Fan Coil Units for use with a (cooling) ASHP

[Dan F]

  On 26/07/2019 at 22:33, ragg987 said:

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

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I read it as, with 350m3/h and an exterior temperature of 32C, temperature at room valves should be 18C.  Wasn't sure what the corresponding 2,65KWh was.

 

But yes, seems very usable.

 

[ragg987]

That example is 2.65kW not kWh. Google translate calls it "thermal power".

 

Mighty have to think about retro fitting one of those for bedroom supply if these hot days keep happening. Should be a simple take off our buffer tank which is supplied by the ASHP.

[PeterW]

The problem is that you need to get the water temperature low enough - they will be listed as something like 6/11 which means 6c in and 11c out. You then need to look at the water flow rate and for some it’s going to be quite high - 400l/h or 6.5l/min is a lot for an ASHP to chill down so you’ll need a corresponding 5-7kw ASHP on the other end. 

[NSS]

  On 26/07/2019 at 22:31, Dan Feist said:

 

We are planning for external blinds almost everywhere, so don't think we'll need any really serious active cooling like you are planning.

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It's worth remembering that solar gain via glazing is only part of the issue though. Our SageGlass blocks 97% of solar gain but, in sustained periods of high temperatures such as the last few days, heat permeates through the roof and walls irrespective of how well insulated your build is. Okay, it may permeate more quickly through some insulation types than others, but the real issue is getting it out again once it does get in. Let's face it, if @JSHarris is using active cooling so much then I'd suggest you are wise to at least be making provision for active cooling. I'm very glad we did, I just wish I'd tried out the UFH element of it before this week ?‍♂️

Edited July 26, 2019 by NSS

[Jeremy Harris]

The point @NSS makes is a good one.  Good insulation and a structure with a high decrement delay only slows down the rate of heat transfer, it can never stop it, so if there are a few days where the mean temperature is above a comfortable level then the house will still get too warm.  That's pretty much what happened this week.

[ProDave]

I have ruled out a duct cooler, there is only one place I can fit such a thing and that would cool all the rooms, upstairs and down. Downstairs is not the problem.  So I am still set on fan coil units and will probably take a punt on some from Alibaba but not yet, other more important things to spend the money on.

[dpmiller]

what about using cold mains straight into a fan coil (with suitable flow/pressure control of course)?

[joe90]

  On 27/07/2019 at 09:02, dpmiller said:

what about using cold mains straight into a fan coil (with suitable flow/pressure control of course)?

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Not if your on a water meter?

[joe90]

I just asked family who are staying fir a week or so if they think our new build needs cooling and the answer is no, it’s a bit like heating, @JSHarris lives in a hot spot, we live in a flattish area near the Atlantic so any winds cool us enough. It’s true the conservatory gets hot (we were told on here we would cook in summer) but with windows at either end air flow is enough to keep temps reasonable. So location location makes a real difference. The only advantage of needing cooling over heating (if you have PV) is that the cooling is required when the sun shines ?.

[joth]

  On 26/07/2019 at 22:28, PeterW said:

@joth is you plan to use a small ASHP to chill the water then..? 

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Same monoblock ASHP as heating and DHW, about 5kW.

Mitsubishi is my M&E guy's go to make, but now we've agreed cooling is legal he's thinking Panasonic is better as it multiple flow temperatures and better cooling modes.

I can see myself pouring over @ProDave's excellent research in the near future

 

 

  On 26/07/2019 at 22:31, Dan Feist said:

 

We are planning for external blinds almost everywhere, so don't think we'll need any really serious active cooling like you are planning. 

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LOL, yes we're also doing external blinds and calcs say solar gain is going to be negligible.

The only reason for the ott cooling plan is that I was getting advise from 2 sides to put heating in upstairs, and didn't want radiator clutter, upstairs ufh would have minimal cooling potential (had to be between joists due to limited head height so no slab, no thermal mass), but recirculating air via a fan coil had been discussed a lot here so thought we'd give it a go.

The fact we were designing it this week also leaves its mark. If the air temperature doesn't go below 20 overnight, overheating is eventually inevitable however good the passive cooling design.

 

  On 26/07/2019 at 22:33, ragg987 said:

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

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Definitely, bit the limiting factor is probably not the capacity of the heat exchanger, but the maximum rate the MVHR system design will pass air over it. 

 

 

 

Edited July 27, 2019 by joth

[joth]

  On 27/07/2019 at 09:02, dpmiller said:

what about using cold mains straight into a fan coil (with suitable flow/pressure control of course)?

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  On 27/07/2019 at 09:08, joe90 said:

 

Not if your on a water meter?

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I was surprised to discover this actually is a thing

https://www.airconco.com/no-outside-box-air-conditioning/

 

This might not be totally terrible if they had a buffer tank and recirculate water through, and use that as a preheat for DHW and medium temperature uses like washing machine and dishwasher. Legionella compliance nightmare and highly disruptive to retrofit so I doubt this is their design in practice. But surprised they don't warn about increased water costs. It actually makes me sad as it's aimed at London flat owners, but SE is already running out of water and Thames water are one of the main culprits of emptying all the streams around us.

 

If you have a stream going through your plot it might be a wholely different argument. But... You then probably have enough space to hide an external heat pump anyway.

 

Edit to add: the above mentioned buffer tank would have to be incredibly well insulated and get used fairly frequently else this is just standing in the boat trying to blow your own sails, as Ed would say.

Edited July 27, 2019 by joth

[Jeremy Harris]

  On 27/07/2019 at 09:36, joth said:

 

 

I was surprised to discover this actually is a thing

https://www.airconco.com/no-outside-box-air-conditioning/

 

This might not be totally terrible if they had a buffer tank and recirculate water through, and use that as a preheat for DHW and medium temperature uses like washing machine and dishwasher. Legionella compliance nightmare and highly disruptive to retrofit so I doubt this is their design in practice. But surprised they don't warn about increased water costs. It actually makes me sad as it's aimed at London flat owners, but SE is already running out of water and Thames water are one of the main culprits of emptying all the streams around us.

 

If you have a stream going through your plot it might be a wholely different argument. But... You then probably have enough space to hide an external heat pump anyway.

 

Edit to add: the above mentioned buffer tank would have to be incredibly well insulated and get used fairly frequently else this is just standing in the boat trying to blow your own sails, as Ed would say.

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Might work well for those of us next to a stream.  Just needs a pump and filter plus a bit of pipework.  The flow volume would have to be kept down to less than 20,000 litres per day, though, as that's the limit before needing a licence from the EA (not sure about SEPA or NIEA, but suspect it's much the same).

[ProDave]

  On 27/07/2019 at 09:36, joth said:

I was surprised to discover this actually is a thing

https://www.airconco.com/no-outside-box-air-conditioning/

 

This might not be totally terrible if they had a buffer tank and recirculate water through, and use that as a preheat for DHW and medium temperature uses like washing machine and dishwasher. Legionella compliance nightmare and highly disruptive to retrofit so I doubt this is their design in practice. But surprised they don't warn about increased water costs. It actually makes me sad as it's aimed at London flat owners, but SE is already running out of water and Thames water are one of the main culprits of emptying all the streams around us.

 

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That is the unit I described a few posts back that we had in an office.  I didn't think they would still be allowed.

 

I would be very careful with thoughts of storing lots of warm water for use elsewhere, you would want to be sure it was HOT water, not warm.  As these are basically an ASHP I doubt they heat the water much above 50 degrees before dumping a tankful down the drain and starting again.  Or perhaps unlike the one we had, they just work on a constant slow flow of water through them so continually emit a dribble of warm water but again I doubt it will be much more than 50 degrees.

 

You would not want to be putting water that waste warm into a stream, I am sure SEPA or the EA would not like that.  Nor I doubt would you be wanting to put that in a treatment plant.

[jamieled]

With SEPA the abstraction limit is 10,000 litres although beyond that there is a sliding scale of complexity in the effort required to get permission.

 

We used to go kayaking in December/January on some of the speyside rivers where the distillers discharged waste warm water straight into the burns. Nice to warm your hands up with, but sadly not so common now.

[Jeremy Harris]

Doing some quick and dirty sums shows that quite a bit of heat could be shifted by one of these things, if they are water source heat pumps, rather than just fan coil units.

 

If the incoming water was at 10°C and the outlet water was at 40°C (so a 30° ∆_T), with the SEPA 10,000 litre/day limit, then in theory one of these could pump out nearly 350 kWh/day.  That's roughly 14.5 kW of heat pumping power that's available, which is a heck of a lot.  We're finding that 2.5 kW is pretty impressive in the recent hot weather.

 

If these water-cooled units are just really a fan coil unit, with no heat pump, then that reduces the cooling capacity a fair bit, but it would still be pretty useful.  If a fan coil unit was fed with water at 10°C and had an outlet temperature of around 18° (assuming that there may be a couple of degrees difference between the water discharge temperature and the air discharge temperature) then for 10,000 litres per day that still equates to a cooling power of nearly 3.9 kW.

[ProDave]

  On 27/07/2019 at 10:30, JSHarris said:

Doing some quick and dirty sums shows that quite a bit of heat could be shifted by one of these things, if they are water source heat pumps, rather than just fan coil units.

 

If the incoming water was at 10°C and the outlet water was at 40°C (so a 30° ∆_T), with the SEPA 10,000 litre/day limit, then in theory one of these could pump out nearly 350 kWh/day.  That's roughly 14.5 kW of heat pumping power that's available, which is a heck of a lot.  We're finding that 2.5 kW is pretty impressive in the recent hot weather.

 

If these water-cooled units are just really a fan coil unit, with no heat pump, then that reduces the cooling capacity a fair bit, but it would still be pretty useful.  If a fan coil unit was fed with water at 10°C and had an outlet temperature of around 18° (assuming that there may be a couple of degrees difference between the water discharge temperature and the air discharge temperature) then for 10,000 litres per day that still equates to a cooling power of nearly 3.9 kW.

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The one in our office was definitely a heat pump, it certainly made that sort of noise.

 

And the ones linked to above talk of a separate box in a cupboard that is usually outside, that sounds like the heat pump bit with just the fan coil on the wall in the room.

[Dan F]

  On 26/07/2019 at 23:25, NSS said:

 

It's worth remembering that solar gain via glazing is only part of the issue though. Our SageGlass blocks 97% of solar gain but, in sustained periods of high temperatures such as the last few days, heat permeates through the roof and walls irrespective of how well insulated your build is. Okay, it may permeate more quickly through some insulation types than others, but the real issue is getting it out again once it does get in. Let's face it, if @JSHarris is using active cooling so much then I'd suggest you are wise to at least be making provision for active cooling. I'm very glad we did, I just wish I'd tried out the UFH element of it before this week ?‍♂️

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Planning on some active cooling yes.  UFH cooling like @JSHarris @jack and others.  Just not sure I need to be planning for more than blinds and UFH cooling and so I'm not currenlty plannign for any additional fan coils or anything like @joth.

 

Edited July 27, 2019 by Dan Feist

[ProDave]

  On 27/07/2019 at 11:46, Dan Feist said:

 

Planning on some active cooling yes.  UFH cooling like @JSHarris @jack and others.  Just not sure I need to be planning for more than blinds and UFH cooling and so I'm not currenlty plannign for any additional fan coils or anything like @joth.

 

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Like @JSHarris my experemints this last week showed cooling the downstairs floor kept the downstairs okay but did nothing to stop the bedrooms overheating.  We are lucky that I have a route to add extra cables and pipes for 2 fan cooling units in the bedrooms.

 

I would certainly plan to put flow and return pipes and ducting or cabling so you can add those later should you find you need them, even if you don't plan to install them straight away.

[Stones]

  On 27/07/2019 at 09:24, joth said:

 

Mitsubishi is my M&E guy's go to make, but now we've agreed cooling is legal he's thinking Panasonic is better as it multiple flow temperatures and better cooling modes.

 

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We have a Mitsubishi Ecodan and I have just tested the cooling function.  Somewhat limited - I can set the flow temp (down to 5C IIRC) but other than that, it's on or off (or timed).  Heating function has to be switched off, otherwise it would kick the heating back on to rewarm the slab once you had switched off the cooling.

[j_s]

https://www.engadget.com/2019/07/29/the-morning-after-sony-wearable-air-con/

 

How about personal cooling?

[joth]

It has arrived! Although the box it arrived it was 90% destroyed, visual inspection it seems ok and mercifully the loose items in the box were still there. Next up will be an electrical and water (air??) leak test

 

 

 

€289.00 delivered from ShopClima, took about a month from order to on-site

 

 

Edited September 26, 2020 by joth

[tanneja]

@joth have you got the direct link to the product to hand?

[joth]

  On 26/09/2020 at 19:14, tanneja said:

@joth have you got the direct link to the product to hand?

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I ordered this one

https://www.shopclima.it/en/panasonic-paw-fc-d15-aquarea-compact-fan-coil-with-left-side-connection-1-5-kw.html

 

It's clearly just a systemair unit: https://shop.systemair.com/en/scc202plg2/p402066 

 (haven't worked out exactly which model number) - they didn't even bother reprinting the MI with Panasonic branding, says Systemair all over it

 

Edited September 26, 2020 by joth

[JamesP]

  On 26/09/2020 at 10:01, joth said:

It has arrived! Although the box it arrived it was 90% destroyed, visual inspection it seems ok and mercifully the loose items in the box were still there. Next up will be an electrical and water (air??) leak test

 

 

 

€289.00 delivered from ShopClima, took about a month from order to on-site

 

 

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@joth  trying to understand how this all  works. You are planning to use the cooling function from the ASHP to pass cold water through the unit which is fixed on a wall to cool the room.

Do just tee off from the heating circuit into the unit and how do you stop the rest of the house being cooled? I have UFH with 3 manifolds.

The price is very good, was AC an option for you ?

[joth]

  On 26/09/2020 at 21:04, JamesP said:

@joth  trying to understand how this all  works. You are planning to use the cooling function from the ASHP to pass cold water through the unit which is fixed on a wall to cool the room.

Do just tee off from the heating circuit into the unit and how do you stop the rest of the house being cooled? I have UFH with 3 manifolds.

The price is very good, was AC an option for you ?

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We're using the mitsubishi FTC5 controller that has specific function to manage 2 zones at different flow temperatures, here's a snippet from the MI that explains it. Fan coil will be zone 1 and ufh zone 2, we'll set the zone 1 to a higher target temp so the fan coil should rarely come on. For cooling we'd probably reverse the preference so fan coil runs first.