Gasification boilers

Here we have a totally different beast from a traditional boiler stove. These boilers are designed to be installed in an outbuilding or utility room. They have high heat outputs and nice big fireboxes to let you easily heat your house and domestic hot water with wood. Essentially you fill the big firebox up with logs and then walk away - the log gasifying boiler takes care of the rest. Gasifying boilers are batch burners - meaning that you load them right up, burn them hard, let them burn down, and then reload if needed. This is a very efficient way of burning wood which produces a low level of emissions/smoke too. The heat from the wood is often stored in a hot water heat accumulator tank for use as and when needed, although you can connect a gasification boiler directly to a standard heating system.

A log boiler used with an accumulator tank gives you the ability to decide when and how you want the heat in the house. Your programmer can be set to draw heat from the accumulator and warm your radiators for the hour before you wake up, turn them off in the day when you are out at work and then turn them back on an hour before you return from work.

The term gasifying means that the wood is being superheated and largely turned to wood gas and it is this that is burning. Modern stoves do this to some extent but often do not reach the high firebox temperatures of a log gasifier. The log gasifiers introduce a supply of air to the gases to effectively burn them off which is how they manage to achieve high efficiency ratings of over 80%.

But don't get too hung up on efficiencies - how much heat your boiler gives out for the wood you put in is far more dependant on the dryness and quality of the wood you put in, as opposed to what efficiency the boiler managed to achieve in ideal test conditions.

Running your whole house with a log boiler does mean using a fair bit of wood - we would recommend these boilers to people who have sufficient room to store a decent amount of firewood, ideally with some storage in the boiler room itself for simplicity and to further dry the wood. They are perfect for people with access to woodland, or where you can arrange to have fuel delivered freshly felled (and therefore cheap) outside of the burning season.

We have chosen two types of log boiler, both of which have the robustness, reliability, and build quality we would look for in an appliance that will be used for many years to come. The Vigas uses a reverse combustion boiler which means it pulls the hot flue gases downwards into a heat exchange chamber below the fire which requires the use of an electric fan and a taller chimney, which gains it a couple of % more in efficiency.

The Perge boiler is an upward combustion stove, and thus has no need of fans or moving parts, and achieves its high efficiency through a superbly arranged firebox, and uniquely designed heat exchangers - and does not need electricity to run.

The other reason we have chosen these two boilers is because of chimney height: the Perge can go on a 3000mm chimney (which is fantastic), the Vigas on a 5000mm chimney. Most of these boilers get installed into fairly low outbuildings, where even the Vigas' relatively low 5000mm chimney is going to poke above the roof by a couple of meters. Other makes of log boiler often need prohibitively tall chimneys - just think what a 8000mm chimney would look like coming out of your garage.