New build Air source heat pump high energy usage

dazzer567

hi
dont know if anyone can shed any light on this
im just moving in to a rented housing association new build which has been fitted with air source heat pump ( Vailent aroTHERM)

the issue we are having is that the energy usage seems to shoot up (around £1.50 per day ) as soon as hot water is set on its timer for a few hours a day ( we adjusted it from running all day every day as it was initially)

we have not even moved in fully yet so barely any hot water usage , maybe a odd bowl to wash up in + hand washing , so i wouldnt expect the hot water tank to require a great deal of heating in the times which i have set which is something like 6am-8am and then 5pm-8pm

if i turn the hot water off and leave just the heating on auto then usage is much lower , most we had was just short of 50p a day and that was with using other things such as kettle and microwave .

dont know if it helps but there is a 24hr timer switch which appears to go to the tank ( immersion heater ?) which has been off since we moved in , dont know if this will have affect on it or if this is purely to boost to above 60C to prevent bacteria

any help / thoughts ?

matelodave

What temperature is your hot water set to - anything much over 50 degrees will probably activate the back-up or immersion heater.

What size hot water tank have you got and what model/rating is your heat-pump.

We've got a Daikin 11kw feeding a 200litre tank and have the hot water set to 45 degrees for two hours a day before we get up which uses around 3-4 kwh day in the winter and 2kwh in the summer.

We pay 12p/kwh which equals around 48p in the winter and 24p in the summer. We get two showers and a bit of washing up a day but can manage two more showers before it's too cool for comfort.

We don't spend much time in the shower, I can do all of it in less than two minutes and my wife takes around four. We also try to avoid running off small amounts of hot water because it wastes around half a gallon of cold and then leaves half a gallon of hot in the pipework to get cold.

The uplift to 60 degrees is controlled by the heatpump which cranks up to 55 degrees and then requires the immersion heater to get to 60. This obviously uses more energy but then the hot water doesn't need heating the next day.

You need to learn how to use it effectively and not try to use it like a conventional boiler fed heating system. How is the house heated - rads, underfloor, fan convectors. What controls have you got and how are they set. It took me quite a while to get mine optimised and I know how it all works.

Make sure you are on a decent tariff - we are on a single rate at 12p/kwh. I'd suggest that you start a spreadheet and read your meter every day for a while (ideally at roughly the same time and use KWH not £££) Hopefully it will then give you some idea of what effect tweaking the controls will have.

Heatpumps are very sensitive to temperature and how they are being used and the general advice is to keep the flow temp as low as possible and leave the unit on all the time.

There are 90 pages and 10 years worth of info on this thread https://forums.moneysavingexpert.com/discussion/1464827/updated-air-source-heat-pumps-air-con-full-info-guide-is-it-cheaper-to-run-than-mains-gas&page=91 and several other threads on the same subject if you have a search around so try working backwards to see if you can get any tips.

Get hold of the manual for your system and the operating instructions and really learn how to operate it. Either download them or ask the HA to proved you with a copy and if you aren't sure then get them to come and show you how to operate it properly. Most people are dissatisfied with their heat pumps because they dont know how to use them or they aren't set up properly.