economy of underfloor heating

[King sound]

Howdy. We recently moved in to our new house just before Xmass and very pleased so far. However we have underfloor heating with wood pellet burner. The burner seems to be going thru pellets at a ferocious rate 2 bags + per day. There are thermostats in every room which the electrician set I presume as you would in any normal house, that is to come on in the morning and evening times etc. However, as it is underfloor heating, it takes several hours for the ambient temp. to rise. Would it be better to set all Thermostats at a fixed temp all the time, therefore having the boiler merely top up the heat every now and then, or what ?? I would appreciate your thoughts and experience in this. Thanks

 

[JohnD]

If you run the heating 24 hours a day it is always more expensive than running it for a limited number of hours. However if there is a big time lag you can try setting the start and stop times an hour earlier as an experiment.

Underfloor heating is generally an expensive way to do it. Some people like to use it to give a low level of background heat with (say) an open fire or radiant heater in the living rom.

Wood contains much less heat per weight than coal, oil or gas.

 

[Agile]

The thing to remember is that the WEIGHT of your wood is quite low and worse they contain up to 30% of water in their weight.

The point of wood pellets is that they are from a sustainable source as trees will still be growing after 2020 when the oil has mostly run out.

UFH is not a very efficient way to heat a property unless you are retired or there all day.

UFH is best started about 0400 and switched off about 2100 as this allows the three hour thermal lag to be used most effectively.

Being in Ireland, can you buy well dried peat? Or is that now a labour intensive DIY fuel source just for those who like a lot of physical work?

Tony

 

[King sound]

Thanks for the quick reply guys. I chose underfloor because I dont like the idea of radiators they take up too much space and people have a tendancy to practically sit on them in cold weather. One of the problems with wood pellets is the inconsistency you get in pellet size and quality from the different suppliers. Because of the the new grant system that came in in Ireland last year, there was a rush to avail of it, with the result that there was a huge demand for pellets and very few suppliers. In this kind of situation we are left in a risky position in that you have to take pellets from where you can get them. It shoud balance out eventually, hopefully. One supplier before Xmass was quoting a 7-8 week waiting list !!. As to peat, it is very labour intensive and also it is quite slow burning and therefore would require a specialised burner. Also quite a lot of bogs are now protected.

 

[Agile]

Yes, I should have also mentioned that another problem with wood pellets is that they take up a lot of space and a months supply will take up enough space in the garage to make the car stay outside!

Thats the problem with all these "green" solutions, they are mostly not very convenient! Using a bicycle is fine but you have to pedal it to go anywhere!

Tony

 

[King sound]

Well I built a silo in my garage which is roughly six meters sq. so it doesnt actually take up that much room. I built it up to the roof to take up less space so its not too bad. Bulk delivery is minimum 3 tonnes and 2 tonnes is supposed to be the equivelant of 1000 ltrs of oil. Now, if I could just get someone to deliver in bulk !!!!!!

 

[RigidRaider]

Interesting post. I have often wondered if it would be cheaper to run the heating set on, say, 19 degrees all day and night rather than let the boiler struggle to achieve 21 mornings and evenings.

How are the wood pellets produced? Aren't they sawdust that's been re-compressed? If so, how can they be considered green? They have already consumed a fair bit of energy in their production.

Peat smells lovely but it's a disappointing fuel. It burns slowly and produces lots of tar. A pal of mine who grows orchids (2 acres under glass) uses finely ground coal for his boilers.

 

[Agile]

I think the original idea would be that the pellets would be using waste sawdust.

Since all the woodwork is now done overseas I can only assume the wood is chipped to make the pellets, perhaps from wood offcuts?

Like a lot of these good ideas, some are not as good as they sound. If the whole of the UK used wood pellets then all the country would be covered with trees to supply the wood and we would still have to import some to meet the demand.

Wood pellets fine as long as its a minority usage!

Tony

 

[King sound]

There is a sawmill in County Cork which for years had to pay to have waste sawdust removed, Some years ago they installed a processing plant to convert the waste, sawdust and offcuts, to pellets. They now have one large boiler heating the drying house for the timber, and another drives a steam turbine which provides electricity for the running of the entire mill. They even manage to sell surplus power to the supply board. I have about 2 acres of wetland around my house and I am seriously considering planting it with willow for coppicing in order to at least supplement the cost of the pellets. There arent enough processers in the Country at the moment to facilitate this, but with the amount of people changing to wood pellet burners at the moment, the amount of companies who are interested in becoming involved in their supply is growing. Hopefully it should progress rapidly to the point where this should be feasible.

 

[Agile]

It sounds as if you should have installed a wood burning stove!

The advantage of wood pellets is that the boilers can be virtually automatic although when giving full power presumably have to be loaded every couple of days or so.

Tony

 

[King sound]

I am a lazy soul at heart, therefore the 3 tonne silo which should keep the boiler going for a few months with only the ashes to clear every few weeks. The auger from the boiler feeds directly from the silo.