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House heating system upgrade?

  • 30-10-2021 6:18pm
    Registered Users Posts: 589 ✭✭✭

    Myself and my wife are buying (hopefully) a house. It was built in 2006 and has OFCH. The current boiler in the house is not a condensing boiler.

    The house has a (very dubious) B3 energy rating which I am pretty sure, it is nowhere near that. House has open fireplaces, wall vents (non closable) and double glazing.

    Instead on investing in a new condensing burner, we are considering about installing a heat pump.

    Has anyone upgraded from oil to heat pump? What are your thoughts on this?

    What other work was involved? Did you insulate or replace windows too?

    Is it as simple as switching out heating system or does the plumbing and rads need to be upgraded too?



  • Registered Users Posts: 1,952 ✭✭✭jkforde

    I'm interested to hear informed experience, lots of stuff on the net about how HPs are only suitable for new builds with UFH and rating of A3+ and active ventilation. HPs are not economic for retrofits by and large is the internet 'wisdom'.

    🌦️ 6.7kwp, 45°, SSW, mid-Galway 🌦️

  • Moderators, Home & Garden Moderators Posts: 4,961 Mod ✭✭✭✭graememk

    Been looking into this a bit recently, And want to run some numbers myself. - I am on solid fuel and oil (if i get lazy and dont go out for more) And ignoring the insulation etc for now (but insulate, insulate, insulate).

    Assuming the Heatpump can heat the house, Lets run some (rough) numbers.

    Found a spec of a high temperature heat pump (needed for "normal" radiators) it has a cop about 3.5ish at 55c

    Higher you go the lower the COP is, so say 3 for easy counting. So 1 kWh of electricity in , you get 3 kWh of heat out.

    So we need some base figures to work from : each litre of kerosene has 10.35kWh of energy, and an condensing oil boiler can be up to 99% efficient. So lets say 10kWh per litre. Also say 85c /litre for kerosene. That is 8.5c/kWh of Heat.

    Energia, the 24hr rate is currently about 18c/kWh. And you get 3kWh of heat for that 18c, so 6c/kWh of heat. Saving 2.5c/kWh of heat.

    This website, says that the average UK household uses 26,000kWh of heat (or 2500L of oil), that works out at about €650/ year. - I'm actually surprised that there is a saving, but as always devil is in the details.

    Anyone have any rough prices for a condensing oil burner and a heat pump? Also whats other people's average oil usage?


    The specs on the grant vortex boilers, (only one i looked up) are about 90-95% efficient, and only on the high end at low temperature and 30% heat output.

    90% efficiency is 9.315 kWh, which would be 9.12c/kWh

    95% efficiency is 9.833kWh, which would be 8.64c/kWh

    New non condensing are 85% and older ones are 60-70% (source.. quick google)

    80% efficiency is 8.28 kWh, which would be 10.26c/kWh

    65% efficiency is 6.73 kWh, which would be 12.63c/kWh < my boiler is old, but works, rarely used, this is what is dragging down my BER.

    Coal : about 8kWh/kg, Peat Briquettes about : 5.36kWh/kg (just for reference!)

    Post edited by graememk on

  • Registered Users Posts: 607 ✭✭✭farmerval

    A new kerosene Grant Vortex 90 120 boiler and circulating pump just cost me €2,000.00 to purchase. Fitting will be extra

  • Registered Users Posts: 3,202 ✭✭✭cruizer101

    Surprised a 2006 new build didn't have a condensing boiler.

    In general heat pumps are only suitable for properties that have lower heat demand due to good insulation well sealed etc.

    They require larger rads as the water is at a lower temperature so there is more than just swapping the boiler out.

    My advice would be move in and see how it feels, definitely upgrade insulation if it needs it, that is one of the best bang for buck improvements.

    Windows? maybe. If they are decent enough double glazed, which they should be from 2006, there won't be huge gains in upgrading, but might be worth it. Air leaks is another big heat loss so look to seal up the house.

    We've oil and I did look at getting heat pump but through my research I just don't think it makes sense from a financial point of view and also just would it give out enough heat.

  • Registered Users Posts: 589 ✭✭✭loctite

    Yeah that is 100% the plan to live in it and see. But I suspect we are in for a bit of a shock as our current home is very well insulated - built about 2008 but we went above and beyond the building standards at the time with insulation so it is a very low cost house to heat.

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