The Ultimate Efficient A Rated Heating System 

Don’t worry it’s not as expensive as you might think! 


With concerns over energy costs and environmental impact it is now more important than ever to ensure your heating system is as efficient as possible.

Installing an A rated new boiler is a good starting point but installing it onto an antiquated system designed in the 70s, 80s, 90s or even 2000s can end up not really saving you much money at all, if any.  Whilst modern boilers do have an A rating for efficiency this does not necessarily mean that they always operate at their most efficient. Realistically, in most homes these A rated boilers are only working at C or D efficiency at best! The key to efficiency amongst other benefits is low temperature heating. 


You may have read news articles or seen on television advice about turning your flow temperature down to save you money and energy. The thought process behind this is that by heating your radiators at a lower temperature you will use less gas and in-turn force your boiler into ‘condensing mode’. In theory this makes sense, but here are the issues with this advice. 

Boilers condense when the return temperature (pipe returning from your heating system to the boiler) is at 50C or below. These boilers need a temperature difference of 20C between the flow and return. 
  • Say you set your boiler flow temperature to 50C, this may be fine on milder days (dependent on the size of your radiators and how well your home is insulated) but when it’s -2C outside this low flow temperature will not be enough to heat most UK homes to the desired room temperature. You could just go to the boiler and turn the flow temp up but who wants to be doing this on a regular basis, considering how much UK temperatures fluctuate? 


  • What about hot water? It is recommended that you store your hot water at a minimum of 60C to kill legionella bacteria. This makes it potentially dangerous to reduce your boiler flow temperature to a lower temperature as the cylinder will never achieve a 60C stored water temperature. If you have a combi this is not an issue, but you can still benefit from low temperature heating. 

  • Your radiators may be old or not suitably sized for low flow temperatures. This can be a problem with lower flow temperatures as most heating systems have their radiators specified for high flow temperatures. Whilst upgrading your radiators will certainly allow for lower flow temperatures, this can be very expensive. 


The solution: 

So how can we use lower flow temperatures to heat our home comfortably and efficiently without encountering the problems above? The solution is in the controls that we use to heat our home. 


Weather compensation (WC)


Weather compensation uses an outdoor weather sensor and an indoor sensor or thermostat to control both the temperature of your home and the flow temperature of your boiler. The weather compensator and the indoor sensor will work together to work out how much heat your boiler needs to produce to heat your home to the desired internal temperature. For example, if it is a mild winter day say 5C outdoors and your home is already at 16C. The compensation system will know that to achieve a required internal temperature of 20C the boiler will only need to produce a 50C flow temperature. This is known as load compensation. A smaller load means that less energy is required thus increasing efficiency. Alternatively, If the outside temperature is -2C with an internal temperature of 16C and a desired temperature of 20C the compensation system will tell the boiler to produce a 70C flow temperature. 

Now this is all very well if you have a combi boiler but what if you have stored hot water, you will require higher flow temperatures to heat the cylinder to 60C? This is of course correct but there is a very simple solution to this, known as priority domestic hot water. 


Priority domestic hot water (PDHW) 


Through another set of controls PDHW allows us to have two flow temperatures from one boiler, one flow temperature controlled by our WC system and one temperature controlled by our PDHW system. There are many different ways you can configure PDHW for many different systems but I won’t go into that now. Simply put we use a cylinder stat or cylinder sensor which communicates with the boiler so the boiler knows how much heat to produce during a demand for hot water. Being a priority hot water system the hot water demand is prioritized over heating so this means that the heating will not be on during a hot water demand but we have ways of getting over this to minimize the time you are without hot water. 

If you have an unvented hot water cylinder you will most likely already have a large coil meaning that the cylinder recovery time will already be rapid and you won’t notice the heating is off. If you don’t have an unvented hot water cylinder then we can plate load your cylinder to create a rapid recovery time to minimize the time that the heating is off. 



Upsizing your radiators – not crucial but beneficial 


Upsizing your radiators may not be within your budget and understandably so, but if you do have the means to upgrade your radiators then it is certainly something to consider if you wish to create the ultimate efficient A rated heating system, although bare in mind in a lot of homes the radiators are already oversized due to the addition of insulation and the old rule of thumb calculation from the original installer. We can provide a full room by room heat loss survey to determine the exact power requirements for the radiators in your home. 

In case you do need to upsize your radiators or if you want to get the absolute best out of your heating system, upsizing your radiators will allow your home to be heated very comfortably with much lower flow temperatures. Modern radiators are generally designed with a flow temperature of 60C or DT50C mean water temperature. For example if you require 1000 watts to heat your room you will need a double panel radiator sized at 400x800mm. If you want to reduce your flow temperature to say 50C (DT40C) this would now mean that your room requires 1333 watts. You will need to upsize your radiator to a 400x1000mm double panel radiator to achieve this output. 


Key points: 


  • Weather compensation allows your boiler to operate at higher efficiency
  • Lowers the radiator temperature during milder weather conditions
  • Increases the radiator temperature on colder days
  • Easy to install and relatively cheap
  • Can be retrofitted to most modern boilers (10 years old or less)
  • Priority domestic hot water allows for your hot water to be heated to 60C whilst being capable of heating your radiators to a lower temperature
  • Priority dometic hot water allows for smaller hot water cylinders due to faster recovery times 
  • Your hot water system will work almost like a combi boiler but with much better flow rates 
  • Easy to install and can be configured to work with most heating systems and existing hot water cylinders 
  • Upsizing your radiators will allow for lower flow temperatures even during freezing conditions 

So how can I have the ultimate efficient A rated heating system in my home? 


If you think having the ultimate efficient A rated heating system is for you, simply contact us and we will provide you with a tailored quote for your home. This will include: 

  • A survey visit if required 
  • A full heat loss calculation if required 
  • A discussion with you on what system and products are most suitable for your home 

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