Heat pumps are inherently 'efficient' and very good at heating open spaces - like large shop floors, open offices and stuff like that. The system is really simple; you put in, say, 3kw and you get about 10kw of heat out. The heat is transferred from one heat exchanger, via a bit of simple pipework, to another heat exchanger where it is blown out with a simple fan. Very efficient, very controllable and in the Summer you can put it into reverse and it will do cooling for you as well. These systems have been around for donkeys years and work very well.
Problem is, not many people live in large open spaces and not many want a large fan unit in the middle of the living room. So, in a house, that model doesn't work, because you need to heat several small spaces, and often at different times and temperatures. Plus you need to produce hot water, which heat pumps don't do well because they run at a relatively lower temperature than conventional gas boilers. So, in housing, the functional requirements are much less simple and much of the inherent efficiency is lost. On top of that, HPs don't work well with radiators - because of the lower temperatures. To get sufficient heat into a room generally requires a radiator about three times bigger than a conventional radiator. In other words, practically speaking, HPs only really work with underfloor heating, which rules them out for the vast majority of existing houses. Unless you are an 'energy manager' for a housing association. In which case you fit them anyway, but they don't work, but as least you can write up an end of year report and tell everybody how well you are doing with green energy management.
Not saying it can't work, but the emphasis is on 'fabric first'. A HP system is way more expensive than a conventional system but you should also add the cost of changing the ridiculous radiators plus the structural insulation that should go with it plus all the disruption that goes with that plus the cost of heating hot water. Yes, it might be efficient, but it will take years to get the money back.
Heat pumps have a place but in very, very few cases is it worth it for retro-fit. And that's where a lot of claims will be flying about going forward. Because not all the people selling the stuff tell the whole truth.
Problem is, not many people live in large open spaces and not many want a large fan unit in the middle of the living room. So, in a house, that model doesn't work, because you need to heat several small spaces, and often at different times and temperatures. Plus you need to produce hot water, which heat pumps don't do well because they run at a relatively lower temperature than conventional gas boilers. So, in housing, the functional requirements are much less simple and much of the inherent efficiency is lost. On top of that, HPs don't work well with radiators - because of the lower temperatures. To get sufficient heat into a room generally requires a radiator about three times bigger than a conventional radiator. In other words, practically speaking, HPs only really work with underfloor heating, which rules them out for the vast majority of existing houses. Unless you are an 'energy manager' for a housing association. In which case you fit them anyway, but they don't work, but as least you can write up an end of year report and tell everybody how well you are doing with green energy management.
Not saying it can't work, but the emphasis is on 'fabric first'. A HP system is way more expensive than a conventional system but you should also add the cost of changing the ridiculous radiators plus the structural insulation that should go with it plus all the disruption that goes with that plus the cost of heating hot water. Yes, it might be efficient, but it will take years to get the money back.
Heat pumps have a place but in very, very few cases is it worth it for retro-fit. And that's where a lot of claims will be flying about going forward. Because not all the people selling the stuff tell the whole truth.
