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Ommm

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  1. Well yes, which is why they normally have an enormous fan mounted behind them :-)
  2. There aren't generally pumps inside each radiator, which is what you'd need to avoid stratification. Of course the pump is moving water around the system, but that doesn't distribute heat/cold across the surface of the radiator - we rely on convection inside the radiator to do that. To do it for cooling, you'd either need a radiator with inlet and outlet plumbed at the top (cold water sinks, pushing up hot water) which would be no good for heating, or you need a serpentine tube making the radiator a long pipe run rather than a vertical body of water. For example this is sold as a 'transmission cooler radiator' for a car: https://www.amazon.co.uk/Transmission-Cooler-Auto-Manual-Radiator-Converter/dp/B08JGQQLYY/ and it doesn't matter which way it's mounted as the fluid flows through the whole loop. A central heating radiator isn't like that - you can 'short circuit' from inlet to outlet and bypass most of the water inside.
  3. You’re mad, but not for the reason I expected. I’ve been playing with 80mm fans on top of radiators with the ASHP on cooling. The problem was not condensation (which isn’t very bad) but limited surface area and lack of convection. They don’t really cool at all. The convection issue is the fatal flaw. In heating systems you feed the radiator with hot water at the bottom. The hot water rises and, at the other end the cold water sinks. The outlet from the radiator is the cold water from the bottom of the other end, resulting in the heat evenly distributed across the radiator. When you use the same setup for cooling, the cold water stays at the bottom, and the hot water stays at the top. Hence you get a strip of cold maybe 6” high at the bottom as the water passes from inlet to outlet and the rest is cool but not cold. Condensation only forms on that strip. When putting a fan on top you’re mostly passing air over the cool part, and the cold part is untouched. If you put the fan at the bottom the condensation drips on it. The radiator fins also aren’t very fine and so you’re mostly sucking air past the radiator (I can’t seal well enough to go from only the closed part of the fins). Result is a cold wet radiator but not troubling the room air very much at all. So unless you’re willing to turn your radiators upside down in the summer I don’t think they’re going to work.
  4. I suspect the 4YH noise is due to the aluminium crossflow fan barrel spreading out as it spins due to centifugal force, which then sets a resonance up against the plastic casing. It only seems to be at particular speeds (which includes both of the speed settings). I'm going to send it back, otherwise I would take it apart to investigate. 45 degrees is a good thought - would stop it interfering with curtains etc over the radiator. I did wonder about 80mm guttering for that (in white): https://www.floplast.co.uk/product/offset-bend-3 although probably a trough style arrangement a bit like the 4YH case but wider would be better. Might be possible to make something neat with white uPVC sheet eg fascia board, perhaps on a wooden frame. Or possibly large-section electrical trunking (also uPVC).
  5. @ian192744 Your setup's really interesting - I hadn't realised computer fans were so cheap (I'm used to buying the full CPU cooler). The Arctic fans are about £4-5 each which makes it cost effective to fit loads of them. I bought a couple to try out: the non-PWM versions of the Arctic F8 and the Arctic P8 (my rads are 60mm deep so need to stay small). At full 12V power the background sound with the fan off was about 29-30dBA at 1 metre and with the fan on 32-33dBA. That's just holding the fan in my hand and pointing the airflow towards my phone measuring sound. I couldn't measure a difference between the two models on the phone, but when holding them the P8 sounded slightly louder. Each fan took about 0.09A at 12V, so about 1.1W. So those are much better sound wise than the 4YourHome unit. I haven't compared them for airflow yet: I suspect I'd need several fans to equal the output of the 4YH (which has no specs for air volume, but is rated at 12W) - the F8 claims 52.7m3/hr at 2000rpm, the P8 claims 40.3m3/hr at 3000rpm with higher static pressure (which it was not experiencing in my test). For cooling I'll have to consider the mounting. I'll have to mount them on the top of the rad so there's space for condensate collection at the bottom (gutter and water bottle?). Maybe it makes sense for them to blow cold air up, to encourage room air to mix and warm air to come in underneath (fighting convection). Or maybe a room fan is needed to destratify the room. Things to ponder...
  6. 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.
  7. 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)
  8. I am a novice at this, but if I understand it right the Aquair is just a big fan coil box: hot water goes into a heat exchanger, fan blows air over the fins, heat is transferred from the water to the air. In an air2air system the emitters are roughly the same, only with refrigerant fluid rather than water. As discussed on other threads on this forum recently, fan coils don't seem very complicated to make. It's a case of having a suitable fan/heat exchanger combination to do the transfer, and sizing it for enough airflow/heat exchanger area to transfer the amount of heat at the flow temps that you want (I agree it's not obvious how to calculate this). Fan coils for ducts are very common in commercial premises. As you say, the diameter of your ducts is going to limit how much air you can deliver and the temperature of that air how much heat. But you can still increase the airflow (until you hit limits like noise) and the flow in the fan coil. Perhaps you might be able to divide your ducts and install multiple fan coils in strategic locations - that increases the total heat exchanger area and so each one has to work less hard. For cooling, if you can get at the outside of your ducts you can (and should) insulate them. If they are buried it would seem to me condensation is less of a problem - there's no free air hitting the outside of the duct. You might eventually cool the concrete/etc to the point where it drops below the dew point, but that might take a lot longer and offer more chance for evaporation if you aren't running the system continuously.
  9. 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.
  10. 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.
  11. 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.
  12. 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...
  13. Agreed. The main issue with wall-hung FCUs (either radiator style, or traditional A/C wall units) seems to be that they try to pack everything into a small package, which means forcing air at moderately high pressure through relatively small apertures. Whereas I'm looking at 200mm ducts, which means it may be possible to dial down the fan speed to keep the airflow noise down. Also avoiding flexi ducting should help. However many of the basic heat exchanger boxes don't have good datasheets so it's hard to know the relation between airflow and cooling power. Might just have to experiment.
  14. https://github.com/aerona-chofu-ashp/modbus There are some slightly unusual default baud rate settings (by default 19200 bps, no parity, two stop bits), but it's enabled by default. Modbus is a request-response protocol, so if you don't send a valid request you won't hear anything back. Once I had the baud rate settings (and got my +/- the right way round) it worked straight away.
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