Fan assisted radiators

[JamesPa]

Has anyone here tried/have any practical experience of fan assisted radiators. 

 

A couple of my rooms need about 1.2 1kW and Im trying to design for a flow temp of 45C.  That makes for a large radiator for the free wall space available, and sadly type 33 is too thick to fit conveniently in the space. 

 

So I'm looking at alternatives (if only to rule them out).  Fans seem the obvious one, but Im concerned about noise particularly as the bearings wear.  Any practical experiences or recommendations?

[SteamyTea]

When you find out how much noise they make, let me know.

Realistically it is the best way to add a wet heating system into my house.

[TW9]

We have them. Climaveneta i-Life2. They work well but aren't perfect.

 

There's hardly any mechanical noise but you get the noise of air blowing through the vents. It isn't very loud and we got used to it quickly. You have to clean the filters every few weeks, which I do when vacuuming the house.

 

They don't start up until the water temp is 30 degrees so it you're running a low flow temp and the rad is near the end of the circuit you might have problems. You should be fine with a 45 degree flow temp but it's something worth bearing in mind.

 

The controls aren't great although once you've managed to get them set as you want you can mostly just leave them alone.

 

The biggest problem is the cost. They're about £600 each. I did see someone on one of the Facebook heat pump groups selling their i-Life2 rads so you might be able to pick one up for less.

[SteamyTea]

I was thinking more along plinth heaters.

[Wil]

Hmm, the plinth heaters require a plinth though? Although I suppose one could get creative with built in furniture/ raised floors. Also interested in the noise.

 

I bought one of the Fan Coils from Cool Energy when I got my HP. It’s got an unbalanced fan deck so sounds like a clacker which is irritating. I’d asked about repair but have had no joy so I’m trying to go through a returns process soon. I’m sure the unit would be excellent if it weren’t unbalanced and the heat output seems good.

 

Still looking for better and cheaper options…

[Ommm]

I was expecting the Cool Energy fan coils to be some Alibaba special, but it seems they're Italian and the Reverso range made by Aerfor:
https://aerfor.com/ventilconvettori-idronici

(the engineer's name is on the wiring diagrams and they're on LinkedIn ;-)

I've never heard of them so no idea if they're a reliable make, but perhaps worth talking to them if you get nowhere otherwise.

 

The specs look decent and the pricing isn't terrible, so I'm a bit sad they're not up to scratch.

 

In general Italy seems to be the place to look.  This place will supply to the UK:

https://www.shopclima.it/en/hydronic-system/hydronic-fan-coil.html

but a lot of theirs are out of stock at the moment.  Pricing not massively different from the Reverso.

 

Otherwise time to take your chances on Alibaba?  Cheaper, but plus shipping, and an unknown quantity...

 

Edited May 17, 2022 by Ommm

[Ommm]

There's also:

https://www.plumbnation.co.uk/site/smith-s-ecovector-ll1200-low-level-hydronic-fan-convector/

and

https://www.ebay.co.uk/itm/403556834346

which looks like it's Chinese, one similar to these:

https://yuexinlengnuan.en.alibaba.com/productgrouplist-907113836/ultra_thin_exposed_fan_coil_unit.html

 

I've asked a few companies for quotes for radiator FCUs (Daikin, Systemair, Aermec, Olimpia Splendid, probably some others), they all come in roughly at £500 kind of ballpark.  Which does make the Alibaba option somewhat attractive.

 

[Wil]

17 hours ago, Ommm said:

I was expecting the Cool Energy fan coils to be some Alibaba special, but it seems they're Italian and the Reverso range made by Aerfor:
https://aerfor.com/ventilconvettori-idronici

(the engineer's name is on the wiring diagrams and they're on LinkedIn 😉

I've never heard of them so no idea if they're a reliable make, but perhaps worth talking to them if you get nowhere otherwise.

 

The specs look decent and the pricing isn't terrible, so I'm a bit sad they're not up to scratch.

 

 

 

Ah that’s good research. I knew they were Italian and a Reverso unit but hadn’t gone as far as looking up the manufacturer. I’d like to think my issue is a one off and if the deck wasn’t catching it would be fine. I had to supply my own controls and actuator for it which was fine but needs added to the cost. I had a chinesium controller I had been testing which happened to fit fine.

 

The eBay unit is interesting. I’d be far keener to hide it behind some ‘radiator cover’ and let the fan do the work in spreading the heat. The rad cover shouldn’t kill the output as it does with a passive convective rad. It just depends if it was quiet!

 

I can’t find a decent tangential fan to build my own FCUs using cheap Type 22 rads in an enclosure with some fans. Had considered using multiple 120mm computer fans but there seems to be a reason someone hasn’t tried this before.

[joth]

18 hours ago, Ommm said:

In general Italy seems to be the place to look.  This place will supply to the UK:

https://www.shopclima.it/en/hydronic-system/hydronic-fan-coil.html

 

Yes, I bought my "Panasonic" FCU from shopclima, (actually rebranded Systemair unit). Rather tatty condition package by the time it got here, but otherwise do drama  (pre-Brexit).

 

17 hours ago, Ommm said:

they all come in roughly at £500 kind of ballpark.

 

Note the size of FCU makes a big difference to the price, and you need to size it (and the buffer tank) carefully both to be effective and to avoid short-cycling the heat pump. 

 

[Ommm]

25 minutes ago, Wil said:

I can’t find a decent tangential fan to build my own FCUs using cheap Type 22 rads in an enclosure with some fans. Had considered using multiple 120mm computer fans but there seems to be a reason someone hasn’t tried this before.

 

Ah, that's an idea.  Seems the search term is a 'cross flow fan' and there are quite a number on Aliexpress, although mostly <500mm long.  As to whether they're good or quiet I have no idea...

 

There isn't actually a whole lot to a FCU, and I was wondering about DIY options: fan, heat exchanger, condensate collection (when cooling).  Seems like the heat exchangers are available on Aliexpress (search term 'fin tube radiator' or 'condenser').

 

There are also heat exchangers in a ducted box: ebay.co.uk/itm/203459846544 - I was previous pondering using one in a ducted form with an external fan, but now back to looking at wall or ceiling mounted boxes. 

 

[JamesPa]

You can buy add on gizmos using computer fans 

 

https://www.speedcomfort.com/

https://www.amazon.co.uk/4YourHome-Electric-Radiator-Fan-Power/dp/B0764HNSWM/ref=asc_df_B0764HNSWM/?tag=googshopuk-21&linkCode=df0&hvadid=344405143865&hvpos=&hvnetw=g&hvrand=16317663834846469275&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007050&hvtargid=pla-716714793109&psc=1

 

and others.  That's an option I was also considering particularly as my 'problem rads' are already behind radiator covers.  I would prefer something 'properly built' but the impression I'm getting from the posts on this forum is that there is no such thing in which case DiY may well be the way to go.

 

[Wil]

2 hours ago, JamesPa said:

You can buy add on gizmos using computer fans 

 

https://www.speedcomfort.com/

https://www.amazon.co.uk/4YourHome-Electric-Radiator-Fan-Power/dp/B0764HNSWM/ref=asc_df_B0764HNSWM/?tag=googshopuk-21&linkCode=df0&hvadid=344405143865&hvpos=&hvnetw=g&hvrand=16317663834846469275&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007050&hvtargid=pla-716714793109&psc=1

 

and others.  That's an option I was also considering particularly as my 'problem rads' are already behind radiator covers.  I would prefer something 'properly built' but the impression I'm getting from the posts on this forum is that there is no such thing in which case DiY may well be the way to go.

 

I have one of the ‘sit on top fans’ from your second link as well. (I have a lot of solutions without getting the right one yet!) It’s a bit noisy, ok when the TV is on, but couldn’t be used in a quiet room. I didn’t feel it massively improved my rads either (but that’s anecdotal in a room with undersized rads and no proper testing).

 

Possibly could be taken apart and used to create the DIY FCU discussed above.

[Wil]

3 hours ago, Ommm said:

 

Ah, that's an idea.  Seems the search term is a 'cross flow fan' and there are quite a number on Aliexpress, although mostly <500mm long.  As to whether they're good or quiet I have no idea...

 

There isn't actually a whole lot to a FCU, and I was wondering about DIY options: fan, heat exchanger, condensate collection (when cooling).  Seems like the heat exchangers are available on Aliexpress (search term 'fin tube radiator' or 'condenser').

 

There are also heat exchangers in a ducted box: ebay.co.uk/itm/203459846544 - I was previous pondering using one in a ducted form with an external fan, but now back to looking at wall or ceiling mounted boxes. 

 

I haven’t had the time or skill to devote to this yet, but FCUs are incredibly simple when it comes to it so Shirley it can’t be that hard.

 

Perhaps a collection of AliExpress parts would be the way to go.

 

This was the post that put me onto the DIY FCUs in the first place:

https://originaltwist.com/2018/11/14/diy-fan-coil-heater/

 

Some interesting ideas there.

[Ommm]

I had looked at those commercial radiator fans: currently the ASHP is plumbed into radiators and I can turn it onto cooling mode and it makes the rads nice and cold, but that doesn't do much for the rest of the room.  I wondered if they would be a short term fix for cooling, before I can plumb in a better solution (needs a complete new zone fitting).  But they're quite expensive for what they are, quite small fans and hence likely noisy, and I don't think a K22 rad is going to be much good for cooling (maybe OK for heating).  The Amazon reviews aren't very good, and I'd really want a horizontal top mounted one (condensate would drip onto a bottom mounted one, and blowing air at the ceiling isn't much help)

 

So personally I'm looking at ceiling mounted units, which makes the aesthetics more tricky.  But I could definitely see a built in piece of 'furniture' with integrated FCU having some potential.  There are also commercial FCUs designed to be integrated (to be boxed in or otherwise), if the DIY plumbing approach doesn't cut it.

 

Although... looking at:

https://radiatorfan.co.uk/radiator-fans/

it doesn't look like it would be impossible to 3D print the end pieces, and then you just need some strip plastic and the blower to go inside.

 

Somewhat tempted to get one of the 4YourHome ones to play with and return it if unsuitable, but can't help but feel it's too small for the job.

[JamesPa]

I also fear the bolt on units are too small.  Fundamentally a small fan has to go faster to shift a given volume of air, so the fan noise will be greater than if a larger fan is used.  Having said that some of the noise is clearly friction at the grilles, which is dependent only on flow rate not fan size.  

 

Cross flow fans seem to have quite narrow blades so I do wonder how efficient they are.  It's not inconceivable that an array of computer fans with well designed blades could be less noisy.  Unfortunately this is either a lot of 'suck (or rather blow) it and see' or a horrible problem in fluid- and thermo-  dynamics  to optimize.  I sincerely doubt that the manufacturers of fancoil units employ fluid dynamicists to do their design, although it might make a good PhD topic.  After all this is not an abstract question, there will be plenty of retrofit examples where conventional radiators are too big conveniently to fit and a properly designed fan would fix the problem.

 

On another tack, looking at the specs of commercial units they all claim to be low water content and the grant ones at least have dire warnings about the perils of combining them with regular radiators.  Does anyone know the reasoning behind this.  For an ashp application it's far from clear that this is helpful.

Edited May 19, 2022 by JamesPa

[SteamyTea]

29 minutes ago, JamesPa said:

Fundamentally a small fan has to go faster to shift a given volume of air, so the fan noise will be greater than if a larger fan is used.

Bit more complicated than that because of the effective area lost where the motor spindle attaches to the fan.  Small fans loose a greater fraction of area.

But that lost area also has less of an overall impact on airflow.

Then, approaching the blade tips, 'apparent wind' effects can dominate, why blades are twisted and have different areas/profiles. This can also affect the air vortices  after the blade, too low a pressure and the airspeed speed stalls.

Small fans i.e. computer cooling fans, are basically blunt tools to shift as much air as possible, within a fixed form factor i.e. fit on the CPU and within the case.

This is why liquid cooled systems are now used.  My old Acer had a phase change system that allowed for a very low profile, but a larger fan fitted in a more convenient place (I cooked the CPU as I never cleaned the fan out).

Quite simply, when it comes to shifting air, fan diameter, and therefor surface area, is the governing factor.

[dpmiller]

Pricey I know, but Papst do some lovely quiet and efficient tangentials, I see these used in cooled incubators and the like

 

https://uk.rs-online.com/web/p/centrifugal-fans/2436423

[JamesPa]

Thinking around this topic, I wonder what the design characteristics are in terms of speed of airflow (and hence noise) vs extra emission. 

 

My thought is that the manufacturers probably tend to go for max emissions per unit area, but perhaps that's not what is needed in all applications.  The Grant fancoils, which are 410mm high, do 2356W/1830W per metre length @DT50, respectively on 'High' and 'Low' speed.  A 400mm high type 22 radiator is about 1200W per metre length, suggesting that a 'gain' of about 2 is possible.

 

So if (say) only a 30-40% 'gain' is required in a particular application, (and presuming the fan is turned down accordingly) does this reduce the noise level to inaudible?  

 

There may be considerable room for 'playing around' here with the trade-offs.  It would be nice if they had variable speed and an emission curve!

 

 

[Ommm]

On 19/05/2022 at 07:56, JamesPa said:

On another tack, looking at the specs of commercial units they all claim to be low water content and the grant ones at least have dire warnings about the perils of combining them with regular radiators.  Does anyone know the reasoning behind this.  For an ashp application it's far from clear that this is helpful.

Having looked it up, the instructions for the Grant units say not to combine them because of different flow requirements.  I presume that if you put a fan coil and a radiator in parallel, one will take all the flow leaving the other one ineffectual.  I think it might be helpful to put them on separate pumped circuits so that flow is achieved through both (bit like UFH manifolds often have their own pump)

 

(I don't have a good handle on whether the FCU or the rad will take more of the flow)

[SteamyTea]

I have just changed the resistor pack for the heater fan on my car. Part was cheap.

What a bigger to get to.

Make sure whatever you do has easy access.

 

[Ommm]

Out of skepticism I thought I’d give the 4YourHome HT500 sit on top fan a try. Turns out it’s imported by Qualtex who supply appliance parts, hence sales by ‘white goods spares’ shops. It’s a centrifugal fan along the whole 500mm length, rather than some others which just have computer fans every 300mm or so. Probably 50mm diameter of the cylinder. The cylinder has a bit of wobble in it, possibly it’s not fixed perfectly on axis.

 

 Some pictures below. A quick test measured 32dBA at one metre  with the unit off (NIOSH SLM app, iPhone 8+), 40dBA on speed 1 and 43dBA on speed 2. The noise appears to be directed out the front, with a whiny component: can’t decide if it’s resonance of the cylinder or coming from the motor/far end bearing. I think it might be the blades buffeting air against the plastic grille at certain speeds.

 

At that distance you can’t really feel the draught, but you can closer in. I don’t have a good feel for airflow, but probably ‘not a lot’. The air does feel cooler, being drawn past a radiator full of water that hasn’t been on, compared with ambient air which is about 20C at the moment. Will have to wait for a hot day and radiator cooling to see how it performs. 

[Ommm]

and in ‘action’:

 

[markocosic]

Do you really need that power in that room?

 

E.g.

 

I would fit a "boost" air to air heat pump with the indoor unit in the upstairs landing plus "undersized" rads to the bedrooms.

 

Dump excess heat into the landing with doors open during cold snaps.

 

Dump coolth into the landing with doors open during warm spells.

 

The overall cop of the a2a unit at say -7C plus your radiator heat pump at 40C will be higher than just your radiator just pump at 45C. Especially as the a2a runs in daytime high air temp and is off at night.

 

And the cooling will spank what you can do with rads.

[ian192744]

I looked at the commercial units and decided a) too small b) no control over the quality or noise level of the fans used (undoubtedly cheap crap) c) quite pricey for what they are so I'm building my own.  

 

Fitted 

 

 

unmounted

 

controller

ler

 

 

fan unit components:

• Arctic F9 or F8 PWM PST Fans (daisychained)
• Cable ties to hold the fans together
• Circular Neodymium magnets with countersunk holes, Bolts to hold them on

Magnets itself to the underside of a flat panel K2 rad very nicely.

Not nice enough to be commercially sold obviously , or to be on display to the world, but if its out of the way or you're not fussed about elegance, its ok.

 

control unit:

• 12V PSU
• ESP32 controller , PWM output for fan speed, 3.3v (ESP) ->5v (FAN PWM) level shifting . Using a board from https://www.mottramlabs.com/index.html
• 12V relay for fan power on/off
• DS18B20 temperature sensor (gaffer taped to back of radiator)
• All run from ESPHOME and HOMEASSISTANT

Photos are of the prototype version, tested end of 2022 winter. Temp sensor turns on the fans when rad is over 30C, ESP32 PWM controls the fan speed between 20% and 35% up to 50C flow. Its silent, and generates a noticeable improvement in room warmup time (I have not measured scientifically just by the "does Mrs Ian put more jumpers on or not" test....)

 

I currently have a gas boiler was running it at 50-55C flow (with heating only of course!) whilst testing this in preparation for ASHP hopefully later this year.

 

Ian

 

Edited May 25, 2022 by ian192744
additional

[SteamyTea]

13 minutes ago, ian192744 said:

I'm building my own

Brilliant.

You going to add some monitoring while you are at it?