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Urgent- which heating system?

  • 07-11-2021 8:41am
    Registered Users Posts: 67 ✭✭

    Currently have no heating and need to make a decision... my house is 3200 sq feet and was built in 2007. It has underfloor upstairs and downstairs and doube glazed windows. My BER is a B2 with a Heat loss indicator of 1.85.

    I have been quoted for a Thermia 16kW iTec Eco Air to Water Heat Pump.

    I'm also considering a condenser oil boiler.

    Just can't decide what is the best route. I will have a high outlay with heat pump (around 10,000 incl. Grant) ,unknown electricity bills and then then to factor in annual service.

    On the other hand the price of oil is going up and will my underfloor guzzle oil?

    How do I decide? Any advice or experiences welcome. Thanks in advance!

    Post edited by niteowl1 on


  • Registered Users Posts: 9,757 ✭✭✭antoinolachtnai

    What did you have before? How much energy did you per year to run it?

    are you in an inland county or near the coast?

    maintenance on the heat pump? Maintenance on the oil boiler would be more significant I would have thought.

    what are your expectations in terms of heat delivery? Do you want to be able to heat up the house quickly?

    does your heat pump provider experienced and come well recommended?

    You really need to go through all this with the heat pump people and see if it is suitable. If it were me I would go the heat pump way but it all depends on the factors above and maybe other factors specific to your house.

  • Moderators, Home & Garden Moderators Posts: 5,467 Mod ✭✭✭✭graememk

    No experience with them but have been looking into them lately, like to know options so I'm not rushed into something.

    Do you know how much oil is being used per year? Or is this house new to you? You are in a good position with a heatpump, with UFH everywhere.

    I done some napkin math for a high temp heat pump for rads (lowish COP) on another thread : but with UFH you should easily reach a COP of 4-5 (increasing the savings)

    The condensing boilers can hit 97%+ when they are run at a "low" water temperature too, but has to be sized accordingly.

  • Registered Users Posts: 10,356 ✭✭✭✭the_amazing_raisin

    I've an air source heat pump with radiators and it works fine. Our house is around half the size of yours and is A3 or A2 rated. We've a 6kW Dimplex and it does the job

    The main thing to get used to with heat pumps is they don't really heat up very quickly, so it's best to leave the heating and hot water on a setpoint and rely on the thermostats to control your heating

    In terms of brands, do your research and ensure whatever brand you go with has decent support and experience in the field. Personally I'd only go with fitters who are officially certified by the brand

    One handy aspect of an air source heat pump is that if you get solar panels your can get cheap hot water or heating in summer, you can't do that with oil

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Registered Users Posts: 67 ✭✭niteowl1

    I have geothermal up until now. A disaster from Day 1 but that's another story!! I am not prepared to spend any more money on it now. I use about 12,500 kWh per year, that would be for both heating and general household usage. About 55-60% at day rate and 40-45% at night rate. I'm inland in Co. Limerick

    The reason I mentioned maintenance of heat pump is that I've heard that it costs about €150 per year to service them but maybe that is incorrect?

    I am used to heat from geothermal so am aware that heat from heat pump with ufh is not instant. That's no problem.

    Yes air to water provider is very experienced and highly recommended.

    I'm afraid of more faults and breakdowns, high bills and a few people are saying that I won't make my money back as the compressor can go from 10 years on...

  • Registered Users Posts: 67 ✭✭niteowl1

    No oil. I had geothermal up to now. Used about 12,500 kWh per year for heating and all general household usage

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  • Moderators, Home & Garden Moderators Posts: 5,467 Mod ✭✭✭✭graememk

    You're supposed to get the oil burner serviced every year too so I'd say that point is moot.

    As your moving from a heat pump to a heat pump. Ground source is supposed to be more efficient but as your having issues.. I can see why your going to an air to water system.

    Say 5000 kwh for house hold usage. Thats 7000kwh of electricity used for heat. Lets say an average COP of 3, that's 21,000 kwh of heat put into the house.

    10Kwh/litre of oil, and assume 90% efficiency that's roughly 2300L of oil. Which is currently about 85c. that's 2k a year on oil.

    7000kwh at 20c (tbh a bit high for electricity) is 1400. Suppose that would answer your oil question. The install of oil isn't just the burner, its also the oil tank too to bear in mind.

  • Registered Users Posts: 11,997 ✭✭✭✭KCross

    I'm a little confused by your posts.

    You have a Ground source heat pump which is/has been giving trouble and you need to change it out for something else. You're considering an air to water heat pump? Is that it?

    If yes, the bit that confuses me is that the underlying technology in a heat pump regardless of whether it is air to water or ground source is the same.... a compressor running to transfer heat from an external source to the inside of your house. If you dont like the ground source heat pump then dont go for air to water as that is inferior on a few levels.

    What issues exactly have you had with the ground source? I think thats important here to understand what your best route is. Were the problems with the heat pump itself or did you also have issues with the collector outside? Is the UFH heating working ok (stats, pipework etc)?

    If the collector is giving trouble (e.g. leaking fluid) then I could maybe understand walking away from that then as that would require digging your lawn to fix it but if the issues are all internal and you decide on the heat pump route I would definitely continue with using your external collector (i.e. get a ground source HP) and not air to water. Ground source will be cheaper to run as its more efficient, last longer as it will be running less, less noisy (no external fan), less maintenace.

    If your issues were related to the UFH, stats, pipework etc then those issues will continue to exist regardless of what system you use to drive the heat into the house.

    TL;DR... assuming your plumbing, UFH and collector are working and spec'd correctly I would stick with ground source as you have the hard work done already since you have the collector already in place.

  • Registered Users Posts: 67 ✭✭niteowl1

    Sorry about the confusion. Yes I'm considering moving from geothermal to air to water or oil.

    We have had lots of problems with our geothermal. High pressure faults in the beginning , then very regular low pressure faults, turned off hot water due to very high bills, leaks, low anti-freeze levels, no heating during really cold spells

    But the main issue is that an engineer has told recently that the collector area is half the size that it should be!!! The ground source heat pump is now 14 years old so I've decided to not spend anymore money on a system that has given us nothing but grief and problems.

  • Registered Users Posts: 67 ✭✭niteowl1

    And I should have said...the ufh, stats & pipework all seems to be fine

  • Registered Users Posts: 3,408 ✭✭✭John.G

    Purely on cost saving, assuming energy demand at 25,000kwh/annum, oil at 84c/litre, combined elec day&night rates 18.5c/kwh, and (the big one) a Heat pump SPF (seasonal performance factor) of 2.5 (and assuming oil fired boiler efficiency of 90%) then the savings are €438/annum and with a Heat Pump SPF of 3.0, €746/annum, these "savings" can only improve as taxation on kerosene increases. You already have the UFH etc in place, you might ask the HP supplier about defrosting method and hot water production method.

    The defrosting can impact severely on the SPF as Irish humidity/outside temperatures can result in a big demand for it, so its important that its done properly, the geothermal didn't suffer from this problem.

    Post edited by John.G on

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  • Registered Users Posts: 11,997 ✭✭✭✭KCross

    The biggest issue in there is "the collector area is half the size that it should be". If thats true then the only solutions are double its size which is a dig the lawn job or do as you are considering which is to abandon the collector and switch to something else.

    Air to water is fine if done right. Getting a recommended and reputable installer is clearly the key here. Go look at some of the installers existing customers. See the unit, hear the fans, feel the heat in the house, ask questions about running costs, backup service etc. All key issues before you spend your hard earned.

    Outside the heat pump, have you also ensured your house is well insulated, draughts around windows/doors etc. Some easy wins there will make a difference to running costs.

  • Registered Users Posts: 205 ✭✭Skygord

    We have a Thermia Atec air-to-water installed 4 years ago. Very happy with it.

  • Registered Users Posts: 67 ✭✭niteowl1

    Good to hear. Do you mind me asking if it was a home heating retrofit or a new build?

  • Registered Users Posts: 205 ✭✭Skygord

    Renovated a derelict 160+year old cottage, knocked back to bare walls and installed high-spec insulation, and dug out for underfloor heating.

    Nice constant temperature throughout the place now, and constant hot water, are a joy. No problems so far.

  • Registered Users Posts: 938 ✭✭✭Mr Q

    You can also use the excess solar to cool with some of them in the summer. I find this very useful

  • Registered Users Posts: 10,356 ✭✭✭✭the_amazing_raisin

    That's one of my plans for when I get solar PV, we'll likely be doing an extension around then and will need a bigger heat pump, so it makes sense to get one that does cooling as well

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost

  • Registered Users Posts: 444 ✭✭alan kelly

    Silly question on the Heat Pumps during winter... Can they maintain the same temp levels of an oil boiler ?

  • Moderators, Home & Garden Moderators Posts: 5,467 Mod ✭✭✭✭graememk

    In short yes. But they have to be properly installed and sized to fit the house.

    In a drafty house with little insulation. Not so much. Although an oil boiler would be very costly too to run, all the heat is escaping!