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Does it make sense to install geothermal these days?

  • 04-11-2022 3:11pm
    Registered Users Posts: 753 ✭✭✭

    Curious what the views of the brain trust might be on this please.

    Moved into a new house over the summer, currently has a kerosene boiler. BER B2 which I'll be working on by improving airtightness, new windows, MVHR, cavity wall filled, more attic insulation etc.

    I would love to put in a heatpump to get off fossil fuels and am weighing geothermal vs. air source. The soil in the area is apparently very suitable for geothermal and we have space around the house to put in the horizontal loops. However with air source heatpumps getting better and better, prices coming down and so many being installed that I imagine there will be lots of knowledge to support them in the coming years, I wonder if geothermal might be a mistake? The sense I get from reading forums like this is that there isn't a great knowledge on how to spec, install and maintain geothermal.

    Perhaps it is better to go air source which will be much cheaper, potentially allowing me replace it again when they get even better in a decade or two for similar cost to ground source.


  • Registered Users Posts: 2,365 ✭✭✭ECO_Mental

    I think you are right the ASAP will be good enough and there isn't too much difference in efficiency between the two. I had the same dilemma when building a year or two ago and went with ASAP.

    While you think you might have the space don't forget your percolation area if you need one and then you can only put grass on it afterwards. You could get a borehole but then again while you might think you might only have to drill 100ft you could end up going 200ft...and it gets expensive real fast

    6.1kWp south facing, South of Cork City

  • Registered Users Posts: 1,484 ✭✭✭poker--addict

    Moved into a house with geo last year.

    To my knowledge geothermal remains more efficent despite Air getting better? However that needs to be balanced with the upfront capital required for geo. Have you had quotes to compare yet? How many years would it take to recoup the difference?

    I have had heating issues, with huge bills, however I’m not sure it is relevant whether the source is air or ground in terms of trouble- I have read about lots of trouble but almost none of it relates to the source. Problems tend to be in the pump itself or the wider system installation. As such I think it is largely a spreadsheet decision in terms of ROI comparison.

    I have an interesting dilemma in terms of replacement; air or continue with ground, given I have little knowledge of what the ground loop’s condition, depth, or length is. Safe bet is to go air, but then a shame to not use an already installed loop. Good old sunk cost theory dilemma.

    This used to be a referral link 😎

  • Registered Users Posts: 11,850 ✭✭✭✭KCross

    Ground source will always be better than air source purely in technology terms. If air source is getting more efficient then ground source is as well.

    Whether the capital cost difference is worth it, is another thing entirely.

    In terms of knowledge and support, there should be no issue with ground source. They are fundamentally the same technology (compressor etc). Ground source just have pipes under the ground and a circulating pump whereas air source has an external unit sitting outside in the air.

    If anything, ground source is easier to maintain as pipes under the ground don’t need maintaining as long as it’s done right.

    My view is buy right and buy once. You need to get quotes for both systems and then factor in lifespan, maintenance and running costs and decide from there.

    Lastly, go with a company that has a long standing position in the market and get references from customers. Don’t necessarily go with the cheapest.

    Too many stories of people being left with a cheap unit and the install company gone bust and then they are staring down the barrel of a complete replacement. Buy quality regardless of GSHP or ASHP.

  • Registered Users Posts: 11,850 ✭✭✭✭KCross

    I have an interesting dilemma in terms of replacement; air or continue with ground, given I have little knowledge of what the ground loop’s condition, depth, or length is. Safe bet is to go air, but then a shame to not use an already installed loop.

    If you have the collector already and it’s in working order it would be mad to ditch that. Should be easy enough for an installer to test the collector and determine if it’s holding pressure and adequate length etc.

    The extra cost for GSHP is the collector.

    Since you have that already the difference in cost for the actual HP should be small particularly when you spread it over its lifespan.

    In terms of your heating bills, an assessment of the whole system needs to be done. Could be anything…. bad config, inadequate collector, compressor struggling, zones, stats, ufh, etc.

    Get a good installer out that does both GSHP and ASHP and get them to assess the whole system so you know where you stand, then decide based on a quote for each.

    I would lean to GSHP, particularly since you have the collector already.