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Running A2W Heat pump night time only

  • 20-11-2023 11:48am
    Registered Users Posts: 19


    We have just switched to a smart meter night saver plan and trying to run as much as we can at night, dishwasher, water heating, clothes drying etc. We are wondering whether it would be more economical to set the heat pump on timer and to only heat the house during the cheap night rate (11pm - 7am)? Naturally it may get cooler as the day goes on but might be okay as the house is A2 new build.

    For anyone experienced with heat pumps, do you think this is a more economical or even a viable solution? I know these systems are designed to just be left on and running themselves and let them do as they need but it would be nice to take advantage of the cheaper night rate electricity!


  • Moderators, Sports Moderators Posts: 18,443 Mod ✭✭✭✭slave1

    sure try it and see, every HP and house is different

  • Registered Users Posts: 2,934 ✭✭✭Casati

    I’ve been doing it and it consumes on maybe 20% more power running at night versus the day in winter - but as your night rate is probably 50%+ cheaper it’s still a saving. Do it for water heating first and then experiment with heat Id say

  • Registered Users Posts: 1,367 ✭✭✭DC999

    A fair few here have done that and UFH helps a lot. If you've rads the temp will drop more V UFH. Deffo worth a try as you've an 8hour night rate. Link: Heat Pumps - post here. - Page 105 — - Now Ye're Talkin'

  • Registered Users Posts: 19 esc123

    Yeah we have UFH downstairs and rads upstairs so that sounds promising.

  • Registered Users Posts: 19 esc123

    Yeah we've already done it for the water. We're on a plan whereby the electrcity is a quarter the price of the day rate between 2am and 4am. So that's when we're going to heat our water. We'll just heat it a little hotter than we normally would to compensate that we're heating it at an earlier time.

    With regards to heating the home, I was just concerned that only using it at night would make the system work harder and that may mean higher maintenance fees/servicing costs. But I'll go ahead and give it a lash anyway. Thanks!

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  • Registered Users Posts: 753 ✭✭✭staples7

    Running get pump at night works a charm for us. Doing it for about 5 wingers now. Need to get your timers right. Bit of playing around with it.

  • Registered Users Posts: 19 esc123

    You don't happen to have a Daikin Altherma heat pump do you? I cannot find the setting on the control unit to set the heating of rooms to a schedule like I can for the hot water. There is only a weather dependent mode and fixed setpoint mode but neither allow you to run the heating at night time only.

  • Registered Users Posts: 2,440 ✭✭✭ECO_Mental

    I live in an A1 rated house (A2 without the PV) and I don't have any timers on at all. What you will find is that naturally (in a well insulated house like yours) most of the heating will only come on at night anyway as during the day you will be getting the solar gain which will bring you into the evening, when then again you will naturally heat up the house but just being in it (TV on cooking etc.)

    My heating seldomly comes on during the day hours only if its really cold and very windy. Without any trying 50% of my HP energy usage is at night rate. Where the rest comes from is heating hot water for DHW for showers etc. Again I don't have this timed and it heats up as required...I don't want to be getting my ear bent when my missus goes for a shower and its cold!!!

    The most critical part is setting the temp stats to the correct temp...nothing over 21 degs (the most I have is 20.5) and bedrooms set to 18-19. If you have anything set to 22 -23 degrees the heating will be on all the time. It makes a massive difference

    6.1kWp south facing, South of Cork City

  • Registered Users Posts: 437 ✭✭zoom_cool

    I run my heat pump at night from 2-6 on the EV tariff from Energia, that generally keeps house warm till about 7pm and then Heat pump tops up the UFH which sally in about 2 hours the stats are all at 21 again that will do till nearly the 2am window.

    My house is a 4 bed and 200m2. It is a B2 rating

    I have Alu Rads upstairs and rooms are all @19 my heat pump is a R290 rebadged Phinx

  • Registered Users Posts: 2,934 ✭✭✭Casati

    I do have a Diakin system but rather than control it centrally I do it via programming each room stat. In reality its the kitchen/ living area that is calling for heat during the night.

    I don’t think the heat pump will have to work drastically harder so it won’t break down as a result or need more servicing, it’s just a slight increase as they are designed to work down to -10 anyway.

    note on a cold evening you might find rooms getting a small bit colder than you like and might have to run the heating again at expensive rates but for a short period

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  • Registered Users Posts: 145 ✭✭johndoe11

    I think the main factor in determining whether night running will work is the type of screed you have. If you a have a liquid screed, I believe they don't work as well as they heat up and cool down quicker. I have a concrete screed and it retains the heat longer, but it is slower to heat up which is not really an issue at night. I run mine 2 degrees lower during the day, so it almost always never runs, except on cold mornings.

  • Registered Users Posts: 3,328 ✭✭✭randombar

    So currently with Energia night rate myself 10% discount. 0.4062 day 0.1949 night.

    My sums on oil vs day vs night depending on COP.

  • Registered Users Posts: 19 esc123

    Thanks, I am finding that about half of the energy the HP uses to heat the home is used at night. Frequently though the HP is active in the afternoon evening as well. This may be because we have cold air coming in through our extractor fan ( and we do not have a heat recovery ventilation system. But yeah, maybe get those issues fixed and like yourself the heat pump may only work at night time for heating the house.

  • Registered Users Posts: 19 esc123

    That's interesting, this is a new build house but I have no idea what type of screed went down. I must get onto the construction company and find out out of curiosity. Thanks

  • Registered Users Posts: 19 esc123

    Do you have a thermostat fitted in every room? We have one thermostat in the kitchen and another in the landing upstairs. I suspect to control the temperature in each room you will need individual thermostats, is that right?

    Anyway I haven't found a way to schedule the heat pump to only work during that time so as of now we are still on the weather-dependent function with the pump just responds to the outside air temperature.

  • Registered Users Posts: 2,934 ✭✭✭Casati

    Yes I have a stat in each room except the bathrooms - which seem to be linked to halls or bedrooms