Questions to ask before you upgrade | Purbeck Energy Group

Before you start

Three questions that apply to every job, whatever you are buying.

Have I got more than one quote?
Get three, in writing. Each one should include its own design for your home, so you can compare like with like. Tell every installer what kind of home you have: flat, terrace, semi-detached or detached. It changes what is possible and what it costs.
Do I qualify for a grant?
Check before you sign, because some grants cannot be claimed after the work starts. Our guide covers grants for insulation and heating and the Boiler Upgrade Scheme.
Can I see a job you have finished?
Ask for references, and if you can, visit a previous installation. Dorset Greener Homes opens real homes to visitors, and the owners will tell you what worked.

The cheapest savings come first, and they make every later step smaller.

Will my insulation need upgrading?
Heat lost through the roof, walls and floor is money spent on heating. Insulate first and a heat pump can be smaller and cheaper. If you are not sure where you stand, the free Dorset Homewise tool will tell you.
Where are the draughts?
Look at doors, windows, the letterbox, the loft hatch and the floorboards. Draught-proofing is the cheapest job on the list, and a warm room costs less to heat.
Is double glazing worth it for my home?
New glazing can make rooms more comfortable, but it is usually one of the slower jobs to pay back. Ask your assessor to put it in order alongside the other work.

Free help is available. See free local help and grants in our guide.

Where will the heat pump go?
The outdoor unit should sit close to where the pipes enter the house. Longer pipe runs add to the cost, so ask the installer to show you the route.
Will my pipes and radiators work with it?
A heat pump runs the water at a lower temperature than a boiler. Some radiators then give out too little heat, so the installer should check room by room. A quote without a heat loss survey is a warning sign.
Would a bigger heat pump be better than new radiators?
Either can solve a shortfall in heat. Ask for both options priced, and ask what each one does to your running costs.
Would an air-to-air heat pump suit me, especially in a flat?
Air-to-air units warm the air with indoor units, a bit like air conditioning in reverse. They usually cost less to fit and the Boiler Upgrade Scheme pays £2,500 towards one. They do not make hot water, so ask how you would heat it.

Do I need a hot water cylinder?
A combi boiler has no cylinder, but a heat pump usually heats water stored in one. Cylinders come in many sizes, so ask about compact ones if space is tight.
If there is no room, what else could work?
Compact electric options exist, such as a heat battery like a Sunamp. Ask the installer to explain what each one costs to run and why they would pick it.
Is my mains water flow strong enough?
Some cylinder designs rely on your mains pressure and flow, so a weak supply can mean a weak shower. Ask the installer to measure both before they choose.

Is my roof big and sunny enough?
Roof area, direction and shade decide how much you generate. The Homewise tool gives a first answer, and an MCS installer should give you a proper assessment. Tell them if you plan to add a heat pump or an electric car.
What if the roof needs repairs later?
Panels have to come off and go back on. Ask what that costs and who does it. If your roof is near the end of its life, repair it first.
Will the panels work on cloudy days?
Yes, but they make less. Ask for the expected yearly output in kWh for your roof, and how the installer worked it out.
How long will the panels last?
Energy Saving Trust puts the life of panels at around 25 years, with the inverter replaced once, around year 12. Ask what the warranty covers for both.

How big a battery do I need, and for what?
The answer depends on the job. A battery can use cheap overnight power, store spare solar, or keep the lights on in a power cut. Ask the installer to size it for your job, not the biggest one they sell.
How many charge cycles is it warranted for?
A cycle is one full charge and discharge. Energy Saving Trust gives 10 to 12 years as a typical life, so ask how many cycles the warranty covers and how much capacity it guarantees at the end.
Where will it go, and is there a fire risk?
Manufacturers set rules on where batteries can be fitted. Ask for them in writing, and tell your home insurer.
Will it keep the lights on in a power cut?
Many systems switch off when the grid does. Backup needs extra equipment, such as a battery gateway and an automatic changeover switch. It also needs proper earthing, so power cannot flow back onto the grid and endanger line workers. Backup covers chosen circuits only, usually the fridge, lights and wifi, not the whole house. Ask which circuits, and what it adds to the quote.
How long would it last in a long outage?
Divide the battery size in kWh by what you are running in kW. A 10kWh battery feeding 0.5kW of lights, fridge and wifi lasts around 20 hours. An induction hob or oven draws several kW and empties it in hours. To run bigger loads, the inverter has to supply them too, so ask about that.

Would a low-cost tariff suit me?
Cheap overnight rates matter most if you have a battery or a heat pump. A battery can pay or not depending on the tariff, so ask your supplier what is on offer.
Do I need another meter?
Ask your supplier. Many cheap-rate tariffs work through a smart meter, so you may not need a second one.
What will it cost to charge the battery in winter?
Ask the installer for a figure in pounds, based on how much electricity you use and the tariff you would be on. Ask them to write down the unit price they assumed.
Will it cope if I run everything at once?
Think of the heat pump, your appliances and an electric car charging together. Batteries, inverters and your home’s electricity supply all have limits. Ask the installer to show their working.

Lifespans from Energy Saving Trust. Checked October 2026.

If an installer gave you a good answer, or a poor one, we’d like to hear about it. It helps us keep this list useful for the next household.