My geothermal heating system experience

jlptheman

Hi all,

Having done lots of research before installing my heating system I thought Id share my experience for anyone doing the same.

I opted for UFH powered by geothermal for my new build 2600sq ft dormer bunglow and since it was switched on around 70 days ago, the total unit usage is 915 which is around (915*0.16c) 146euros. That includes the first 2 weeks when the heating system was on full blast to dry out the house for the first time.

Since then the house has been at a constant 21 degrees, day and night. Such a pleasant heat, its like you hit an invisible wall of heat when you come in the front door but once in the house, it never feels too warm.

I picked the supplier/installer after doing my research on boards here. I worked with them from day one to ensure that the house was insulated to their standards. This includes 100mm under the downstairs floors, 50mm under the upstairs floors, 50mm dry lining on all exterior walls, 75mm between the rafters (expanding form in any gaping joints), 300mm fibre glass in the voids in the attic space, pumped cavity and windows with u-value of under 1. The screed depth was the other thing that my installer was very specific about, it had to be between 60mm and 75mm IIRC. The heat pump itself is a heliotherm, a Swiss brand I believe.

My house is in the Lifford area in Co. Donegal. The soil is very sandy, almost like gravel in place where the collector pipes situated. The heat pump is inside my house, in the utility room which is close to the center of the house. UFH upstairs and downstairs. I was advised not to use room stats as apparently they shorten the life of the pump. The heatpump calculates how much heat to send out to each room to get everywhere up to the same temp. There is a weather compensation stat on the north facing wall, but thats the only one.

The temperature is consistent day and night throughout every room in the house.

I have hot water 24x7 although there are only 2 of us in the house so its not had too much demand yet. My water temp is set to 38 or 40 degrees I think, you can set it to what ever you want but I find that this is perfect temp for a shower or washing dishes. Any hotter and you would be cooling it down with cold water to use it.

I hope Im not jumping the gun as its only been running just over 2 months and this has been a particularly pleasant winter/spring season but this far I am delighted with the performance of the heating system. Even though the weather has been good, we regularly have to de-ice the car windows in the morning so heating system still has a job to do.

I'd like to thank Brian Cooley for his advice, for answering the phone at all hours to answer my questions during the build and for installing what seems like a great system. A true professional service and a gentleman. Only one hiccup was a slight delay in some of the parts but that was out side of Brian's control.

Feel free to asked any questions, I will answer as best as I can.

Gimli30

Hi

Just wondering could you PM with the supplier details.
As I am trying to determine the price of Geothermal with UFH, before I decide to go with this option.
My insulation will be something similar to yours and It is good to see the actual running cost as I have heard to many negative stories in regards to how much GEO with UFH will cost on electricity.
Looking to build a two story 2380 sf house in Galway, so it would be good to get an idea of the price vs rads and oil etc

Cheers

jlptheman

PM sent

AidanD12

Thanks JLP - good post and just the story I wanted to hear as at the decision stage myself and leaning towards a similar system.
One question though - how do you heat your domestic water? I'm finding it very hard to justify solar but not sure what the options are. I've been reading about heat exchangers and the likes but would like to know what the 'standard' approach is for dhw with geothermal.

brinks_18476

I have a Heliotherm heat pump installed by the same company as OP for around 3 yrs. Very happy with system. Very cost effective. Very happy with service. I spoke to lots of heat pump companies at the time and can honestly say that Brian from Climate Control was the only one who knew what he was talking about. As an engineer myself I could not believe some of the sh* ite I was being told by other companies. I know lots of people with heatpump issues but have only heard positives about Heliotherm and would def recommend the company I have mentioned (i have no association with them other than being a happy customer).

jlptheman

AidanD12 wrote: »

Thanks JLP - good post and just the story I wanted to hear as at the decision stage myself and leaning towards a similar system.
One question though - how do you heat your domestic water? I'm finding it very hard to justify solar but not sure what the options are. I've been reading about heat exchangers and the likes but would like to know what the 'standard' approach is for dhw with geothermal.

Cheers..

My Heliotherm heat pump heats the DHW too, I have no solar or any other form of energy.

I do have a log burner in my open plan living room/kitchen but until now, it has not been needed.

My DHW tank is a huge space-age looking device! I cant find it on their website so I cant tell you what type it is. If I remember I'll look this evening when I get home and post the details.

My personal opinion is that solar is a bit of a waste.. when you need it the most is during the winter and this is when we have least amount of daylight hours in the day. At least with the GSHP, the ground temps are fairly consistent throughout the year so it should be relatively efficient in the depths of winter too. I know very little about solar though so feel free to ignore my opinion!

Most important thing about GSHP though is the installer. Every single piece of the puzzle most be to exact spec and installed correctly otherwise the whole thing will be inefficient. Do your homework before choosing the installer...

tred

jlptheman wrote: »

Hi all,

Having done lots of research before installing my heating system I thought Id share my experience for anyone doing the same.

I opted for UFH powered by geothermal for my new build 2600sq ft dormer bunglow and since it was switched on around 70 days ago, the total unit usage is 915 which is around (915*0.16c) 146euros. That includes the first 2 weeks when the heating system was on full blast to dry out the house for the first time.

Since then the house has been at a constant 21 degrees, day and night. Such a pleasant heat, its like you hit an invisible wall of heat when you come in the front door but once in the house, it never feels too warm.

I picked the supplier/installer after doing my research on boards here. I worked with them from day one to ensure that the house was insulated to their standards. This includes 100mm under the downstairs floors, 50mm under the upstairs floors, 50mm dry lining on all exterior walls, 75mm between the rafters (expanding form in any gaping joints), 300mm fibre glass in the voids in the attic space, pumped cavity and windows with u-value of under 1. The screed depth was the other thing that my installer was very specific about, it had to be between 60mm and 75mm IIRC. The heat pump itself is a heliotherm, a Swiss brand I believe.

My house is in the Lifford area in Co. Donegal. The soil is very sandy, almost like gravel in place where the collector pipes situated. The heat pump is inside my house, in the utility room which is close to the center of the house. UFH upstairs and downstairs. I was advised not to use room stats as apparently they shorten the life of the pump. The heatpump calculates how much heat to send out to each room to get everywhere up to the same temp. There is a weather compensation stat on the north facing wall, but thats the only one.

The temperature is consistent day and night throughout every room in the house.

I have hot water 24x7 although there are only 2 of us in the house so its not had too much demand yet. My water temp is set to 38 or 40 degrees I think, you can set it to what ever you want but I find that this is perfect temp for a shower or washing dishes. Any hotter and you would be cooling it down with cold water to use it.

I hope Im not jumping the gun as its only been running just over 2 months and this has been a particularly pleasant winter/spring season but this far I am delighted with the performance of the heating system. Even though the weather has been good, we regularly have to de-ice the car windows in the morning so heating system still has a job to do.

I'd like to thank Brian Cooley for his advice, for answering the phone at all hours to answer my questions during the build and for installing what seems like a great system. A true professional service and a gentleman. Only one hiccup was a slight delay in some of the parts but that was out side of Brian's control.

Feel free to asked any questions, I will answer as best as I can.

Hi ,great feedback. what was the ballpark cost of this install. Including heatpump, tanks and underfloor and installation costs?. I think its this investment upfront that is still cost prhobitive to a lot of people.

AidanD12

Thanks again JLP,
Pity yourself and the supplier are so far away (I'm down in Cork) as would be good to see it in action and it sounds like they did a very good job. Be good to get ball park prices for comparison.

jlptheman

Ball park prices.. hope this is not against forum rules..

You're looking at around 22000 euro for UFH, HP, DHW tank, Collector and complete installation

Plus - things that I never thought about in advance..
~800 for digger to dig out and back fill the area for the collector pipes (20m x 30m x 1m-2m deep)
~200 for sand for above and below the collector pipes
~1000 for a plumber for the rest of the domestic plumbing

AFAIK - traditional oil burner and radiators for my house would have cost in the region of 10-12,000 euros.

So yes, a big investment up front and given that it was paid for out of my mortgage means that it will have cost about 1.5 times that amount by the time it is all paid back then it is quite expensive but I strongly believe that it was the right heating system for my house.

Hope his helps:cool:

heinbloed

@ the OP:

How much energy did you get out of the HP (kWh) in the period observed?

Does "geothermal" stand for vertical bore holes (real geothermal energy) or surface near ST collectors (geologically stored solar thermal energy)?

The beginning of this year was an "extreme weather", JaFebMa being at least 2 degrees Celsius warmer than average.

Heating degree days here:

http://www.ecad.eu/utils/mapserver/anomaly.php#bottom

(click onto Index "HD17")

Thanks!

PS

Here is an independant data base where HP users can enter their data. It would be great to see some Irish real data!

http://www.waermepumpen-verbrauchsdatenbank.de/index.php?lang=en

jlptheman

tred wrote: »

I think its this investment upfront that is still cost prhobitive to a lot of people.

Yes I agree but you have to be sensible about the whole thing. I built a relatively simple house so that I could afford to install the best heating system and insulation possible while still keeping my mortgage small.

While some people compete in the war of the square footage and most bedrooms, my aim was to build a house that would be very comfortable and very easy to heat. As a result, 600 euros should heat my house and DHW per year and I have no other energy bills. Its almost too good to be true!

I know electricity prices will rise but oil prices will soar and eventually run out. Its time to plan for our futures!

jlptheman

heinbloed wrote: »

@ the OP:

How much energy did you get out of the HP (kWh) in the period observed?

Does "geothermal" stand for vertical bore holes (real geothermal energy) or surface near ST collectors (geologically stored solar thermal energy)?

The beginning of this year was an "extreme weather", JaFebMa being at least 2 degrees Celsius warmer than average.

Heating degree days here:

http://www.ecad.eu/utils/mapserver/anomaly.php#bottom

(click onto Index "HD17")

Thanks!

My system has horizontal collector pipes around 1.5 meters deep.

Yep, I'm well aware of the mild winter/spring seasons hence my statement "I hope Im not jumping the gun as its only been running just over 2 months and this has been a particularly pleasant...." !! All I know is that so far its been very good and more efficient than my brothers house next door which was built at the same time, almost same size (prob 100sqft smaller) and to the same insulation spec but using oil burner and rads instead.

I dont know how much energy the HP produced, I'll check tonight to see if its displayed in one of the menus. All I know is how much electricity that it used as its fed through its own meter.

tred

jlptheman wrote: »

Yes I agree but you have to be sensible about the whole thing. I built a relatively simple house so that I could afford to install the best heating system and insulation possible while still keeping my mortgage small.

While some people compete in the war of the square footage and most bedrooms, my aim was to build a house that would be very comfortable and very easy to heat. As a result, 600 euros should heat my house and DHW per year and I have no other energy bills. Its almost too good to be true!

I know electricity prices will rise but oil prices will soar and eventually run out. Its time to plan for our futures!

I agree 100 percent. logically we should all be aiming for passive standard if possible the more you read. i aint knocking the system sounds fantastic. i just wish the heatpumps were gauranteed for ten years or something......

TPM

Thanks for taking the time to put the information up.
Just one thing I want to emphasise to people reading this and thinking about doing something similar.

One of the major factors in the efficiency of a heating system is the insulation and jlptheman has also put a lot of time and expense into this as well.

jlptheman has researched a lot and followed the supplier recommendations and this is paying off for him too

The Hurricane

Hi jlpthe man,

Good post well done, I also have geothermal since 2007 very efficient system after initial investment and I too researched it well before deciding on investment.

Just two things your working out you ESB consumption at day rate dont you have a night meter its only 8 cent approx at night ? I have a night meter and my heat pump runs 90% at night.

Also on heating the water Im not certain but if its a closed system I think you may need to heat water to 55 or even 60 degrees to prevent Legionaires disease ? Apparently some typer of bacteria can be in water if not geated to certain temperature. Again not sure but ask your plumber.

Cheers

jlptheman

The Hurricane wrote: »

Hi jlpthe man,

Good post well done, I also have geothermal since 2007 very efficient system after initial investment and I too researched it well before deciding on investment.

Just two things your working out you ESB consumption at day rate dont you have a night meter its only 8 cent approx at night ? I have a night meter and my heat pump runs 90% at night.

Also on heating the water Im not certain but if its a closed system I think you may need to heat water to 55 or even 60 degrees to prevent Legionaires disease ? Apparently some typer of bacteria can be in water if not geated to certain temperature. Again not sure but ask your plumber.

Cheers

I dont have a digital meter yet so I'm on flat rate ESB. I was going to leave it a while to see how the bills work out as I wasnt sure when the heat pump would run most. I figured that even if it runs 50/50 night and day then the appliances and tvs etc that I use during the day during the higher rates might offset the difference.

Is there a way to find out when the HP is using power the most?

Yeah I've heard about legionaries disease but there's something about my DHW tank that means its safe to use at any temp. I forgot to check what type it is, I'll try to get a look tonight.

jlptheman

I cant find exact details on my DHW tank. Its a latento and looks something like the one in this document but has nothing to do with Solar: http://power-options.fortro.com/assets/400/Latento4S2008EN.pdf

I cant determine how much energy the HP has produced since it was switch on, if any knows how to do that let me know and I will check

heinbloed

The OP wrote:

I cant determine how much energy the HP has produced since it was switch on, if any knows how to do that let me know and I will check

You'll find this in the manual - if a caloriemeter had been installed at all.

What exact make and type is the HP, what manufacturing date ? We could check then further via the www. on instructions how to read the delivered energy, if possible.

jlptheman

This is the HP - not sure of exact model.

http://www.heliotherm.de/asp_service/upload/content/ground-source-heat-pump-with-surface-collector%281%29.pdf

I see in the manual there should be a menu item called Efficiency, which seems to hold this information but the menu item is not available on my HP. So I assume that either it has been disabled/hidden from me, or that the supporting hardware was not installed.

I'll contact my installer for more info.

brinks_18476

jlptheman wrote: »

The Hurricane wrote: »

Hi jlpthe man,

Good post well done, I also have geothermal since 2007 very efficient system after initial investment and I too researched it well before deciding on investment.

Just two things your working out you ESB consumption at day rate dont you have a night meter its only 8 cent approx at night ? I have a night meter and my heat pump runs 90% at night.

Also on heating the water Im not certain but if its a closed system I think you may need to heat water to 55 or even 60 degrees to prevent Legionaires disease ? Apparently some typer of bacteria can be in water if not geated to certain temperature. Again not sure but ask your plumber.

Cheers

I dont have a digital meter yet so I'm on flat rate ESB. I was going to leave it a while to see how the bills work out as I wasnt sure when the heat pump would run most. I figured that even if it runs 50/50 night and day then the appliances and tvs etc that I use during the day during the higher rates might offset the difference.

Is there a way to find out when the HP is using power the most?

Yeah I've heard about legionaries disease but there's something about my DHW tank that means its safe to use at any temp. I forgot to check what type it is, I'll try to get a look tonight.

My Heliotherm water tank (and yours i guess) are "fresh water" systems. Water is heated via a heat transfer system. The water in the c900L holding tank is heated to 40-50 degrees C. "Fresh" cold water from mains or holding tank passes through the heat exchanger to get heated. It never contacts the hot water in the holding tank.

Normal hot water tanks have to be heated above a certain temp 60 degrees or something to kill bacteria eg Legionaries etc as the water from inside normal tanks contacts us humans when we use it. But with the heliotherm heat exchanger ghe "fresh" water never contacts the heated water as a heat exchanger is used. With a very efficient heat exchanger this allows water to be heated in the tank to a lower temperature of 40-50 degrees C which is cheaper than trying to heat a masd of water to 60 degrees +. Normal shower temp is 35-38 so it plenty hot and also prevents young and or stupid scoulding themselves.

This is my interpretation of my system.

jimmytom

JLP i would be grateful if you could pm me details of your system. I am about to start blocklaying a 230sqm house in galway. V interested in geothermal. hard decision with all the options out there. i am considering underfloor downstairs with rads upstairs. I take it that back up oil system will be needed for rads. Again info on your system would be most appreciated. I am also installin a stove with back boiler so that may be an option to provide heat for my upstairs rooms

jlptheman

jimmytom wrote: »

JLP i would be grateful if you could pm me details of your system. I am about to start blocklaying a 230sqm house in galway. V interested in geothermal. hard decision with all the options out there. i am considering underfloor downstairs with rads upstairs. I take it that back up oil system will be needed for rads. Again info on your system would be most appreciated. I am also installin a stove with back boiler so that may be an option to provide heat for my upstairs rooms

Hey,

Let me know what details you would like and I'll happily provide you with what I can.

In my (non-professional) opinion, rads up stairs would not be the best option due to the fact (like you mentioned) that you would need a second heat source to heat them.

As you already know, Geothermal is a low temperature heat source and while I believe it is capable of heating up to 60 degrees Celsius, it is very inefficient at doing so.

I have a log burning stove installed and was interested in putting in a back boiler to aid the geothermal in some way. When I asked my installer about this he simply said don't bother. While it is possible to plumb the back boiler through a buffer tank which in turn could relieve the HP when the fire is lit, the cost of the install far outweighs the benefits. My installer also told me that I would not need it and I have to say, thus far he was right.

I was raised in a house where an open fire provided all the heating in the house and thought that I'd have the fire lit every day when I moved into my own house. The truth is, the house is never cold enough to make it worth while lighting the fire. I tend to light it on a Saturday night if myself and the missus are in for the night but its only for show and the window usually gets opened a little to keep the heat comfortable.

If I was you, I would count up how much you would spend on oil burner and back boiler and put that extra money towards good windows and/or insulation. My windows have 4 panes of glass - 2 outer and 2 inner and filled with Argon gas in the middle. Due to various coatings, they apparently allow heat in but prevent it from escaping.. and so on. The key with windows is U-Value, the lower the better and total U-Value of less than one is required/preferred for Geothermal to work properly.

My point is, make sure your insulation is up to scratch and Geothermal by itself should be more than sufficient.

illionman

AidanD12 wrote: »

Thanks JLP - good post and just the story I wanted to hear as at the decision stage myself and leaning towards a similar system.
One question though - how do you heat your domestic water? I'm finding it very hard to justify solar but not sure what the options are. I've been reading about heat exchangers and the likes but would like to know what the 'standard' approach is for dhw with geothermal.

Hi

I have a Geothermal Heat Pump providing underfloor heating and DHW from a different company also in Donegal. House approx. 3300sq.ft. UFH is excellent, however, DHW is not - very expensive. I find my ESB bills are higher in summer when we have a lot of people staying and are using water for showers etc. This summer I intend fitting an electricity meter and a flow meter to calculate a cost per litre of hot water. I have a 300 litre tank that is heated to 55 degrees. The cold water suply is passed through a heat exchanger and is heated by the water in the tank. Suply is very good - can provide hot water to 3 power showers at the same time (obviously not for a very long time) but I find it expensive. I would consider an alternative for DHW if I was doing it again.

jlptheman

illionman wrote: »

Hi

I have a Geothermal Heat Pump providing underfloor heating and DHW from a different company also in Donegal. House approx. 3300sq.ft. UFH is excellent, however, DHW is not - very expensive. I find my ESB bills are higher in summer when we have a lot of people staying and are using water for showers etc. This summer I intend fitting an electricity meter and a flow meter to calculate a cost per litre of hot water. I have a 300 litre tank that is heated to 55 degrees. The cold water suply is passed through a heat exchanger and is heated by the water in the tank. Suply is very good - can provide hot water to 3 power showers at the same time (obviously not for a very long time) but I find it expensive. I would consider an alternative for DHW if I was doing it again.

Hey,

This is kinda falls in line with what I mentioned previously - as a low temperature heat source, geothermal is not very efficient at heating water to above 40 degrees, let alone 60 degrees.

The new "fresh water" DHW tank (sorry I dont know the correct name for this) means that the water is only heated to around 40 degrees (38 in my case). I have a 500 litre tank and so far it seems very inexpensive to run ( only 2 adults in the house though).

Perhaps you should consider upgrading your DHW? Mine is a Latento.

illionman

jlptheman wrote: »

Hey,

This is kinda falls in line with what I mentioned previously - as a low temperature heat source, geothermal is not very efficient at heating water to above 40 degrees, let alone 60 degrees.

The new "fresh water" DHW tank (sorry I dont know the correct name for this) means that the water is only heated to around 40 degrees (38 in my case). I have a 500 litre tank and so far it seems very inexpensive to run ( only 2 adults in the house though).

Perhaps you should consider upgrading your DHW? Mine is a Latento.

At what temperature does your heat pump come on at to heat the tank back up to 38 or 40 degrees? Mine comes on at 45 degrees and brings the temp up to 55 degrees. If you start to run a bath and the water is at less than 38 degrees will it still be hot enough when the bath is full. Do you run showers from this suply?

jlptheman

I was slightly wrong on the figures I wrote previously.

My DHW target temperature is 43 degress. I've seen it dip as low as 36, so I assume this is around the temp that the HP will fire up again.

Mine is a 500 litre tank. I often take 15min showers and have not yet noticed the water getting colder, never mind getting cold altogether. On several occasions I have had a 10 min shower straight after the woman had a 10 min shower and still no problem. Thats about the biggest test I've given it yet.

I don't have my bath plumbed yet..

TPM

The main problem with hot water from heat pumps is that the temperature is usually 45oC or less, this means that in general when hot water is used it isnt mixed with cold water which means you require very large storage and or very high recovery.
Another thing I noticed was in relation to filling baths. This is almost an art form Because the low temperature of the water you dont really have the ability to "heat up" the bath if you let in too much cold water.

My heat pump is a SWECO system which heats the hot water through a coil in the buffer tank one characteristic of this system is that when using relative volumes of water the higher the flow the lower the water temperature

heinbloed

@ the OP:

Did you find out which heat pump you are using and how much energy it did produce ?

Thanks.

jlptheman

TPM wrote: »

The main problem with hot water from heat pumps is that the temperature is usually 45oC or less, this means that in general when hot water is used it isnt mixed with cold water which means you require very large storage and or very high recovery.
Another thing I noticed was in relation to filling baths. This is almost an art form Because the low temperature of the water you dont really have the ability to "heat up" the bath if you let in too much cold water.

My heat pump is a SWECO system which heats the hot water through a coil in the buffer tank one characteristic of this system is that when using relative volumes of water the higher the flow the lower the water temperature

Hey good point about filling baths, this is an "art" that I'll have to learn at some point

jlptheman

heinbloed wrote: »

@ the OP:

Did you find out which heat pump you are using and how much energy it did produce ?

Thanks.

Hey,

Im quite busy organizing my wedding at the moment (5weeks to go :eek:) so never got around to contacting installer about this.

I promise I will though, for the sake of anyone keeping an eye on this thread and thinking about geo.

One small update on usage, the total unit usage as of today is 1109. If you compare to my original post made around 3 weeks ago (915) then you'll note that it has used around 200 units since, which as far as I know is around 32 euros (not using night rate electricity yet)

To some that might not sound that cheap but given around 2600 sq/ft bungalow that is same temp 24x7 with constant hot water, I think its a bargain :cool:

mrsloftus

Hi jlptheman, thanks for such a detailed and informative thread. Our build is very similar to yours, although the u-value of our windows won't be a match for yours. Could you pm the details for your installer as we are looking for quotations at the moment for a geothermal,UFH system.. Thanks..