quantify house “air-tightness” and exhaust fan air flow rates to house depressurization.

Technical Concerns and Past Research The chart that follows shows allowable exhaust flow rates for a range of house air-tightness ratings that produce safe and reliable chimney venting. The chart that follows shows allowable exhaust flow rates for a range of house air-tightness ratings that produce safe and reliable chimney venting. A “house depressurization limit is calculated. A “house depressurization limit is calculated. When the total exhaust air flow is below this line the house is safe. When the total exhaust air flow is below this line the house is safe. When it is above this line the house may not be safe as chimney backdrafting may occur. When it is above this line the house may not be safe as chimney backdrafting may occur. House depressurization limits vary from house to house so this is not a general solution. However, it does illustrate the importance of treating the house and vent as a “system”, and can help to diagnose venting problems if the approach can be applied in a general way. House depressurization limits vary from house to house so this is not a general solution. However, it does illustrate the importance of treating the house and vent as a “system”, and can help to diagnose venting problems if the approach can be applied in a general way.

Technical Concerns and Past Research

This work is important because it shows the interaction between the house and the venting system that directly impacts the operation of chimney and venting system. This work is important because it shows the interaction between the house and the venting system that directly impacts the operation of chimney and venting system.

Technical Concerns and Past Research A Brookhaven National Laboratory report in May 1991 summarizes the current state of chimney venting research: A Brookhaven National Laboratory report in May 1991 summarizes the current state of chimney venting research: “The occurrence of low vent-system temperatures, acid corrosion and the potential for corrosion in the vent system is an issue of major importance for oil-fired heating equipment. The areas of immediate concern include the corrosion of metal vent connectors and chimneys in the field operation of mid- to high-efficiency equipment… Based on this work and validation efforts on vent design programs, recommendations for oil-fired residential equipment categorization will be provided to the industry.” This work has not been completed as US Department of Energy funding was re-directed away from vent research to other projects. This work has not been completed as US Department of Energy funding was re-directed away from vent research to other projects.

Preliminary Conclusions a. Masonry chimneys that are unlined or lined with clay tile may degrade over time if excessive flue gas condensation occurs after installing new oil heating equipment with lower exhaust gas temperatures and reduced fuel firing rates. b. Chimneys serving natural gas fired heaters began to experience condensation concerns as Annual Fuel Utilization Efficiencies reached 82 percent. Oil equipment operates with about 4 percent less heat loss due to water vapor in the flue gas (latent heat). Therefore, as oil appliances approach AFUE efficiencies in the upper 80 percent range, then increased chimney degradation through excess flue gas condensation is more likely to occur.

Preliminary Conclusions c. Oil heating equipment efficiencies have increased substantially over the past three decades increasing concerns related to the suitability of existing chimneys. Average AFUEs have increased from 78 percent twenty years ago to the mid-80 percent range today. The US Department of Energy is considering increasing minimum efficiency levels even further which increases these concerns. d. Many variables impact the rate of condensation in individual chimneys as discussed in this report. There are no industry accepted guidelines for prescribing the maximum efficiency for heating equipment in chimneys of varying designs and sizes.

Preliminary Conclusions e. Fire protection and building standards and codes require lined chimneys for new installations. Code inspectors and authorities having jurisdiction are free to interpret and enforce the provisions of fire and building codes. This has limited the installation of new oil heat equipment in the past.

Recommended Actions 1. Draft initial guidelines for oilheat equipment manufacturers and identify the need for additional research to address areas of uncertainty or concern. The information contained in this report and references are a starting point for this effort. OMA can play a key role in drafting these initial guidelines. 2. Revise initial oil heat chimney guidelines based on review comments submitted by equipment manufacturers and installers, and other interested parties. Identify areas where additional information is needed so that research efforts can be planned and conducted. 3. Develop a Project Plan with the goal of producing final guidelines for oil heat equipment and initiating and supporting new research.

STATEMENT OF NEED STATEMENT OF NEED The absence of industry consensus The absence of industry consensus standards for the venting of oil-fired heating appliances leads to confusion in the market which is an impediment to oil use generally and to the upgrade of existing systems with new, high efficiency equipment specifically. standards for the venting of oil-fired heating appliances leads to confusion in the market which is an impediment to oil use generally and to the upgrade of existing systems with new, high efficiency equipment specifically.

1.Field measurements of surface temperatures on inner walls of selected chimney systems Logged over 1 week time periods Correlated with weather conditions 12 sites targeted – lined masonry, steel, one- and two- story, “good” and “problem” sites 8 or more measurement points along length of vent, local data loggers Purpose: To begin to establish criteria for what is acceptable with oil To develop and demonstrate simple temperature measurement method Identify need-for and scope-of a more comprehensive field test

2. CFD Simulation of Model Chimney Systems Commercial Fluent Code, 3-D, transient Model and run several of field test sites Purpose: Evaluate low-cost modeling method Validation against field results

3. Initial Draft of Preliminary Guidelines Develop initial guidelines based on Draft Phase I Report Prepare “strawman” guidelines for industry review Collect, review, and incorporate industry comments Identify specific areas where additional research is needed Purpose: Develop preliminary venting guidelines Identify the need for addition research for formulating final guidelines