Installing a heat pump in a Victorian terraced house

Hi there!

This community was suggested to me by someone online so here I am!

I recently installed an air source heat pump (Mitsubishi Ecodan) at home and I wrote up a detailed account of what was involved, in the hope this information would be helpful to others. We’re in a terraced house with not much space, so hopefully it’s reassuring for people to see that stopping use of gas is possible even without large gardens and ample space, which you often see on projects involving heat pumps.

You can read all about our installation here, I hope it is helpful!


Awesome input. Thanks Tom and great site! :heart:

Thanks Tom. We’re in a Victorian terrace too and have been starting to think about this, so your blog piece will be very helpful!


Thanks for your excellent blog post. We are also thinking about getting an ASHP for much the same reasons as you: boiler on its last legs, seems crazy to get
a new one now. I was just wondering how you have been getting on now that it is winter. Is the heat pump giving you amle heat, and has the extra electricity demand outweighed your previous gas costs? We’re nervous about going ahead because we don’t have the extra internal wall insulation you have. The info about the cost of disconnecting from gas was also very interesting as we figuered not having to pay the standing charges into our calculations, but seems that we will probably continue to pay that. Thanks for your input. Matt

1 Like

Hi Tregy,

Thanks for the message.

Yes we’ve been getting on great! I love it!

I’ve been recording usage (manually) where possible and so far, average daily usage is around 3.4kWh with the heating off (just a hot water) and 10.6kWh with the heating on. Although, apart from reducing the HW temp (because it was too hot!), I’ve been really bad at optimising the system so I can definitely improve those numbers with some effort. Those usage numbers mean that the annual cost should come in just below gas, which is very pleasing.

It works great! I use the central heating on a timer. The radiators don’t get super hot so it takes longer to heat the house, but not that much longer (1.5hours on a cold day, maybe?) - it’s normally set to 21° where the thermostat is (individual rooms vary a bit). It is actually possible to get the radiators very warm (hotter than I thought), but I’ve not because I’ve been trying to be economical.

I do miss my nest thermostat a little (for remote/internet control), but I can upgrade in the future to an internet connected thermostat, I just don’t have the money right now.

The RHI payments have worked out more than we expected so we will infact be able to pay it off with just those payments, and have left over.

I would recommend insulation however. Our internal wall insulation I did myself and made a big difference in the coldest rooms, it wasn’t that expensive (plus we did one room at a time). You could always do the insulation after the heat pump, it might even work out better for you in terms of your EPC rating when you apply for your RHI payments :man_shrugging:

I plan on posting some of the findings online when after winter, and will post back here when I do that :slight_smile:


Hi, Thanks for the information - really useful and your pump looks really sleek outside! - contrary to what I had seen online. Our boiler is fine but getting on in age, and we also need to move it from a bedroom to the kitchen (new house reno). With this green homes grant I am debating the idea of a heat pump. If we have to change our boiler (2k), and move it (2k) and also move the gas metre outside (2k) - why not just get a heat pump and have the govt pay for some of it? Where do you keep your hot water tank and how big is it? The internet and your blog also say you need ‘bigger’ radiators, what does this actually mean? (We also will be getting all the insulation done we can with the scheme) Thanks for any advice/help! Sally

1 Like

Hi Sally.

I’ve actually covered the costs from our first year in a separate post since then, you can read about it here:

Just quickly to answer your question - heat pumps operate at a lower temperature and so they can be better at heating a room by giving off more energy if they are slightly larger. However, we found that because we had already replaced our radiators with new triples, we didn’t have to replace any. Plus, it’s the sort of thing you can do later if you find any rooms underperforming or cold.

My follow up post should help with any costs questions, but suffice to say with the green grants the heat pump should be a much cheaper option than gas; at least if you get the right installer and your house isn’t enormous.


Thanks Tom.

I think we will definitely go for it. Turns out my mum has had one for years and I never knew! But she doesn’t have an ancient house.

Finding a trust worthy installer appears to be the difficult bit!

One last question - if you needed to do anything to the wall behind the pump is it very difficult to move it? Or can a plumber/electrician do it relatively simply?

Your website is brilliant by the way. We have a lot of respect!

1 Like

Thanks Sally.

The unit is quite big and heavy, plus it’s plumbed in so it’s not very moveable but realistically there should be any need to move it, and there is a big enough gap behind it to get the balls, toy planes and other items we find heading in that direction.

If you’re in the south east I can recommend BSW enough. They were the cheapest but also had the most experience which meant they were very confident with the quote and installation process.


These two blogs should be very helpful for anyone looking for an air source heat pump, and whether to use the green homes grant:

1 Like

I’ve just chanced upon this site and your blog post. We’re moving into our new house next week - a Victorian terrace with a creaking gas combi boiler, no current space for a cylinder, tiny garden, small radiators and poor insulation - so not ideal for this at all!. Regardless, I really don’t want to put in a new gas boiler in 2021, so your blog is very helpful - thank you.

1 Like

Oh dear! Sounds like a very similar situation. Putting the cylinder in a small insulated lean-to outside really helped. We were fortunate that the heat pump fitted where an old shed had been, although it still required half of the heat pumps plinth to be on a non-load-bearing breezeblock, removable for access to the manhole cover! Outdoor space about 5 m x 4.5 m. As I mentioned in another post, the Ecodan specifically was perfect because it’s so quiet, it can be installed less than 1 m from the Boundary line without contravening planning regs.

Anyway good luck on your mission!

1 Like

Hi Tom, I find myself in a similar situation to you pre-work, and I’m looking into the insulation to use on a Victorian terrace for an ASHP, whilst maintaining the “breathability” of the property (as I understand is required for buildings of this period). Did you look at this, considering lime plaster, insulating lime plaster, breathable boarding/insulation, or did you opt for more modern gypsum insulating plasterboard. I’ve had a browse round your site, but not found that out yet.

Kind regards, Ed

Excellent article, it’s about the only comprehensive piece I can find, the professional journalists are not doing their work and the interested party sellers not clear on impacts.

I’m still watching tech and finance developments, but this is a very re-assuring piece of work.

Victorian and Edwardian houses do require special love, but remain superior in many respects to much 20th and 21st century domestic buildings, I’m pleased see your experience is positive and did not devastate your home.

1 Like

What’s the distance between the outdoor unit and our neighbors (habituated rooms)? I’ve had British Gas around to quote and they are saying it is a struggle to site the outdoor unit at my terrace property re noice issues. Has anyone else had this issue?

The same issue raised in this post,

Sorry @Tarx, I ended up replying to the wrong thread, my reply is over here:

Hello Tom, looking forward to reading the details of your project. Similar scenario here. I wonder, when you switch over to a heat pump, do you use existing pipes / rads? Or do you have to re-plumb the house? I ask because I’m just about to lay parquet flooring throughout so access would be difficult !. Thanks Jesse

Hi Jessbel, So long as it’s standard piping and adequate for the house size, yes you can use existing pipe work. The heat pump for us just replaced our gas combo boiler. So the only new plumbing was connecting up to the existing central heating and hot water systems. All our existing radiators were fairly new and adequately sized for each room, so we didn’t need to replace any rads. It was very easy!

If you do have old or outdated radiators then they will likely need replacing.

But every property is different and you may want to get some advice from an installer before you lay that flooring.

Thanks Tom, very helpful indeed. I guess rising cost of electricity has blown the cost model. Do you need solar power to feed heat pump? J