--- title: Turning Up Turndown description: Patterson-Kelley will introduce 10:1 turndown capabilities for the first time during 2019. No more nuisance flame failures that have traditionally plagued high turndown boilers. image: https://info.pattersonkelley.com/hubfs/AdobeStock_40733858.jpeg --- [![har-pk-logo-rgb-450.png](https://info.pattersonkelley.com/hs-fs/hubfs/SPX%20-%20PK%20Logo%20Long.png?width=250&height=68&name=SPX%20-%20PK%20Logo%20Long.png "har-pk-logo-rgb-450.png")](http://harscopk.com) - [Solutions Blog](https://info.harscopk.com/blog) # Patterson-Kelley Solutions Blog ## [Turning Up Turndown](https://info.pattersonkelley.com/blog/turning-up-turndown) \[fa icon="calendar"\] Dec 27, 2018 2:14:15 PM / by [Patterson-Kelley](https://info.pattersonkelley.com/blog/author/patterson-kelley) ![Patterson-Kelley](https://info.pattersonkelley.com/hs-fs/hubfs/PK%20Logo%20Original-1.png?width=35&name=PK%20Logo%20Original-1.png) - [Tweet](https://twitter.com/share) ## Commercial Boiler Efficiency ![AdobeStock_40733858](https://info.pattersonkelley.com/hs-fs/hubfs/AdobeStock_40733858.jpeg?width=216&name=AdobeStock_40733858.jpeg)Placing system efficiency at the forefront of commercial boiler acquisition continues to be a trend in the heating and water heating industry. Manufacturers are racing ahead to push the limits of technology by offering aggressive [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown) capabilities approaching, and even exceeding 20:1, at the detriment of system efficiency.  In an age where energy conservation is important and [condensing boilers](https://www.harscopk.com/solutions/boilers/) are increasingly being adopted, the dewpoint plays an important role in system efficiency because it determines whether the boiler will condense or not, as well as how much condensation will occur. The dewpoint is the atmospheric condition below which water droplets condense and dew can form, releasing heat that can then be absorbed back into the system. Condensation can occur at up to 130º F depending on pressure and humidity. The returning water in the heating system is used as the cooling medium; as the temperature of the returning water drops, the amount of condensate increases.  The potential amount of condensate estimated at 100,000 BTU’s per hour is one gallon, if the boiler is operating at reduce temperatures.   ## Heating System Flexibility Although [heating systems](https://www.harscopk.com/solutions/) are designed to meet peak loads, they spend most of their run-time hours off peak. Along with efficiency, flexibility is an important factor in boiler operation. As the building loads change, the heating system must be flexible enough to change with it. In the instance where the heating system is sized at a higher capability than is required, the flexibility of a boiler could accommodate the imbalance by turning down the input to match the load. This has become the key driving factor in the high[turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown) story. Traditionally, [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown) has been the limiter of efficiency. To maintain stable flames, excess air is introduced which depresses the dewpoint of natural gas. The *dirty little secret* associated with high [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)is that, in most cases, the boiler is no longer condensing. Aggressive [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)capabilities usually lower the dewpoint and reduce the window of opportunity to condense due to excess air. The 970 BTU/lb. of condensate that engineers expect to get from the system, will continue to go straight up the flue. ![combustion-excess-air-2](https://info.pattersonkelley.com/hs-fs/hubfs/combustion-excess-air-2.png?width=301&name=combustion-excess-air-2.png) Excess air to achieve highest possible efficiency: - *5 - 10%* for natural gas - *5 - 20%* for fuel oil - *15 - 60%* for coal # Patterson-Kelley Solution ![Mach-730494-edited](https://info.pattersonkelley.com/hs-fs/hubfs/Miscellaneous%20Images/Mach-730494-edited.png?width=160&name=Mach-730494-edited.png) Due to technology improvements, [Patterson-Kelley](https://www.harscopk.com/) introduced 10:1 mechanical [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)capabilities for the first time during **March 2019**. Patterson-Kelley has achieved higher [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown) with a unique process that allows the gas valves to reliably turn down without adding large amounts of excess air, resulting in flexibility and efficiency. This method delivers a 10:1 [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)rate while preserving the dewpoint of a 5:1 [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)rate, which helps maintain high condensation levels. This higher [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)capability will provide designers the ability to match input to building loads without sacrificing reliability. No more nuisance flame failures that have traditionally plagued high [turndown](https://info.pattersonkelley.com/blog/breaking-down-turndown)boilers. Patterson-Kelley will continue to emphasize system efficiency, reliability, and serviceability as the focus in commercial heating system designs. To learn more about the implications of excessive turndown ratios in  condensing boilers, check out Dave Connors exclusive presentation.  ***[Click here to watch the video](https://www.harscopk.com/media/) now. ***   **Source** *Machines* **2016**, *4*(2), 10; doi:[10.3390/machines4020010](https://dx.doi.org/10.3390/machines4020010) [https://www.engineeringtoolbox.com/boiler-combustion-efficiency-d\_271.html](https://www.engineeringtoolbox.com/boiler-combustion-efficiency-d_271.html)  Topics: [Boiler](https://info.pattersonkelley.com/blog/topic/boiler), [Condensing Boilers](https://info.pattersonkelley.com/blog/topic/condensing-boilers), [Hydronic Boilers](https://info.pattersonkelley.com/blog/topic/hydronic-boilers), [Condensing](https://info.pattersonkelley.com/blog/topic/condensing), [aluminum boilers](https://info.pattersonkelley.com/blog/topic/aluminum-boilers), [commercial boilers](https://info.pattersonkelley.com/blog/topic/commercial-boilers), [turndown](https://info.pattersonkelley.com/blog/topic/turndown), [10:1 turndown](https://info.pattersonkelley.com/blog/topic/101-turndown), [low turndown](https://info.pattersonkelley.com/blog/topic/low-turndown), [turndown ratios](https://info.pattersonkelley.com/blog/topic/turndown-ratios), [high turndown](https://info.pattersonkelley.com/blog/topic/high-turndown), [5:1 turndown](https://info.pattersonkelley.com/blog/topic/51-turndown) ![Patterson-Kelley](https://info.pattersonkelley.com/hs-fs/hubfs/PK%20Logo%20Original-1.png?width=100&height=100&name=PK%20Logo%20Original-1.png) #### Written by [Patterson-Kelley](https://info.pattersonkelley.com/blog/author/patterson-kelley) Located in East Stroudsburg, Pennsylvania, Patterson-Kelley is a recognized market leader and major producer of heat transfer equipment. Our hydronic boilers and water heaters are installed in institutional, commercial, and industrial building applications such as schools, offices, apartment buildings, dormitories, hospitals, and hotels. ### Subscribe to Email Updates - Recent - Popular - Categories ### Lists by Topic - [Condensing Boilers (18)](https://info.pattersonkelley.com/blog/topic/condensing-boilers) - [Boiler (13)](https://info.pattersonkelley.com/blog/topic/boiler) - [Hydronic Boilers (12)](https://info.pattersonkelley.com/blog/topic/hydronic-boilers) - [commercial boilers (10)](https://info.pattersonkelley.com/blog/topic/commercial-boilers) - [Non-Condensing Boilers (9)](https://info.pattersonkelley.com/blog/topic/non-condensing-boilers) - [Condensing (8)](https://info.pattersonkelley.com/blog/topic/condensing) - [Water Heaters (6)](https://info.pattersonkelley.com/blog/topic/water-heaters) - [Water Quality (5)](https://info.pattersonkelley.com/blog/topic/water-quality) - [aluminum boilers (5)](https://info.pattersonkelley.com/blog/topic/aluminum-boilers) - [Condensing Water Heaters (4)](https://info.pattersonkelley.com/blog/topic/condensing-water-heaters) - [Primary-Secondary Piping (4)](https://info.pattersonkelley.com/blog/topic/primary-secondary-piping) - [Variable Primary Piping (4)](https://info.pattersonkelley.com/blog/topic/variable-primary-piping) - [stainless steel boilers (4)](https://info.pattersonkelley.com/blog/topic/stainless-steel-boilers) - [Boiler Design (3)](https://info.pattersonkelley.com/blog/topic/boiler-design) - [Direct-fired (3)](https://info.pattersonkelley.com/blog/topic/direct-fired) - [PK-COMPACT (3)](https://info.pattersonkelley.com/blog/topic/pk-compact) - [controls (3)](https://info.pattersonkelley.com/blog/topic/controls) - [smart controls (3)](https://info.pattersonkelley.com/blog/topic/smart-controls) - [10:1 turndown (2)](https://info.pattersonkelley.com/blog/topic/101-turndown) - [Indirect Water Heating (2)](https://info.pattersonkelley.com/blog/topic/indirect-water-heating) - [replacement parts (2)](https://info.pattersonkelley.com/blog/topic/replacement-parts) - [watertube (2)](https://info.pattersonkelley.com/blog/topic/watertube) - [5:1 turndown (1)](https://info.pattersonkelley.com/blog/topic/51-turndown) - [Delta-P and Delta-T (1)](https://info.pattersonkelley.com/blog/topic/delta-p-and-delta-t) - [Firetube (1)](https://info.pattersonkelley.com/blog/topic/firetube) - [Insider (1)](https://info.pattersonkelley.com/blog/topic/insider) - [Instantaneous (1)](https://info.pattersonkelley.com/blog/topic/instantaneous) - [aftermarket sales (1)](https://info.pattersonkelley.com/blog/topic/aftermarket-sales) - [boiler maintenance (1)](https://info.pattersonkelley.com/blog/topic/boiler-maintenance) - [combustion (1)](https://info.pattersonkelley.com/blog/topic/combustion) - [energy storage (1)](https://info.pattersonkelley.com/blog/topic/energy-storage) - [heat pump (1)](https://info.pattersonkelley.com/blog/topic/heat-pump) - [high turndown (1)](https://info.pattersonkelley.com/blog/topic/high-turndown) - [low turndown (1)](https://info.pattersonkelley.com/blog/topic/low-turndown) - [spare parts (1)](https://info.pattersonkelley.com/blog/topic/spare-parts) - [turndown (1)](https://info.pattersonkelley.com/blog/topic/turndown) - [turndown ratios (1)](https://info.pattersonkelley.com/blog/topic/turndown-ratios) see all ### Posts by Topic - [Condensing Boilers (18)](https://info.pattersonkelley.com/blog/topic/condensing-boilers) - [Boiler (13)](https://info.pattersonkelley.com/blog/topic/boiler) - [Hydronic Boilers (12)](https://info.pattersonkelley.com/blog/topic/hydronic-boilers) - [commercial boilers (10)](https://info.pattersonkelley.com/blog/topic/commercial-boilers) - [Non-Condensing Boilers (9)](https://info.pattersonkelley.com/blog/topic/non-condensing-boilers) - [Condensing (8)](https://info.pattersonkelley.com/blog/topic/condensing) - [Water Heaters (6)](https://info.pattersonkelley.com/blog/topic/water-heaters) - [Water Quality (5)](https://info.pattersonkelley.com/blog/topic/water-quality) - [aluminum boilers (5)](https://info.pattersonkelley.com/blog/topic/aluminum-boilers) - [Condensing Water Heaters (4)](https://info.pattersonkelley.com/blog/topic/condensing-water-heaters) - [Primary-Secondary Piping (4)](https://info.pattersonkelley.com/blog/topic/primary-secondary-piping) - [Variable Primary Piping (4)](https://info.pattersonkelley.com/blog/topic/variable-primary-piping) - [stainless steel boilers (4)](https://info.pattersonkelley.com/blog/topic/stainless-steel-boilers) - [Boiler Design (3)](https://info.pattersonkelley.com/blog/topic/boiler-design) - [Direct-fired (3)](https://info.pattersonkelley.com/blog/topic/direct-fired) - [PK-COMPACT (3)](https://info.pattersonkelley.com/blog/topic/pk-compact) - [controls (3)](https://info.pattersonkelley.com/blog/topic/controls) - [smart controls (3)](https://info.pattersonkelley.com/blog/topic/smart-controls) - [10:1 turndown (2)](https://info.pattersonkelley.com/blog/topic/101-turndown) - [Indirect Water Heating (2)](https://info.pattersonkelley.com/blog/topic/indirect-water-heating) - [replacement parts (2)](https://info.pattersonkelley.com/blog/topic/replacement-parts) - [watertube (2)](https://info.pattersonkelley.com/blog/topic/watertube) - [5:1 turndown (1)](https://info.pattersonkelley.com/blog/topic/51-turndown) - [Delta-P and Delta-T (1)](https://info.pattersonkelley.com/blog/topic/delta-p-and-delta-t) - [Firetube (1)](https://info.pattersonkelley.com/blog/topic/firetube) - [Insider (1)](https://info.pattersonkelley.com/blog/topic/insider) - [Instantaneous (1)](https://info.pattersonkelley.com/blog/topic/instantaneous) - [aftermarket sales (1)](https://info.pattersonkelley.com/blog/topic/aftermarket-sales) - [boiler maintenance (1)](https://info.pattersonkelley.com/blog/topic/boiler-maintenance) - [combustion (1)](https://info.pattersonkelley.com/blog/topic/combustion) - [energy storage (1)](https://info.pattersonkelley.com/blog/topic/energy-storage) - [heat pump (1)](https://info.pattersonkelley.com/blog/topic/heat-pump) - [high turndown (1)](https://info.pattersonkelley.com/blog/topic/high-turndown) - [low turndown (1)](https://info.pattersonkelley.com/blog/topic/low-turndown) - [spare parts (1)](https://info.pattersonkelley.com/blog/topic/spare-parts) - [turndown (1)](https://info.pattersonkelley.com/blog/topic/turndown) - [turndown ratios (1)](https://info.pattersonkelley.com/blog/topic/turndown-ratios) see all ### Recent Posts \[fa icon="chevron-up"\]Back to top