Now the design stage is complete & the kit has been delivered to site (this was easier said than done as the kit had to get half way up a mountain & then the only access to the bunkhouse is through a stream!) the real fun begins as we can actually begin the install, in this blog we’ll concentrate on the heating side of the install which comprised of a 15kW ETA automatic fed wood pellet boiler, a 500Ltr buffer tank/thermal store & the recommissioning of the existing Solar thermal system.

So first things first and we start by draining down the existing heating system & removing the existing undersized cylinder & old pellet boiler, next we get the new boiler & buffer tank into position as per our designs. The new boiler is now in its own designated locked plant room with an outside pellet store, this means it’s at a safe distance from the battery bank, it’s fuel supply & any bunkhouse residents that might want to mess with the controls!

For the pellet store we opted for a 550ltr wheelie bin in its own water tight fenced enclosure, this worked out the best option in terms of cost & convenience. Once the boiler is in the correct position we installed the flue & made our hydraulic connections to the buffer. The boiler is set up to manage the buffer tank/thermal store so it keeps at a high enough temperature to make sure there is plenty of domestic hot water for the guests & set up a heating circuit on a timer through the boiler to bring in the underfloor heating when required.

Next we connected the existing solar thermal system to the control board of the boiler. Once we switched on the boiler it became apparent that the thermistor measuring the temperature of the solar collectors on the thermal system had failed, most likely caused by the loss of power of the previous off grid system which will have left the thermal collectors in stagnation for long periods, never a good idea! We replaced the offending thermistor & then flushed, cleaned, pressure tested, drained down & then refilled with a water/glycol (anti-freeze) mixture, the thermal system was now up & running again like new. One important point to mention here is about the electrical supply to the boiler, the inverter/charger is set up with a load shedding contactor to shed the loads should the generator fail to start when the inverter/charger calls for it.

This prevents the batteries becoming too deeply discharged which would cause damage to the batteries, however this would be no good for the boiler if it was on a full burn! To overcome this we installed a consumer unit before the load shedding contactor to supply the boiler, the UV system and the Sunny Boy PV inverter, this allows the essential loads to remain in operation until either the sun comes up or someone refills the generator with fuel!

So now the heating system is up & running with plenty of hot water for all the guests & underfloor heating to keep them nice & toasty, in the next section we’ll run through the electrical installation.