Octopus Energy launches heat pump as cheap as a gas boiler

Air Source Heat Pumps (ASHPs)

Last Post by AllyFish 3 years ago

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Mars

(@editor)

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Topic starter 16/02/2023 8:29 am

Another interesting move by Octopus: read the article <here>

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ChickenBig

(@chickenbig)

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16/02/2023 8:42 am

Looks interesting, a joint Octopus/RED development, so it bodes well for efficiency of installation and operation respectively. Let us hope they achieve sufficient adoption to get further economies of scale.

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Thylacine333

(@thylacine333)

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16/02/2023 9:22 am

I wonder if this is a ‘high temp’ heat pump approach so attempting to reduce need for alterations to gas boiler set up? (Or at least that seems to have been a hinted plan by RED and others)… interesting to see if the efficiency pay offs are compensated by installation cost reductions and minimising disruption… let’s hope so for the sake of ASHP adoption.

Airwell Wellea 12 kw monobloc ASHP (rebranded Midea unit - feeling lonely)
200 sq m detached 1960s bungalow with 2006 extension
mix of rads and ufh

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AllyFish

(@allyfish)

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18/02/2023 6:12 pm

The economy of manufacturing scale comes into it, with Octopus' backing, RED will have more purchasing power for the major ASHP components. I'm personally delighted that Octopus is backing and partnering a UK manufacturer, RED. They can design a ASHP optimised for the UK climate. Nearly all ASHPs currently on the market are from far-Eastern OEMs, and they don't like our damp winter climate spending far too much time in defrost once the air temperature drops below 3 or 4degC. The evaporator coil is not designed for our humid climate. It if was, it would not have a fin pitch of 1mm! Defrosting the coil using reverse cycle rather than hot gas injection is also not very clever. It's frequently taking energy out of the house heating circuit in weathers when you really want as much energy as possible going into the heating circuit.

There does seem to be a fixation on matching ASHP costs gas boiler prices. That's fine and perfectly achievable. BUT, wanging a £2,500 ASHP in a house formerly heated by a system boiler in a 'straight swop' is unwise. It may have to run at a high leaving water temperature to provide adequate heating. That's costly. Whatever is spent on insulating the property, then changing the heat emitters for lower flow temperature ones, will be recouped over the life of an ASHP in lower energy bills. As things stand, an ASHP needs a SCOP of 3:75-4 to cost less to run than a good efficiency gas boiler. That means, for a reasonably insulated property, a design heating flow temperature in the mid 40s at most. The claimed COPs from most manufacturers are seldom realistic or achievable in most retrofits. Once you get into the mid 50s design flow temperatures ASHPs get very costly to run, more so than mains gas at present. The benchmark is every 1degC increase in design flow temperature = 2.5% more running cost. So 55degC compared to 45degC is 25% more expensive. High temperature ASHPs can be great for providing hot water at 60degC, to avoid a 3kW immersion legionella control, but high temperature ASHPs for heating circuits is not a good solution.

Another complication with ASHP retrofits is the need for a system hot water cylinder. Most ASHPs cannot provide hot water generation on demand, but we may see products on the market soon that can. Houses with combis might not have the space for a 200L cylinder and the piping to and from it may be challenging. All these considerations push up the install costs.

it will be interesting to see how ASHP designs develop. Most on the market at the moment are modified air to air heat pump products, and are something of a compromise product by their very nature.

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