Heat pump myth - your home has to be well insulated
Many people say that "heat pumps don't work in badly insulated buildings.", which is a slight variation on "heat pumps don't work in old buildings".
Let's put that to the test. A tent is perhaps one of the least insulated buildings we can think of. In the heating design software that we use we created a 6 x 8m tent, thinking that this size would also be perfect for an imaginary NYE party!
It's 2m high at the sides and 3m to the ridge. The fabric has a huge U-value of 4.5, and the air changes per hour were set at 2 ACH (perhaps slightly unrealistically we're keeping the door shut and making people zip it up again when they go in or out).
With the calculations run that ends up with the tent needing 14.27kW of heat when it's -2.26ºC outside.
Next we planned for a maximum flow temperature of 55ºC, which is definitely doable for a heat pump. (Note - usually we'd design for a lower flow temperature to get the running cost right down.)
Nine massive 900mm x 1000mm K3 rads, plus a small one provided enough heat, taking up around two walls of the tent, but leaving two free for decks, the sound system, decor, and a small bar.
So we have now shown that it is possible to use a heat pump to heat a badly insulated building.
Now on the night there will be at least 20 people dancing, and they will each give off at least 300W, plus the DJ, and the usual 2 hangers-on, gives an grand total of around 7kW to add to the mix. This more or less halves the heat load.
Luckily the heat pump will automatically adapt and reduce its flow temperature, otherwise it'll end up like a sauna in there!
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So when people say "heat pumps don't work in badly insulated buildings." one of the things they might really mean is "The building owners were unwilling to install underfloor heating and/or enough extra radiators, which is what was needed to keep the running costs down. As a result the running cost is high, and everyone is now blaming the heat pump and saying they don't work in badly insulated buildings."
It may not be essential in order for a heat pump to work, yet insulating a building is still a very good idea because it reduces the heat consumption every year - providing a cost and carbon saving, and reducing the peak load on the electricity grid. It also allows you to install smaller heating appliances and associated parts, which also cost less money.
Roof insulation, draughtproofing, closing off unused open fires, and heat recovery ventilation are some of the best value for money ways to reduce the heat demand of a building.
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To the trade we are a supplier of renewable heating kit, including heat pumps. We supply, support, and provide guidance.
For homeowners we answer questions and provide advice, check project feasibility, design considerations for lower running costs. We then make an introduction to the local engineer in the network to take things further.