Design considerations

four broiler shed schematic

four broiler shed schematic

Are four 199KW boilers better than one 800KW boiler?

Four individual boilers, or one big boiler on a district heating system?

This is another question we get asked a lot by potential clients. We have done our own research and priced both options, as well as looking at the level of convenience from the standpoint of both installation and ongoing maintenance.

As you would expect, there are many pros and cons for both systems, but at Commercial Biomass LLP we believe the best system for the UK broiler industry is the individual boiler one, for several reasons:

  • Higher RHI tariff on the majority of your heating load = 60% more income
  • Classed as ‘Simple’ installation on RHI forms — fewer questions to answer
  • One breakdown doesn’t leave you relying solely on your backup heating
  • Straightforward installation — no earthmoving equipment necessary
  • Straightforward maintenance — a more domestic scale of equipment
  • Cheaper spares

The most important part of this equation is surely the return on capital. A multi boiler system means you have to find slightly more capital for the installation, but with the Tier 1 payment at 8.3 pence/kw it means you will get over 60% more income from the RHI over the 5.1 pence/kw rate for boilers sized from 200 to 1,000kw, or eight times more than a boiler larger than 1,000kw. And with this being a twenty year index linked payment, that’s a lot of extra income to miss out on.

When a single large boiler system goes down you lose heat to all your sheds for however long it takes to get it fixed, and there aren’t that many engineers who are competent to work on big biomass boilers, meaning you may well be at the mercy of your original installer for the next twenty years. Many of the big boiler manufacturers only supply through one or two installation companies in the UK, and if for any reason you fall out with your installer, or don’t like his prices, you are stuck. The smaller boilers, such as the ETA Hack 200, have more in common with domestic boilers, and ETA supply through a distribution company to dozens of installers, so you should never find yourself limited to one company for service.

The smaller boilers are also less daunting for the end user — some of the bigger boilers have more in common with an industrial process than a domestic boiler. Many have the appearance of a steam locomotive with the wheels knocked off — hulking behemoths with valves, buttons and switches all over the place. An ETA Hack boiler has a simple touch screen in comparison. Nothing to worry about.