Excessive temperature warmth pump or radiator improve?
Though one of the simplest ways of working an air supply warmth pump is to run it on the lowest temperature doable, excessive temperature warmth pumps at the moment are extra broadly out there and will be thought of choice for older houses the place decrease temperatures won’t suffice.
However, do the additional working prices that include greater temperatures offset the power effectivity benefits, or are they nonetheless value contemplating?
Power professional, David Hilton explores why the upper stream temperature is not all the time a problem and the best way to ensure you nonetheless acquire most effectivity and power financial savings from any such heating system.
How excessive temperature warmth pumps work
For the reason that introduction of R290 as the most typical alternative of refrigerant for warmth pumps, propane (R290), because of the nature of what it’s, will be compressed to greater temperatures than a number of the gasses which have beforehand been utilized in air supply warmth pumps.
Temperatures of as much as 75°C are fairly doable, whereas beforehand warmth pumps had been usually restricted to 55°C, which means householders needed to weigh up the variations between low vs medium vs excessive temperature warmth pumps.
Trendy air supply warmth pumps nevertheless now use variable pace compressors, that facilitate modulating energy outputs to match the houses warmth demand. And, whereas the Microgeneration Certification Scheme (MCS) – which units the requirements for warmth pump installations – beforehand restricted the stream temperature to a most of 55°C to fulfill effectivity necessities, now that trendy warmth pumps can produce greater temperatures and nonetheless meet the minimal effectivity, we are able to subsequently deliver greater temperatures into the house.
However, simply because a excessive temperature warmth pump can produce excessive temperatures, does this imply it ought to, and the way usually are you more likely to want them?
Advantages of a excessive temperature output
Though in a new-build, nicely insulated, power environment friendly house you might be unlikely to wish excessive temperatures out of your warmth pump, it isn’t the identical in older houses the place an air supply warmth pump is perhaps thought of as a substitute for a boiler powered by fuel or fossil fuels, and might lead folks to query are warmth pumps appropriate for previous houses?
A central heating system was sometimes designed for a boiler led system with excessive temperatures. That signifies that your radiators and pipework had been specified for fast heating of the room – hotter temperatures imply that the warmth transfers to the room faster.
Nevertheless, while you design a warmth pump heating system, it’s an MCS requirement {that a} room-by-room warmth loss calculation is carried out.That is in an effort to decide the quantity of warmth that the room requires in a selected space, and at a selected design temperature.
For instance, in the event you stay in Plymouth then the design temperature is -1.2C however in Edinburgh (as a result of it will get a bit colder there) the design temperature is -3.4C. The warmth pump should then be specified to ship the required quantity of warmth to the house, at that exact temperature.
In all instances, the very best and best design for a warmth pump system is to run the warmth pump on the lowest temperature doable whereas nonetheless delivering the correct quantity of warmth to the house.
However, as a result of trendy air supply warmth pumps can modulate, they’ve a software program in-built that screens the ambient temperature outdoors and lifts the stream temperature to the house because it will get colder outdoors.
So how does this profit the house owner?
In current houses, it means now you can be supplied a alternative in case your current radiators are usually not sufficiently big for the low temperatures required to run a warmth pump effectively.
The installer, as a substitute of suggesting you modify all of your radiators – which normally means rising the dimensions and or amount of them, can as a substitute specify a excessive temperature warmth pump.
In fact, the offset of that is that whereas this may seemingly provide you with a less expensive total set up price, it means you should have a barely greater working price.
The second profit of upper temperature refrigerants is that you would be able to retailer water in your scorching water cylinder at greater temperatures, which means that you would be able to have a smaller cylinder. A 300 litre cylinder at 50°C has the identical quantity of useable water as a 250 litre cylinder at 60°C and a 210 litre cylinder at 70°C.
Nevertheless, remember that in the event you retailer your scorching water at greater temperatures it’s extremely really helpful that you just match mixing valves to your scorching water shops (faucets) to keep away from scalding. It is a constructing laws requirement in new construct dwellings, however a advice in current houses.
Set up prices vs working prices
Whereas an installer will be capable to share extra particular calculations, basically they are going to use related calculations to determine how a lot additional your working prices will likely be versus the prices of upgrading your radiators.
For example, if in an effort to optimise the warmth pump you would wish eight new radiators and some lengths of pipe, given the disruption, supplies and labour we are able to estimate the associated fee for this may be round £3000.
If the warmth pump solely wants a few levels greater temperature for many of the yr, and the a lot greater temperatures for say 5 days a yr, the extra price of this is perhaps estimated at £150 a yr.
It is then a case of dividing the price of upgrading your radiators by the additional working prices, to see which sum sits most comfortably with you. On this instance, you may run at these elevated ranges for 20 years earlier than you reached the sum of £3000.
In fact, these are usually not actual figures and an installer will be capable to provide you with extra sensible numbers so that you can work with, however you possibly can see the reasoning.
What it additionally would not bear in mind, is that as you redecorate rooms or full extra home renovations, you even have the choice to improve the present central heating system over time, due to this fact bettering the warmth pump total effectivity and decreasing your working prices even additional.
In conclusion, it is vital to do not forget that excessive temperature warmth pump choices are precisely that: choices. The professionals and cons of every mannequin must be thought of, and whereas the general finest environmental answer will all the time be the low temperature, optimised set up, that is probably not the ‘finest’ answer for you.
Select your installer rigorously, do the maths after which make the knowledgeable choice. A really barely much less environment friendly warmth pump system, with the potential to enhance over time, that does not require main disruption and capital price, and that’s nonetheless eligible for the £7500 Boiler Improve Scheme grant, could possibly be simply the ticket.
