Replacing oil fired central heating with storage batteries and off peak power - is this possible without solar panels?

Userlevel 2

We currently use electricity for general lighting, cooking and heating three upstairs bedrooms and two bathrooms with far infrared ceiling panels.

Downstairs radiators and water heating are through an oil fired boiler.

We plan to stay in the house for at least ten more years and would be really interested in replacing the oil fired system with a completely electric system (even if we don’t get all our money back) using cheap off peak power and batteries.

If we got rid of the oil tank, we have a large concrete base that could house these.

We’d need a water heating system and six new electric radiators.

Can current batteries large enough to last the whole day, especially in winter, be charged up from off peak power?

We live in an old Grade II listed building and do not want to use solar panels.

Is this is a feasible option?


Best answer by nealmurphy 5 August 2021, 18:27

View original

18 replies

Userlevel 7
Badge +2

Hi @Chisi1 

Firstly, getting rid of the oil tank sounds like an excellent idea!

As for batteries, if you’re not having solar you are limited to how much power you can pull off the network. A Tesla Powerwall 2 has a capacity of 13.5kWh which could cover your daily demand, but generally I use between 10 and 30kWh per day. You should be able to charge a couple of batteries of this size in say a 4 hour cheap time period. You may need to check how much power output you need. I believe the Powerwall can provide up to 5kW steady output and 7kW peak output.

Have you considered an air source heat pump at all? This would operate at 3 times the efficiency of electric radiators and you could still make use of cheap electricity time periods to heat the tank. It could also possibly be used with your existing radiators.

There are topics on ASHPs on the forum such as :


Userlevel 2

Thanks for the info and it is these numbers that I need to start checking.
I looked at air source heat pumps when we moved in but we have an old house and was advised at the time that we would probably need to have oil and air source heating for winter conditions. Maybe things have changed, I’ll check. 

Thanks again for the battery numbers, I’ll start checking. 

Userlevel 7
Badge +2

Hi @Chisi1 - I’m on the OVO Trial of a PowerVault Storage Battery. It can be charged from Solar Panels or the mains. I have lots of data about this which I can post here if required.

My battery has 8kWh capacity, which is a long way short of what you’d need if you required space-heating or domestic hot water (DHW).

8kWh battery towards the end of on-site installation

I’ve checked the UK Battery Storage market, and the Tesla Powerwall is expensive but has the lowest figure for £_per_kWh.

Other people who live in listed properties have installed ground-mounted PV Solar Panels. These don’t literally have to be at ground-level. As they’re made of glass they also lend themselves to a greenhouse roof because there will still be enough daylight coming through the remainder of the building :slight_smile:


As part of your research here on the Forum I suggest you explore two other topics:


1: the possible use of underfloor heating rather than radiators. This uses water at a much lower temperature and is therefore better suited for slow/steady heat sources such as a Heat pump supplemented with solar-thermal.

Start here on a general tutorial about Heating Strategies.


2: The point that @nealmurphy makes about the amount of power you can take from the Distribution Grid is important. If you would be drawing more than 60A at any time then your regional Distribution Network Operator (DNO) may be wanting to supply you with 3-phase. This is particularly the case if you need  consent for Low Carbon Technology (EV charger or Heat pump).

Have a look at the tutorial on Permission for Import and Export.


Finally, please fill out your Forum Profile page. Knowing whereabouts you are in the country will affect what we can suggest. It might also enable us to put you in direct contact with a Community Energy Group in your area.

Userlevel 2

Hi Transparent

Thanks for the info and I’m slowly building up a picture on the feasibility of my project.

The information about the PowerVault battery and numbers really help but to give you a better idea of where we’re at and what we’re trying to achieve:

  • Location:  Somerset TA14 (tried to put this on Profile Page but I’m missing something)
  • House built in 1585 with Hamstone and Rubble construction, walls 300mm thick, concrete/wooden floors downstairs 
  • Although listed, house double glazed throughout with 300mm roof insulation.
  • The stone construction means that if house gets cold, it needs some time to heat up again, so upstairs rooms are kept to minimum 15 degrees 24 hours/day.  Timers and thermostats used to increase temperatures in bedrooms and bathrooms independently of downstairs heating as required.  And, downstairs heating used with thermostat and timers as required.
  • Because house is kept warm, upstairs panels only kick in for short periods outside of timed periods on a few days during the winter
  • We bought and renovated the house nine years ago. The oil central heating system required complete replacement so looked at simple complete oil replacement, air and ground source heat pumps, electric radiators and ceiling mounted far infrared heating panels.
  • Even then I wasn’t happy with oil but was told, then, that using an air source pump would require oil backup heating for winter conditions.
  • Electric radiators using standard rates were not cost effective
  • I liked the far infrared panels but then they were considered relatively new technology at the time and I couldn’t find enough feedback to be confident enough to use them throughout the house.
  • So, we zoned the house.  Downstairs and water heating, oil.  Upstairs, electric far infrared panels which are set to maintain temperature upstairs at 15 degrees 
  • These panels really work.  They are controllable, efficient and effective and, considering the comfort factor we achieve set against the cost, good value for money.
  • Out of interest we used Sunjoy panels,, Eamon McGrath +353 86 385 3000
  • They were easy to fit during the renovation nine years ago but now would be too disruptive.
  • If possible, the plan is to remove the oil tank and boiler, remove current wet radiators and water heating system and replace with electrically powered units, fit batteries and tie into existing system and operate using off peak power with facility to occasionally top up at standard rates during the day in extreme conditions if required.

My wife and I are both 75 and plan to stay here for at least the next ten years, or until they take us out in boxes.  We are not ultra-green but like the idea of the long term benefits and convenience of electric power and remove the reliance on oil.

However, we do not want to get involved in large scale renovations again and realise this will limit us as to what we can do.

Now I some good information from the group I will start looking in more detail about equipment and costs but would appreciate comments from the group on the following:

  • We do not want to fit solar panels to the old building
  • We do not want to fit air source heat pump because of disruption to fit underfloor heating and still have to retain some other form of heating
  • Ideally, we would remove the oil tank and boiler creating space for batteries
  • Remove the downstairs wet radiators and replace with electric and I will check power requirements.  I realise this option will not be the most cost effective heating method so would appreciate any comments and possible manufacturers from members on their experience.
  • The current oil heated water tank has an immersion heater fitted.  It would be easy to use this but I’m sure it will not be economical so I will check operating costs and would appreciate member’s comments.
  • Check state of the art, electric powered water heating system and power requirements.  Again, appreciate member’s comments.
  • I know the actual current power usage so with the new requirements I will have total power requirements.  With this I can determine:
    • Power requirements and if it’s possible to draw this down at off peak rates
    • Don’t think 3 phase power will be feasible as the local pub was recently quoted a silly number to install this for a new kitchen cooker
    • Battery size and limitations
    • Again, members comments would be appreciated on what I should watch for and important questions to ask

I am realistic about what we are trying to do and the effect of what we don’t want to do, at our age, has on what equipment we can use.

It would be good if we can get it to work but if not the information package I will put together could possibly be useful to members looking at similar projects.

If anything is not clear, please ping me and I look forward to your comments.

Userlevel 7
Badge +2

I think a good place to start, if you haven’t already, is to get some heat loss calculations for each room. By working out how much heat leaves the property you’ll know how much heat you need to put back into it to keep it at a chosen temperature. This applies to whatever heating system you go for so as not to undersize or oversize the heaters or heating system. What is the floor area of the house?

I still reckon Air Source is worth considering. I have a High Temperature unit that can heat up to 65 degrees if required and is a straight replacement for my old gas boiler. What is your existing central heating pipework like? Diameter of pipes? Are your radiators single/double? If necessary, would there be space to either increase the size of these or convert to double/triple?

Userlevel 7
Badge +2

That’s welcome background information @Chisi1 

We have a lot of common thinking between us! I don’t think I’d be classed as ultra-green either… but my common-sense practical approach to energy-efficient renovation also ticks so many of the boxes which green-activists favour.


A few bits of good news:

1: You’re on the eastern edge of the Distribution Grid, SW Region, managed by Western Power. They have generously allowed me access to a wealth of their technical background material. I have the entire electricity map of your area including the size of every conductor!

So whatever may have been the case for your local pub can now be re-checked against the actual data for your locality.

There seems to be only 16 ground-mounted substation transformers within TA14 and you’re almost certainly supplied from the Primary (33kV) transformer at either Martock or Montacute.


2: Have a look at the illustrative maps I uploaded recently in the topic about Energy Demand, Supply and Flexibility.

You can view the map for your particular Primary transformer by going directly to Western Power’s page showing their Distribution Future Energy Strategy.

That means we can see what network infrastructure is being planned by WPD for each type of electricity usage for the next 29 years.

For example Martock currently has 237 Heat pumps, and is expected to have 996 within 5 years. This enables you to choose an energy strategy which Western Power is already geared up to support.


3: Have you, or would you consider a ground-source Heat pump operating from a borehole? These are one-third more efficient than an ASHP, and a bore-hole means you don’t have to start by digging up the garden to a depth of 2m!


4: I understand your point about using the thermal mass of the building to retain heat. Although my house has a cavity-wall, I still use this technique for part of the UFH system and one thick internal wall (my heat reservoir!).


5: You have a Transition Towns group to the north of you at Langport. I suggest you send them an email and find out what energy specialist members they might have and what is their strategy post-Covid.

Some Transition Towns groups have members trained to undertake energy assessments of homes. These are free for certain categories of people - so well worth while enquiring about.


That’s not the entirety of my response, but it’s probably enough to be going on with. :slight_smile:

If you want more detail on your electricity supply, send me a PM with your full address. I’m not allowed to post the maps here, but I can certainly check if your house has particular constraints.

Userlevel 7
Badge +2

I’ve just made a few further checks @Chisi1 and I think your constituency is currently represented by Marcus Fysh MP.

If that’s correct, then he lives in a Grade-1 listed 14th century building. I wonder what strategies he’s invested in to heat that?!

Userlevel 2


Thanks for all this information which I will start sorting my way through and build a specific plan for the house.

This will be slow as I’m mechanical, not electrical, and am lost when I get past the light switch on the wall.

A couple of good points from your comments in helping me determine best equipment and power requirements are those regarding heat loss calculations and high temperature air source pumps which I will check.

Total area of house is about 2,200 square feet split 1,200 downstairs/1,000 upstairs.

Regarding radiators, we have a mix of single and double but in all cases we have space to increase.

Regarding your high temperature air source pump, realistically how noisy is this?  We live in the centre of a village with a neighbour close to us on the side any heat pump would be located and this would be a big consideration.

Marcus Fysh is our MP and lives a few miles from here and I will ask how he heats his old house.

Thanks for your help so far and any other comments would be appreciated.

Userlevel 7
Badge +2

Don’t be concerned at your skill-set being limited to mechanical, @Chisi1 - the whole point of a Forum like this is to combine our skills and knowledge.

I’ve also just read the Historic Environment Strategy for your District Council. It’s dated 2017 and contains nothing whatsoever about ‘energy’.

I also live in an area with a high proportion of historic properties. Our (very small) Borough Council has combined the work of its Conservation Officer with a well-qualified engineer from the local Community Energy Group. This has resulted in a guidance document to inform occupants/owners of historic buildings what they can do by way of ‘Conservation of Heat and Power’ (ie Part-L of the Building Regulations).

This pro-active approach reduces the burdon on the Planning Dept who don’t then have to cope with hosts of applications requiring amendments or enforcement.

It might be a good moment to write to your ward-member(s) and ask South Somerset to create a similar energy-guidance document for your area. In any case the current generic Environmental Strategy document precedes  the increase in public awareness of the need to tackle Climate Change in spring 2020.

Looking at South Somerset website, you seem to be one of the few District Councils who have not (yet) passed a motion declaring a Climate Change Emergency. Your Council’s Environment Strategy relates to actions of the council itself rather than providing assistance to its constituents to take action.

There is expertise available, but it will be up to your Council to request the help they need… perhaps through the Local Government Association.

If there needs to be additional funding available to assist those with historic buildings in their quest to install the right types of Zero Carbon Heating, well then that is surely a question for your MP. I doubt that Parliament will want to proceed towards its 2050 target of Net Zero at the cost of degradation of our country’s historic heritage!

Let us know how you get on, and remember that this Forum hosts an abundance of answers. :slight_smile:

Userlevel 7
Badge +2

Regarding your high temperature air source pump, realistically how noisy is this?  We live in the centre of a village with a neighbour close to us on the side any heat pump would be located and this would be a big consideration.

Honestly, it’s quieter than my old gas boiler’s flue. I’ve walked in front of the outdoor unit and not realised that it was on until I felt a cold blast of air! When background noise is quiet, and I mean very quiet, you can hear a faint hum but there is a quiet mode (that I’ve never tried) if it is an issue.

Heat pumps will need to be 1 metre from the property boundary for permitted development, and a simple noise calculation will be carried out to confirm suitability of location.

Userlevel 7
Badge +2

Neighbours… I don’t suppose those adjacent properties are also historic/listed by any chance, are they @Chisi1 ?

If so, then it opens up further possibilities.

Userlevel 2

Thanks again, I have a lot to work with now and have a better understanding of the possibilities and difficulties than just a couple of days ago.

Good to hear about the minimum noise levels of your unit but location of a unit in ours will be a problem if it needs to be a metre away from the property boundary for Permitted Development.  However, it could be sited within the metre (with planning) if it’s quiet enough and not upset the neighbour.  I will check.

An alternative is to locate it a couple of metres away from the house and run pipes to the house if this is possible.  Again, I will check.

Unfortunately, the adjacent houses are not historic.

Thanks again for your help.


Userlevel 7
Badge +2

If it’s within a metre of the boundary then it’s likely that any fence or hedge might prevent it getting adequate through-flow of air.

Positioning a unit up to 5m from the house isn’t a problem. There are such installations on the Zero Carbon Heating trial which OVO are currently running. Several members of the Forum here will have 1st hand knowledge of what’s required.

In general the experiences of the 250 trial participants have revealed widespread failures in the installation process itself. We now know what to look out for and which parts of the installation are critical to get right. You can of course call on us to help you decide on the right Installer and the best design for your particular site.

Here, for example, is a photo of the correct sort of pipe for an underground link to your house:

This this Rauthermex from Loco-2-Heat and is ready-insulated to the required level.

Feel free to do the general research that you want. But please continue to come back to us for clarification of anything which needs detail.

I’m just going to tag @briannolan in case he wants to add anything because he probably doesn’t yet know this discussion is happening.

Userlevel 4

Thanks @Transparent I hadn’t seen the discussion.

@Chisi1 well done for taking on the project and looking at getting rid of the oil. No more tank to get filled or to check with the dipstick! Plus, it’s greener.

It sounds like an air source heat pump with radiators could work for you, because your setup wouldn’t need to change much, and it sounds like you don’t want a major building project. You might be able to keep your hot water cylinder, your pipes would be unchanged, and you might be able to keep some of the radiators.

My pump is 8m down my back garden, with pipes running underground into the house to the unvented cylinder. Like you, I’m thinking about getting a battery, without PV panels, because I recently started getting 5p electricity at night. Note that some batteries can go outdoors but they’re normally wall mounted, so your concrete slab might need another use. Once you calculate your summer and winter energy needs, you should be able to figure out if batteries make sense.

The placement of a heat pump would partly depend on whether you need planning. I might be wrong, but I believe for a listed building like yours, permitted development doesn’t allow heat pumps and you would need planning. Heat pumps are incredibly quiet - it’s like a fridge. But the regulation treats them strangely. So, you need to do a relatively complicated noise calculation that takes into account things like your neighbour’s nearest window. You would need to submit a noise calculation as part of planning, but I believe you wouldn’t have the 1m boundary constraint.

I don’t think anyone has mentioned domestic RHI yet - definitely look at that and factor it into the costs. It’s a big plus for a heat pump compared with some of your other options.

Userlevel 2

Thanks again for the information.  At my age I’ve never been into blogs and forums so the last few days has been an enlightening experience.

I will, as suggested, do general research and come back to the forum for detailed clarification as there seems to be so much practical experience available here.

It’s good to see that air source pumps can be located a couple of metres away from the house connected by insulated pipes.

Taken note of RHI, I’ve seen it mentioned and I will check and build it into my calculations.

When I started looking at this I was against air source pumps because of what I’d been told in the past but will now take an open and unbiased view.

We currently pay the standard rate of about 16p/kWh and I can see a rate of around 5p is available at night.  Excuse me for being a bit cynical but will this price differential be maintained once the power companies have us all hooked into overnight charging?

Now . . . . to the drawing board and I’ll be back.

Userlevel 7
Badge +2

Great to have you here @Chisi1 . It’s always good to share experiences. I’ve learned a lot from the posts in the forum.

As your property is listed I think it will require planning for an ASHP. Not sure if the same applies for other options.

If you can accurately predict what the electricity prices will be in the future then I think you could make a lot of money advising companies! It’s a point I’ve raised before about whether there will be levelling off of prices in the future. If so, then the cost calculations for home batteries completely change. Is it worth relying on them if you can’t use or export electricity at significantly more expensive times? It may be that overnight electricity becomes 10p/kWh and daytime becomes 25p/kWh or it could all become the same price with balanced demand, or perhaps it’ll all be free apart from admin charges! :wink:

Userlevel 2

Agree about predicting electricity prices but it would be good to have OVO’s view on their medium to long term policy on this issue. 

Userlevel 7
Badge +2

I can answer a fair bit of that question @Chisi1 because I had the opportunity to discuss it in January with Stephen Fitzpatrick, CEO of OVO Group Ltd.

Although there’s no immediate plans to withdraw the ‘Economy 7’ type tariffs, they will need to be modified in some fashion because of the increased ownership of Electric Vehicles. Charging these overnight is quickly going to eat up the available night time capacity on the Distribution Grid.

Having recently bought an EV, I had to apply for consent to install a home charge-point. As you’ll be able to see from the explanation in the topic on Energy Supply, Demand and Flexibility, this increased the power required for my house by 2½ times :scream:

There are constraints on the capacity of each substation transformer providing that power, and also the feed cables which deliver it to our properties. The energy required for night-time EV charging will overheat underground feed cables, thereby causing insulation to fail and the circuit trips to cut off the power.

The solution is to employ two new techniques:


a: change customers onto a Time Of Use tariff which supplies electricity at differing price points for each half-hour of the day. Octopus have offered such a tariff for many years already, and their website describes the calculations used to operate it.

OVO are developing their own Billing System which supports half-hourly price points for customers with Smart Meters, but this functionality is not yet available.


b: use Smart chargers which are controlled by central computer. That ensures each EV owner gets the charge they specify by the time they set, but the computer decides how and when to deliver that charge according to grid-demand.

OVO already offer a Smart charger, which is described on their website. Their Kaluza division is also busy creating a matching computer system called the Flex Platform. In about 6-weeks time, Flex will take over control of my PowerVault Storage Battery, which is part of another trial.

I’m going to stop here @Chisi1 because I realise that this is a lot to take in!

But let me point out that these innovations are not being thrust upon us by the government or the Energy Suppliers. This is just as much a consumer-led strategy because there is widespread public demand for energy systems which better use renewable resources and help us to combat Climate Change.

Whether you understand the technology I’ve mentioned doesn’t matter that much. It’s more important that we get the message out and let people know of the possibilities which will shortly be available. We don’t need to know how an internal combustion engine works in order to drive a car. :red_car:

So in similar fashion please tell everyone you know (in the pub!) that the energy equivalent of the automobile is being developed here in the UK and it’s time for everyone to start reading about it here on the OVO Forum:clap_tone2: