Is a heat pump the best solution for hard to heat homes?

An explanation and questions you need to ask yourself

Properties with large heat loads that may not be insulated or are poorly insulated, can be very difficult to heat. The cost of heating these properties can be prohibitive and therefore many owners are seeking to reduce these costs. There are many ways of looking at this issue which will include moving to renewables. With this in mind we need to look at the reasons why renewables are to be considered and the implications of choosing a renewable system.

The renewable heating system needs to be split into the different options available.

There are high temperature systems that will operate at a similar temperature as the existing fossil fueled system such as oil. A system such as this would be bio-mass running on wood chip or a bi-valent using a heat pump with the addition of another high heat source.

With biomass we have to consider the storage of pellets and the maintenance schedule required to remove the ash. With the clean air policy also a consideration, does the burning of wood still pollute the air and is this reason enough to look at a heat pump?  

With heat pumps being looked upon as the cleanest form of heat production, the government is keen to support this technology with the renewable heat incentive (RHI) until 2021. After 2021 the scheme will no longer accept new applications, however applicants already in the scheme will continue to receive the renewable heat incentive payments.

With heat pumps you need to understand the incentives available and the limitations of such systems.

The renewable heat incentive is a scheme in which the government will pay you for the production of heat for your property. This is divided into two categories, domestic and non-domestic.

The domestic is aimed at households, and payments are based on the house energy use. This scheme pays over seven years and is capped. This will limit your payback depending on the efficiency achieved and the technology chosen. For air source heat pumps the tariff cap is 20,000kwh @ 10.49 p/kwh and ground source is 30,000kwh @ 20.46/kwh.

For non-domestic premises, which can still be residential, there is no capping scheme, payments are made on heat produced. This is measured by a heat meter that is attached to your system, however there are certain criteria which limit payments. The scheme is not designed for a way to make money but to assist with the switch to renewables based on the extra expenditure incurred.

With heat pumps the water temperature achieved for distribution through the heating system will be the limiting factor. Most fossil fueled systems can achieve flow temperatures in excess of 80°c, heat pumps in general, will only achieve 50°c. This will be more than enough to heat the property, provided that the heat emitter (radiator, fan convector etc.) is designed to work at this flow temperature. If you are thinking of changing to a heat pump the emitters throughout the property will need to be evaluated as to their suitability. The larger you size an emitter the lower the flow temperature can be. The lower the flow temperature the less energy is used, lower energy use means lower bills. If you have underfloor heating throughout your property no upgrades are generally required.

Is a heat pump right for you?

Consider the following questions To help you decide whether to consider a heat pump, you will need to ask yourself;

• Am I thinking of this purely for the payback? If so a rethink is needed as this will not be a way to make money but is likely to cover the cost difference between an oil boiler and heat pump purchase.
• Am I doing this for running costs? Both air and ground source are good solutions.
• Do I have space for a ground array or bore holes? If not then air source may be the only solution.
• Do I have a river/stream or open well? Water source heat pump may be a viable option.
• Am I only doing this for environmental issues? All options would be appropriate solutions.
• Am I willing to have upgrades to my existing system? This will mean work in most/all rooms that do not have underfloor heating. If yes, then all options are appropriate solutions.

When looking at renewable heating systems it is wise to look at the performance of the manufacturer’s products combined with the performance of the heating system.  You are looking at the seasonal coefficient of performance (SCOP).  Ideally you would want your property to achieve a SCOP of at least 3 but you may achieve 5.

Remember not all manufacturers are equal.

At R A BROWN we aim to offer at least two alternatives for every project and will advise on any aspect of your heating installation.  If you would like to discuss a solution for your property then please give us a call on 01603 898904 and we would be happy to help.