Replacing Your Gas Boiler with a Heat Pump: A Step-by-Step Lancashire Guide
Replacing your gas boiler with an air source heat pump is the single biggest energy upgrade most Lancashire homeowners will make. The process from first enquiry to a working heat pump typically takes three to six months and involves surveying, grant applications, installation, and a period of adjustment as you learn how the new system works. This guide walks through every stage so you know exactly what to expect, what decisions you will need to make, and how to get the best result for your Lancashire home.
Stage 1: Research and Initial Enquiries (Week 1-2)
Start by understanding what a heat pump means for your specific property. Read up on how air source heat pumps work, check your eligibility for up to £7,500 in government grants (most Lancashire homeowners replacing a gas boiler qualify), and begin thinking about where the outdoor unit would go. Common positions for Lancashire homes include the back yard for terraces, the side passage for semis, and the back garden for detached properties.
Contact at least three qualified heat pump installers in the Lancashire area for initial discussions and quotes. You can find installers through the installer installer directories (), personal recommendations, or through Green Reach Energy’s installer network. When contacting them, be ready to describe your property type, size, current heating system, and any insulation improvements already done or planned.
Stage 2: Home Survey and System Design (Week 2-6)
Each installer will visit your home for a detailed survey, typically lasting one to two hours. The surveyor measures every room, records window sizes, identifies wall construction, checks insulation levels, assesses each radiator, inspects the electrical supply, and determines the best position for the outdoor unit.
A crucial part of the survey is the room-by-room heat loss calculation. This determines the total heating demand of your property and the size of heat pump needed. For a typical three-bedroom Lancashire semi with reasonable insulation, a 7kW to 10kW heat pump is usually appropriate. Larger or less insulated homes may need 10kW to 14kW.
The surveyor will also identify which radiators, if any, need upgrading and whether your electrical supply can handle the heat pump without an upgrade. After the survey, you receive a detailed quotation showing the system specification, total cost, government grant deduction, your net payment, and estimated running costs.
Stage 3: Comparing Quotes and Making a Decision (Week 4-8)
With three quotes in hand, compare them on system specification (heat pump brand and size, hot water cylinder size, proposed flow temperature), scope of work (which radiators are being replaced, what electrical work is included), total cost and net cost after the government grant, expected SCOP and running costs, and warranty and aftercare terms.
The cheapest quote is not always the best. An installer who proposes a larger system running at a lower flow temperature with minimal radiator changes may deliver better comfort and lower running costs than one who suggests a smaller system at higher temperatures. Ask each installer to explain their design choices and how they arrived at the system size.
Consider the insulation position. If your home has uninsulated cavity walls or thin loft insulation, addressing these before or alongside the heat pump installation significantly improves performance and may allow a smaller, cheaper heat pump. Some installers will coordinate insulation work as part of the project; others will recommend you get insulation done first.
Stage 4: government grant scheme Grant Application and Preparation (Week 6-12)
Once you accept a quote, the installer submits the government grant application to the energy regulator. This typically takes five to ten working days for approval. The voucher is valid for three months, giving a clear window for completing the installation.
During the waiting period, prepare your home. Clear the area where the outdoor unit will go. If a concrete pad is needed (common for ground-level installations), this can be done in advance. Ensure the airing cupboard or utility area is ready for the new hot water cylinder. If electrical upgrade work is needed, this can be scheduled ahead of the main installation.
If you plan to disconnect from the gas network entirely (eliminating the £372 annual standing charge), notify your energy supplier and gas network operator. The gas meter can be removed after the heat pump is operational. Alternatively, you can keep the gas connection temporarily as backup while you gain confidence in the new system.
Stage 5: Installation (Week 10-16)
Installation takes two to four days for a standard replacement. Day one covers outdoor unit positioning, refrigerant line installation, cylinder fitting, and main pipework modifications. Day two focuses on electrical connections, system filling, commissioning and initial testing. A third day may be needed for complex installations involving multiple radiator changes or underfloor heating connections.
You will be without heating and hot water for one to two days during the changeover. If installing in winter, arrange temporary electric heaters for essential rooms. Some installers can stage the work to minimise the gap, keeping the old boiler running until the heat pump is ready.
After commissioning, the installer should walk you through the controls, explain the weather compensation curve, set initial heating schedules, and demonstrate the monitoring app. Take notes and ask questions – understanding how your system works is key to getting the best performance.
Stage 6: The First Month – Adjustment Period
The first month is an adjustment period for both you and the system. Heat pumps operate differently from gas boilers – they provide steady, gentle warmth rather than bursts of high heat. The house may feel different: radiators will be warm rather than hot, the system will run for longer periods, and hot water will take longer to reach temperature.
Common adjustments during the first month include extending heating periods (running the heat pump for more hours at a lower temperature rather than short blasts at high temperature), reducing the flow temperature if the house is overheating (a sign the system is working well), and learning when to use the boost function for extra hot water before baths or showers.
Monitor your electricity consumption closely. Your electricity bill will increase (because the heat pump uses electricity) while your gas bill drops dramatically. Compare the total energy cost against your previous gas and electricity bills to confirm you are saving money. Most Lancashire heat pump owners find their total energy costs are similar to or lower than before, with significant savings once the system is properly optimised.
Stage 7: Optimisation (Month 2-6)
Over the following months, fine-tune the system for optimal performance. Adjust the weather compensation curve to match your comfort preferences (your installer can help with this remotely through the monitoring platform). Experiment with heating schedules to find the best balance of comfort and efficiency. Check radiator balancing – if some rooms are warmer than others, adjusting the lockshield valves can even out the heat distribution.
Many Lancashire heat pump owners find that their system performs better than expected once properly optimised. A system achieving COP 2.5 in the first month might reach COP 3.0 or higher after the weather compensation and flow temperatures are fine-tuned. Each 0.1 improvement in COP saves approximately £30 to £50 per year.
Book your first annual service for 12 months after installation. This is usually included in the installer’s aftercare package and ensures the system is performing correctly before the warranty period milestone.
How long does the whole process take from start to finish?
Typically three to six months from first enquiry to working heat pump. The longest waits are usually for installer availability and government grant processing. Planning ahead and contacting installers early reduces delays. Spring and early summer are the best times to start the process for an autumn installation, avoiding the winter rush when installer demand peaks.
What is the total cost after the government grant?
For a typical Lancashire three-bedroom semi, the total installed cost is £10,000 to £13,000. After up to £7,500 in government grants, you pay £2,500 to £5,500. Additional costs may include radiator upgrades (£250 to £500 each for two to three radiators) and electrical supply upgrade (£400 to £800 if needed). All work benefits from 0% VAT.
Will my energy bills go up or down?
Your electricity bill increases and your gas bill decreases dramatically (or disappears if you disconnect gas). The net effect for most Lancashire homes is similar total energy costs or modest savings of £100 to £300 per year. Eliminating the gas standing charge saves an additional £372 per year. Over time, as gas prices are expected to rise relative to electricity, the savings should increase.
