Heat Pumps Today

26 The era of the Domestic Heat Pump is well and truly in vogue and correctly so, says Bruce Boucher M Inst R (CIBSE) from Bruce Boucher Consulting & Design Vouge… but not as Madonna would tell it An accurately selected Heat Pump for a given property is more than capable of replacing an existing fossil fuel heating boiler. In reality the above paragraph does need an element of qualification. The established heating Industry has not delivered for decades the best results for heating domestic properties. As a result, the HP is facing significant and unfair scrutiny. The energy crisis we face today has forced the established fossil fuel solutions to be examined more closely. The costs of primary fuels had exposed a well- documented underperforming Fossil Fuel Heating Industry. Safe refrigerant On the other side of the coin the Heat Pump as produced today is far superior to earlier type of product from only a few years ago. One recent significant change is the use of R290 (propane) by some manufacturers, and new product coming in 2023 using R290. This widely used and safe refrigerant provides far higher LWT (leaving water temperatures) than many of the HfC’s such as R32, 407,410 etc, therefore providing a greater degree of application opportunities. This does not suggest Heat Pump’s using these other refrigerants are not suitable solutions, far from it. In monoblock outdoor units the refrigeration system is hermetically sealed for life, and unlikely to be tampered with similar to other refrigerants. NG requires much more strict regulation for obvious reasons as it is live and open in many instances. Poorly performing installations As a result of many 10’s of 1000’s of poorly performing existing fossil fuelled installations, the LWT varies dramatically as low as +35°C > 70°+C. So, when a Heat Pump is being considered as a retro-fit, supply water temperature is paramount, and the existing heat emitters require scrutiny. Perhaps most importantly a December | January 2023 Bruce Boucher “Building Heat Loss Calculation” should be the first port of call. The property structure, age of, the existing thermal performance, such as double glazing, cavity wall insulation, roof space insulation. However, homes do need to breath, some have MVHR (mechanical ventilation heat recovery) more-so in new builds. R290 is capable of delivering a LWT of up to 70°C, moreover the lower the flow temperature, the better the Heat Pump CoP. To compete with NG a CoP of 3+ will compete with current NG prices. So far, we have not mentioned possible levy changes, the environment and future Net ZERO carbon ambitions. The scrutiny of the Heat Pump has been contrived from significant ignorance of the technology and negative press, much of the poor-quality social media has not helped the cause. It would be reasonable to state the Heat Pump existed well before the modern non condensing and condensing boiler. A poorly performing existing heating installation is just that! No Heat Pump or fossil fuel appliance will resolve that situation. Sadly, some home owners don’t tell the full story of their existing poorly performing systems. This can prove the death knell of the new HP, getting the blame for all the previous malfunctions of the existing installation. It is imperative, the existing controls are examined but unlikely to be used in the new installation. The system should be thoroughly flushed through if not fitted recommend a “magnetic” water filter is installed. The existing heating emitters (radiators) be examined, TRV’s work if fitted, insulation fitted in exposed areas such as roof space, in between floors if accessible if not contributing to the space temperatures. Microbore accounts for much comment, specifically below 12 mm in diameter. This can be an issue with very low flow temperatures. But that debate for another time. Mockery & Flak The average heat loss of our common housing stock is around 5-8 kW’s, making a mockery of an existing installed boiler of 30kW’s. The Combi Boiler is coming in for a lot of flak, specifically older ones that are unable to vary the burner output. Weather compensation can save energy by compensating for the outdoor temperature for both the HP and NG boiler. It should be fitted, sadly some boilers have them already fitted and part of the controls O P I N I O N