Improved Gas Efficiency
Contact Otter Heating to discuss installing any of these Energy saving steps
Whilst Heat Pumps can offer exceptional efficiency ratings they do not respond well to being turned ‘off’, and ‘off’ is the most economical setting for any heating system. They are excellent at maintaining a comfort temperature at a low energy consumption. However, not all homes and especially lifestyles are suited to Heat Pumps.
Otter Heating do not offer heat pump installations as there are a large number of companies offering this service, many profiteering from the Government Grant Scheme. This means that you are guaranteed all of our advice is impartial and fact based. We specialise in maintaining these systems at a low cost and offer alternative and cost effective solutions to decarbonise your existing heating system. In this section we discuss how your existing gas boiler can be made more efficient. An efficient home boiler can provide nearly 98% efficiency which is an incredible figure for burning fossil fuels. In comparison, Gas Fired Power Stations have an efficiency of 32-38%, which would considerably change the Nett figure to running heating systems that use electricity. Electricity is also 3 times more expensive than gas at the moment and so the return on investment for many households fitting heat pumps may well equal the lifetime of the pump itself.
Part L Building Regulations. Approved Document L: Conservation of fuel and power, Volume 1: Dwellings Existing Dwellings L1b. Part L: Page 39 Section 6.1
The latest version of Part L is January 2021. Little has changed in this document in the last 15-20 years regarding Gas Heating. The target for boiler efficiency remains at 92%, although few installations achieve this figure through poor work practices, the minimum target figure being 78%. There are 4 main areas of improvement, yet even now, the guidelines say 1 out of the 4 steps for energy efficiency ‘should’ be adopted. One of these steps is Flue Gas Heat Recovery (page 40 Section 6.2 Part L). This describes a condensing boiler. As ALL gas boilers since 1st April 2005 had to be condensing, no further improvement by the installer are need. This however has been mostly a waste of effort as you will discover under Step 1 below.
This page brings your attention to all 4 improvements listed in the Part L document as well as our own. These system upgrades will improve the efficiency of all gas boiler installations.
Note: A number of other alternatives available to you can be found on our Residential Design page, as this page focuses on your Gas Boiler only. Much of what is discussed may be found in your User Manual. Some information is repeated on our Heat Pump page. According to 2018 Part L Building regulations only 1 of the following 4 steps ‘should’ be installed, highlighting that there may be still room for considerable improvements in your gas heated home.
Basic Weather Compensation Chart
Additional Benefits of Weather Compensation
Reduced boiler wear / Greater reliability / Longer boiler life / Lower running costs
Reduced system scaling & corrosion / Reduced noise & pump cavitation
Higher EPC / Reduced temperature swing / Greater comfort & air quality
Contact Otter Heating to discuss all the improvements on this page
Note: Load Compensation needs to be done after calculating Load Demand. It is not a guess. Load Compensation can only be done for your Heating as this is a closed loop system. It cannot be done for Domestic hot water. When you reduce your Domestic water temperature the boiler will provided the correct amount of energy to lift the mains water temperature to the target temperature as this is an open system. The boiler will reduce its output for Hot water depending on the time of year and a lower target temperature, but you cannot range rate a Combi boilers Hot water.
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Stats footnote: Due to the different Bus Languages manufacturers use, Otter Heating cannot recommend a particular brand. It depends what boiler you have. There are many advantages to using a manufacturers complete package, especially if warranties or heat packages are purchased. There is no denying the quality of devices or their pleasing aesthetics.
In addition to generic products such as Hive (On / Off) and Nest that use the OpenTherm modulating Bus, Tado offer a range of Smart Room Stats with wireless OpenTherm modulation suiting most boilers. They also offer refurbished units allowing the user to reduce their capital cost of upgrading their system and lowering the pay back period . Their page is good place to start if you wish to further research modern Programmable Room stats.
Zoning Options: Direct Zoning uses 240v heating controls to zone an area and requires access to the pipe work and power. It may not always suit existing pipework depending on the existing design.
Indirect zoning uses motorised, battery powered TRV heads to operate individual radiators.
Type 1 uses wireless communications such as the Honeywell HR92UK.
Type 2 uses the internet to communicate through an App such as the Tado Smart V3+.
From experience, Otter Heating recommend Direct Zoning. Not only is indirect zoning inconvenient with battery swaps, they represent an ongoing cost whilst disposing of used batteries is unhealthy for the environment.
Step 1 Condensing Boilers: Part L page 40 Section 6.2 a.
In condensing mode, the boiler operates at maximum efficiency by using a second heat exchanger to condense water vapour from the flue gases and pre-heat the circulating water. In order to operate, the water temperature must be set to 55 degrees C or below. Historically, most homes with gas boilers were designed to provide 65C or more of heat, negating the benefit of the condenser. This was based on the radiator size, fabric and ventilation heat loss and hot water cylinder temperature if one was fitted.
The requirement and challenge now is to use the benefits of additional insulation methods to lower the water temperature to heat your home to 55C. You can easily do this yourself simply by setting your boiler heat output to 55C and deciding if your home is sufficiently warm. If not then additional insulation or larger radiators will likely address the issue at a low cost.
The importance of Radiator Sizing:
The tables show typical radiator sizes with a DT of 30 and 50. When we add 20C room temperature to these two numbers this is the temperature your heating water needs to be. You can see that a heating system using 70C water (dt50) needs a much smaller radiator than a heating system using 50C water(dt30) for the required output your room needs.
This is also the first step in preparing your home to be Heat Pump compatible. However, it must be noted that a heat pump running at 35C will be more efficient than at 55C but this is an exception in the UK.
If you require new radiators in order to run at a condensing temperature of 55C water temperature (dt30), then very often it is possible to reuse your existing larger radiators to replace the smaller ones reducing the overall cost.
This is an exercise many householders may wish to try for themselves. Use the link to help you resize your existing DT50 radiators to DT 30 using the same Kw output. Further saving may be made by completing an up to date Heat Loss Survey which will accurately calculate the Kilo watt output required for each room . Details available on our Pre Purchase Home Survey page.
Step 2 Weather Compensation: Part L page 40 Section 6.2 b.
Modern boilers modulate or vary their output. This depends on the temperature of the heating water leaving and returning to the boiler and the max operating temperature. As the water warms, the boiler will reduce its output. The boiler itself will be simply turned ‘on’ and ‘off’ by older room stats.
A Weather Compensation sensor should be fitted on an external North facing wall in the shade which then communicates to a suitable boiler. Weather compensators modulate or tailors the output of the boiler to the amount of heat required based on the external and internal difference in temperature and raises the room temperature steadily without overshooting. This also prevents your boiler from simply being switched ‘on’ and ‘off’ by the room stat, but now modulates the output of the boiler based on internal room and external temperatures, not heating water temperature only.
Manufacturers use 3 or 4 different types of Bus communications, so care must be taken when pairing Weather compensators with your boiler. Weather compensators are fully programable and settings can be adjusted overtime to fine tune the compensation slope to suit your home.
A basic External sensor only will save 2% energy whilst an Advanced / Intelligent sensor and controller with programmable temperature and time settings will save 4% minimum.
Step 3 Load Compensation or Range Rating: Part L page 40 Section c.
Load Compensation is also known as Range Rating and is a feature many boiler have. It is likely that you have one or two large radiators in your home. A typical 1400 x 600 double panel radiator at 70C outputs 2.5Kw of heat. This is 1/10th of the output of a small 24kw boiler. It is easy to therefore how most boilers which are factory set at maximum output, provide far more energy than your home needs.
A Heat Loss calculation or survey will accurately calculate the amount of Kw needed to heat each individual room The appropriate sized radiator can then be chosen. By adding together these figures the total amount of heat your home needs can be calculated.
Your boiler output can then be adjusted to this figure which is often considerably less than its full Kw rating. Typical heating systems require 50% or even less of the rated boiler size.
This feature is available on many boilers and is useful if your room stat is a older ‘on’ and ‘off’ or wireless version. If you have a modern modulating wired room stat, then the room stat will Range Rate the boiler for you and there is no need to Range Rate the boiler manually through the boiler control panel.
A Weather Compensator will automatically Range Rate your boiler too. Whilst a room stat looks at two parameters, current room temp and target room temp, Weather Compensation considers the third, outside air temp giving further savings.
Step 4 Smart Room Thermostat with Optimisation: Part L Page 40 Section 6.1 d.
Smart Stats connect to the internet allowing the user to operate their heating remotely. These again suit users depending on their lifestyle or property usage. Not all modulate. Hive Smart stats are ‘On’ / Off’, whilst the latest Nest stats do modulate and use the OpenTherm Bus language which is compatible with many Boilers
Modulating or Optimisation stats, like Weather Compensators use a 2 wire Language Bus so must be hard wired. Programmable room stats whether they be Smart, On/Off or modulating allow the user to change the temperature of their home at different times and days. Users are likely to want to reduce their heating before going to bed, but not turn it off completely on the coldest winters night. Heating requirements are likely to change over the weekend compared to the working week.
Programming ‘Automatic temperature set backs’ when done correctly will save energy when compared to a simple single target temperature on a simple time clock. It also provides greater convenience for the user whilst providing the addition benefits mentioned early under Weather compensators to the entire system. Other features are provided such as Holiday settings and anti-frost.
Step 5 Zoning for homes over 150sq/m: Part L Page 37 Section 5.14
Zoning creates one than more heating circuit in larger properties. Direct zoning can either close a circuit completely or change the target temperature between the two zones. A typical example would be separating the 1st floor with bedrooms and the ground floor.
In the evening the bedrooms would remain cool and set back. When needed, the bedroom temperature would rise below the living area temperature whilst the living space temperature would set back until the morning.
Whilst zoning is criticized by some, it remains a requirement under Part L Good Practice. Zoning may not suit heat pumps as well as it suits gas heating systems. This is because gas boilers can respond to flow and return water temperature changes far quicker than heat pumps.
Heat loss through the fabric of walls is another critique of zoning, but much depends on the architecture of the building and the insulation.
Zoning can be achieved by isolating or controlling an entire circuits temperature or individual radiators with motorized TRV heads. Individual programable heads do however have the added inconvenience that they require batteries whilst an entire heating circuit can be controlled from 240v mains supply.
Summery
There is no single step to achieving a high efficiency heating system. Rather each step contributes to the whole by complimenting the other. Our real goal is to reduced heating temperatures below 55C whilst maintaining comfort and increasing ease of use through automation.
Developing an economical system must be balanced against not just reduced running costs but many of the direct benefits mentioned in Step2, Weather Compensation. These include greater reliability, lower maintenance cost, improved comfort and a higher EPC, or Energy Performance Certificate rating. These improvements add to the value of your home and make your property more attractive to buyers or renters. Plus you can do these improvements at your own pace, whilst reducing the payback. There is also the immediate benefit to our environment any improvements make.
By building a more economical gas heated home, permits us to stand back and monitor the development of heat pump technology, without feeling obliged to commit too soon. Whilst an efficient gas heating system can allows us to install a hybrid heat pump system, ensuring that our earlier investment in gas C.H supports any shortfall a heat pump may have.
Contact Otter Heating to discuss any aspect of your home heating servicing or upgrades.