Good afternoon all, sorry if this seems like a stupid question but I am looking for advice. We recently had our bathroom done and were advised a Radox RXPS-1800400-CH would be man enough to heat the room. It isn’t, having done a bit of homework I think I’m going to go down the route of a convector radiator, the rest of the rads are convector rads. Is this the way forward?
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I'm not a plumber (well I DIY some) but I did design my heating system 
The best thing to do is look at the quoted output of the radiator or towel rail in watts. This will usually be quoted at a "delta T 50C" (delta may be written as the greek letter, a triangle).
So the bigger this number, the more heat you'll get out. Towel rails are poor - you'll be looking at 100-200W for a typical size. A finned single panel radiator of the same size will beat it by a significant factor.
My rule of thumb: if you have some idea how much heat it takes to keep the room warm, look for a radiator quoting 1.5 times as many watts at Delta-T 50C. If you want a cold room to heat up fast, add another 50% or more.
Cheers, Tim
Now - if you want to do actual calculations: (I apologise if this is egg-suckage, but if you're not aware)
"Delta-T 50C" means that when the average radiator temperature will be 50C above the room temperature, the heat output will be X watts.
No one designs to Delta-T 50C any more as the boiler will be running beyond its efficient point for a modern condensing type (where it wants the return to be less than about 55C - a little cooler is even safer/better)
A modern condensing boiler will more likely be running at roughly 60-flow/50-return or 65/55 at best, so your radiator temperature will be average of those, so 55C to 60C. If you're interested in heat output to maintain the room at 20C, that's a Delta-T or difference of 35C to 40C.
Delta-T 40C gives about 75% of the heat output compared to Delta-T 50C. Delta-T 35C is about 65% (some numbers I found online once).
So if you have some idea how much heat it takes to do the job, look for a radiator quoting 1.5 times as much at Delta-T 50C.
The best thing to do is look at the quoted output of the radiator or towel rail in watts. This will usually be quoted at a "delta T 50C" (delta may be written as the greek letter, a triangle).
So the bigger this number, the more heat you'll get out. Towel rails are poor - you'll be looking at 100-200W for a typical size. A finned single panel radiator of the same size will beat it by a significant factor.
My rule of thumb: if you have some idea how much heat it takes to keep the room warm, look for a radiator quoting 1.5 times as many watts at Delta-T 50C. If you want a cold room to heat up fast, add another 50% or more.
Cheers, Tim
Now - if you want to do actual calculations: (I apologise if this is egg-suckage, but if you're not aware)
"Delta-T 50C" means that when the average radiator temperature will be 50C above the room temperature, the heat output will be X watts.
No one designs to Delta-T 50C any more as the boiler will be running beyond its efficient point for a modern condensing type (where it wants the return to be less than about 55C - a little cooler is even safer/better)
A modern condensing boiler will more likely be running at roughly 60-flow/50-return or 65/55 at best, so your radiator temperature will be average of those, so 55C to 60C. If you're interested in heat output to maintain the room at 20C, that's a Delta-T or difference of 35C to 40C.
Delta-T 40C gives about 75% of the heat output compared to Delta-T 50C. Delta-T 35C is about 65% (some numbers I found online once).
So if you have some idea how much heat it takes to do the job, look for a radiator quoting 1.5 times as much at Delta-T 50C.
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Bain of my life these things , its a “ towel rail” not a radiator.
No one can really answer this without knowing heat loss and usage patterns for your bathroom.
600-800W (which is what your model seems to promise) should be enough to heat a typical medium-sized bathroom. Of course if you insulate it by covering it with towels it may struggle. I like one heated and one unheated towel rail in each bathroom for this reason. I also like heated towel rails to be dual fuel, on a CH loop that is not shut off by zone valves and controlled by a TRV. The electric heater is on a four-hour countdown timer that is just outside the door to help in the autumn/spring when the CH is not on for much of the time and the bathroom needs a boost. Use the heated rail to dry the towels after bathing but move them to the unheated rail so the rail can act as a heater.
3400mm X 2120mm, there are two external walls, one window and a tiled floor.
Yep. You can just about get away with a typical towel rail for heating with an tiny islanded bathroom right in the centre of the house like I have (and assuming the ceiling is warm or insulated, not onto a cold roof space). Anything else would be unlikely to work well unless you have other heating as well.
Edit: that's not to say you couldn't find a massive towel rail with a decent output of course - just thinking the typical type here...
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No chance pal , have you room for a rad and a towel rail?
at a pretty hot water flow temp (dT-50C/dT-60C) - if the OP runs his system at condensing temperatures, could be more like 400W
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As above if towels are going on it then you need a second rad / underfloor elec heating
If I was to get rid of the towel rail and replace it with a radiator would I be looking for a convector radiator as the rest of the ones in the house are or could I go for a a more contemporary designer? Bearing in mind I am looking for an 1800mm vertical by about 400-500.
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