Geo Theromal Heating

Direct geothermal energy is generally only any use if you've found a particualr 'hot spot'

Far more common is to use a heat pump arrangement with the underground elelemnt acting as a heat sink in summer and a heat source in winter. Again this is largely associated with underfloor heating as there are synergies between both systems ie using large amounts of moderate temperature water.

Originally posted by yop
Daveg - Have a look at the site lad, all the info is there. You need the same sq footage as ur house if u use the coil system for the capture area.

This will depend slight on the aspect of your house - a south facing slope will do better than a north facing one.

mmm - interesting topic - but i just scanned it so forgive me if i've missed something - just delivering my experiences in case they're of any benefit to anyone


i just moved in last night to my new house which is heated by a ground source heat pump. first off i can advise is that ( in my case anyway ) - it works .. however the underfloor heating part of the system takes a bit of tweaking to get the temperature to where you're comfortable with it --- at least i've heard this from friends with it too

the company i went with was ecoheat from carlow - colum lawlor is the boss and his number is 087 2568791. the system was sort of expensive 18k plus installation for a house of about 2300 sqft. but that included underfloor heating and a pretty imressive hot water system too. that was one of the reasons we went with them is that they were the only company which addressed the issue of hot water properly. heat pumps dont get really hot, so they can only heat water to a certain temperature. put that together with a standard size cylinder and a large bath and a deluge shower and you've got a problem, especially if you have a big family or lots of people wanting showers at the same time - so we spent about 4k extra on this 500L insulated hot water cylinder with it's own special heat pump which can heat the water to 55deg cent -- some of the other systems were actually relying on an imersion ( which is not the kind of house we wanted to live in ) -- plus we get hot water 24 7 even during the summer ( i know it's a bit of a luxury but what the heck !! ) - oh and seing as the cylinder is pressurisable we put a pump on it an pressurised the plumbing too - no need for shower pumps

our heat pump is situated outside and ive heard some companies have pretty loud pumps which are situated in the utility room


i would advise ecoheat - they spend ages with you answering your questions etc which is good in this new area - also one of the directors, fritz has been working with heat pumps for many years in austria

in our system there are no room controllers, you set the temp using the manifold manually. some other companies make a big deal about being able to set all the rooms to special temperatures - i think it's not really necessary - i mean i dont care whether my hall is exactly 2 degrees colder than my kitchen !!

also on our system we have night rate electricity - and the system is set to a lower then required temp during the day and a higher than required at night so the system generally draws power on cheap rate

if i were doing the system diy the one area to NOT mess up is the heat loss calculations -- if you get these wrong you are screwed as you may have to take up your collectors and replace them or something nasty like that - we got an 18 kw system btw ( which can handle a bit of an extension i think )



hope this has been of some benefit to someone - pm me if you need any info

ps i cant understand ---- is the govt asleep?? - why on earth is there no grant for this stuff --- and how much was that fine we had to pay to kyoto last year ?????? ........... a bit irish

does that include the presurrised cylinder (Is it a thermal store)???

yes that includes the pressurised cylinder - but it's not a buffer tank or anything - ie it's part of the hot water system and it doesnt share energy with the heating system - there's no real need for a thermal store as i am on nightrate electricity and i am not using solar/ wind or anyting - so it just heats up the slab and the hot water tank in the night time and i have the heat during the day - but it can also come on at daytime if it gets cold

Are you sure it is an 18kw heat pump, I have got in roughly 10 quotes for a 2100sq ft house and the max pump they recommend is 12kw.

pretty sure yea !!! - it was a size too big for the house but the company says its better to go a little too big so you have room to expand, etc. however the plumber who put the system in ( who is not really connected to the heating company ) said that he just worked on a house where the heat pump recomended was too small - so it can happen - i would at least give ecoheat a shot at a quote - they have a completely different approach to all the others - imo the more aspect/perspective you can get on a job like this the better !!!

What sort of electric bill are you running?

dont know yet -- but be warned power bills for underfloor heating are massive for the first three months while the slab heats up and dries out

How long does it run for at nite?

not sure yet - too much other stuff on my mind

Does it mean you have constant heat in the UFH and hot water on demand?

well having ufh more or less implies constant heat anyway afaik - even if it's on a trad boiler - that's the way the systems are designed to operate - so the heat pump doesnt change this afaik
-- yes 24 7 hot water !!!

I presume it is a brine system you have in?

i dont think so !!! why would it be - you mean in the ufh - ?? - no the pipes are filled with regular water

Anybody know if it's possible to mix geothermal and wood pellet systems (as a kind of back up/supplement to the geo) or am I going for overkill?

first off i'd say imo it's a tiny bit overkill - but then it's your house so do it your way - on my system i know there is a facility for a backup boiler but a regular oil boiler would probably do as you will hardly ever need to use it - i mean it's not like the geothermal will not get enough heat or anything - however it's worth remembering that geothermal runs on esb so if the power goes for a few days you could be screwed unless you have a generator ( i invested in one myself - buy and sell 400 for a 5.5kva and then i got the electrician to install a transfer switch ) - which i suppose could be a little overkill in itself .... in general though i would be thinking more in terms of a backup system than a suppmental system - unless you go for solar/wind in which case i think you need a buffer tank to work it properly - and when i investigated that it was pretty costly
also the hot water cylinder which i got has a few spare coils which mean that i could potentially suplement the domestic hot water heating using solar/wind/backboiler or whatever ---that could save on the esb

I think you can go for a dual coil buffer tank with some systems, one coil supplying heat from the geothermal and the other coil supplying heat from the open fire with back boiler, stove with boiler, oil boiler, gas boiler, etc.

yes it would make sense that if you had a buffer tank for the ufh you would be able to have a couple of coils in it which means that you can store heat from whatever heat source is available at the time - ie solar/wind/back boiler - so solar when it's sunny, wind when it's windy, back boiler when you've got the fire lit -- but it makes no sense to me to have an oil boiler connected to a buffer tank as it's always the same - ie you can turn it on at anytime an so there's no need to store the heat for later when you need it - the only real place an oil boiler has with a heat pump is in a backup scenario as the two do basically the same thing and if you are running a backup system then there's no need for a buffer tank as that's more for supplemental - you could however have a heat pump running an oil boiler as a backup and then having a buffer tank for use with solar/wind/bboiler but that could get really expensive

---

myself i have the generator as backup in case the power goes down and i MIGHT get a buffer tank in the future for use with a wind gen but afaik those things take about 14 years to pay for themselves

ps all this reminds me that dedicated cylinders are huge - and buffer tanks are even bigger and you really need to incorporate a suitable space for them aswell as all the rest of the plant - hot press just wont do- except it's a cool place for the ufh manifold --- also if you stick it on the end of a bungalow as i did then you'll have to wait a full minute for the water to come hot in the tap !! dont say you werent warned !!!

The argument some companies have is that if you have your large thermal store or buffer tank is that there is store of water built up over night and you use it away, I presume you have the same idea, did you say you paid 4k for the cylinder???

the store of water i have built up overnight is not for use with the heating system but the domestic hot water - there is no connection - i dont have a buffer tank at all - other than the fact that the cylinder is it's own buffer tank !! of course the slab is in a way it;s own buffer too in that it gets heated on night rate electicity and then stores it - buffers really only come into their own with wind/solar - saw a house in austria which depended enirely on a combination of solar and a buffer system - no other heating - on duncan's program last year i think

yes i paid about 4k for it ( i think it might have been a bit less ) - can get the exact figure if you want --
it is not just a pressurised cylinder, but it has it's own dedicated heat pump backup immersion and also is really well insulated, along with having about 3 spare coils for solar etc

this is the main heat pump and the cylinder is a bit like this


we are in kilkenny - we got about 4 quotes i think

in case you're interested in the system we used then i see you're in mayo but i dont think it would make a lot of difference to the price to be honest because they just explain in detail to local trades how to fit the thing and then they drive up and commission it

I wonder how possible it would be to primarily run off solar and have the ESB connection as back up... and how practical would it be? Maybe I would need the wood pellets as a back up too...

yes as i mentioned earlier in the post there was a guy on that program with a house in austria which ran entirely from solar - but he had something like a 200hectolitre tank surrounded by about a metre of insulation and he had a custom built computer control system for managing his store of heat - then he had some special design in the house which maximized passive solar heating too - however i think what you need is a cut down version of the same thing - get as big a buffer as you can and as much solar panels as you and then get maybe the wool pellet boiler as a supplemental / backup ( in that you can turn it on when you need it ) and you should be sorted

it all really boils down to payback time -- i mean you can easily get free energy if you really want it but it might never pay for itself - heat pumps and wood pellet boilers i think are a better bet than wind power - not sure about solar but it's useless for heating unless you've got a buffer and i think buffers start at about 7 grand ( could be wrong here - but if you think about it they have got to be humungous to get the desired effect )

Anyone know the electricity needed to power a pump like that (like KWh per year etc), and whether wind/solar/both will do the job most of the time with ESB power there as back up.

i think in our case the system takes 3.3kva -- which would mean that for instance if you had a petrol generator or something like that ( i know you wouldnt but just for ilustrative purposes) then you would need a 3.3kva generator for the heating alone

please double check that figure it is only from memory and i was never 100% sure of it anyway

oh and i think the esb provide you with a 12kva supply for a domestic house




the trouble with alternative sources of power like wind and solar is that they are not there all the time -- which means that you need to store them - which from an ufh point of view means that you either need in the case of wind power to get a battery bank and an inverter ( very expensive ) or in either case you can use what i think is called a buffer tank - also very expensive and very large ( though i think your domestic hot water cylinder can be incorporated into it also which saves a bit of space )
next problem is that with the battery/inverter setup the batteries will only last so long before you have to replace them - and they are the most expensive bit --- it all comes down to payback time and afaik the payback time on these systems is just too long ( it could be 10 - 15 years ) with very little other benefits

-- this seems to be one of the major benefits of the windsave system in that you dont have to worry about storage as the electricity is used straight away - having read about these in the last day or two i am not considering the notion that as heat pump houses would have a normally high esb bill that they could benefit from more than one of these devices - any comments anyone ???

wind/solar/both will do the job most of the time with ESB power there as back up

this is the idea i originaly toyed with but i gave up on it because of the high cost of storage -- you should have a look into the windsave yourself as it seems a better idea than a standard turbine

solar - an ideal use of solar is to heat your hot water --- i think you can get 60% of your hot water free from the sun or something like that - i plan on investing at some stage myself

Have 4 showers - do I need to go the "Bob" route in terms of hot water - hoping not?? If I don't go down Bob's route - what options do I have for hot water outside of immersion??

im offended -- no just kidding !!!


afaik the only real options are:
1 - use main hp to heat dom hw - ( prob is main hp comes on during summer and water may not be that hot so supplement with immersion and/or use a large ( HUGE) cylinder - or else put up with only one bath/shower at a time as cylinder will have to fill and heat again - ok for small occupancy )

2 have a secondary heat pump - this is what i did - pretty expensive but obviously i thought it was worth it - 24 7 365 cheapish hot water / pressurised system - no need for shower pumps - main heat pump doesn't come on if not needed

3 supplement either 1 or 2 using solar/wind/back boiler --- starting to get a bit expensive again i think but you might manage free hot water - in fact this is what i'm aiming at

4 same as 3 but have the primary emphasis on the solar/wind etc power

5 immersion only - argghh

6 cooker or something like a range heating the hot water

there are many other ways of heating your water but these seem like the most likely ones to me - it basicaly comes down to having either one or 2 heat pumps and either supplimenting that or not with wind/solar etc or else relying primarily on wind/solar and use an immersion for backup


i think this covers it but i'm open to suggestions and corrections

Can I integrate a solid fuel option with UFH and hot water even when using geo thermal??

not sure about the ufh ( you might need to have some kind of a buffer or something where the hp heat and solid fuel heat can mix ) -- but you can certainly do it with reguard to the hot water anyway i think because all you need is to have an extra coil on your cylinder and put the solid fuel heat through one and whatever you're using to heat the water through the other ( get lots of spare coils is my advice - you never know when you''ll want them)

UFH on both floors

pitstop i did ufh upstairs on my house and i did the concrete screed method upstairs ( you can use the battens method either ) -- well just to say that it was a great decision - i dont think it was a large expense and the floor upstaris is very solid with minimal floor/ceiling noise too - everyone comments on it

another thing i think you should do is to put insulation between the floors - this is not normally done but it gives you a better chance of containing downstairs heat downstairs because all that heat downstairs can make upstairs pretty hot and you might not like it that way

I presume when the mains is not on the windsave doesn't provide your power.

i would say you are correct -- the windsave system needs to put it's ac output in phase with the house's , so it presumably copies it - and if the house has none then i would think it might not have anything to copy so it wouldnt surprise me if it just stopped - also it would not be safe to provide the power to the house though the ring main - i mean if someone turned on the hob ,oven and drier or something toghter then the ring main would be under serious pressure to cope --

personally i have a small backup generator powering the house via a transfer switch in case of powercut but i would imaging that the windsave would reference against that and it would take some of the load off the generator and give me a bit more headroom in terms of what i could turn on if the esb power was off-