oil boiler v geothermal.. need advice urgently

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flashover

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hi folks am truly at the hair pulling stage and need to finalise my heating design with the next few days. i had decided on a vertical bore ground source heat pump with underfloor heating. from following threads here and eleswhere i am seriously questioning my choice.
i have a ber spec compiled along with heat demand etc.
House details 150mm cavity bead filled.
all external walls are drylined with kingspan 38mm boards
i have also installed triple glazed windows, composite U-value of 1.1
house is air tight also and MTD HRV unit installed

so what to install, my good wife wants underfloor through out, however we could put radiators upstairs.

two options
1. condensing oil boiler + solar panels
or
2. geothermal heat pump, air to water or ground source

i am not interested in wood pellet etc, too much labour involved and i dont have the space
my big problem is the cost of geothermal, and if i will ever recover the initial outlay.. second problem is i dont go geothermal whats the best option to work with underfloor heating...
thanks in anticipation
 
My 0.02 as they say, is this: I did a new build in 07, and had the same dilemma. In the end, at that time, I came to the conclusion that the Geo would never pay for itself, and put in condensing gas + solar.

Meanwhile, over the wall from our factory, a new conc built bungalow decided to put in deep bore geo, and they ran into a problem that I never even contemplated - they could not drill satisfatorily, to the depth required, and had issues with the bore collapsing, etc. They spent a full week drilling, and in the end, had to give up: the drilling job cost 9k. So, 9k down.........and still no geo ! They put in condensing oil in the end.

I'm also worried about electricity use & costs: I know there are examples of good installations, but there seem to be a lot more about poor ones.........at the price of these installations, it was a gamble I wasn't prepared to take - YMMV, as they say.......

Your choice of how to heat has no bearing on whether you use UFH or not - UFH will work quite happily of any heat source, so don't let that put you off that.
 

whats your projected heat demand?
 
hi house speced to A3, heating demand 54Kh/M2/per annum

i have heard some horror sttories on the cost of heating a house on oil with under floor heating. should i be safe and put in radiators? we prefer the underfloor option as it future proofs if GT pumps get better
 
Hi,

We have a 2,500 sq ft timber frame house with under floor heating on both floors running with Condensing oil boiler. The total cost for our oil bill last year was 750euro. We also have solar panels for domestic hot water which I think are just brilliant - last year I would have only boosted the hotwater about 12 times in total. Its built to a reasonable level and its south facing. We were considering Using Geo but the inital outlay put us off and I am glad now that we went with oil.
 
Interesting post... on side note be careful with freezer and underfloor heating.. do not run heating under freezer unit ... know someone that did and had major issue
 
chlipps said:
Interesting post... on side note be careful with freezer and underfloor heating.. do not run heating under freezer unit ... know someone that did and had major issue
Click to expand...

can you expand on this what was the issue? thanks.
 

I to was interested in the geo thermal but the initial cost was much too high for me to afford. My neighbour went with it and is very happy.

Redlady, sounds like your solar panals are very good. How much did they cost you overall?
 
I built in 2007/8. Did a lot of reseach at the time and put in geo, underfloor and solar panels. Got grant and lot of help from a guy in SEI that I got talking to.

With the recession I probably would not have the courage to do it now as the total net cost of installation came to nearly 16k - we had to deep bore and put in extra lining in the end.

However its just brilliant - even in the depths of the freeze the house never went off 20 C - a wonderful constant heat. The solar panels drive the hot water and even in the freezing sunny days was getting the water to over 40 C.

We are still spending less than we did in the old house on electricity/oil but it is incomparably more comfortable.
 

54kh/M2 per annum is low,
On saying that, it is over 3 times more heating than say a Passive house.
You havent told use how big your house is.
If it's say 100sqm (it probably bigger Im sure), you could heat it with around 800 Euros a year with electricity from the national grid....or for say 300 Euros with geothermal (given that gethermal gives around 3 units of heat for one unit of electricity consumed). Very rough calculations here.

If I were you, I'd try to increase the spec of the house to more passive levels, and dont bother with oil or geothermal......just use electricity from the national grid, a simple and cheap heating element part of the heat recovery system.
Id invest the money which would have gone into the geothermal system (or oil system) into a better spec of insulation etc. get your annual heat requirement down a bit more. If you do that, it wont make economic sense to have oil or geothermal
 
I have a slight interest in this field as I hope to start building my own house in a few years time.

I was getting my boiler serviced the other day and was chatting to the guy and happened to ask about the current range of oil burners and their efficiency.

He said that the new ones are excellent btw.

I mentioned that a friend had gone the geothermal route for his new build and that it cost €24k after grants were applied. He thought that this was too much and that it would take too long to pay for itself (if it ever did). He commented that this amount would keep you in oil for an awful long time. Plus he knew a guy who has geothermal and his pipes near the surface froze in the recent cold snap and so the geothermal was useless. He also asked me if my friend ever admitted how much his electricity bill had gone up - he says it is expensive to run.

So in summary, when asked, he said if he was building a new house he would put in a new efficient oil burner.
 
house size is 380sqM, this includes office and gym etc, hence larger than normal build. i have increased my insulation spec by including a dry lined 38mm insulation board on all external walls. the heat demand is the worst case senario (no curtains, blinds etc).
reckon now will go with the oil option and future proof the installation if i wish to change over to geothermal. i have also installed a MHRV system.
basically the design is
cond oil boiler
solar panels for DHW
underfloor heating downstairs and radiators upstairs.
still undecided if i put underfloor upstairs.

has ayone ever heard of radiators (low heat) that will work with a geothermal system?

thanks for all the feedback
 
You can use large surface area radiators with heat pumps and there are also aluminium radiators that are suitable for heat pump heating outputs. These are expensive though and in my opinion I would opt for a condensing oil boiler (irish manufacturer) a solid fuel stove with a boiler, solar panels for your hot water. I would install radiators upstairs and a mix of underfloor( tiled areas) and radiators downstairs. Be carefull with underfloor heating as it has to be controlled properly especially with our erratic winter temperatures in this country.
People are being conned into installing rediculously expensive heating equipment and systems in this country when there is simply no need for this kit. Just like everything else that happened during the Tiger years conmen sold heating equipment that was way overpriced will little or no back up or service. Look at all the troublesome pellet burners that are being replaced by home produced oil boilers.
Insulate your house properly and install a efficient/controlled heating system. I'm involved in the Heating and Plumbung industry for over 30 yrs and I've seen so many people spend vast amounts of money on installations that they will never re-coup.
 
Interesting conversation 'fabric insulation and airtighness improvements versus a big heating system' is a no brainer. Build it tight and ventilate with MHRV, then it becomes less important how you heat your house. With 200,000 empty units why build another celtic tiger era substandard house as it will be worth very little in future( site value excepted), build a near passive house, which will still be relevant in ten years time. Insulation and airtightness is cheap when assessed over ten years. Big fancy eco-bling heat pumps are very pricey and inefficient if using Part L 2008 insulation levels. Get a higher spec fabric and then use a cheap oil boiler but have the house plumbed for future renewable technologies such as solar thermal and seasonal storage and wired for use of off grid electricity if you have a good wind resource or solar aspect. It really is reckless to follow the lead of our politicians and use reactionary short term decision making. their some tough times ahead, build a house that will maintain 16 degrees through the cold snaps without any heating system.

Flashover, icomposite drylining board leads to mould growth in the still air spaces behind the phoenic insulation after a number of years. the 150 wide cavities will help, have you eliminated cold bridges as far as possible at rising walls and eaves. Passive spec windows are now only about 15%-20% more expensive than standard double glazing. Good call on the treble glazing. Using AAC block on the inside of rising walls to eliminate the huge heat loss to the ground at the rising wall inner leaf junction is necessary when using underfloor. Your HRV will deliver the heat from downstairs underfloor to upper rooms. Use solid ducts where possible and only use the flexi to connect duct to diffuser.

I'd work out your heatload empirically using the PHPP program. That will help ascertain the exact size of heating and ventilation systems and allow you to work out the investment costs of weach option. In my experience, oil and solar wins out commbined with facility for future renewable upgrade. Surface area to volume ratio is the big factor in determining your heat loss to be compensated from your boiler. PHPP accounts for this much more accurately than DEAP.
 
Thanks for your comments. i have pushed my budget as far as possible on the windows, composite U-Value of 1.1, any better would cost me a further 30k euro. i have alot of glazing... trying to maximise solar gain. should i be worried about the dry lining, siga (spelling, air tightness company/supplier) advised me to go ahead with the dry lining. originally dry lining was not planned due to similar comments you made.... reckon i will go with Oil and solar, although i was going to complete the house in undefloor through out.. thanks for your comments
 
Hi Buildright, why use solid ducts with the HRV?
Im curious because one of the bigger suppliers that Im looking at to supply my own system will only do flexible ducting .
 
Just to add one more opinion......
I built four years ago and went as far as a deposit on a geothermal before I changed my mind! In the end I went with a high efficiency LPG condensing boiler and the evacuated tubes for solar hot water. I believe I made the right choice and agree with the posters that with geothermal there seem to be as many (if not more) bad installations as good and it can vary significantly based on the piece of land i.e. soil type, drainage profile etc.
My final point is to recommend going with UFH upstairs and downstairs, my feeling is if you are committed to UFH (and I do believe its a great option) then don't do the thing by half go the whole way and avoid mixing different systems.
 
just to share my experience and agree with villa. I went for underfloor heating on the say so of a plumber who also fitted. My expierence is what im sure many more had...the plumber blamed the electrician for not wiring the thermastats properly ( old dial ones) and the electrician is adamant that they are wired properly. Eventually it got nasty with the plumber so Im left with a system that I dont know if its working efficiently or not but I can guess the anwser to that one...

BTW, the system was a polypipe one... any one know someone with experience (proper, that is. not that they learned it by handling the pipes at the hardware store) to sort me out. Thanks.
 
can anybody comment on their experience of installing a geothermal system, cost of esb bills etc? Does anybody have an approx cost difference in installation between geothermal and oil ufh. Also at what point in your build do you need to commit to this decision?
 

impossible to compare... many other factors must be considered

a 1.0 litre engine will perform great on the back of a quad but not so well in a tractor....

as to at what point does the decision be made... preferrably before a sod is turned...

there are many competent professionals out there using proper design tools to aid you in these decisions. Passive house designers can tell you specifically how your house will perform from an energy usage basis... you dont actually have to build a passive house to get these calculations done.

other tools such as DEAP (the BER software) are less specific but can be useful for an "overview".....

these decisions no longer have to be a shot in the dark... there are trained educated people out there who can help you make these decisions and their fees would be paid off many times over, over the length of a dwelling and energy costs saved,....
 
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