Ground source heat pumps are a fantastic way to heat a home, for a number of reasons, however they are often considered a more rural technology, only suitable to properties with lots of space available. Is this really the case though? Can ground source heat be a viable option for a city like London?
Before you read any further though you might want to learn a little more about the ground source heat pump technology, if so click here!
Trenches vs. Boreholes
The number one consideration in a city is usually space. A typical Ground Source system installed out in the country will utilise long trenches with pipes run for hundreds of metres zig sagging under the ground. If you have the space, this is a perfectly reasonable way to get access to that stored heat under the ground. And the more loops you install the more efficient the system will be – the pipes will last for 50 years or more, so it is worth adding as much pipe work as you can whilst the system is being installed. This would obviously be an issue in a city environment where space is at a premium.
Drilling a borehole is the other option you could consider. Instead of having 1.5 to 2m trenches, a 25 meter deep borehole is drilled vertically, allowing the heat pump to operate within a much smaller surface area. Even in a densely populated area like London, if you have a bit of garden, a borehole is feasible.
You do have to take a few things into consideration however. A heat pump with a borehole will set you back around £25k in total, probably about £5k more than a trench style system. You should also note that the borehole will likely be drilled by a separate company to the actual heat pump installer, as it is a very specialist job. The costs are high and it is no small task. In London especially, it will be the responsibility of the borehole drilling company to make sure that you aren’t going to hit anything in the drilling process – like a gas line, water pipe, or any other underground excavations. It makes working in a city environment slightly more tricky than the country. The drilling machinery is also really hefty, and you will need decent access to the area your borehole is going to go.
Other considerations for heat pumps in cities
Heat pumps are very efficient for most homes, but cities generally have a very cheap gas supply, which is always going to be cheaper to run than a heat pump, so even if a ground source heat pump is feasible, it might not be the best option.
Heat pumps can be a really great way to heat your home, but it does need to be very well insulated. Most houses in the city are fairly old and inefficient, so heat pumps might not be a good option unless the property’s efficiency is going to be massively upgraded. If you live in a new build, heat pumps could be ideal however.
So don’t rule out a heat pump if you live in the city. If your urban property has a decent strip of garden with good access, and the property is off gas grid and reasonably well insulated, a ground source heat pump could be a good option. If space is an issue, maybe you should look at air source heat pumps. These are a good alternative in city environments as they take up less room, have a lower cost, and are easier to install. They don’t quite offer the same level of performance however – the efficiency will always be lower with an air source system.
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