You could try under kitchen unit coils such as https://www.plumbworld.co.uk/myson-kickspace-500-hydronic-plinth-heater-with-grille-103137-1261277?utm_source=organic&utm_medium=shoppingfeed&utm_campaign=googlebase&gad_source=1&gad_campaignid=22942933411&gbraid=0AAAAAD_lDOggKrCkLMlZk6jAC7EU5YefM&gclid=Cj0KCQjwmunNBhDbARIsAOndKplMIOzMlSSMX1BZbCdBlCxnjHKvsgMG0FLWeorUtregxocbNrbRfMkaAvSHEALw_wcB

We have a 1kW version in the kitchen and if the oven has not been on in very cold weather then we flick it on. It makes a huge difference to the house comfort. Ours is always on the summer fan setting because it’s from boiler days and will automatically stop when the flow temp is below a value (guess 45C) which is not what you want on a heat-pump circuit. I’ve never looked for a ufh/heat pump version. 
It’s the ideal quick supplemental heat solution.

Why do you specifically want ducted?  Is the ductwork already in place?

Posted by: @nettechie

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UK or EU suppliers for ducted hydronic fan coils,

We have installed Jaga Strada fan-assisted units which work well with our ASHP and provide light cooling in summer.

They are conventional rads but Jaga also manufactures a Briza model that is designed for in-wall or in-ceiling installation.

https://jaga.com/ex/radiators/installation-in-a-wall-recess/

Note also that you can get the Stradas without a casing and we have 3 of these installed at the bottom of built-in bookshelves in our living room.

These are all made to order (in Belgium) and supplied to me by GoGeothermal.

Here in France fan coils are pretty rare for residential so when I contacted distributors they simply didn't want to talk to private individuals lol

Thus you can get fan coil units at acceptable prices from the usual suspects in Spain and Portugal, like amifrigo and climamarket. Watch out for the warranty though, it may or may not exist as some manufacturers simply refuse to warranty export products. So don't buy heat pumps from these websites unless you like fixing it yourself.

I ended up buying them used "like new" from the demolition of a large store so that's also a way.

Notes if you want to cool your house with cold water:

- It is a lot more flexible than refrigerant AC since you don't need refrigerant pipes and the associated regulatory headaches

- All pipes carrying water below the dew point will attract condensation and drip unless they are vapor tight insulated which is an annoying and time consuming job. It must be done perfectly. Otherwise condensation will drip, this will rot your house.

- Never ever send the chilled water into your UFH or you will have condensation under the floor

- Motorized valve actuators do not like to have condensation in them, so they tend not to last very long unless special precautions are taken: put them on the return, use longer stalks to keep the motor warm, etc.

- Due to water freezing at 0°C you can't cool with sub zero water, which means the fan coils have to be huge, and I do mean absolutely enormous, compared to an AC unit which may actually cool the heat exchanger below 0°C and thus get away with a smaller heat exchanger.

- Dehumidification is more important than cooling. 25°C with high relative humidity is unbearable, but with low relative humidity it's fine. In dry air, sweat evaporates easily which cools your body. Air conditioning is about dehumidifying as much as it is about cooling. Just cooling the air without dehumidifying (as done by "cooling" UFH) keeps the absolute humidity constant but relative humidity increases, thus sweat doesn't evaporate, and it feels like a cool damp swamp. Not recommended. Therefore any "cooling" unit which doesn't have a condensate pipe coming out isn't that useful. You have to route the condensates to the sewer, preferably using gravity.

- Air carries very little heat by volume. Thus to move some useful amount of heat, you need to move a ridiculous amount of air. This tends to make noise and waste power.  The smaller a fan is, the faster it has to spin to push the same amount of air. So you can have small and noisy, or large and quiet, but not small and quiet.

Thus you have three choices:

A non ducted unit, which has no airflow restriction, but it's in the room besides you, so you will hear it directly.

A ducted unit with tiny ducts like 200mm, which will need a powerful fan to move enough air through the ducts, so the fan has to work hard, it is noisier, so it needs a lot of soundproofing, which further restricts flow, wash rinse repeat, and you need an aeraulics engineer to check your flow.

Or a ducted unit with properly sized ducts (ie, large enough to crawl through) but then you need space for all that stuff.

What I'm going to do with my pile of fan coils is mount them in a non-living space, sucking air from a room and blowing it into another, which should create cool air circulation through the whole house. The living spaces are several rooms away, so hopefully the noise should be attenuated after passing through the entryway and corridor. I haven't done it yet, so... grain of salt and all that. But I did try the FCUs, they're Panasonic FD30, and they're very quiet.

Posted by: @bobflux

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A non ducted unit, which has no airflow restriction, but it's in the room besides you, so you will hear it directly.

Our experience of two UK summers with the Strada fan-assisted rads in a barn in Herts is that they reduce bedroom temps by around 5C on a hot day with OT around 30C provided we keep the cooling on and bedrooms closed up during the day.  Emitter size is 1200mm wide.

We run the flow at 17C which avoids condensation.  The fan units are very quiet and cause no disturbance even during the night.

The Jaga website has loads of performance data on their products for both heating and cooling.

@jamespa We are doing a deep renovation with new joist, ceilings etc so makes sense to hide everything away and have a ducted system.

Posted by: @nettechie

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@jamespa We are doing a deep renovation with new joist, ceilings etc so makes sense to hide everything away and have a ducted system.

OK

Ducted warm/cold air is unusual in the UK.  We had it in a house I lived in in the 80s, it was dreadful.  Perhaps others had a similar experience hence lack of popularity.  The fundamental problem is the amount of air you need to move (because of the low heat capacity) but for a very low loss house with mvhr I can see it could make sense.

If it's a deep retrofit why not hide fancoils in ceiling/floor, connected hydronically but blowing air straight out.  The wall mounted (mitsubishi) one I have also cones in concealed version.  Made in Italy by climaventa.  Italy seems to be the epicentre of the fancoil market!

This is just a long way to say sorry, I can't help!  

Yes, I was initially thinking of hiding the units in the ceilings, however I wanted to get access to them to clean the filters or if there was ever a need to carry out maintenance. So hiding them would be an issue and I don't want ugly access panels on the ceiling. The duct runs would be short, I was thinking of placing these units in riser / store cupboards on each floor which are centred in the house and have short duct runs out from each unit into the rooms, not whole house ducting. 

The units will be primarily used for cooling, I agree Italy seems to be the main market where you can get these items. Seems I might be out luck with this and whilst I wanted to avoid AC, it might be the only option I'm left with.