We get asked this question a lot, so we decided to write a piece about it.
The short answer to this question is yes, you can install an Air Source Heat Pump and keep your old boiler as a backup. And its called A ‘Hybrid System’ or ‘Dual Fuel’.
In this article were going to talk about Hybrid Systems, the Pros & Cons and whether keeping your old boiler as a backup is worth it.
What Is A Hybrid System
A Hybrid system or a Dual Fuel system uses a combination of renewable energy with fossil fuels. A hybrid system is meant to efficiently heat your home in all circumstances. The idea behind it, is in the summer when the weather is considerably warmer the Fossil Fuel Boiler is shut off and the ASHP slowly heats the home using small amounts of energy, saving you money.
Once the winter rolls in and the outside temperature hits below 0 degrees, the ASHP shuts off and the Fossil Fuel Boiler kicks in providing instant heat in the colder months, which is then considerably more expensive. Providing you comfort all year round.
Is It Necessary?
The short answer is no. A correctly sized and designed ASHP will be able to comfortably heat your home and keep it at your desired temperature even in weather as cold as -24 degrees.
Not only is having a backup boiler not necessary but it also drastically reduces the amount of RHI you’ll receive. This is because the RHI is calculated by how much heat you produce with your ASHP, if there’s a backup boiler then it reduces the heat produced by your ASHP and in turn reduces your RHI.
Having a Boiler as a backup massively reduces the efficiency of the whole system. An ASHP has an efficiency of up to 380% meaning for every KW of energy you put into a Heat Pump it produces 3.8KW of heat. Compared to a fossil fuel boiler that has an efficiency of 90% at their best.
Lets have a look at the Pros & Cons of having a hybrid system.
Pros & Cons
- Guaranteed heat all year round. (Achievable with an ASHP alone)
- Reduces the amount of RHI you receive for your ASHP
- Reduces the overall efficiency of the system
- Added cost of buying fuel for the backup boiler
- Maintenance for both the boiler and the ASHP
- Have to re configure the system once the Boiler breaks
We understand that the want for a hybrid system is because of a lack of trust that an ASHP can comfortably heat a home in all weather.
The question we always get asked is how can a Heat Pump heat my house in the winter if it only heats to 55 degrees?