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Fan Coil Units for use with a (cooling) ASHP


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Whilst we are all "enjoying" the present spell of hot weather, many of us are thinking of ways for cooling our houses.

 

Many of us have an air source heat pump that can operate in cooling mode as well as in heating mode.  So I would like to look at using mine to cool the bedrooms.

 

What I am looking for therefore is two wall mounted Fan Coil Units (FCU's) one to go on the wall in each of the 2 bedrooms that we use.  They need to be wall mounted as one bedroom has a full vaulted ceiling and the other a partial vaulted ceiling.  It makes sense to get two identical units so bot can be wall mounted.

 

What I had in mind was something that looks a bit like the inside unit of the air conditioner that @JSHarris has just fitted and detailed in this thread 

It seems to me that it would be a very simple unit.  It would take the chilled flow and return water from the ASHP pass it through a heat exchanger with air passing through that from a fan inside the unit.  It needs the minimum of controls, it really just needs a manual fan speed adjustment and control of the fan on or off by a (cooling) room thermostat, probably separate to the FCU.

 

I thought this might be something easy to find and cheap.  but 45 minutes on a browser and I am disappointed with how few units seem to be available, how expensive they are, and how over complicated their controls seem to be.

 

So I open it up to the forum to discuss options and try to find a small, simple, basic, cheap FCU to put in each of our bedrooms.

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One thing to watch for with the fan driven water heater type units is that if designed just for heating they probably won't have a condensate tray and drain, and for cooling one of these is essential.  There is a steady trickle of condensate coming out of both the MVHR drain and the air con drain right now, as water condenses out on the cool heat exchanger.

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4 minutes ago, PeterW said:

You need to look for a water heat battery

 

should be £80-150

Searching "water heat battery" on ebay just lists mostly fancy thermostats and controls. Searching that on a search engine gives lots of links to the Sun Amp hot water systems.

 

Nothing resembling what I want?

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Just now, JSHarris said:

One thing to watch for with the fan driven water heater type units is that if designed just for heating they probably won't have a condensate tray and drain, and for cooling one of these is essential. 

That is why I am specifically looking for a cooling unit, without much luck apart from the huge things meant to go in office ceilings.

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Found these, but they are probably pricey: http://www.quartz.co.uk/products/wall-mounts/

 

Looks like using the search terms "chilled water" might yield some results, perhaps.

 

Edited to add:

 

https://www.hushonuk.co.uk/hitesca/chilled-water-fan-coil-units/

 

https://www.trane.com/commercial/asia-pacific/th/th/products-systems/commercial/TerminalDevices/FanCoilUnits0.html

 

https://www.carrieraircon.co.uk/product/42n/

Edited by JSHarris
Found a few more links
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11 minutes ago, PeterW said:

 

 

I have one of those.  I bought it to try and see how easy it would be to use it as a cooler - the answer is not very.  I took it apart and concluded I'd need to make a new housing, as there was no easy way to make the existing housing watertight enough to allow a condensate drain to be fitted.   When I get around to it the plan is to make a new housing for the heat exchanger from bonded together PVC sheet, so that it will be easy to fit a drain, with no corrosion risk (the plated steel case on the thing didn't look as if it would last long if it got wet).

 

It's in bits in the garage, but I could dig it out and take some photos of the inside if that might be useful.

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13 minutes ago, ProDave said:

 

Might be worth a punt at that price.  There isn't much in one of these things to go wrong.

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i presume you have come across the panasonic aquarea air rads and filed them in the "too expensive and complicated" group, i have them fitted although using them for heating, they are a lot more aesthetically pleasing then what i was thinking they would be, although they arent running yet  

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10 hours ago, Hobbiniho said:

i presume you have come across the panasonic aquarea air rads and filed them in the "too expensive and complicated" group, i have them fitted although using them for heating, they are a lot more aesthetically pleasing then what i was thinking they would be, although they arent running yet  

I can only seem to find those sold as a packaged system with the heat pump.

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Not wishing to digress this thread but been reading it with interest. I don’t think we have a cooling need but did consider a heating wet battery fir the main bedroom fir really cold weather, my problem is I cannot run pipes from the plant cupboard to the bedroom without major works (which I have no stomach for after the build). However the DHW tank is next to the bedroom and with a diverter valve could feed it with hot water intended for the DHW tank with a bit of juggling. 

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1 minute ago, joe90 said:

Not wishing to digress this thread but been reading it with interest. I don’t think we have a cooling need but did consider a heating wet battery fir the main bedroom fir really cold weather, my problem is I cannot run pipes from the plant cupboard to the bedroom without major works (which I have no stomach for after the build). However the DHW tank is next to the bedroom and with a diverter valve could feed it with hot water intended for the DHW tank with a bit of juggling. 

In my case I could tee into that flow and return for anything.  All my flow and return branches run to their destination with the 2 port valve at the destination, so in the case of the DHH tank, the 2 port valve is on the pipe feeding the coil.  I could tee off below that if I wanted with another 2 port valve for any other circuit e.g another heating circuit.

 

Just occasionally we could do with a little heat in the bedrooms so I will organise these FCU's in the bedrooms so they can do heating as well as cooling,

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12 hours ago, ProDave said:

I can only seem to find those sold as a packaged system with the heat pump.

you could send stu gray an email, he is the panasonic dealer for the north of scotland and the islands "info@heatorkney.com" he would let you know how expensive they are, although i think they are ~£500 each so not exactly cheap

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I don't know what MVHR system everyone has, but Zehnder have a document on there website about overheating (https://www.zehnder.co.uk/overheating-in-homes) that mentions a product called "ComfoPost":

 

----

Chilled water coil

ComfoPost

  • De-humidification of filtered supply air via MVHR, during peak conditions (water at 7°C)

  • Complete control and setting of temperature and humidity to improve the indoor climate

  • Good thermal and acoustic solution, no draughts or nuisance noise

------

I can't find any further informtion on this anywhere on the internet though!! Anyone heard of it, or used it?  (asking as we'll likely be using a Zehnder unit)

 

 

 

 

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3 minutes ago, Dan Feist said:

I don't know what MVHR system everyone has, but Zehnder have a document on there website about overheating (https://www.zehnder.co.uk/overheating-in-homes) that mentions a product called "ComfoPost":

 

----

Chilled water coil

ComfoPost

  • De-humidification of filtered supply air via MVHR, during peak conditions (water at 7°C)

  • Complete control and setting of temperature and humidity to improve the indoor climate

  • Good thermal and acoustic solution, no draughts or nuisance noise

------

I can't find any further informtion on this anywhere on the internet though!! Anyone heard of it, or used it?  (asking as we'll likely be using a Zehnder unit)

 

 

 

 

 

Its a very expensive water duct battery unit...!

 

https://www.reclima.it/en/prodotto/zehnder-batteria-di-post-trattamento-zehnder-comfopost-cw12/

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16 minutes ago, PeterW said:

Ouch!

 

In practice the amount of cooling (or heating) you can get in through MVHR ducting is limited as MVHR moves air very slowly, and air has low specific heat capacity, so even worse value with that in mind. So after a lot of back and forth I've moved off that plan to using a separate recirculating fan coil for the upstairs bedrooms, as these can operate at a higher fan speed without messing up the MVHR balancing.

As we have easy access to each room from the loft, I'm thinking a single ducted fan coil (maybe like Courier 42EM-09) branching to a small linear diffuser in each room. Return path via door-gaps to landing and a single larger return diffuser back into the loft plenum.

I didn't know any of these words a day ago so hopefully that makes sense! My M&E guy thinks it's doable and looking into a concrete plan on this. It's quite a few parts, but may not be too bad compared to 4x fan assisted radiators and associated plumbing and control (or vs. 1x comfopost for that matter!). Also, very little bulk / space needed in each room for it (although the loft is going to become a ducting rats nest).

 

If this was only for the occasional upstairs heating we're anticipating would be needed it would be way overkill... but the fact the design is being done this week has somehow made me very mindful of how useful having some highly effective cooling capacity would be.

 

Edited by joth
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12 minutes ago, ragg987 said:

Anyone tried one of these? I doubt they will deliver enough cold air to make a huge impact, but should drop the temperature to something more comfortable.

https://www.bpcventilation.com/cold-water-duct-cooler-range

 

Looks like a cheaper/generic version of the "ComfoPost".

 

This datasheet might give an idea of how well something like this might perform: http://www.alternativeadvancedenergy.eu/AAEnergy06/it/dwn.asp?ID=243

 

 

 

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9 minutes ago, joth said:

Ouch!

 

In practice the amount of cooling (or heating) you can get in through MVHR ducting is limited as MVHR moves air very slowly, and air has low specific heat capacity, so even worse value with that in mind. So after a lot of back and forth I've moved off that plan to using a separate recirculating fan coil for the upstairs bedrooms, as these can operate at a higher fan speed without messing up the MVHR balancing.

 

We are planning for external blinds almost everywhere, so don't think we'll need any really serious active cooling like you are planning.  Instead we plan to use PV to run HP in reverse and cool the ground floor slab in the summer, as I think others on this forum do.  What I was thinking though, was that if we could also use something to run cold water through HRV and not just UFH it would help with upstairs better (and be cheaper than any kind of brine ground loop)

 

Edited by Dan Feist
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4 minutes ago, Dan Feist said:

Looks like a cheaper/generic version of the "ComfoPost".

So somewhere between 1 and 5kW of cooling available depending on incoming air temperature and flow. Seems usable?

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