Our Wood Pellet Boiler decisions.........

R0b279

Only just found this thread today, and I've found it useful - thanks. We installed a biomass boiler just about a year ago, a MCZ RED Compact24. I approached 4 different installers, all offering different solutions before deciding on this model. Whilst we live in a new build 4 bed house, we are off mains gas grid. We previously relied on LPG, which was becoming increasingly expensive to fund, with no visibility on actual cost. Our biomass system effectively "plugged" into the existing heating system, although we did need to install a water tank.

I'm extremely pleased with the investment we've made, and so far (touch wood, no pun!) no problems with our boiler. We can now heat our house in winter without worrying about the bills. I've found White Horse Energy the cheapest fuel providers, though admittedly have only purchased two tons from them. I did carry out a decent amount of web research on pellet suppliers before ordering from White Horse. Early days, but it's been a positive experience.

I'm interested to learn about how other users operate their respective systems. I rely on pellets for both CH & HW, it's programmed to come on early in the morning, staying on once throughout the day, until bed time. We use a thermostat in the hall to regulate the space heating temperature. I was advised that for the boiler to operate efficiently it needs to be on, and not stopping and starting. We've used almost 6 tons of pellets in the first year and I do monitor exactly what our usage is on a weekly basis - our hopper (200 kilo capacity) generally gets filled once a week, with top ups needed during cold weather.

I'm interested in how other biomass users operate their systems, as while it's certainly more cost-effective for us I'm keen to make our usage as efficient as possible.

Thanks

ModelCitizen

I'm a bit worried by how much pellet you've consumed. I had calculated our usage at less than 5 ton a year. This to heat a 100 year old 9 inch solid wall brick built detached four bedroom house in an exposed position.

Since my last posts i've understood that pellet boilers are not good at cycling and to reduce cycling it is better to have a larger heat store. I am thinking of 1000 litres, although even 800 litres would easily be fine with the 25kw boiler required for my property.

The next part of my equation I is whether to combine the heat store and cylinder (i'm installing a pressurised hot water system). There seem to be a number of possibilities here (plate?) which I have yet to fully get to grasp with.

I've seen a system running the Hungarian Centrometal pellet boiler. This seemed quite good to me, simple, robust and inexpensive and from a company right on the Austrian border with a long engineering history. None of the bells and whistles that in my experience (as a long time ex-heating a plumbing engineer) make a system less than robust and expensive to maintain. The boiler comes with as 240kg pellet store so can be used with bags of pellet.. and in the future be fed by a 5 ton hopper (which is what I want to do next year).

What still gets me about all this is that there are so many options. Whacking in gas combi boilers in Brighton was so simple in retrospect..... until they went wrong that is.

R0b279

Thanks Modelcitizen

My usage has actually came in at under a ton below all the estimates I was given by the various suppliers who quoted. Independently they all estimated usage at around 7 tons (at the low end).

When I posted I made a mistake in respect of our boiler model, it's a red 28, not 24.

ModelCitizen

Ah, so a 28kw boiler? What size store do you have?

R0b279

Sorry, yes the boiler is 28kw. The LPG combi-boiler we replaced was around the same output. We did consider some smaller sized boilers, but after taking advice from Energy Savings Trust Scotland I decided it was better to replace like for like.

We didn't require a thermal store with our Red. Only one of the companies that quoted for our work discussed an accumulator (not sure if that is what you're referring to as a thermal store). The other three who I approached didn't believe I needed an accumulator. This boiler was a HDG Pelletmaster, with an 800 litre accumulator. To provide an idea of scale, our house has 23 radiators (although 3 or 4 are pretty small in size). Don't know if that helps you.

DanRichards

We have our boiler starting at 6 in the morning. At 7 it starts heating the hot water for an hour then everything goes off at 8. Then we have the heating come on for about 4 hours in the evening.
From this we get plenty of hot water and are looking at about 5 tonnes of pellets per year, although this cold March isnt helping!
We've got 12 radiators (i think!) and loft insulation but no cavity walls.
Ive not thought about leaving it on during the days, it would seem to me that you would use more pellets that way?

R0b279

Our boiler has an ECO mode, which is the default factory setting (I can alter it if required, but keep it on ECO as choice). My understanding of this mode is that it allows the boiler to modulate, so when the external thermostat is satisfied, the boiler shuts down. It automatically starts up again when the external thermostat requests heat again. Hence my rationale for leaving the boiler operational throughout most of the day. So hopefully we are not using any more pellets than is required.

Is your boiler set the same? I have tried a few different alternatives, but eventually gave up as the different combos I was trying was through the summer months, when I only needed HW. I thought I would ask other people's experiences to save me a bit of trial and error.

Thanks

DanRichards

R0b279 wrote: »

Our boiler has an ECO mode, which is the default factory setting (I can alter it if required, but keep it on ECO as choice). My understanding of this mode is that it allows the boiler to modulate, so when the external thermostat is satisfied, the boiler shuts down. It automatically starts up again when the external thermostat requests heat again. Hence my rationale for leaving the boiler operational throughout most of the day. So hopefully we are not using any more pellets than is required.

Is your boiler set the same? I have tried a few different alternatives, but eventually gave up as the different combos I was trying was through the summer months, when I only needed HW. I thought I would ask other people's experiences to save me a bit of trial and error.

Thanks

Yeah ours is set on Eco mode too, and regulates with the thermostat indoors.

R0b279

My rationale may well be flawed, but the discussion I had with the installer was that by allowing the boiler to modulate whilst it is on through the day should be more efficient, as it (in theory) should require less power to get it back up to temperature. However he did say that he had customers who ran their boilers 24/7, or others that stuck rigidly to programmed timings.

The (few) setting combinations I played about with (mainly scaling back the time the water was on) I found that I actually ended up using more pellets, hence why I went back to leaving the boiler on through the day.

Who knows!

ModelCitizen

I've just had a slightly worrying chat with a 'green' architect. He has stopped recommending pellet boilers for the properties he designs as he say efficiencies quoted by the manufacturers and installation companies are never reached. He blames much of this on the quality of the pellets, stating that the UK produced pellets are inferior and that to get anywhere near the efficiencies quoted you'd have to import top quality pellets from Sweden (not something I want to do).

As a result of his comments I've researched and found that there's an EU standard for pellets called EN Plus (Google it. As a 'new user' I am not allowed to post links).
Does anyone know of this standard or have any comments about efficiency and pellet quality?