# Pellet stoves



## Relyat (Sep 29, 2013)

Afternoon. 

I'm considering a pellet stove to replace a log burner. This is in our back room which we use as our winter living room. 
I know very little about these things other than they will be less messy. 
Any advice, experiences etc would be appreciated to help form my decision.


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## Alcalaina (Aug 6, 2010)

The pellets are much more expensive than leña but cleaner and less polluting. People say they give out more heat, but I suspect that depends on what wood you use. If the cost isn’t an issue, I’d go for it.


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## Stevesolar (Dec 21, 2012)

Hi,
Pellet boilers can be very temperamental - they are very fussy about the size and quality of the pellets.
Also - the pellets need to be stored very carefully as they are hygroscopic and really swell up if they get damp or wet.
If this happens - they will block the bolier!
1 ton of pellets produces 1 bucket of ash - so when they work properly - they are very efficient!
I supplied loads of them when I worked in renewable energy in the UK during 2012 - before relocating to the Middle East.
I considered one for our house in the UK that has an oil fired boiler and underfloor heating.
As we are renting it out - we will wait until we return to the UK before changing the heating source.
For ease of use - I would probably fit a heat pump (ground or air source)
Cheers
Steve


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## Relyat (Sep 29, 2013)

Thanks both. 
I was aware of the sensitivity of storage for the pellets and that's not an issue, consequently as long as it's regularly cleaned reliability should be OK. 
Apart from the initial cost of the thing I don't expect a noticeable difference in running costs as we only use the burner for a few months in the winter. 
I'm attracted to them by the cleanliness and ease of use day to day. 
As for heat pumps, that's something I know nothing about!!


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## fortrose52 (Nov 29, 2018)

Do they make a noise?


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## Stevesolar (Dec 21, 2012)

Hi,
Heat pumps use a reverse of the refrigeration process to gather and concentrate heat from either air, the ground or water.
They are more than 100% efficient - a Ground source heat pump will give you around 3.5kw of heat for 1kw of electricity.
An air sourced heat pump will give you around 2.2kw of heat for 1kw of electricity used.
By comparison - pellets are around 90% efficient - you get 900w of heat for every 1kw of pellets burnt.
Heat pumps are great for houses with underfloor heating (as this uses lower water temperature than radiators)
Cheers
Steve


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## Relyat (Sep 29, 2013)

Stevesolar said:


> Hi,
> Heat pumps use a reverse of the refrigeration process to gather and concentrate heat from either air, the ground or water.
> They are more than 100% efficient - a Ground source heat pump will give you around 3.5kw of heat for 1kw of electricity.
> An air sourced heat pump will give you around 2.2kw of heat for 1kw of electricity used.
> ...


That's interesting. 
In practice, what would they look like? An a/c unit perhaps... 
I don't have underfloor here and I won't be installing it, so I won't get the benefit of the pairing. Worth me finding out some more about the heat pumps though as they may present a viable alternative, although getting 2.2kw out for 1.0kw going in goes against all the physics I remember from school!!


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## Stevesolar (Dec 21, 2012)

Relyat said:


> That's interesting.
> In practice, what would they look like? An a/c unit perhaps...
> I don't have underfloor here and I won't be installing it, so I won't get the benefit of the pairing. Worth me finding out some more about the heat pumps though as they may present a viable alternative, although getting 2.2kw out for 1.0kw going in goes against all the physics I remember from school!!


Hi,
No - it does not go against laws of physics - as heat pumps extract the available heat from the air, ground or water and then concentrate it to heat the water in the house.
They are not burning a fuel like an oil, gas, wood or pellet boiler!
You do not need to have underfloor heating to use a heat pump - it is just is a very good pairing.
An air source heat pump looks like a split aircon unit.
Ground source units look like big fridge freezers - and these are connected to a maze of pipes dug underground in your (big!) garden.
Once you get below a meter down - the ground temperature is fairly constant, all year round, and the liquid is circulated around these pipes to extract heat from the ground.
The pipes need to be more than 1 meter down - if they are too near the surface it can cool the ground too much and nothing would grow on it!
Water source is similar - great if you have a big lake in your garden or fast moving stream - the pipes are submerged.


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## Nomoss (Nov 25, 2016)

Relyat said:


> Thanks both.
> I was aware of the sensitivity of storage for the pellets and that's not an issue, consequently as long as it's regularly cleaned reliability should be OK.
> Apart from the initial cost of the thing I don't expect a noticeable difference in running costs as we only use the burner for a few months in the winter.
> I'm attracted to them by the cleanliness and ease of use day to day.
> As for heat pumps, that's something I know nothing about!!


I installed a Kozi KSH pellet stove, KOZI Shop Heater Pellet Stove made in Canada, which I bought from an Ebay seller in Ireland, in February 2008. It is not so pretty as some on the market, in fact it is rather industrial, but its look suited our house. It was a really good buy at the time, when they were quite expensive, at £1,400, and was shipped through one of the web sites where carriers bid for part loads,for only £200.
It has been in use for about 5 months every winter since, whenever the outside ambient temperature is too low for the air/air heat pumps to function efficiently (below about 7ºC).
I liked it so much that I took it out and installed it in the new house when we moved. I replaced it in the old house with a Ravelli stove, which we drove to Italy to get, as it was considerably cheaper there, and a pleasant trip during the summer. The buyer of our old house was not at all technically minded. He called in a local company when he had a problem, and they persuaded him to buy a new one after five years, as they couldn't get the electronic control to work, and told him new ones were not available.
The double stainless steel flue (Poujoulat) cost almost as much as the stove, and runs vertically through the loft floor and the roof. I discarded the top outlet, as it became blocked, and the open top is protected by the cover on our regular chimney.
After every five 15kg sacks of pellets, about once a week when it is cold, I brush down the inside of the combustion chamber, remove the ash, and clean the glass door. This takes a maximum of 30 minutes.
Once a year I completely clean the interior and exhaust pasages, sweep the flue, and lubricate the motors as per the manual.
It is very simple, and I have needed very few spare parts in the 12 years we have had it. One exhaust blower, which I got from an agent in the US, three igniter heaters, bought in France by wattage and dimensions, and a mesh glass saver screen, which burnt through last year.
We normally buy a nominal 1 ton full pallet, delivered in the summer, when they are cheaper, but once when we ran short we bought small batch of damp pellets from a supplier in Narbonne who did not have them stored properly. They were probably in stock too long, and were a lot of trouble, with the fire not lighting and even going out, so have never bought a small batch since. We have a large store within the house where there is plenty of room for them.
We have burned 40 sacks, which cost on average €175, per year for the last 8 years.
For a comparison of running costs, the last time we bought logs for our wood stove, in 2007, we paid €260 for a "pile" - a nominal m3, which often didn't last the winter.

EDIT: We usually buy our pellets from our nearest TOTAL agent. In 2017 we bought a ton from Mr Bricolage, as the local branch is owned by our next-door neighbour, but they seemed to burn less well and produce more ash, as well as being slightly more expensive.


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## Nomoss (Nov 25, 2016)

An alternative to underfloor heating, which is probably easier to retrofit, is a radiant ceiling.

Rather counter-intuitively, they are more efficient than heated floors.

This is a Spanish company producing them.Radiant Klima System | Heating and radiant cooling

There are many others all over the world. Google "radiant ceilings"


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## NickZ (Jun 26, 2009)

A wood stove pollutes more if you have an old inefficient one or if you run it badly. You'll see people burning everything from beach wood to plastic to coated paper.

The advantage of the pellet is it's much harder to do it wrong. Buy good pellets and keep them dry. Storage of pellets is easier and cleaner. But a good wood stove doesn't produce huge amounts of crap either.

A good high efficiency heat pump system is less costly to run. Plus it will handle cooling during the summer.

Problem with both the pellet and the heat pump is they use electricity. If you're in an area with frequent blackouts a wood stove is better.


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## Relyat (Sep 29, 2013)

Interesting points. 
We don't get power cuts where we are now, so that's not a consideration. 
My comment about physics was meant tongue in cheek. However, they do consume electricity although the actual exchange of heat may be an entirely passive process leading to the seemingly impossible! 

I'll research heated ceilings but ideally I'm looking for the cheapest replacement for the log burner which will at least match it's heat output. It's a relatively new model and runs quite cleanly on well seasoned olive. 
I'm not decided on replacing it yet, but looking to the future a days ration of pellets is easier carried than a days ration of logs


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## NickZ (Jun 26, 2009)

Ease of use an air to air heat pump wins. It's just a button on the remote to push. 

Cost depends on how big an area you need to heat? Higher efficiency models are more expensive to buy but cheaper to operate. If you're in a real cold winter area you need to check the units performance at low temperatures. The better (AKA more expensive) models can work quite well even well below zero. 

The other cost saving is it's one unit for both heating and cooling.


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## sadlybroke (Jun 19, 2012)

I researched different methods of heating a house for our self-build villa in Benalmadena. A very important aspect no one has mentioned is insulation. I lived in a house with an air-to-air heat exchanger with hot air heating but because the house wasn't insulated well (apart from triple-glazed windows), most of the heat escaped through walls, floors and ceilings and the house felt very cold. 

You don't have to have a passive house to benefit from air-to-air heating but you should insulate it and plan the ventilation system carefully (e.g. inflow in dry rooms, dump air out in wet rooms, etc.).

What I want to say is, I think installing the heat exchanger on its own won't be as effective, you have to do more - insulate the house, plan the air flow, consider post heaters, etc.


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## NickZ (Jun 26, 2009)

That's true no matter what heating system you pick. If you don't insulate you'll need a bigger system and even that will be running more.


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## Barriej (Jul 23, 2012)

We have hot/cold air con units and the heated side works well in closed rooms (same as cooling really) 
The units we have are standard but can improve the temperature of the room to a degree. 
Would second and third the insulation part.

We have double glazing but the window units rattle in the frame, the patio doors wobble and the wind rushes through the shutter cassettes.
Ive done what I can but to improve the draught, we put an oil filled rad in front of the doors, so warm air is moved around instead of a chilling wind..


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## Jamglish (Mar 15, 2014)

At our smallish house in Coin, we have a Bronpi pellet stove which is pretty good at heating up the living room and downstairs, with some of the heat also going upstairs and slightly warming up any bedrooms if the door is kept open. An electric blanket makes up for the difference. The stove is pretty efficient, with not much ash or cleaning required. Starting and stopping it is just the push of a button on the stove or on the remote. Similarly, there are 5 power levels selected with button pushes also. Presumably, the higher the power level the faster the pellets will be burned and more heated air pumped out. As I understand, the forced air fan requires 150 Watts of electrical power. A bag of pellets (15kg) runs around 4 euros +- depending on where you buy them, and running at around the middle power level, lasts 2 days if the weather is cold and the stove run judiciously. All the different bags of pellets I have used have the energy content specified, and it is typically 16.5 MJ per kg. If I have done the conversion correctly (someone please correct me if I am wrong), burning 1 kg of pellets in 1 hour on a stove that is 90% efficient is equivalent to about 4 kW-Hr of energy. There is also, for us, the psychological satisfaction of seeing the flames, and having a source of heat to warm up hands etc. So, my 2 cents worth is that, for us, the pellet stove is a good way to heat during the winter here, is pretty economical, and is using a renewable resource.


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## Relyat (Sep 29, 2013)

All good stuff. 
I think that the heated ceiling might be a step too far for what we want. 
Like Jamglish I also like to be able to see the fire and feel the direct heat. Having said that our last house in the UK had gas central heating for 20 years.


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## Relyat (Sep 29, 2013)

Jamglish and Nomoss, is the inlet vented to the outdoors on yours, or does it just draw from the back of the stove?


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## Nomoss (Nov 25, 2016)

Relyat said:


> Jamglish and Nomoss, is the inlet vented to the outdoors on yours, or does it just draw from the back of the stove?


The stove in our current house has a concentric flue, with exhaust gas expelled through the inner duct.
Originally, the combustion air was drawn in through the outer annulus by means of a flexible duct connected between a tee on the annulus and the air inlet on the stove, as shown here:










However, the height of the flue is 7 metres, and in cold weather the exhaust gases were cooled too much, resulting in heavy tar and soot deposits at the top, which eventually blocked the top outlet, which I removed as mentioned in my post above.
The inlet tee on the annulus is now blocked be means of a well-fitting tin can, which is angled slightly to leave a small inlet slit, so that just enough air enters the annulus to keep the lowest part of the flue, where it passes through the ceiling, warm to the touch. No further problems after about 5 years.
The disadvantage now is that all the combustion air is drawn out of the room, plus some is drawn out by the flue, although this is kept to a minimum by the tin can.
Where the flue passes through the floor it is supported by a steel bracket, with an air space around it of the mandatory dimensions (which I forget) to separate it from the timbers and loft floor insulation. At the loft floor level there is a concrete pad supporting a masonry chimney for the rest of the way through the roof, so the outer temperature of the flue running inside it is unimportant there.
If I were installing another pellet stove I might put it on an outside wall, so that combustion air could be easily drawn in from outside. I would also have a short flue, horizontally through the wall and up, with a cleanout tee at the bottom so that sweeping could be done on the outside of the building.

For the new pellet stove, below, which I put in the house we sold, I used a single 8 cm black enamel flue pipe, connected with an adapter at ceiling height into the existing large rigid stainless steel chimney liner used for the previous wood burning insert. I had demolished the hideous standard French fake stone fireplace with massive wooden beam and chimney breast to ceiling height when I took out the insert. The hot pipe within the room gave some additional heating to it.


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## Relyat (Sep 29, 2013)

Thanks for the comprehensive reply. 
Mine, I'm getting close to deciding, will be on an outside wall. 
I'd thought that it would make sense to draw the intake from outside but wondered if there were disadvantages that I hadn't thought of. Seems like excessive cooling of the exhaust is something to consider.


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## Nomoss (Nov 25, 2016)

fortrose52 said:


> Do they make a noise?


Sorry for not replying sooner. Yes, they do make a noise, not objectionable to us, but some may not like it. There are two blowers, both of which whine quietly.


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## Relyat (Sep 29, 2013)

Morning. 

Just to let you know what eventually happened, the decision was taken for a pellet stove. 

As mentioned, I have installed it on an outside wall and so far all is good. Much easier to store the fuel and carry in what's needed, less mess and quicker to clean. 
Happy with the advice I received and how it's worked out.


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