Fan Coil Units for use with a (cooling) ASHP

[Dave Jones]

8 hours ago, Crispy75 said:

These look quite good: https://theheatpumps.co.uk/4kw-concealed-fan-coil-unit-for-heating-cooling.html - nice and compact.

 

But there's little technical info, and all these guys seem to offer are their own badged units, no big name brands. Has anyone had experience with Megawave? Or recognise these FCUs from their travels on alibaba?

 

would lose a fair bit of space to mount them as they are very deep, could be a solution for hallways/landings though. Just check they have a condensate drain.

[Ommm]

11 hours ago, Crispy75 said:

These look quite good: https://theheatpumps.co.uk/4kw-concealed-fan-coil-unit-for-heating-cooling.html - nice and compact.

 

But there's little technical info, and all these guys seem to offer are their own badged units, no big name brands. Has anyone had experience with Megawave? Or recognise these FCUs from their travels on alibaba?

I didn't manage to find a match on a brief look around Alibaba, but Megawave's radiator-style FCUs are a dead ringer for a kind of generic boxy FCU style (Megawave v  random Alibaba example), and (for some reason) Chinese heat exchangers are often anodized in blue. So I'd guess they are Chinese, even if I can't pin down the ODM.

You could ask Megawave for a datasheet?  The thing that would bother me is the noise of the fan, which can vary depending on what kind of motor and controller they have (and is hard to picture the raw dB numbers without listening to it).

 

If it is Chinese, they often have relatively simple electrical connections to the unit (valve on/off/bypass, temperature sensor/thermistor, fan speeds 1/2/3 via mains terminals or 0-10V if an electronically commutated variable-speed DC (EC-DC)) and the wifi module is a drop in third party module.  Often on the Tuya smart platform, I wouldn't put a whole lot of store by these units (they are cheap), but at least you have access to the raw connections to do something better if you prefer that.

Edited September 17 by Ommm

[NCXo82ike]

On 23/05/2024 at 07:31, Dave Jones said:

 

It's the other way round.

 

We have this exact setup working at the moment with 7 fancoils and UFH coil.

 

We have the ASHP setup (we use Home Assistant to automate everything) to provide cooling 2c above the current dewpoint running 24x7. Dont need it for DHW as eddi and solar more than takes care of that. 

 

The fancoils (panansonic) can individually be turned on and off. Thy are just dumb radiuators at the end of the day all your controlling is a fan.

 

Commissioning the Zehnder unit the weekend which has the intake cooling/heating battery also in the ASHP loop so will see how that assists as well.

 

 

Dave, how has the heat/cool battery attached to the MVHR performed over the summer? 

Edited September 17 by NCXo82ike

[NCXo82ike]

12 hours ago, Crispy75 said:

These look quite good: https://theheatpumps.co.uk/4kw-concealed-fan-coil-unit-for-heating-cooling.html - nice and compact.

 

But there's little technical info, and all these guys seem to offer are their own badged units, no big name brands. Has anyone had experience with Megawave? Or recognise these FCUs from their travels on alibaba?

I've also spotted these recently. I don't love the look personally but appreciate the price and flexible mounting options. I presume these would also give the option for some individual room control of cooling (for examples different preferences for bedroom temperature), although with the small buffer volume issue that's been already mentioned.

 

It also strikes me that the optimal positioning and airflow direction does vary between heating and cooling applications, but I don't know how much difference that would actually make. 

Edited September 17 by NCXo82ike

[Crispy75]

1 hour ago, NCXo82ike said:

I've also spotted these recently. I don't love the look personally but appreciate the price and flexible mounting options. I presume these would also give the option for some individual room control of cooling (for examples different preferences for bedroom temperature), although with the small buffer volume issue that's been already mentioned.

 

It also strikes me that the optimal positioning and airflow direction does vary between heating and cooling applications, but I don't know how much difference that would actually make. 

 

Yeah I was attracted to them by their simple shape and slim profile. 190mm is very compact.

My understanding is that you care more about directed airflow for heating, otherwise all the warm air collects at high level and gets recirculated through the FCU. For cooling, convection does the work for you.

 

Managed to find the Chinese manufacturer via google image search:

https://aircolder.com/product/fan-coil-unit/horizontal-concealed-ultra-thin-fan-coil-unit/

 

power	48W-148W
Noise	16dB(A)-51dB(A)
Air flow	530m³/h-1750m³/h
Cooling capacity	2.95kw-9/0kw
Heating capacity	4.4kw-13.5kw

 

Looks like the intake can either be from below or from the rear if you squint carefully. Also worth noting there are no filters, so you'd either need to roll your own or make sure you can acess the heat exchanger for cleaning.

 

 

Product components	Coil	Fin	0.105mm thickness aluminum fins, distance between fins is 1.3mm
		Cooper tube	Three rows, 0.28mm thickness, 7mm diameter, 30 tubes in total, FP-136,24tubes
	Drain	Drain pan	High density polyurathane material with plastic coating
		Drain pump	Available(Biult-in for advanced, external for standard)
		Alertor	Available( only for advanced)
	Shell	Panel	0.8mm Al-Zn-Si hot-dip galvanized steel sheet
		Insulation	EVA insulation pasted outside and inside the panel， B1 rating
	Motor	Standard	Low noise 3 speed fan motor , DC motor available
		Advanced	DC motor with 0-10v thermostat
	Label	Labels: model label, wiring diagram, precautions, fan rotation, logo, etc.
	Fan	ABS material Centrifugal, forward-curved blades
	Control	Standard	LCD thermostat available
		Advanced	Equiped with 0-10v thermostat

 

 

 

 

Edited September 17 by Crispy75

[NCXo82ike]

I forgot to include the link to the product I was referring to- these are what I spotted https://aerfor.com/en/reverso

 

1 hour ago, NCXo82ike said:

I've also spotted these recently. I don't love the look personally but appreciate the price and flexible mounting options. I presume these would also give the option for some individual room control of cooling (for examples different preferences for bedroom temperature), although with the small buffer volume issue that's been already mentioned.

 

It also strikes me that the optimal positioning and airflow direction does vary between heating and cooling applications, but I don't know how much difference that would actually make. 

 

[JohnMo]

You can get them from Cool Energy, often sell on eBay at reduced prices

[Ommm]

3 hours ago, Crispy75 said:

 

Yeah I was attracted to them by their simple shape and slim profile. 190mm is very compact.

My understanding is that you care more about directed airflow for heating, otherwise all the warm air collects at high level and gets recirculated through the FCU. For cooling, convection does the work for you.

 

Managed to find the Chinese manufacturer via google image search:

https://aircolder.com/product/fan-coil-unit/horizontal-concealed-ultra-thin-fan-coil-unit/

 

Ah, YESNCER have been spamming me every few months ever since I messaged them on Alibaba in 2021 🙂
https://yuexinly.en.alibaba.com/index.html
 

Their horizontal FCUs are between $50-200 depending on the size and options, obviously there's shipping and tax to add to that.  Typically they have a basket of options and the price depends on which options you pick and how many units you want, so the price displayed is a bit hypothetical.

When I looked they seemed OK - hard to judge quality.  If it has the DC motor with 0-10v analogue speed control that's the better quieter motor.

[Andrew D]

Anyone any experience of Jaga Briza High performance fan convectors and fan coil units for heating and cooling (jaga.co.uk)

They do wall and concealed versions that can be connected in different ways.

Also have very good outputs for the larger ones.

No pricing though so I assume they could be pricy.

[Ommm]

24 minutes ago, Andrew D said:

Anyone any experience of Jaga Briza High performance fan convectors and fan coil units for heating and cooling (jaga.co.uk)

They do wall and concealed versions that can be connected in different ways.

Also have very good outputs for the larger ones.

No pricing though so I assume they could be pricy.

Euro pricing:
https://netzero.jaga.com/docs/Briza_Net_Zero_Listing_EX.pdf
 

I have a feeling I contacted them in 2021 but can't find any email - maybe I filled in one of those web forms and they didn't get back to me?  I don't remember exactly.

[Crispy75]

(quoting from another thread)

23 minutes ago, JohnMo said:

I did indeed. But then even more reason not to zone. Heat pump you really have too options no zones and super simple, or a big buffer (never a small one), additional pumps to buy and run and zones with controls. I am down the simple route and now only have a switch to change over from heating and cooling and a diverter valve for the cylinder heating to CH change over.

So yes you're right about zones. I was confusing myself reading the Aquarea installation docs >_<

 

But I can't send cooling water round my existing pipes and rads. The condensation would be a nightmare. I was assuming something along the lines of this, where the FCUs are all on a (short) run of new well-insulated pipe, while all the rads are on the existing loop, or extensions of it:

 

 

Valves A1 and A2 operate at the same time to isolate the cooling loop from the DHW/CH loop and valve B switches between the rads and the tank. (No need for a bypass valve in the heating loop as the bathroom rad has no TRV fitted).

 

I have only ever been MEP adjacent so am here to be schooled

[JohnMo]

You actually have volumisers not really a buffer.

 

A2 valve isn't really needed. If A1 closes the flow entering FCU is stopped and so is reverse flow.

 

Why will condensation be an issue, just pump the water around in cooling mode above dew point which will give you plenty of cooling power from the fan coils and no condensation issues. 

 

With a heat pump you have a minimum flow requirement, it is very unlikely you will get through a single radiator. My 6kW is 9L/min minimum flow not sure you will squeeze that through a bathroom radiator.

 

From your info on the other thread your heat load is around 2kW, but you are planning 11 radiators and 4 FCUs - seems a lot, plus two volumisers. Think some simplification is needed somewhere. You're well insulated and you really don't need heat in every space or under every window to heat up drafts, that may exist in a more normal house. 

 

[Crispy75]

11 sounds like a lot, but it's the existing compliment of 8, plus 1 in each new main bedroom and 1 in the new bathroom (towel rail). The total rad area gives me the heat output I need, so I'd only be able to reduce the count by replacing some with larger units. 4 FCUs would be the maximum. Obviously fewer larger units is better but it will be tricky squeezing ducts in.

 

Talk of skirting the dew point makes me nervous I have to say. Not to mention the losses through all the uninsulated pipes. Distributed heating is ok (the way the previous owners installed the system, it means the hall and landing effectively have UFH!) but I'll only want cooling in specific places.

 

In any case, I won't be doing this DIY. While I'd relish the challenge and love a project, I just won't have the time (family life, busy day job, postgrad studies). So for now I'm just settling on a strategy that I can then take to some installers.

 

Thanks for all the advice btw. This is an excellent forum and I wish I'd foudn it sooner!

[Dave Jones]

On 17/09/2024 at 11:03, NCXo82ike said:

Dave, how has the heat/cool battery attached to the MVHR performed over the summer? 

 

crap, made zero difference to cooling. Hoping it will be better for heating. Definately wouldnt bother with one again.

[NCXo82ike]

2 hours ago, Dave Jones said:

 

crap, made zero difference to cooling. Hoping it will be better for heating. Definately wouldnt bother with one again.

Exactly the clear answer I needed! Out of interest though, have you got any data through HA about it? What size heat battery have you got, and what flow temp and air flow were you using?

[JohnMo]

2 minutes ago, NCXo82ike said:

Exactly the clear answer I needed! Out of interest though, have you got any data through HA about it? What size heat battery have you got, and what flow temp and air flow were you using?

Just look at a datasheet, they even say they are rubbish, when you apply your airflow rates. Think from memory a typical 200m2 house is going to get a kW of cooling if you are lucky. I was getting a CoP of about 7 doing floor cooling and a fan coil, doing a a cool battery you need to flow at lower temps and CoP is likely to be nearer 4.  So rubbish output and higher running costs, what is there to like.

[Dave Jones]

exactly. i think they are more for heat but at the price would take several lifetimes to pay back. 

[JohnMo]

All of a sudden we have moved from our cold weather into hot, so flicked the heat pump back into cool mode for awhile yesterday, as the house was starting to get a bit toasty. Over a period of 2.5hrs we pulled 12.5kWh of heat out the house floor and summer house using 2kWh of solar energy.

 

The fan coil decreased summer house by 5 degrees in 2 hrs. Similarly the house temp dropped a similar amount but with a 15 min lag over the fan coil. Cooling in house is via UFH loops only.

Edited September 19 by JohnMo

[NCXo82ike]

18 hours ago, JohnMo said:

Just look at a datasheet, they even say they are rubbish, when you apply your airflow rates. Think from memory a typical 200m2 house is going to get a kW of cooling if you are lucky. I was getting a CoP of about 7 doing floor cooling and a fan coil, doing a a cool battery you need to flow at lower temps and CoP is likely to be nearer 4.  So rubbish output and higher running costs, what is there to like.

Yeah I had looked at the datasheets- the largest comfopost can do 2.8kw cooling (ERV MVHR) with 600m^3/hr air flow. So noisy and limited cooling- but I think it's useful to get actual experience of that too.

 

There's another useful thread on here from someone who decided against heat battery/cooling in the end. 

 

[NCXo82ike]

2 hours ago, JohnMo said:

All of a sudden we have moved from our cold weather into hot, so flicked the heat pump back into cool mode for awhile yesterday, as the house was starting to get a bit toasty. Over a period of 2.5hrs we pulled 12.5kWh of heat out the house floor and summer house using 2kWh of solar energy.

 

The fan coil decreased summer house by 5 degrees in 2 hrs. Similarly the house temp dropped a similar amount but with a 15 min lag over the fan coil. Cooling in house is via UFH loops only.

Hi John, what's the floor area and the floor construction inc covering your UFH is in? Was this ground floor only, or upper floors?

 

That's superb efficiency and personally I'd see the money as well-spent to maintain a comfortable temperature. I still come across lots of people who happily burn oil to heat their house to 25 degrees but think it's unacceptably wasteful to apply cooling using (renewable or even self-generated) electricity. 

[Dan F]

3 minutes ago, NCXo82ike said:

Yeah I had looked at the datasheets- the largest comfopost can do 2.8kw cooling (ERV MVHR) with 600m^3/hr air flow. So noisy and limited cooling- but I think it's useful to get actual experience of that too.

 

There's another useful thread on here from someone who decided against heat battery/cooling in the end. 

 

I have one.  They are useful for ensuring MVHR doesn't gradually heat up the house when external termperature is high, but I wouldn't recommend for "active" cooling and if I was doing this again I'd definitly opt for fancoils instead.

 

That said, because we have automatic external blinds and cooling load is very low we aren't in a rush to install fancoils and Comfopost does help keep first floor temperatures more comfortable than if we didn't have it installed. If we didn't have the external blinds though, it would be a different story.

 

You do have to run the comfopost fairly constantly for this work though, and I've gradually adjusted circuit flow temp to ensure this doesn't cause ASHP to cycle like mad.  I've put a Loxone automation in place to automatically turn on comfopost circuit when MVHR is delivering warm air to bedrooms, and boost if required.

 

[JohnMo]

10 minutes ago, NCXo82ike said:

2 hours ago, JohnMo said:

Expand  

Hi John, what's the floor area and the floor construction inc covering your UFH is in? Was this ground floor only, or upper floors

Bungalow so ground floor only. 192m² area, UFH at 300mm centres. 200mm PIR with UFH pipes stapled to insulation. 100mm concrete screed. Summer house also well insulated.

[NCXo82ike]

1 minute ago, Dan F said:

 

I have one.  They are useful for ensuring MVHR doesn't gradually heat up the house when external termperature is high, but I wouldn't recommend for "active" cooling and if I was doing this again I'd definitly opt for fancoils instead.

 

That said, because we have automatic external blinds and cooling load is very low we aren't in a rush to install fancoils and Comfopost does help keep first floor temperatures more comfortable than if we didn't have it installed. If we didn't have the external blinds though, it would be a different story.

 

You do have to run the comfopost fairly constantly for this work though, and I've gradually adjusted circuit flow temp to ensure this doesn't cause ASHP to cycle like mad.  I've put a Loxone automation in place to automatically turn on comfopost circuit when MVHR is delivering warm air to bedrooms, and boost if required.

 

Thanks Dan, your comments on that other thread I linked were very helpful. 

 

My understanding is that if you have active cooling, the MVHR should cool intake air using exhaust air if you disable the summer bypass?

Are there any benefits you can see you the comfopost additional to fancoils +/or UFH at all? 

I.e. if money were no object (unfortunately not the case) then could you argue for both comfopost plus the UFH/fancoils?

[Dan F]

35 minutes ago, NCXo82ike said:

Yeah I had looked at the datasheets- the largest comfopost can do 2.8kw cooling (ERV MVHR) with 600m^3/hr air flow. So noisy and limited cooling- but I think it's useful to get actual experience of that too.

 

 

2.8kw cooling is actually a fair amount for a very insulated house in the U.K, assuming you have shading/overhangs.  Our calculated cooiing load was <1kW from what I remember. 

 

The thing is, and I didn't realise this at the time, those numbers are based on:

- Water temp of 7C which isn't particulatly efficient.

- Air temp of 28C

 

But post-MVHR air temperature is never 28C assuming you keep internal temperature under control.  If external temperature is 41C, internal temperature is 21C and MVHR efficency 90% you are looking at closer to 23C.   And, if post-MVHR temp is 23C and not 28C cooling power is only 75% of what is quoted.

 

On top of that, you can't really compare cooling power of Comfopost with cooling power of fancoil if you need run mvhr on boost to increase cooling, as it's cooling warmer incoming air, not air at existing room temperature.

 

A simpler approach to stopping first-floor heating up via MVHR on all but the very hottest days is to turn MVHR to minimum during the day on very hot days.  Not as effective, but lot simpler..

 

 

Edited September 19 by Dan F

[Dan F]

11 minutes ago, NCXo82ike said:

My understanding is that if you have active cooling, the MVHR should cool intake air using exhaust air if you disable the summer bypass?

 

You don't have to disable anything, this is all automatic.

 

11 minutes ago, NCXo82ike said:

Are there any benefits you can see you the comfopost additional to fancoils +/or UFH at all? 

We have UFH on ground-floor and Comfopost on first floor.   (not a great idea as boosting MVHR to increase first-floor cooling brings in more warm air on ground floor)

 

If you have UFH and/or fancoils on both floors there is no reason to install Comfopost no.  In our case installing UFH on first-floor wasn't justified and given the cacluated cooling load was so low we felt that fancoils weren't justfied either.  The comfopost was more of an insurance than anything else.  What we realised living here though is that bedroom temperature can be quite important for some people to sleep well, and controlling bedroom temperature would have been very easy and effective with fancoils, but much harder with comfopost where you need to run it for extended periods of time and maintain the whole first-floor at a lower temperature.

 

Edited September 19 by Dan F