Cooling is becoming a requirement for homes, the UK planning system makes hard to legally install A2W and A2A (aircon) unless a home is detached. Installers are not yet setup to provide functional cooling from A2W systems. Will homes that can’t have Aircon become harder to sell?
It clear that with good DIY skills, money and willingness to create own control system we can make many A2W heatpumps cool a home. But it too complex at present for normal people and often require hacking the heatpump to enable cooling as well as a deep understanding of dew point and plumbing.
A2W often gives higher standard heating than A2A, a basic A2A system that is good enough for cooling is often not good enough for heating so can’t replace the gas boiler. Few A2A installers can be trusted to design systems that work well for heating unless property is very small.
Octopus may have a cooling system for their heatpump next year, but we don’t know the installed cost and what other heatpumps they will surport. We don’t know if they will sell the hardware for a pratical price.
But if a friend ask me today if they should get a heatpump to replace their gas boiler I would have to start with asking them if they will ever wish to have aircon…
Not difficult to install A2W in any home, some flats may be an issue. Cooling isn’t permitted via permitted development. Mine on cooling have to go next to it to see if the fans spinning as it just ticks over at a very low output and you can’t hear it.
Mine and my last heat pump did cooling out the box. Not sure what control system you need in most decent heat pumps heating and cooling can be configured to auto switch between heat and cool if you want. Or stick a heat/cool thermostat as a start permission. Plus many or most will cool out the box. If it doesn’t cool out the box, cross it off the list. MCS doesn’t exclude heat pumps that cool. But most installer don’t have clue about cooling. But you really need fan coils and or UFH cool. Radiators wouldn’t bother unless you convert it to work like to rubbish fan coil.
The most recent English wording dates from may 2025. The previous wording excluded use for cooling but did not exclude devices capable of cooling. It was widely misinterpreted to exclude devices capable of cooling (and thus to exclude a2a even if used solely for heating), however this was incorrect.
Does Scotland have less need for cooling? Anyway it’s a matter for the devolved administration! The Scottish wording as you have quoted it would allow a2a for heating so far as I can see. The probability of a challenge is negligible and the only thing an enforcement notice could reasonably do (provided there was no other substantive space heating system) is to instruct the householder not to use it for cooling.
The people that would be in a difficult corner are a house that obviously has gas or oil heating system and then an A2A system for cooling stuck on the front of the house.
It’s definitely cooler here than ‘down south’. But we can still get room temps of 27 without cooling. Even with big roof overhangs etc. the sun drops in the evening when it’s starting to go down and shines in circumventing the roof overhangs especially so in spring and autumn.
The people that would be in a difficult corner are a house that obviously has gas or oil heating system and then an A2A system for cooling stuck on the front of the house
Worce is having A2W for heating than not being able to easily find a trade person to sort out cooling.
In my semi detached house my Vaillant 7kwh combined with Trimley fan emitters is giving good cooling from three rooms.
Combined with standard tactics of airing house in early morning to remove accumulated heat, opening windows in cooler evening plus curtains drawn during day where direct sunlight, and outside screen on front door, it is giving steady 23-25 deg temperatures throughout the day even in 34-36 deg days.
Need to select the room(s) that you want as cool sanctuaries for emitters to avoid condensation but with open internal doors the downstairs stays cool throughout and the upstairs cools down with breeze from open windows in evening/nighttime.
Very interesting! Would love more detail of the Trimley convectors; photos and any documentation would be much appreciated. Their website is very sparse on info!
Remember you can’t cool below dew point unless all pipework is insulated with aircon type insulation and all gaps in the insulation sealed. Otherwise you get condensation and hence dry rot in your wooden floors and ceiling beems.
So you may need something else to lower dew point.
Here are photos of the eight fan unit - excuse the dust, it shows that I need to vacuum them regularly as can eventually affect performance.
No documentation as these have evolved as Trimley refine their approach - e.g. mountings, electrical connection etc. This one replaced a 1600mm T3 radiator so connecting pipework not so elegant.but could obviously be cleaned up eventually. We have another 8 fan unit in another 4x4m room and a 4 fan unit in main bedroom.
When door is closed and room left so you can feel the temperature difference as you enter, or leave the door open and get more widespread but lesser effect. I keep the Vaillant Sensoconfort control box in the cooled lounge as placing in a no
n-cooled room would find it continually trying to cool.
The power comes from a usb-c port in adjacent socket. These are 12v, I think, not standard to give sufficient power to drive the fans. Works pretty silently. The air is drawn in from the front and cold air emitted from wall side. You can feel the cool air movement with your hand or sitting close by when it is on.
Attached is a screen shot from yesterday (we are in Cambridge) showing electricity consumption by function plus inside and outside temperature. The Vaillant generally gives a cop of 7 for cooling. We come off Havenwise in summer as their algorithm does not support cooling. In prolonged heatwave the fabric of the house heats up (beneficial in winter, not in summer) so the internal temperature can push up a bit on hottest afternoon/early evening but never above 26 deg. so far.
Wow, thank you for such a swift and detailed response!
Very interesting construction, seemingly a couple of automotive heat exchangers plumbed in series, a (3D-printed?) fan shroud, and off the shelf Arctic P-series fans.
How long have you had these fitted? Are you a guinea pig for Trimley?
Could say guinea pig but more like they introduced upgrades as they came along. That’s a real benefit that they are continually bringing new improvements - initially a little clunky with fittings but that got the system going and improved from there - e.g. cover with fans engages with power when pushed on so easily removed for vacuuming.
I’ve had the Vaillant since Sept 24 and Trimleys were installed then - so two summers of cooling experience and upgrades. The emitters are ready for remote/app control but not yet available - though it shouldn’t impact our use as constant running in warm periods works fine with 23 deg setting.
The fan shrouds are 3-D printed so units can be added for the bigger emitters. Also means they can come in myriad of colours as the website shows
How did you come to having these installed, if you don’t mind the question? Did your heating engineer spec the Trimley units?
Always intriguing to discover ‘UK made’ speciality parts like these!
The fans are oriented to suck air in through the front grilles; where does the heated/cooled air emanate from once it’s passed through the heat exchanger?
