John retweetet

Gas boilers are not 95% efficient (in the real world they’re lucky to be 85)…
Great to see the reception to our unique transparent dashboard showing the real world performance of all Octopus Cosy Heat Pumps installed in customers’ homes.
Of course, some people who like burning stuff are always looking for “gotchas”. One of the most common is the assertion that “modern gas boilers are 95% efficient”
This is horseshit. Just like cars hardly ever deliver the official miles per gallon figures, so boilers underperform too.
Whilst an A rating boiler does indeed achieve 92% in lab tests, in the real world 80-83% efficiency is the norm for an “efficient” gas boiler (and older ones are much worse. Like 70-80%).
There’s surprisingly little investigation into this - but here’s an official field study assets.publishing.service.gov.uk/media/5a75149b…
If you’re interested
- a condensing boiler typically needs to be set to 50 degrees
- it then needs a return temperature of 30 degrees to ensure proper condensing
- and needs to be running long enough to get into condensing mode
—> characteristics pretty similar to a traditional heat pump in its most efficient mode! For which heat pumps are slammed by fossil fuel lovers.
- it also needs thermostats set correctly and to be right-sized for a property whilst most are oversized
Of course, if any boiler manufacturer wants to put their full fleet online so we see the real world data, we could compare to Octopus’s Cosy Heat Pumps.
Being generous to boilers, if they have a typical efficiency of 0.85 and a real world Cosy has efficiency of 3.7, an Octopus heat pump is 4.35 times more efficient.
With electricity being about 4.3 times more expensive than gas after April, this makes a heat pump cheaper to run.
But a heat pump can use smart tariffs to access cheaper electricity, so it’s typically quite a lot cheaper to run - the real world data says someone on a heat pump has electricity at a 3.7 multiple per unit vs gas - so will be paying 17% less on average to use a heat pump than they would a gas boiler.
Even more so if you can terminate the gas supply and save the standing charge (once you have a heat pump, you can get an induction hob and ditch the gas hob..) - another £130 annual saving from using a heat pump.
Octopus’s huge investments in R&D and manufacturing are bringing costs down all the time, and you can see why the fossil industry is scared. Like canal owners looking at trains in the 19th century…
Of course - Scandinavia’s already there. Norway is a huge gas producer but heat pumps are their dominant heating, whilst only 5% of homes have gas.
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