I would find a great builder with links with a structural engineer to help you see what might be possible and how much it would cost. When you know that you have sufficient funds to proceed you should then consider the creative side of things. You can explore layouts with a designer, concept planner or architect. The architect may be the most expensive option but you would have their technical expertise. A concept planner sells only design but you can explore many layouts at a lower price point than the architect. A designer can work in the same way as the concept planner but can also help with the finished look and procurement. When selecting which professional to work with you should think about whether you will need a project manager for the build and if you want the design professional to take on that role.

I think your choice depends on who you are renovating it for. If you are reselling or renting consider the return on investment- if it is a high priced area a higher priced solution might pay for its self. In my humble opinion an electric combi boiler is the best option- buyers like radiators and the green credentials of an electric combi. An electric combi will cost about 40 % more to run (than gas) but will probably help the saleability more than storage heaters. If it were my own home and I had stripped out everything I might be tempted to consider the combi to a wet underfloor heating system- although more expensive to install it should be cheaper to run and adds another layer of sound insulation to floors which can help reduce noise in flats. Underfloor heating is also supposed to be better if you have a high ceiling and no radiators means more wall space.

I looked into air source heat pumps for a house that I didn’t buy in the end. I concluded that if a gas boiler is possible then it’s initially an easier and cheaper option but an ASHP is a better option long term because although there is a higher acquisition and installation cost the grants reimburse this and long term the running costs will be much less than oil. Grants pay out for 7 years- most people claim to have clawed back the set up costs after 5/6 years and then enjoying lower fuel bills are much better off. There are a couple of things to bare in mind- that the initial cost is high, that the grants reimburse people without gas better than those with gas, to get a grant you have to have a wet system which means radiators or wet under floor heating (so you can’t have a hot air system as they would have in lots of other cold countries). You would lose a bill for oil but gain a bigger electricity bill..... overall it will be cheaper by some margin. You might have to upgrade your electrical fuse board. People who have an ASHP complain that it doesn’t get radiators as hot as a conventional boiler which means that they have upgraded radiators too which is an extra cost although possibly one you would be considering if the whole system is old (it does seem that you can get new and smaller radiators that give out more heat than a big old one). You need to have somewhere for the ASHP outside (they are about the size of a fridge). And lastly it seemed to me that an ASHP provides hot water at a lower temperature than a conventional boiler which is why so many people also put panels on their roof in order to offset the cost of boosting the hot water- again this is an extra acquisition cost. My research is now a year old and possibly out of date so if you like the idea of an ASHP you need to find an engineer who specialising in this type of installation to talk you through how it would work for your house.

It seems to me that you can either have a conventional boiler that heats water and pumps it around radiators, or a warm air system or some sort of electrical heat source in every room. (Assuming an ASHP is not practical and installing a wet underfloor heating system is too disruptive and oil is undesirable). When I looked at this I concluded that if I were starting from scratch I would have chosen a warm air system which seems to be the heating of choice in colder countries like Canada and in Scandinavia. Warm air heating does seem to work faster than radiators and modern advances in filters mean it’s no longer associated with dust or allergens as it was in the 70s. You also free up wall space although the ducting will need consideration. Whether or not you decide on radiators or hot air the thing to consider next is the fuel source. It seems to me that with gas price rises the gap between gas and the more expensive electricity is narrowing. It does however seem that more powerful gas boilers are available than electric ones and the water flow rates are better so if you choose a combi then you can get a good flow rate for your morning shower. You might still conclude you prefer electric boilers (apparently they last longer and don’t need the regular servicing of a gas boiler). If you go the electric route then you might decide on more than one boiler, a tank of hot water rather than heating it on demand and thermostats in each room make it more efficient. Whatever you decide- best of luck