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Air to water heat pump system - Advice !



  • Registered Users Posts: 228 ✭✭ blast06

    Lol. Yes well it was -2 outside.. The pressure stat cut out is 28.5 bar for DHW and the HP alarm is 31.5 bar

    normally at +5 or 6 it takes about 25 to 30 min. That last post was just to prove a point.

    This was an 11kw at A7 heating a 300l tank. prob 8 to 9 kw at A zero. but that's the nature of AW heart pumps. That's why I prefer Geothermal.

    Re the size of the tank ..... i looked for advice / recommendation before on what size to get (i'm about 3-4 weeks away from getting HP installed on new build) but nothing conclusive.
    My current plans are for a 180L tank but not sure if i really need a 300L tank (this is my question) .... i have 3 kids and will have 3 showers in total (2 of the showers are the 'rain-head' type showers).
    - Woudl i really need the 300L tank ?
    - Would there be much additional cost per year associated with having a 300L v 180L tank ?


  • Registered Users Posts: 22 housebuilder1

    I have a 180 ltr tank also and I have 2 kids. I don't have rain heads like you just std heads.

    It all depends on how much water per min those heads your going to get use. If they use like 20ltrs per min then be careful with a 180ltr.

    The 180 ltr tank at say 55 degc will yield approx 300ltr of mixed water at 40degc so you divide the ltrs per min of your showers into 300 and you'll get how long it will last.

    Saying that there is not much difference in price. A 300ltr syssystem may cost approx 500 to 700 more. Worth it if you are going to have funky showers lol.

    Also the reheat time on my cylinder from 40 to 58 is approx 20 min so if I do use all the water I have another full tank in 20 min.

    Hope that helps.


  • Registered Users Posts: 11 Easter Sunday

    I’d love your advice on air to water heat pumps...I’ve jst posted to about them.
    Thank you

    Tommyboy08 wrote: »
    Stick with the smart rads for upstairs, your going to need a buffer tank anyway if using air to water for defrosting purposes, it's better in the long run than using an immersion heater to defrost the outdoor, and you'll have no problems heating the rooms with 35 degree water with those rads, I know their expensive but cheaper to run and better for the life of your system,
    But please be wary of the make of unit you choose, I spend 6 days a week fixing heat pumps and don't listen to the salesman bull, some units are very bad, pm me the makes your thinking of using and I can give you the benefit of other people's mistakes.

This discussion has been closed.