Towel Rad Inadequate

[BrianC]

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?

 

[Gasmk1]

what size is bathroom

 

[Tim Watts]

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.

 

[townfanjon]

Bain of my life these things , its a “ towel rail” not a radiator.

 

[Chuck]

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?

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.

 

[BrianC]

what size is bathroom

3400mm X 2120mm, there are two external walls, one window and a tiled floor.

 

[Gasmk1]

my towel rad is 860 watts and is more than adequate but then again i do have underfloor heating in there and it has no outside walls

 

[Tim Watts]

Bain of my life these things , its a “ towel rail” not a radiator.

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...

 

[Gasmk1]

i think the towel rad is about the right size but it depends on how many towels you have. never like normal rads in bathrooms as they corrode very quickly

 

[townfanjon]

3400mm X 2120mm

No chance pal , have you room for a rad and a towel rail?