Air Source Heat Pumps

How do air source heat pumps work?

These units work by absorbing heat from the outside air through an evaporating coil. Now the units compressor will pump refrigerant through the system to compress the gas inside, this in turn will create large pressures within the unit. The pressures create heat that is transferred through a heat exchanger to a primary water circuit.

What are the design considerations for my home?

An air source heat pump is fairly large in size, and will require one metre of access at the front for maintenance. They produce a small amount of noise (like a fridge freezer). Often they are placed beside a garage, down the side of the house, or mounted on brackets on the wall of the property. A free flow of air will be needed for the pump to work efficiently and not to start short cycling reused air.

People talk about 3 phase electrical supply for the unit to work. What are these?

3 - Phase electrics are often needed for heat pumps that have high KW inputs. This is because of the current they draw from the grid. Without 3 phases lights may flicker on and off during startup of the machine. A normal home operates by taking one line from the phase of the power lines above your home. 3 phases is 3 lives taken which increases the amount of current available. This supply will cost around £2000 to install and is not always available so check before deciding on an air source heat pump. Air source heat pumps installed by Solo Heating Installations only require a 3 phase supply if the output you is above 12kw.

What else will I need for this system to work?

Air source heat pumps work more efficiently at lower operating temperatures. For this reason it is advised to have underfloor heating throughout your home. They will also need a buffer tank or thermal store. This will stop them cycling on and off in a short space of time. As a final step the hot water will need a backup energy source such as an immersion heater or small gas boiler. The backup heat can come from many different renewable sources.

You can find more information on Air Source Heat Pumps at the Heat Pump Association Website

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Ground Source Heat Pumps

How do ground source heat pumps work?

Ground loops are installed in the ground and are filled with an antifreeze mixture. The liquid is pumped around the coils by a large pump located at the ground source heat pump unit. After the water is heated through the stored heat energy in the ground, a process of compressing refrigerant within the unit will create high pressures that will release heat to temperatures around 30-40 degrees. This heat is transferred by a heat exchanger to another circuit of water that is linked to a buffer tank or thermal store.

What must I consider before purchasing a Ground Source Heat Pump system from Solo Heating Installations?

The pumps within the unit will create a low humming noise that may cause a nuisance if its positioned in a garage below a bedroom for instance. They are often located in utility or plant rooms as they will need some access for any future maintenance.

Ground source heat pumps work more efficiently in different ground conditions. Some earths types around the UK will not be as suitable to be drilled or they may be of a material that does not conduct heat very well to the ground loops. Ground such as wet soil with underground streams will conduct the heat very well, but at the opposite end of the scale ground like hard rock will not conduct heat so well. A full ground survey is recommended before making any decision or starting any work towards a ground source heat pump. Solo Heating Installations can arrange this survey and any drilling works needed.

People talk about 3 phase electrical supplies for the unit to work. What are these?

3 - Phase electrics are often needed for heat pumps that have high KW inputs. This is because of the current they draw from the grid. Without 3 phases lights may flicker on and off during startup of the machine. A normal home operates by taking one line from the phase of the power lines above your home. 3 phases is 3 lives taken which increases the amount of current available. This supply will cost around £2000 to install and is not always available so check before deciding on an air source heat pump. Air source heat pumps installed by Solo Heating Installations only require a 3 phase supply if the output you is above 12kw

I've heard of high prices for these systems, what will everything cost?

As a very basic guide, a ground source heat pump using the horizontal loop type system will cost upwards of £8500. You will then have to pay for the ground excavation works. This is normally undertaken by the ground worker whilst the plant machinery is on site. If boreholes are used expect to pay around £1500 per hole with a normal installation comprising of two.

You will save around you £500 - £800 in energy bills per year and cut your carbon emissions significantly. Ground source heat pumps have a working life of above 25 years so you will be future proofing your property against fuel cost rises. With the right technology behind them, ground source heat pumps can provide a working basis to create a truly zero-carbon or even carbon plus home.

I've heard that the slinky coil design can create problems with ground freeze?

Currently at Solo Heating Installations it is our opinion that slinky coil design ground collectors are likely to cause problems in the future with ground freeze. Because of the energy extracted by the coils in a relatively small area, radiant energy from the sun can't keep up with the heat transfer into the pipes, so slowly the ground around the coils will loose heat that it cannot regain. It has been seen in some circumstances that the ground completely freezes over in the areas of the coil. It is claimed that it can be worked out so that no problems are created, but we say why take the risk? It is our recommendation to use the horizontal ground collector type (including open loop) or bore hole type design. We would not install any other system.

Find more about GSHP's here at the Ground Source Heat Pump Association Website

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Gas Condensing Boilers

How do these condensing systems work?

Condensing boilers work by using heat energy from a gas flame to heat water. But where they are different is the condensing boiler will reuse hot gases that would normally escape through the flue and extract the heat out of them. This lowers the temperatures of the resulting flue gas' creating a condensation effect. Condensing boilers only work in condensing modes at around 55 degrees so any system designing out of this temperature range will dramatically lower the systems efficiency.

All boilers are judged on efficiency by the SEDBUK which measures each individual boiler and puts its efficiency percentage into a bracket. Only brackets A and B are currently accepted by the Building Regulations Authority for new appliance installations.

Tell me about the extra controls available to make these systems work even better?

It is the law under Part L of the building regulations that specific controls for the system must be installed to increase the efficiency of the system. Many other controls often get overlooked that can further reduce your fuel costs.

One of these controls is a Setback Programmer and Weather Compensator. These work by automatically turning the central heating on at a specific time to reach a certain temperature that the user sets. So if you want the house warm at 7am, the setback programmer will learn how long it will take to bring the system to that temperature and start it up at the relevant time. This can be combined with a weather compensator, which reads the outside temperatures and adjusts the internal temperature and setback controls accordingly. Speak to Solo about bringing your heating system into the 21st century and cutting down your heating bills.

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Unvented Hot Water

Should I choose an unvented cylinder or a combination boiler system?

A hot water cylinder provides a basis for stored hot water that the user can draw off at any time without worrying about the water 'drying out'. This drying out often occurs with combination boiler systems because they cannot cope with large demands and homeowners end up getting no hot water through their taps and showers. It can also lead to poor performance during showers because fluctuations in pressure will alter the water flow coming through the shower head.

Combinations boilers are useful in certain situations like flats and small houses where they will not encounter larger demands. But for detached houses with multiple bathrooms and ensuites, Solo Heating Installations always reccomend a hot water storage centre.

I've heard of secondary return hot water systems. What are these?

A secondary hot water return is used when the draw-off points in the house are far away from the hot water cylinder. Many people experience a long wait when they turn on a tap before they get any hot water through, this system will eliminate that. It will cut down water wastage because you are not having to run water of get the hot supply.

The layout includes an energy efficient pump wired into the programmer that will pump water around a loop to the hot draw-off points within the house. The programmer ensures the pump does not run all the time and will reduce the energy required for the system to the equivalent of running a small bedside lamp.

Solo Heating Installations install secondary hot water returns with thermal store designs. Traditionally it was not possible to combine these systems because of the heat loss sustained into the thermal store. We recommend a small NIBE UKV buffer tank and hot water mixing valve for the secondary hot water to return into which eliminates this heat loss.

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Electric Boilers

Are electric boilers a better alternative to gas boilers?

Solo Heating Installations had a client who did not have a mains gas supply to his home and was deciding whether to put one in at a cost of around £1200, or to stick with electric boilers. After looking at the figures Solo worked out that it was still cheaper to put a gas supply in than run electric boilers systems. This is true for detached homes with multiple draw-offs but for small flats this is not the case.

Electric boilers in certain situations will remove the need for Landlord Safety Checks and multiple gas supplies to blocks of flats. This will reduce initial outlay costs but not running costs for the end user. Electric heating and hot water will cost you around three times more to run than the gas alternative.

Solo Heating Installations will always recommend you look at the gas or renewable energy options before you choose electric boilers. But electric boilers can be a great way to save money on the initial outlay.

People talk about 3 phase electrical supplies for the units to work. What are these?

A 3 - Phase electrical supply is often needed for electric boilers. This is because of the high current they draw from the grid. Without 3 phases of power to your home, lights can flicker on and off during startup of the unit.

A normal 230v system operates by taking one line from the phase of the power lines above your home. 3 phases is three lives taken which increases the amount of current available. This supply will cost around £2000 to install and is not always available so check before deciding on an electric boiler.

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Heat Recovery Systems

There are many upgrades available for heat recovery systems, are these a worth-while option?

Upgrades to the heat recovery systems that Solo provide include better filters, climate cooling and air conditioning.

Upgraded filters are an excellent choice for allergy sufferers as they will filter an even greater amount of particles out of the air. The filters we offer are electrostatic filters that work at higher efficiencies to the standard ones.

Climate cooling is a step down from full air conditioning. It will go a long way to cool the air as it passes into the system during the summer months to ensure your property remains ventilated but cooled at the same time.

Air conditioning upgrade will give you powerful control over the temperature of the air coming into your home through the heat recovery system. It will allow you to bring the fresh ventilated air into your property at a much lower temperature that the outside to give that air conditioned coolness.

Where will the air lines and grilles be installed?

It is most common to run the flexible air ducts through voids in joists and voids in the loft space. Often the unit will be located in the attic eaves, with the lines running around the house and dropping down to each level. The grilles themselves can be positioned on the ceiling or even the walls.

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Thermal Stores

My architect has advised me to go for a thermal store, what design considerations are there?

Thermal heat stores work on the principles of heat layering into different temperature zones within the cylinder. It is for this reason that the cylinders need to be tall, roughly around six feet. They will therefore need to be positioned in a room with clearance for the cylinder and any adjoining pipework. Temperature and pressure relief valves will need to discharge into foul water drains.

There are so many different thermal stores available to buy; how will I know which is the right one?

The key difference to the thermal stores is the amount of external tapings available for the different heat sources. It is always advisable to buy a thermal store with the ability to install a renewable technology in the future in case you decide to. Many renewable energies such as Air Source Heat Pumps will require a certain amount of water in the system to eliminate any high pressure or cycling problems. They will also have to be sized correctly to meet the demands of the hot water draw-offs to the property. Solo Heating Installations will be able to advise you on the correct thermal store for your system at the design stage.

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Solar Panels

Do solar panels have any payback period?

Solar panels are currently one of the best renewable energies in terms of payback. We can install a solar system for around £3400, and because these systems can save you £300 per year, they have a good pay back period of around 10 years. Once you factor in the £400 government grant available, and the steady increase in fuel prices, the period reduces significantly.

My local authority have insisted on using solar panels for my new build?

As popularity for solar panels increases, local authorities are in some cases making it compulsory for homeowners to install solar panels for their new home. If you find this is the case, we would suggest installing a large thermal store cylinder and for you to consider underfloor heating on at least the ground floor of your property. When solar panels are combined in banks of 9sq metres or more, their outputs usually exceed the hot water requirements for the property and so the excess heat the panels produce needs to be heat-sinked somewhere to avoid damage. This is possible by either installing heat dump radiators in an uninhabited room such as a garage, or installing an oversized thermal store that will allow the solar panels to dump the heat safely.

I wouldn't like the look of solar panels on my roof, is there another place to mount them out-of-site?

There are now many different possible mounting positions for solar panel collectors apart from the roof. Solo Heating can now install panels on flat roofs with special mounting 'A' frames, or even have panels mounted to the side of an exterior wall. It is always a consideration to which way the sun faces to determine the location of your panels. A SW to SE angle is always preferred and for it to be away from cast shadows.

Solar panels come in two different designs, the evacuated tube design and flat plate. The evacuated tubes are more efficient but are often not chosen because people prefer the look of the flat panel designs.

Do solar panels require any maintenance activities?

Solar panels require an annual check of the antifreeze fluid levels which you can do yourself. Other than that, there are few moving parts and little to go wrong.

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Combined Heat and Power Units

Will I need a 3 phase electrical supply for my CHP unit to work?

Although not a frequently asked question, it will soon become apparent to homeowners that in order for a combined heat & power boiler to work in their home they will need a 3 phase electrical supply. This is because the unit produces electricity in 3 phases.

Normally a home consists of a 230v single phase supply, this is where one 'power' line is taken, but in certain circumstances where more current will be drawn, 3 phases will need to be taken to increase the voltage to 415v. A 3 phase supply is not always available to be installed and will set you back around £2000, so always check availability before deciding to install a CHP unit.

Will the CHP unit suit my home?

The BAXI CHP Boiler will have minimum output level of 12.5kw for heating. If your home has a lower heat demand, there will be a need to install a buffer tank. This tank is essentially an empty mass of water that gets heated up and acts as a heat buffer between the CHP boiler and heating system. Without this tank the boiler would cycle on and off which would eventually damage the pump and motor. A buffer tank is roughly the size of a standard hot water cylinder found in most airing cupboards. If you unsure of heat demands for your property, or are undertaking a renovation project, speak to Solo Heating Installations about working out the heat loss for your home.

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Underfloor Heating

I've had experience or heard of older systems having poor controllability?

With the older underfloor heating systems, there was a long delay in systems getting warm and keeping the systems at the desired temperature was difficult. This has all changed with modern systems being highly controllable, now surpassing standard radiator systems in terms of efficiency and comfort. Think of the entire floor to your home being one large thermal mass that emits heat evenly around the floor.

Underfloor heating systems have great health benefits for allergy sufferers and will reduce dust traveling through the air. This is because they do not work on convection currents like radiators, with warm spots and cold spots within the room, and so do not transfer dust around within these convection currents.

Underfloor Heating costs more than standard radiator systems, is it a good option?

There is no short answer to this as every situation is different. For many of the new renewable or green technologies to operate at an efficient level, underfloor heating is a necessary part. This is because underfloor heating operates at lower temperatures, units like ground and air source heat pumps operate at lower working temperatures so underfloor heating is needed.

Underfloor heating is also known to increase the value and salability of your home, as homeowners see it as a very desirable option. Quite often people will choose underfloor heating on the ground floor and have radiators upstairs. To lay the pipes on the ground floor within the screed is always cheaper than running them for the 1st floor.

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Biomass Boilers

What do biomass boilers actually burn?

The main substances that will be burnt for a domestic biomass boiler are wood pellets and wood chips. When factories produce waste wood from manufacturing, this wood is recycled into pellets. More and more short crop cycle trees are grown and turned into fuel for biomass systems. Its this sustainability and the fact that they are in effect zero-carbon, why people are looking more seriously at installing a biomass boilers.

What are the main design considerations for such systems?

Fuel

It's important to consider ease of access to load fuel into the hopper heads.

Space

Biomass boilers are relatively large, and unless you want the manual log loading systems, a large hopper head and feed facility will need to be installed indoors. Provision for such space must be taken into account at the early planning and design stage. Many local authorities will need to give prior approval when you wish to install a biomass boiler, especially in a protected area.

Cost

Biomass boiler systems can be expensive to install at around £8500 to £12000. But they can be a great alternative to ground or air source heat pumps as they will not require large amounts of electricity to run.

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LPG Cylinders

Will I have to get replacement cylinders myself, when the gas runs out?

When your gas cylinders run out, the homeowner will have to arrange with a company such as Calor to collect your cylinders. When they collect them they will deliver a new set of cylinders at the same time.

Where will I locate my cylinders?

The propane cylinders need to be situated outside of your home. Butane cylinders can be installed within a garage as long as certain criteria are met. The cylinders will need to be upright, secure and have easy access to change and maintain them. There are also regulations affecting how far they can be from windows, drains and air vents. Solo will advise on the best places to locate the cylinders.

Underground bulk storage cylinders cannot be placed below driveways or near large deep rooted trees. They require an access cover for maintenance of the valve assemblies.

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