Because heat pumps operate at a lower flow temperature than boilers. Smaller radiators designed to operate at hotter temperatures won't bring your house up to the target heat temperature operating at lower temperatures. They often need replacing. [1]
Trials of heat pumps in existing UK housing have found it difficult giving away heat pumps for free, because of all the extra work required for them to operate properly in the house. [2]
> Heat pumps are ~3x as efficient as the best gas furnaces so why would you need a better insulated house?
Heat pumps in comparison to conventional boilers are meant to be on all the time at a lower temperature, as they take a long time to bring a house up to target temperature.
They depend on good insulation, otherwise the heat never accumulates, similar to if you leave a freezer door ajar, it will never freeze.
> So why would you waste all that energy converting from renewable electricity to hydrogen then burning hydrogen (which is not super efficient anyway)?
At times, renewable energy drives electricity prices negative. We haven't got many ways to store this when it happens, converting water to hydrogen would be a good candidate, which can be delivered using existing gas infrastructure.
> Plus, heat pumps already work at scale
Not in existing UK housing, which would require major changes (insulation, underfloor heating, larger radiators), before they work.
[1] https://www.imsheatpumps.co.uk/blog/can-i-use-radiators-with... [2] https://www.housingtoday.co.uk/news/major-challenges-in-pers...
The reality is that we don't have time to wait on unproven technologies like hydrogen boilers (which gas boiler companies are using to try to delay their inevitable demise). We don't have time to wait on an non-existing hydrogen infrastructure. Despite what you say, heat pumps are working at scale today around the world and individuals can go buy them now and successfully heat and cool their homes.
But hey, I'm not a fundamentalist — whatever works! We need all solutions very fast in order to mitigate damage. If part of that is hydrogen then great! It just seems unlikely to scale at the required rate.
It's not an argument, I'm just relaying what heat pump installers need to change in order for the pumps to work.
The system also needs to provide hot water.
> The reality is that we don't have time to wait on unproven technologies like hydrogen boilers
They're not unproven, 20pc hydrogen ready boilers are being sold today.
> Despite what you say, heat pumps are working at scale today around the world and individuals can go buy them now and successfully heat and cool their homes.
That some people have used heat pumps to successfully heat their homes was never disputed.
They're just not the panacea they are made out to be for UK housing.
Also, the problem with hydrogen is how do you produce it? Probably with renewable energy, right? So why would you waste all that energy converting from renewable electricity to hydrogen then burning hydrogen (which is not super efficient anyway)? Might as well just use the renewables to power your heat pump. Plus, heat pumps already work at scale whereas hydrogen needs a lot more work before it's ready for primetime.