At full load, the boiler has an efficiency slightly under 92%. Optimal regulation of the shunt pump is achieved by system sensors monitoring supply water temperature, TF, and return water temperature, TR. In a condensing boiler system, however, the return water temperature should be kept low in order to condense the water vapor and capture the latent heat from the boiler exhaust. BOISE, ID The condensing process is achieved by passing the piped hot flue gases through the cooler return water flowing back into the boiler. In non-condensing boiler systems, these warm-up loops mix supply and return water in order to maintain at least 140°F feedwater into the boiler. Watch the video and hear about the development of the Grundfos MGE motor. Given that condensing boiler efficiency is a function of EWT, we checked manufacturer efficiency curves. As long as you have room thermostats, you can set the boiler thermostat reasonably high to make sure that enough heat is generated. Another point of consideration is Annual fuel utilization efficiency (AFUE), the efficiency metric used in the hot water boiler schedule. See the graph below.

TPE3 has all the built-in functions allowing for optimal boiler shunt control, guaranteeing you boiler efficiency and peace of mind that it operates safely.

This ensures higher operation efficiency by utilising the latent heat potential. Condensation of the flu gas can cause significant boiler corrosion while too high a temperature difference results in thermal shock.. Condensing boilers, meanwhile, must be able to achieve condensation of exhaust gas on the heat exchanger to run efficiently.

Find related articles with research and insights from Grundfos. Flue gas starts to condense when it drops below its dew point of 55°C. It is important that the hot water coils be sized to provide a delta-T that allows for lower return water temperatures. Put another way, you start gaining efficiency only when your return water temperature is approximately 135°F or lower. If you have questions about optimizing your boiler system, contact us anytime. Boiler thermostats set the temperature of the water that will be pumped to the radiators. Discover the intelligent solution here. In a nutshell: is it economical to set the boiler on high for a short time and then turn it off, or is it more efficient to run the boiler at a lower temperature for longer? LONG BEACH, CA (Acidic condensate present during short cycling or warmup, without a runaround loop, will corrode the heat exchanger and result in premature failure.). The lower TR, the better the recovery of latent heat of vaporisation, and hereby better boiler efficiency. During design review for a client, we found the mechanical schedules showing 96% condensing boiler efficiency in a system with a design an entering water temperature (EWT) of 110°F and a 30°F rise.

Modern shunt pumps and variable frequency drives for non-condensing boilers can be configured and controlled in a number of ways. Keeping return temperature low is key to efficiency. Consequently, the very thing that makes a condensing boiler more efficient than an old type model will be compromised.

In addition, primary-only variable flow pumping should be used. Sorry, the comment form is closed at this time.

CARMEL, CA [citation needed] While the effectiveness of the condensing process varies depending on the temperature of the water returning to the boiler, it is always at … Therefore the second method, i.e. Data-heavy files with a lot of detailed information decrease workflow speed. Also, be careful of the approach temperature. Boiler thermostats set the temperature of the water that will be pumped to the radiators. TR depends on the system flow, and determining the correct duty point therefore relates directly to the fuel economy of the boiler. To make a noticeable saving on your energy bill, try setting this thermostat at just one degree lower than normal, after a year you could make a saving of around £70 according the Energy Savings Trust.
With fuel bills representing a considerable proportion of the average household’s expenditure, it is not surprising that many of us want to know the most energy saving and cost-efficient method of running a boiler. But the gain in effectiveness depends largely on the return water temperature, TR. (It would likely need to be 90 or 95°F to achieve an 85°F return water temperature.). In general water pumps currently account for a huge amount of the world’s electricity consumption — but with more energy efficient pump solutions, this amount can be heavily reduced. The higher this is set, the more energy will be used and the hotter your radiators will become. Condensing boilers can benefit from FLOWLIMIT technology as it sets the maximum system flow in order to maintain the right return temperature and allow for condensation. The higher this is set, the more energy will be used and the hotter your radiators will become. Room thermostats make sure that each room doesn’t get any … FLOWLIMIT in TPE3 offers the intelligent solution to this by setting a maximum system flow. That is good, but it is not 96%.

All rights reserved. Condensing boiler systems need the return water temperature around 80°F or lower to achieve peak efficiencies.

Operating with a supply water temperature of 180°F and a return water temperature of 140°F, the boilers never operated in condensing mode and the actual boiler efficiency was around 85%, far from the 98% efficiency advertised by the vendor. Pressurised sewage systems are an alternative to traditional gravitation systems that may present a range of challenges. And water and energy go hand in hand. This shifts the duty point, ensuring optimal temperatures for condensation of flue gasses. By utilising sensors and multiple control modes in one Grundfos pump solution, you can ensure your system never underperforms. TRVs reduce the flow of water through the radiators when the temperature goes above a certain setting. Condensing boiler. It is an effective means of making sure that your radiators don’t become unnecessarily hot, thereby wasting energy. The boilers listed in the mechanical schedule are rated at an input of 2,000,000 Btu/h, and in accordance with AHRI Standard 1500, their specifications refer to thermal efficiency or combustion efficiency, not AFUE. This metric results from a laboratory test that considers the seasonal variations of part-load operation, on/off cycling, and stand-by losses. Elevation, fuel type, and water temperature rise also affect the boiler’s ability to capture latent heat from its flue gases and reach optimal operation. Ensure the optimum return temperature in any boiler system design. But predicting the pressure loss in the system can be a challenge. Grundfos offers the resolution that suits your needs and preferences. Non-condensing boiler systems require the return water temperatures to be above the dew point of the boiler exhaust (hence the warm-up loops). Otherwise it cannot cause the hot flue gases to condense. Note that the 135°F (condensing) temperature is a function of the fuel. The mechanical schedule was perhaps copied from another project with smaller boilers that did have AFUE. The solution is intelligent pump regulation. Combined, these controls will allow you to keep the temperature of your home comfortable without any wastage of fuel or heat. Having paid a premium for the new boilers, the maintenance manager was not happy. Commercial Condensing Boiler Operation. NEW YORK, NY. Image Courtesy: telegraph.co.uk, post-carbon-living.com, atlanticairtesting.com, it’s a good idea to get a new boiler quote, How to prepare your home for the cold weather (and extend the life of your boiler). For condensing boilers, you need a return water temperature of 80°F or lower in order to achieve 97% efficiency. In the design review of another project, we identified a warm-up loop around each condensing boiler. The heat exchanger is therefore an important component of a gas condensing boiler or condensing gas … For this particular model, Lochinvar had efficiency curves based on only a 20°F rise, shown below. A high return water temperature gives you safe operation. In summary, for optimal operation, condensing boiler systems need the return water temperatures well below the dew point of the boiler exhaust (for natural gas, this is around 140°F in the Bay Area and 125°F in Denver), ideally around 80°F or lower.

The chart is for natural gas. We checked other condensing boiler models sold by Lochinvar, which did have efficiency curves for a 30°F rise, and they showed boiler efficiency to be approximately 93% at an EWT of 110°F. (In a commercial building application, this would be the delta-T between the leaving air temperature from the VAV box and the return water temperature off the coil.) This secures optimum boiler protection and reduces cost of operation. SAN DIEGO, CA The efficiency of the central heating system itself, the various possible sets of controls a system can have and the size and numbers of the radiators are all factors in determining a boiler’s most economical operating method. I first encountered condensing boiler woes when conducting an energy audit for a winery which had retrofitted its conventional boilers to condensing boilers. Therefore, we recommended that the design team either revise the boiler efficiency to 93% or adjusting the system to return a lower EWT. I’m going to be brief here because there are a lot of readily available resources that explain condensing boiler technology. AFUE is annual heat output divided by annual energy consumed by the boiler. This is why condensing boilers are designed to accommodate a return water temperature of 54°C or less. Reduce heat loss and increase system efficiency. The sensor measures the temperature of the water returning to the boiler, and ensures the right temperature is maintained at all times. The TPE3 measures and compares the temperature of both the flow and return pipes. If the temperature of the water returning to the boiler is too high, little or no condensation is possible.

Assuming you have a condensing boiler (as is the case with all modern boilers – if you don’t have this type it’s a good idea to get a new boiler quote), it is very important to set the correct boiler power output. Discover the intelligent solution in our whitepaper. But make it too high and efficiency suffers. For non-condensing (i.e., standard (85%) efficiency) boilers, this serves to avoid condensation and fouling of the heat exchanger. Condensing Boiler Setup for Optimal Efficiency.

In primary-secondary pumping systems, with variable flow secondary pumps, the constant-speed primary pumps can lead to unintended mixing between the primary and secondary loops at lower loads, which raises the return water temperature and lowers condensing boiler efficiency. A conventional boiler will typically have a minimum entering water temperature of around 60°C, with an exit temperature of 80°C, and … The heat exchangers of condensing boilers are designed and manufactured for this. A condensing boiler can typically increase efficiency by up to 10-12% compared to a conventional boiler. As long as you have room thermostats, you can set the boiler thermostat reasonably high to make sure that enough heat is generated. Whether you are designing a new construction project or retrofitting an existing system, it pays to do your homework and understand the key variables.
Ideally, a full set of controls will include a thermostat for the boiler, a thermostat for each room and TRVs (thermostatic radiator valves). Most coils are sized for a 20°F delta-T, but to get optimal return water temperatures, they may need to be sized for a 40°F delta-T. To ensure that condensation also occurs, the temperature of the return water must not exceed 57 degrees Celsius. © Copyright 1998-2020 kW Engineering, Inc.®. There appears to be two choices when it comes to setting the boiler, particularly with regards to heating a home, and it is difficult to know which method will result in lower heating bills.