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Chilled Water AC System

Air Source Heat Pumps (ASHPs)

Last Post by Prunus 3 years ago

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Biketrials1

(@biketrials1)

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Topic starter 18/01/2022 9:30 pm

hi all. if any one can point me in the right direction. im looking for a water chilled air handlers for domestic ie same as wall hung ac unit except using chilled water instead of gas as i have ecodan ashp and i belive can chilled water.

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Prunus

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20/01/2022 12:31 pm

I think what you're talking about are Fan Coil Units or FCUs. They're basically a pipe with metal fins to transfer the heat, with a fan to blow air through them. There is additionally a condensate drain pipe to collect moisture that comes out of the air as it cools.

You can get them in ducted versions, which fit in a service space somewhere and the cool/hot air is ducted out (if you've been in a modern hotel room with A/C you may well have had one above the hallway), in cassette versions that fit in the ceiling (like in shops, offices, etc), and in wall hung units that are either mounted high (like an internal A/C unit, but with water) or low (like a radiator).

They are a bit unusual outside of commercial settings in the UK, but they're popular in other countries such as Italy. This thread has likes to various models and sources:
https://forum.buildhub.org.uk/topic/10658-fan-coil-units-for-use-with-a-cooling-ashp/

(I'm looking to replace a couple of radiators with FCUs and pondering ordering from Italy or China...)

With your Ecodan, you would need to enable cooling mode and typically water would come out at 7degC. Then your heating loop becomes 'cold'. Depending on how everything is plumbed, you might need a separate zone for just your FCUs or to change your radiator/UFH controls (with mechanical TRVs, they may decide the room is too hot and stay closed. When the temperature is cooler than their set temperature, they decide to open to allow more water into the radiator to 'heat things up' - which of course will cause the room to get colder. So you can't have useful thermostatic control). You would also need to ensure your internal pipes are insulated otherwise they're at risk of condensation.

This post was modified 3 years ago by Prunus

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Adam C

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21/01/2022 8:19 am

One thing to take in to consideration when using chilled water is condensation.

All of the pipework must be very well insulated without any gaps, anywhere warm air contacts the now chilled pipework will cause condensation and drips. With heating you can get away with this but with cooling it can cause water damage is inaccessible places!

But otherwise a good way to cool a property, especially if you can get a central FCU and ducting to make is almost silent.

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Biketrials1

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Topic starter 27/01/2022 7:51 pm

hi. i have been looking at this but cant find any where on web that sell this???

https://www.daikin.co.uk/en_gb/products/FWT-AT.html

This post was modified 3 years ago by Biketrials1

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Prunus

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27/01/2022 10:36 pm

You will probably need to talk to distributors, since they aren't typically a part stocked in everyone plumbing warehouse. Orion Air Sales have the FWT-CT, for example (I'm not clear on the difference).

Otherwise Italy is a good source (search 'ventilconvettore'). ShopClima have the FWT-GT, and will ship to the UK (or would last year before Brexit border checks):

https://www.shopclima.it/it/daikin-fwt03gt-fan-coil-a-parete-versione-2-tubi-3-kw.html

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