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Oh, the weather outside is frightful...

...but inside the walls of APD, the temperature is delightful!


And here’s why…


Back in March we started our ‘Low Carbon Heat’ journey having designed a renewable energy system which would have the capacity to replace our old oil burner and keep this 50+ year old non-insulated 1260sqm building warm in the depths of winter.


The decision was taken early on to use Air Source Heat Pumps as the engine to give us the heat. The power to drive this engine is another story and the other half of the project but for today we’ll concentrate on the heating.


There was huge scepticism that ASHP’s, even a bank of 6 of them, would be sufficient to heat this building. Well this week the proof of the pudding was certainly forthcoming with night-time temperatures reaching -11C in the Annan area.


Cutting to the chase, we are simply astounded by their performance and to be honest, it’s got us all scratching our heads wondering how exactly are they achieving it! These units are extracting “heat” from these freezing air temperatures and turning it into 60C water held in a large accumulator tank, which is then pumped to radiators in and around our offices, workshop and reception. The building is warmer than it has ever been, in colder temperatures than any of us can remember for some time. Is it magic? It certainly feels like it. Are we happy? Yes we are.


Pictured below are our 6 Mitsubishi Ecodan ASHP Heat Exchanger units, sitting outside in the cold, pulling the latent heat energy from these freezing conditions. Underneath you can see pools of ice, which is essentially the condensed and frozen moisture that the fans have pulled away from the exchanger plates, falling and forming these frozen puddles.



Although APD did all of the associated electrical work for this project we have to take our hats off to Gareth and his team at Ian Lewis Plumbers of Auldgirth. They did heating design and worked over the summer months stripping out miles of old plumbing, countless radiators and the big old boiler before fitting all the new pipe work, pumps, tanks and radiators.



When we first switched the system on, back at the end of September, we were all impressed with how quickly it produced heat. The 250L accumulator tank of water went from around 12C to 60C within half an hour. We thought that was clever when the ambient temperature outside was a mild 18C, but it’s fair to say we were curious to see what would happen in the winter. Well this week has well and truly road tested the system and subsequently put our minds at ease. We can now relax and celebrate knowing that all the hard work has paid off and not only are we warm but we are no longer emitting 40T of CO2 annually to keep us that way.


And for anyone wondering about the cost of electricity to make all this work? Well, we've got that covered too - but that's a story for another day.

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