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Should I install combi-boiler + cost?

  • 19-05-2022 9:50am
    Registered Users Posts: 2,651 ✭✭✭ ShowMeTheCash

    My house runs stove with back-boiler and oil heating system.

    I have gas for gas-hob only.

    I have two types of shower Electric and Mains water shower.

    I prefer mains water shower just better pressure etc.

    My heating system I can choose to heat house or just water however it is a standard water tank whether it is oil or the stove it will take a bit of time to heat the water.

    The stove of course is not something you want on in the summer....

    I was thinking of installing a gas combi boiler for hot water.

    My water system is standard gravity fed system house was built in 1997 anyone got any ball park numbers to the cost of installing a system like this.

    Are combi-boiler showers better pressure than electric showers?

    Are combi-bolier showers cost effective compared to electric showers?


  • Registered Users Posts: 16,354 ✭✭✭✭ Sleeper12

    I'd forget about the combi boiler. You'll never recoup the investment.

    With your existing set up all you need to do is to get a pump installed for the shower or a dedicated power shower. Fitting a combi boiler correctly will require you to get a pump anyway.

    A dedicated power shower or a pump should come inside around the thousand euro mark, give or take a hundred.

  • Registered Users Posts: 12,558 ✭✭✭✭ Dtp1979

    As sleeper said above. And if it’s the summer months you’re worried about, install a solar panel

  • Registered Users Posts: 2,973 ✭✭✭ standardg60

    Amateur question, wouldn't a power shower need an already heated water supply, or are they powerful enough to heat a pumped supply of cold water?

  • Registered Users Posts: 6,547 ✭✭✭ Alkers

    A combi boiler will work with a pump for a power shower. A power shower will need already hot water, either provided on demand from a combi boiler or from a hit water cylinder. Electric showers are rubbish in comparison. It's unlikely a combi boiler would feed two power showers so you'd have to keep the electric

  • Registered Users Posts: 2,973 ✭✭✭ standardg60

    That's what i was thinking, which doesn't help the OP as they'd still need to pre-heat the water with the oil boiler. So a combi would be useful.

    I use my electric shower (mains fed) in Summer when the water is warmer and the combi supplied one in Winter

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  • Registered Users Posts: 6,547 ✭✭✭ Alkers

    Each to their own but it would be more economical to use the combi all year around, gas is significantly cheaper than electricity per unit of energy and I'd be surprised if the electric shower is better than the combi fed one.

  • Registered Users Posts: 410 ✭✭ rosmoke

    Don't agree with some posters, of course you can run 2 showers of the same combi boiler.

    I'm not a plumber but had combi boilers for 20 years. In Romania for example everyone, literally everyone has combi boilers, I'm on my second one which is a condensing combi boiler.

    For a 6 bedroom house with 3 baths you can have heating on and 3 showers at the same time no problem, it takes 5-30 seconds to get hot water depending how far you are from it, usually 20 secs. Condensing combi boiler costed 1k euro for this house, probably 1.5k here.

  • Registered Users Posts: 3,132 ✭✭✭ John.G

    Combi, Using two showers if you want (approaching) power shower flowrates of 10LPM at 40C in winter with a mains temp of say 7C will require a 46kw boiler, leading to a lot of cycling when a oil boiler is on CH where the demand may be as low as 5kw. You can settle for a economy shower restrictor to give 6LPM, a 28/30kw boiler will then suffice, disadvantage being if only one shower in use then you are limited to this 6LPM except you remove the restrictor. While all oil boilers combis are termed storage combis, you can install a lower output boiler to give "46kw" HW output, but only for a few minutes.

  • Registered Users Posts: 812 ✭✭✭ mp31

    Heard this in another thread "Running a combi directly from the mains supply in Ireland is against building regulations, Irish water by laws & local bylaws" - something to keep in mind when making your decision

  • Registered Users Posts: 16,354 ✭✭✭✭ Sleeper12

    A 5 or 10 minute shower is far cheaper using an electric shower compared to the most efficient combi boiler. An electric shower A rated & 100% efficient. The max flow rate of an electric shower is 3 to 4.5 /5 litres of warm water per minute. The maximum flow rate of a combi boiler is around 10 to litres of warm water per minute. For a 5 minute shower you will use 3 to 4 times more hot water compared to the electric shower. Electricity is more expensive than gas but when using 3 to 4 times the amount of water compared to the electric shower the 5 minutes shower is cheaper using the electric shower

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