Sort of but not really.
Quick question for all you pumpers (I assume thats what you like to be called
)
I understand that up to a point as long as you have a large enough heatpump that is correctly configured you can heat houses that aren't particularly brilliant thermally. You can still get the efficiency multiplier high enough to compete with gas on cost.
Correct, the efficiency multiplier is maintained as you go up the sizes of heat pump as long as your heat pump is correctly sized for the property (e.g. it’s being used within its optimal modulation range).
I just want to clarify something because some people seem to suggest that thats the main thing to worry about.
Sizing is very important to get right, if you oversize it, it will Will never get into its optimum performance modes and is usually the issue on bad installs. Likewise if you undersized it, it will not heat the house when it gets to the coldest days of the year.
To my mind, we have a leaky old victorian house currently but are about to move and potentially into a doer upper. We basically heat the rooms we are in, while we are in them now. With heat-pumps you have to look at heating differently don't you. They are supposed to keep areas at constant temperatures rather than heat and cool all the time.
Correct, but also consider that a gas boiler is also inefficient when doing the same thing.
You only get the rated efficiency out of a gas boiler when you use them in the exact same way as a heat pump. The main difference is the impact on performance of using a gas boiler in a sub optimal fashion is lower than a heat pump.
So the reality is, even if you get the efficiency to compete with gas on cost, unless your house can hold that heat, you will be paying a lot more purely because previously with Gas you were letting most of the house sit at a much lower temperature and only heating a small part of it vs the more constant heat of the heat-pump.
This is the part where you need to look at the physics and only heating a small part of your house doesn’t save you as much money as you think.
If the walls between your rooms are uninsulated, all that heat will just leak out into the remainder of the house.
Likewise because the heat loss of the rooms you are trying to heat is significantly increased because it’s leaking into the wider house.
This means your boiler has to work to get the radiators you are using hotter than they otherwise would have to overcome the heat loss this reduces the efficiency.
Have a look at this video:
Is that right? That you really do need to make your home well insulated/draught proof or you are getting a cheaper heating system but you are heating the house much more so any saving is completely gone.
Not really, you can heat pump any house, even old Victorian ones. They only need some very basic adaptions to take a heat pump, just double glazing and loft insulation and that’s usually it.
There is also a thermal comfort consideration. Once you have the fabric of your house up to say 19/20C and keeping it there becomes very easy and you don’t need to feel the drafts as much because the air is equalised.
It also generally means you don’t need to heat it to as high a temperature (can knock 1-2c off I found) because you don’t have that temperature variation across the house and further reduces your heat loss.
The main issue with running costs is the ‘spark gap’ between electricity and gas. Electricity is loaded with ‘policy costs’ and gas just isn’t. The wholesale cost is a hell of a lot closer than the retail rates.
The last point is bonkers when you want people to move over to electricity and stop burning gas.
