I have room for wall mounted radiators but I really don't want to give away wall space to some big white thing.
Are there any small radiator designs that contain discreet tangential fans to enhance their output?
And a quite separate question. Why are radiators white, or even chrome? Surely matt black would make them more efficient, so they could be smaller?
I think Myson have traditionally dominated this sector, but their units were neither compact nor pretty last I saw - but that was a fair while ago.
You can diy your own with a normal rad + several pc fans on reduced V
Presumably you could also put rad + fan under the floor if you wanted, with filtered vents.
But the best option (that Ive never tried) appears to be to put a bunch of microbore inside partition walls. Raising the whole wall to quite modest temps would deliver the same heat. I calculated it once, and it looked like it would work well.
Anyone else considered this?
NT
I have one in my car :-)
Most of the heat transfer is by convection. Large white radiators don't look as crap as slightly smaller black ones, and are easier to paint to match the room decor.
Wouldn't it make more sense to put it under the floor?
Maybe not quite what you want, but Myson do 'Kickspace' fan-blown radiators which fit under kitchen units in otherwise dead space.
The word 'radiator' is a misnomer in this context. Most of the heat transfer is by convection with only a small amount being radiated. Making them matt black would increase the radiated heat a bit - but wouldn't have a dramatic effect on overall heat output - and would be considered less aesthetically acceptable by most!
but all the ones I've seen are noisy and not very effective - they have the fan heater problem of warming the room up quickly but then allowing it to cool down just as fast - there's no thermal mass.
Hmm, yes. This is what concerns me, I definitely do not want the noise a fan heater, nor the draught, but I can't help feeling that a 2 metre long tangential fan rotating at a pretty slow speed could be quite inaudible, yet seriously increase the airflow throw a radiator.
The myson ones work but become noisy. A slow or variable speed tangential fan as you suggest would be alot better if available.
You could fit a few 60mm fans between the 2 parts of a small double convector rad , easy to control and run them from a plugin low volatge adaptor.
Robert royall at which net
================== You might possibly be a suitable candidate for skirting radiators.
They don't suit everybody or every location but they're worth a look if you're determined to avoid standard panel radiators. You might be able to combine skirting rads and tangential fans to achieve a bespoke system, but I doubt if it will be cheap.
Try a 'google' for 'skirting radiators'.
Cic.
AIUI the heat transfer is about 30% by radiation but much less when they are being run cooler using TRVs and/or condensing boilers. The emissivity of the white enamel is not far of the perfect matt black (about 90% as good). In fact most surfaces have emissivities around this figure the only ones which don't are shiny metal ones. If you play about with an IR thermometer you'll soon see which ones have low emissivities.
Or look at vertical radiators that only take up a small length of wall and can be sufficiently decorative to take the place of a piece of modern art that you might have there instead.
Interesting, it would seem, unsurprisingly, that the radiator manufacturers know their science.
... but I would still like my long tangential fan model !
Yes, it is done regularly with radiant floor plates fixed in the studs & covered with plasterboard.
It won't work. CH radiators work by radiation and convection. Fan heaters work by convection and the surface area needs to be vastly increased to achieve the required heat transfer. An example would be a car radiator which dissipates heat by forced convection. The surface area is made vast by the use of lots of sheet metal fins to transfer the heat to the airstream. If you want a fan heater you'd have to use one of the Myson jobs or obtain an air heater battery and go about fabricating a small air handler.
There are commercial fan coil units for heating and/or cooling, similar to the indoor ceiling cassettes on split system AC units. The cheap and nasty fans usually start giving trouble after a few years.
It works very well in fact. I know because I've done it as a temporary measure. Its the same principle as fan cooling a heatsink in tronic goods. Think your CPU wont get hotter if the fan fails?
The only problem is getting or making a long thin fan. I guess in principle one could make a tangential thing and spin it at low rpm, sounds a fair bit of work tho. Practically pc fans are all I've come up with, anything else is too large.
Now how to diy a 5' tangential fan...
NT
It increases the proportion of heat emitted by convection. It reduces the radiator surface temperature and reduces the proportion of heat emitted by radiation. The overall effect approximates to naff all, in respect for the effort involved. If he wants forced convection, he'd be best advised to buy a heater battery which is designed for this purpose. Or some of those finned tube heaters.
This is why car radiators and heater matrices are the distinctive shape that they are. You could bolt on a couple of double-panel Mysons when your car radiator next fails, but I doubt that it would achieve the required heat transfer rate.
Its the same principle as fan cooling a heatsink in tronic
The heatsink usually has extended fins to shift a few watts; I have no idea of typical CPU heat output. To shift a 1 or 2 kW, you need lots of fins, or a large acreage of panel radiators.
Well, yes, but it should take heat from the radiator by design, I am actually trying to tale the most from the radiator. Either way, if the control system and the boiler is correctly specified it should keep the radiator piping hot at the maximum level of air flow forced through the radiator; again, by design.
Ed Sirret, said above that very little energy is emitted from a 'radiator' by way of radiation anyway.
I'm not familiar with 'finned tube' though I think I know those you mean. But it's space I am trying to save. I would love to have a very flat skirting board radiator of 2m length, which is capable of maintaining an already warm room, but which has a fan mode to boost its capacity when the room is being heated from cold.
Yes, but car radiators are cooling pretty inefficient 90kW (or thereabouts) motors. Their design owes a lot to the much greater cooling they must provide, much like the complexity we see in the heatsinks used in power electronics.
If they weren't so ugly it might be fun to try an automotive radiator in a CH system. Though perhaps its fan motor could be replaced with something a little less energetic.
Anyway, in the meantime I think I would like to track down a manufacturer of tangential fans and call them to ask what the longest design they make is. It should be quite a simple experiment.
Not necessarily! Provided the water flow rate is increased to replenish the heat at the same rate as it is being removed, the surface of the rad will stay at the same temperature as before - thus giving increased convection and the same radiation.
How much time/money do you want to spend?
cheers, Pete.
Hard to say but under a thousand for sure.
achievable with rows of computer fans on standard but smaller rads.
NT
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