I am building a new house shortly and have been researching geothermal and wood pellet heating systems for it. For a long time I was going with the geothermal system, despite the high cost of the installation. I also looked into a wood pellet system which at first seemed like a great choice.
The biggest problem with both is that there are just so many unanswered questions that it makes it very difficult to decide which one (if any) to go with.
I have outlined some of the things that still concern me about both these systems below, and am very interested in other peoples opinions on them...
Geothermal
1. If any thing went wrong with the piping the whole garden would have to be dug up. I understand the chances of this are probably slim but there still is a chance.
3. I did have some concerns about the system absorbing all the available heat from the ground on the colder days leading to increased demand on the electricty and increased running costs. This problem seems to be avoided by laying the pipes deep enough and far apart
(i.e. 6ft deep and 4ft apart). Only problem here is that a few of the pictures on websites show the pipes being laid close together and not very deep! Why?
4. Using a water well seems more effecient than laying the pipes under the soil. Only problem is the cost of; drilling the well, a
return well (no stream near by) and an extra pump to pump the water out. This pump is dropped into the well which is then sealed up, but what if this pump breaks down?
And if its running constantly for 10+ hrs a day the chances of a breakdown are high...
And then there's the additional cost of running this extra pump.
4. A lot of the savings calculated are based on the night saver rate but what happens if/when this rate no longer exists?
5. There doesn't seem to much info on vertical closed loops. They are mentioned but nothing about how they rate compared with horizontal and open looped systems.
Wood Pellet Boiler
1. Storage of the wood pellets is a biggest issue and is overlooked by all of the documentation on these systems. You need approx 1m cubed to store 0.6tonne.
2. The quantity required for a year is poorly documented too. Just how long would 1 tonne last? One figure I read suggested that 1 tonne will last for about 2 weeks depending on the size of house, your usage and the moisture content of the pellets. At about 160 - 190 euro per tonne that could work out very expensive.
2. The moisture content should be less than 10% for the pellets but given the irsih climate they are more likely to be 18-20% (based on my research). The only suggestion I have seen for keeping the moisture content at <10% is store them in a well insulated and heated room!
3. There are silos available for storing them but none state whether they would be effective in keeping the moisture levels at <10%.
If they don't then the only advantage of paying 2K for one is that you don't have to keep refilling pellets every 3-4 days as they are connected directly to the boilers. Perhaps there is another reason?
3. Perhaps a mositure content of 18% isn't really that big a problem but all the data I've read is based on a low moisture content so just how effecient is it at the higher content? And what about the CO2 emissions?
The biggest problem with both is that there are just so many unanswered questions that it makes it very difficult to decide which one (if any) to go with.
I have outlined some of the things that still concern me about both these systems below, and am very interested in other peoples opinions on them...
Geothermal
1. If any thing went wrong with the piping the whole garden would have to be dug up. I understand the chances of this are probably slim but there still is a chance.
3. I did have some concerns about the system absorbing all the available heat from the ground on the colder days leading to increased demand on the electricty and increased running costs. This problem seems to be avoided by laying the pipes deep enough and far apart
(i.e. 6ft deep and 4ft apart). Only problem here is that a few of the pictures on websites show the pipes being laid close together and not very deep! Why?
4. Using a water well seems more effecient than laying the pipes under the soil. Only problem is the cost of; drilling the well, a
return well (no stream near by) and an extra pump to pump the water out. This pump is dropped into the well which is then sealed up, but what if this pump breaks down?
And if its running constantly for 10+ hrs a day the chances of a breakdown are high...
And then there's the additional cost of running this extra pump.
4. A lot of the savings calculated are based on the night saver rate but what happens if/when this rate no longer exists?
5. There doesn't seem to much info on vertical closed loops. They are mentioned but nothing about how they rate compared with horizontal and open looped systems.
Wood Pellet Boiler
1. Storage of the wood pellets is a biggest issue and is overlooked by all of the documentation on these systems. You need approx 1m cubed to store 0.6tonne.
2. The quantity required for a year is poorly documented too. Just how long would 1 tonne last? One figure I read suggested that 1 tonne will last for about 2 weeks depending on the size of house, your usage and the moisture content of the pellets. At about 160 - 190 euro per tonne that could work out very expensive.
2. The moisture content should be less than 10% for the pellets but given the irsih climate they are more likely to be 18-20% (based on my research). The only suggestion I have seen for keeping the moisture content at <10% is store them in a well insulated and heated room!
3. There are silos available for storing them but none state whether they would be effective in keeping the moisture levels at <10%.
If they don't then the only advantage of paying 2K for one is that you don't have to keep refilling pellets every 3-4 days as they are connected directly to the boilers. Perhaps there is another reason?
3. Perhaps a mositure content of 18% isn't really that big a problem but all the data I've read is based on a low moisture content so just how effecient is it at the higher content? And what about the CO2 emissions?