It is interesting that the prices for these boilers, even in the most simple form, are of the order of 4-5 times that of an equivalent oil boiler! Is the pellet boiler really that much more complicated that it should justify a price differential of this amount and cost the same as a small car? I doubt it, and suspect that some of these high costs are more attributable to price hiking by unscrupulous distributors and importers trying to take more than their fair share. Whilst we can all accept an additional freight cost, by and large the boilers price should equate to the prices paid in Denmark, Sweden, Austria, Germany and the Czech Republic, where these models originate. Also, bearing in mind the expected longevity of the appliance, it may make sense to stick to sensibly priced models, assuming that the unit will be replaced within 10-15 years.

Types Of Wood Pellet Boiler:

While the wood pellet stove can be used to heat a room, the boiler is designed to replace the existing main boiler in the house. But bearing in mind that wood itself creates a by product of ash, there will be some element of maintenance involved in owning such a boiler.

Here are the main features of the pellet boilers, based on a quick scan of the brochures available to the public:

The boiler will have one, more or all the following characteristics:

• integrated auger or pipe which suctions pellets from a nearby pellet store or mini hopper
• automatic probes/sensors (lambda probes) to control burn rate
• self cleaning to a reasonable degree, such that ash pan needs only occasional cleaning
• blowback control to prevent any possibility of fire
• modulation to control if boiler can remain "on" yet output heat at lower Kwh requirement
• temperature controls

However, in layman's terms, none of this is really important. All we really need to know is a) how easy is it to operate b) can I just replace my current boiler with a wood pellet model and c) how much cheaper will it be to use pellets rather than oil/gas/other fuel source and d) power consumption of the unit.

Hopper Options:

Guess what - you cannot just empty your oil tank and fill it up with pellets instead! However there are a number of options available so ensure the fuel finds its way to the boiler, such as:

• A standalone store with auger feed back, usually via suction, to the pellet boiler
• An internal silo pit designed to hold bulk pellets
• An external silo pit also designed to hold bulk pellets
• An underground tank designed specifically for bulk pellets
• A mini hopper which sits beside the boiler and must be manually filled with pellets
• An integrated boiler with hopper which can be manually or automatically fed

The cheapest options are the mini hopper or integrated hopper; for these you will pay less but will need to fill the mini hopper yourself more frequently than if it is was drawing from a storage area. Very expensive solutions include outdoor and underground storage options with automatic feed to the boiler. I have seen some quotes for silos which cost almost as much as the pellet boiler itself. Avoid unless you have money to burn.  

Boiler Space Requirements:

I did not realise that the basic wood pellet boiler, in most cases, is much larger in terms of footprint to my oil boiler. Where my Firebird boiler takes a footprint of 900x900x1400mm (WxDxH), some of these pellet boilers are over 1000mm in depth, meaning that they will not fit into my boiler room which is 1150mm wide, as you need to allow for access, servicing etc. I am surely not alone here - many of us have boiler rooms sized to house a basic boiler and a few odds and ends, but nothing more. Whether it is by poor design or necessity, I have found myself immediately striking a large number of manufacturers off my final list, due to the excessive space requirements of their boilers.

In addition, many people, myself included, will be thinking about the cheapest option, namely a mini hopper to sit alongside the boiler, or perhaps an integrated hopper, and that means even less space to work with! So think carefully about how a pellet boiler would integrate into your system, before you sign on the dotted line.

Bulk Or Bagged Pellets:

Here is a quoted figure from a supplier of pellets, at Jan 2007: 1 ton of bagged pellets (based on 67 bags @ 15Kgs per bag), costs EUR234. One ton of loose pellets costs EUR165. So the bagged pellets cost on average 40% more than the bulk pellets. If oil and gas prices remain high, you may still save money with bagged pellets, but saving a further 40% by buying bulk would appear to be a "no brainer". And in order to buy bulk, you need storage. And not just enough to store a ton of pellets, but enough to store over 3.5 tons. A 3 ton bulk is usually the minimum delivery quantity, and you need to allow for existing pellets in your store, hence the allowance for 3.5 tons.

Comparing Wood Pellets To Oil:

2 tons of pellets is roughly equivalent to 1,000 litres of oil. Based on calculations from my most recent oil fill (Jan07), the figures can be worked out as follows:

oil: 1000 litres @ 57cent per litre = EUR570
bagged pellets: 2 tons @ EUR234 per ton = EUR468
bulk pellets: 2 tons @ EUR165 per ton = EUR330

So on those figures I would be saving about 40% if I were to opt for bulk pellets. Even opting for bagged pellets would still offer savings of over 15% against oil. However, I have seen some charts indicating that the cost of pellets over a 5 year period has remained relatively constant. This means that when oil rises in price, pellets become really good value, but when oil falls in price there is a possibility that pellets become more expensive, due to their non fluctuating price. Of course this presupposes that oil will reduce in price as it has done historically, which may no longer be true!

Storage Of Wood Pellets In the Irish Climate:

I have spoken to many people about this, and have had different answers from everyone about what is the best practice. One respected Austrian dealer, who has been involved with wood pellets for many years, informed me that the only way to store bulk pellets in Ireland was to keep them in an airtight, sealed, controlled space, with additional closable venting tubes for occasional escape of moisture. He maintained that due to damp Irish climate conditions, pellets left exposed to any outside air simply absorb too much moisture, leading to degradation of boiler, poor firing, and ultimately poor heat returns.

At a recent trade fair however, other dealers insisted that you could store pellets in an open space, and that as long as they were kept dry the natural air flow would keep the moisture content to a minimum and give good burning qualities. Yet another well informed supplier tells me only to use bagged pellets, which have retained their factory approved characteristics until the bag is opened.

So who are we to believe? Bear in mind wood pellets in this country are only beginning their life cycle. Who can say what is the optimum storage condition, unless we have hard facts to confirm. Hmmm.

Building A Pellet Store:

On the basis of the delivery volume for bulk pellets, I estimate I would need a storage area of appx 5 to 6 cubic meters. The cubic metre capacity is calculated by multiplying the length by the width by the height. I would need to plan for this space in my garage, which will need to dry, covered and have some accessibility slots for feeding the pellets in and drawing them out. I will also need to put a sloping floor into the bottom so that the pellets will move naturally towards some form of opening for easy gathering and transporting back to the boiler room. Finally I would need to check with bulk suppliers to ensure that they can gain access to the garage, how they deliver the pellets, how long the hose connection from the truck extends, what type of connector is required and so on. These need to be determined in advance of building such a store.

Which Pellet Boiler:

The pellet boilers that I have decided to focus on are the ones which offer a reasonably small footprint, priced up to a total paid price of EUR12,000, and which have some form of integrated hopper within or beside the boiler. The integrated models, while taking up the least amount of space, tend to require more frequent filling as their hopper capacity is limited. Note: the price column for my particular installation includes the unit cost, installation, flue, mixing value if suggested by supplier, commissioning, and grant of EUR4,200.

Here is a shortlist of the boilers I am considering, to heat a 1900sq foot house:

MANUFACTURER / MODEL	PICTURE	COMMENTS	PRICE
BioTech  PZ-8 Pellet Boiler		up to 15Kw power integrated daily fuel storage uses flexi pipe, not auger narrow depth suits small area self cleaning	EUR8,300
Froeling P2 Pellet Boiler		15Kw power integrated daily fuel storage narrow overall footprint auto cleaning can operate with firewood option of solar thermal input	EUR8,350
ICB SPA 28/P Pellet Boiler		up to 24Kw power integrated daily fuel storage narrow overall footprint manual cleaning required	EUR3,300
Kunzel PL-15 Pellet Boiler		up to 15Kw power side bin fuel storage medium footprint auto cleaning buffer store option	EUR5,950
KWB Pellet Boiler		20Kw power no integrated fuel storage narrow footprint auto cleaning simple ash pan removal	EUR10,900
Ponast KP21 Pellet Boiler		up to 21Kw power side mount daily fuel storage semi-automatic cleaning flue and mixing valve included can be run alongside oil	EUR4,100
Herz Pelletstar Pellet Boiler		up to 22Kw power automatic cleaning compact depth solar system control	EUR6,000

Integration To Oil Boiler:

Bearing in mind the oil price fluctuations, and that I have an existing oil boiler, I would be intending to integrate the existing boiler alongside the wood pellet boiler so that I have a backup heating solution. This would give me some redundancy if, for example, pellets were in short supply or oil became sufficiently cheap and pellets increased in price.

Lets move on and look at the next heating solution, using the concept of a heat pump.