Benefits of hybrid heat pump systems

slizovskiy

Hi all,
 I wanted to share my bit of knowledge and experience on hybrid heat pump systems. This is when you do not need to remove your existing gas boiler, but pass control over it to a new heat pump controller. A small heat pump is connected in parallel with the gas boiler to your existing heating piping. The controller decides which device to run: a heat pump or a gas boiler  in order to heat your home. When it's too cold outside, the gas boiler may work out cheaper due to lower cost of gas compared to electricity (you enter gas and el prices and the controller decides).  An advantage is: you do not need to buy a bulky and expensive water storage tank (water heating may be still done by gas) and you may buy a heat pump with much smaller power  (as it's anyway not sufficiently efficient in frosty weather).   My own bill for hybrid heat pump installation is only £2000,  not £10000 as usually quoted.  

matelodave

Yes but the heat pump still uses leccy which is over three times the cost of gas so unless your heatpump has an SCOP of better than three and a bit , it's not saving you any money and will never really pay for itself until gas costs at least half as much as leccy per kwh.

I've got a heatpump and I'm happy with it but I'd swap it for a gas boiler if we could coz gas is cheaper than leccy, even with a heatpump. Energy efficiency does not equate with cost effectiveness

jrawle

To me, the benefits of heat pumps are environmental, not financial. Also, if I switch to a heat pump when my gas boiler reaches its end of life, much of my reasoning will be to remove the (albeit small) risks associated with gas (leaks, CO); remove the gas supply and associated standing charge; reduce the cost of servicing and the complexity of the system, etc. Having two systems in parallel means two different systems to maintain, and none of the benefits of ditching gas.

I also prefer to have a hot water tank. It means if we do have the threatened power cuts, I can still shower or do the washing up (by the light of my rechargeable lantern, if necessary). Ditto if the water is off for any reason.

Reed_Richards

I think it's quite a sensible idea way to hedge your bets between a heat pump and gas or oil.  You'll use gas/oil when it's cold outside and the heat pump when it's warmer outside (in spring and autumn) so the heat pump can always operate with a high COP (greater than the three-and-a-bit that @matelodave says is necessary).  The moot point is whether the savings you achieve compared to using only gas are enough to justify the cost of the heat pump.   

70sbudgie

Could it be used to transition to fully HP? Ie, install the HP, with control over the gas boiler, then when the boiler reaches end of life, remove it completely and rely only on the then existing HP?

Edit to add: does ff "back up" then mean that the scop is a bit misleading, because you're less worried about winter performance? Ie would the hp mainly, only operate in the shoulder months?