Is the outdoor unit noisy?
All heating products make some noise, but heat pumps are usually quieter than fossil fuel boilers. A ground source heat pump may reach 42 decibels, and an air source heat pump may reach 40 to 60 decibels, but this depends on manufacturer and installation. ... As a rule, heat pumps are not noisy.
Do I need to have large radiators and if so why?
Our goal when designing and installing your heat pump is to ensure the system keeps you property cosy and reduces your fuel bills.
The key to installing any heat pump system efficiently is to ensure that the design flow temperature of the system is as kept low as possible. Although a heat pump will operate at a high temperature it is not in your interest to do so as the efficiency reduces the higher the flow temperature is.
For example:- If your Kitchen requires 1000 watts of heat, we need to size a radiator or radiators that will deliver 1000 watts of heat at a given flow temperature.
If the design flow temperature of the system is 60 degrees then the radiator would need to be 700mm wide x 700mm high to deliver the 1000 watts of heat required and the efficiency of the heat pump would be 3.
If the design flow temperature of the system is 40 degrees then the radiator would need to be 1300mm wide x 700mm high to deliver the 1000 watts of heat required.
Why not just run the heat pump at a higher flow temperature?
By running the heat pump at a lower temperature, the total energy cost (your electric bill) will reduce and your RHI payments will increase.
The tables below shows the effect that the flow temperature has on the efficiency of the both a ground source and air source heating system.
Air Source Heat Pumps
| Flow Temperature | Efficiency (Seasonal Performance Factor) | Star Rating |
| 35 | 3.6 | 6 |
| 40 | 3.4 | 5 |
| 45 | 3 | 4 |
| 50 | 2.7 | 3 |
Ground Source Heat Pumps
| Flow Temperature | Efficiency (Seasonal Performance Factor) | Star Rating |
| 35 | 4.3 | 6 |
| 40 | 4.1 | 5 |
| 45 | 3.7 | 4 |
| 50 | 3.4 | 3 |
For example If a ground source heat pump has a design flow temperature of 40 degrees then the seasonal performance factor is 4.1. which means for every 1kW of electricity you get 4,1kW’s of heat energy if the heat pump is running at 50 degrees flow temperature then for every 1Kw of electricity you get 3.4kW’s of heat energy.
Do heat pumps only work in new build property’s ?
No, this is a common myth. Essentially heat pumps will work in any property regardless of how “leaky” they may be so long as it is designed correctly. It quite simply means you just need a bigger heat pump in an older building just like you would need a bigger oil boiler.
Will I have enough hot water?
Heat pumps can produce domestic hot water on their own up to 55 degrees C, which is generally the temperature that most fossil fuelled boilers store hot water at. You wouldn’t hold your hand under water at 45degrees C.
If you wanted the water hotter than 55 degrees then the heat pump would use the immersion heater to bring it up to the required temperature, much like it does automatically once every 7 days for legionella disinfection.
Are they expensive to run?
No, a correctly designed heat pump system combined should save approximately 30%-40% more than an oil fired boiler. Combine the heat pump with Solar PV and battery storage and the heat pump should cost less to run than a mains gas boiler!
Can I run my heat pump with my existing oil boiler?
Yes, the heat pump can automatically operate your existing boiler to run in an emergency or if the additional heat load is required. Operating the heat pump in such a way is generally only done in very large properties where the heat pump does not match the full heat loss of the property as it can affect your RHI payments as you will be required to be metered for payment. Our design team can advise on this subject and whether it is suitable for your property.
