Biomass boiler vs heat pump : The fight is on!
Posted by Tasha Kosviner on 25 March 2015 at 10:55 am
Domestic biomass installations now outstrip the entire heat pump industry in the UK. But is biomass always better? When might you choose a heat pump instead? We’ve pitted these two titans of the domestic renewable heating world against each other and here’s the fight in full:
Round 1: Cost of installation
The cost of installation depends on any number of factors – size of property, type of installation, make and model and you should get several quotes for both in order to accurately compare costs. This YouGen blog has suggested biomass installations start in the region of £10,000. Air source heat pumps can be much less – from around £4,000 (ground source heat pumps are much higher because of the heat exchanger must be buried underground). However, because heat pumps are most efficient when used with underfloor heating this can bump the cost up dramatically, particularly in a retrofit, bringing it on a par with biomass.
Winner: Heat pump in a new build, biomass in a standard retrofit.
Round 2: Operational costs
Domestic biomass boilers usually run on pellets, heat pumps on electricity. Both are subject to the vagaries of the market. However, the Biomass Energy Centre’s comparison of domestic fuel prices claims that while wood pellets cost 4.1p/kWh (kilowatt hour) electricity costs closer to 15p/kWh. This isn’t the whole story of course, because the efficiency of the system and energy efficiency of the house must also be taken into account.
Assuming you’ve chosen an excellent, well rated (on YouGen!) installer, then the quality of your insulation is your next variable. Whilst in a very well insulated house a properly sized heat pump would require very little electricity to get up to temperature, the reality is that most UK properties are not up to standard. This isn’t to say it is impossible but if your insulation isn’t great and you lack the inclination or the funds to upgrade it, your cheapest option is undoubtedly biomass.
Winner: Biomass unless it’s a new build or complete remodel.
Round 3: Maintenance
When properly installed, heat pumps should be fairly maintenance free, usually requiring little more than an annual service. A biomass boiler, because it is a combustion system, is arguably more prone to things going wrong though again, choosing a good installer and a good manufacturer should help to mitigate that.
Winner: Heat pumps, just.
Round 4: Usability
This is a tough one. Unless you are a technical wizard who likes figuring out excessively complex programming systems, a heat pump requires an engineer to program the flow temperature (the temperature of the water in the pipes). But then, once its set, if it’s a well thought out system, you should be able to control the room temperature via thermostats and zoning.
The major game changer here, is fuel. Unless you get an automatic feeder, biomass boilers require manual loading of the pellets into the hopper, which if you’re older, immobile, (or a bit lazy!), will present a problem. Furthermore, biomass provides almost instant, flick-of-a-switch heat, which is familiar to most people switching from oil or gas. Heat pumps operate at much lower flow temperatures, meaning they take longer to get your house up to temperature. If you install a clever smart system, or have it running at a low temperature all the time, then this shouldn’t be a problem but it can take some getting used to.
Winner: Biomass if you’re agile or install an automatic feeder (can be pricey) or require instant heat, heat pumps if you’re not.
Round 5: Economy of space
While a heat pump takes up little more room than a combustion boiler on the inside, and requires a relatively small space for the outdoor unit, a biomass boiler is much more space hungry. Add to that the fact that you need a (dry) space in which to store your fuel and heat pumps, especially in urban homes where space is at a premium, start to look much more appealing. Ground source heat pumps of course require a large garden or the capacity to dig a deep trench, in order to be viable.
Winner: Biomass where space isn’t an issue, otherwise heat pumps (so long as your insulation is up to scratch)
Round 6: Government incentives
The rapid growth in the biomass market has, in part (or in full depending on who you speak to), been attributed to the fact that biomass is far more attractively incentivised under the renewable heat incentive. Tariffs are currently set at 7.3p/kWh for air source heat pumps compared to 10.98p/kWh for biomass boilers, (the rates are 18.8p/kWh for ground and water source heat pumps to offset the much higher cost of installation). Biomass is due for further degression to 8.93p/kWh for all new applications from 1 April 2015 so if you’re considering it, now’s the time to act.
Winner: Biomass, currently, though this may change in the future.
Round 7: Carbon saving
Heat pumps use electricity to operate, and will use more in very cold weather for an extra boost when they just can’t extract enough heat from the air (which is ironically when you need them most). While this doesn’t always make for low bills (see 2, above), if you buy your electricity from a green supplier such as Ecotricity, you can still claim your system is carbon neutral.
The biomass industry has long claimed that biomass heat is near carbon zero. But this is only the case if the pellets are sustainably sourced (from a forest with a strong re-planting programme), produced and transported. The campaign group Biofuelwatch has claimed that even with the government’s biomass sustainability criteria coming into force next month (April 2015), it is far from clear that biomass can rightfully claim to be carbon neutral.
Winner: This is the subject of heated debate and it’s too tough to call. If you’re confident in your pellet supply then biomass. If you only buy green electricity, the heat pumps are a good choice too.
If you are in an urban area, where space it at a premium or if you are older and do not want to manually load your pellets, you should consider a heat pump. However, this should only be done if your house has maximum levels of insulation, or you are prepared to go to the expense and upheaval of upgrading. In all other instances, particularly if you have plenty of storage space and a good ongoing guarantee and maintenance plan, or if you’re not prepared to adapt to a new way of heating where your system is on all the time, biomass is probably the more attractive option.
Photos: 1, 2 SuperHomes. Also note this helpful article on the pros and cons of biomass boilers from an owner on the SuperHomes website.
More information about Biomass Boilers on YouGen
More information about Heat Pumps on YouGen
Need help with any Jargon?
If you have a question about anything in the above blog, please ask it in the comments section below.
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