Geothermal Setup

tred

query folks. I see a neighbour of mine has had GEO thermal in for nearly ten years. One of the early adopters. He seems to have had problems with the store, and is now changing his collector from horizontal to vertical bore. Are there problems down the line with what options people are using. I havent spoken to him on it yet, on why, but what i heard was the horizontal collector was not working efficiently for him for the last few years.

heinbloed

Geothermal energy comes from the inner part of the planet.
So the problem your neighbour seems to have is NOT to have geothermal energy available.
The temperature increases by about 3 degrees Celsius per 100 meters of depth. Just as a rough estimate, geological faults will be different.

tred

heinbloed wrote: »

Geothermal energy comes from the inner part of the planet.
So the problem your neighbour seems to have is NOT to have geothermal energy available.
The temperature increases by about 3 degrees Celsius per 100 meters of depth. Just as a rough estimate, geological faults will be different.

So are horizontal stores now old school as in, not being used any more, all vertical boreholes

Carlow52

tred wrote: »

So are horizontal stores now old school as in, not being used any more, all vertical boreholes

No because some horz systems are designed to take the heat form the upper layers, even from soil solar gain.

generally the areas involved are very large and hence not practical in many cases. in addition the recovery time can be very long.

Horz also used to extract from running water/lakes/sea/estuaries

jprboy

Have horizontal geothermal and the area over which the pipes are laid could clearly be differentiated from the other areas of the lawn before I cut the grass in early March - much more growth in the other parts of the lawn.

I've no problem with this but am slightly worried by Carlow52's statement that "the recovery time can be very long". Do you mean that the heat in the ground effectively gets depleted and can take a very long time to get back to "normal" levels?

We won't be using the UFH that much from now on (unless we get an unseasonal cold snap) so it will probably be late Sep/early Oct before we start using it to a great extent again. Would that be considered a sufficient recovery time or could we find ourselves in the position of the potential heat that can be extracted from the ground depleting year on year?

Thanks.

heinbloed

Jprboy wrote:

I've no problem with this but am slightly worried by Carlow52's statement that "the recovery time can be very long". Do you mean that the heat in the ground effectively gets depleted and can take a very long time to get back to "normal" levels?

Well, 'normal' ground temperature is the temperature seen and meassured without cooling radiator in it.
With a cooler in it the normal level will be never 'normal'.
That

"the recovery time can be very long"

is a false statement. It will NEVER recover unless the HP's heat exchanger -the cooling radiator- is taken out of action for good. After this it will take a very long time.
From what I've heard this might take 2-3 years/heating seasons.

And the other way around as well: the ground will coool down (the anual average temperature of it) for about 2-3 years until it has reached an equilibrum. Sometimes 4-5 years!

This is another reason why so many HP calculations fail to realise, the ground/collector temperature drops every year a bit.
In the meantime the shading situation usually increases, extensions are build, trees and plants grow.
So 2 factors have to be considered: a colder ground because of thermal drawing and a colder ground because of less solar exposure.

creedp

heinbloed wrote: »

Jprboy wrote:



Well, 'normal' ground temperature is the temperature seen and meassured without cooling radiator in it.
With a cooler in it the normal level will be never 'normal'.
That is a false statement. It will NEVER recover unless the HP's heat exchanger -the cooling radiator- is taken out of action for good. After this it will take a very long time.
From what I've heard this might take 2-3 years/heating seasons.

And the other way around as well: the ground will coool down (the anual average temperature of it) for about 2-3 years until it has reached an equilibrum. Sometimes 4-5 years!

This is another reason why so many HP calculations fail to realise, the ground/collector temperature drops every year a bit.
In the meantime the shading situation usually increases, extensions are build, trees and plants grow.
So 2 factors have to be considered: a colder ground because of thermal drawing and a colder ground because of less solar exposure.

I'd like to see the stats on this ... from a practical perspective during the very cold winter of 2010 (and yes 2011 also Heinblood:)) if you dug down up to 300mm you would get frost, yet within days of a thaw the frost is gone. This is even when the air temp remains very low. How then could it take so long for the ground around geothermal collectors which are normally only around 1m deep to recover heat? Surely, relatively warm rainfall is percolating down around the pipes on a continuous basis thereby raising the ground temperature and this is in addition to direct solar heat from Spring to Autumn. Given that the ground collectors are not actually recovering any heat during the non heating season are you arguing that the ground around the pipes will not recover any heat during this period?

heinbloed

As long as the brine pumped into the ground is colder as the ground itself the thermal impact of it must be negative. That's logic.

Ask your installer for a guaranteed ground temperature in the collector field. He will walk out. He could just say it would be as warm in Autum as it was before. But then he would be lying and the contract would be invalid. Money-back, compensation. That's consumer law.

But it can be calculated using the laws of thermodynamics and a good knowledge of the influencing parameters.

The heating engineer calculating the efficiency of a HP based heating system would have to do that according to EN methods. If this HP based heating system provides for DHW as well it must be done from June of this jear.

That was decided in Brussel some time ago. And NO Irish delayment possible, that was decided as well.
The date of implementation of this EN regulation for space heating systems on their own could be December 2011 or January 2012, this isn't decided yet. Again: no (Irish) delayment is allowed.

So better don't employ the amateurs.

Always ask for a guaranteed efficiency of the heating system, the calculation done to EN.

creedp

heinbloed wrote: »

As long as the brine pumped into the ground is colder as the ground itself the thermal impact of it must be negative. That's logic.

Ask your installer for a guaranteed ground temperature in the collector field. He will walk out. He could just say it would be as warm in Autum as it was before. But then he would be lying and the contract would be invalid. Money-back, compensation. That's consumer law.

But it can be calculated using the laws of thermodynamics and a good knowledge of the influencing parameters.

The heating engineer calculating the efficiency of a HP based heating system would have to do that according to EN methods. If this HP based heating system provides for DHW as well it must be done from June of this jear.

That was decided in Brussel some time ago. And NO Irish delayment possible, that was decided as well.
The date of implementation of this EN regulation for space heating systems on their own could be December 2011 or January 2012, this isn't decided yet. Again: no (Irish) delayment is allowed.

So better don't employ the amateurs.

Always ask for a guaranteed efficiency of the heating system, the calculation done to EN.

Are you suggesting that this upcoming new EN measurement system for HPs will somehow invalidate existing installations? Otherwise nothing really to worry about over and above the fact that stds are always improving. However if you were always waiting to see what tomorrow will bring you would never make a decision on anything. In any case maybe I'm simply the kind of person who would buy a large petrol engined car in June 2008 while you will do the math and always buy the Prius!

heinbloed

Creedp asks:

Are you suggesting that this upcoming new EN measurement system for HPs will somehow invalidate existing installations?

No, I'm not suggesting anything.
This EN regulation isn't new, it's some years old and will be introduced in 10 weeks EU wide.
It's mandatory for all heating systems, not only heat pumps.
DHW in June this year, we'll see about space heating (propably around 2011-12).

heinbloed

http://www.europarl.europa.eu/sides/getDoc.do?pubRef=-//EP//TEXT+TA+P6-TA-2009-0278+0+DOC+XML+V0//EN