Chrome Heated Towell Rail - Good or Bad?

newbie2

Mods feel free if posted in the wrong forum.
Hi, I'm thinking of installing a chrome heated towell rail in my bathroom but I've heard some funny reports regarding the heat they actually radiate. Some people i've spoken to complain that while the rad's are really hot to the touch, they dont radiate the heat outwards - the chrome absorbs it.
Anybody heard of this or has antbody got one of these in their bathroom? Are they worth the cash?
Thanks in advance

Endymion

absorbs it you say? It can only radiate or conduct the heat. Their the same as any raid, you adjust the water flow untill it's heating at the right temperature. People tend to touch them allot more maybe thats why people notice the heat more.

Creamy Goodness

well i have one in my shower room.

the heat doesn't really heat the shower room if you know what i mean so i guess you can say the chrome absorbs it.

they are really nice to have, especially in the winter time when it's hella cold out.

Endymion

chrome isn't magic, the heat goes somewhere. Most likely out a window or through the ceiling. They have less surface area then a standard double raid, so they radiate less, their not really designed around convection so the hot air stagnates. Basically theres nothing wrong with them. They operate as they are ment to. i.e. to dry out towels and the like.

newbie2

Carnivore wrote:

Basically theres nothing wrong with them. They operate as they are ment to. i.e. to dry out towels and the like.

Point taken.
Thanks all for the replies - looks like if I want my bog to be warm I'll have to stick with the original one and stick a towell rack behing the door!

Mellor

The chrome can't absorb the heat, there is no material in the world that absorbs heat when it is hotter than its surroundings. None.
They are just design with a different main purpose

beldin

Well you can get combined ones , a normal radiator with one or 2 bars on top to hang towels on. I have a normal towel rail in my ensuite and it is fine. Only annoying thing is that i didn't fit an electrical element in it so that in summer i have no heated towels

Corkey123

Beldin

My experience is they are good for warming towels, etc, however they are not designed as radiators. You should establish what BTUs your shower room requires before purchasing either a towel rad, rad or both. BTUs are a measurement of the output of radiators, etc.

see the link below to calculate BTU

http://www.diy.com/diy/jsp/bq/templates/content_lookup.jsp?content=/bq_advice/planning_tools/btu_calculator.jsp

secman

I put one in a bathroom, plumber told me it would be sufficient to heat the bathroom. Unfortunately he was wrong, it looks great, but it is noticebly cooler compared to the rest of the house in the winter. As previously stated their purpose is to heat towels not bathrooms, found out the hard way!

air

I was looking at chrome radiators before & IIRC I think that it was mentioned that you need to double the size of your rad to get equivalent output with a chrome radiator versus a normal one.
Radiators "radiate" heat amazingly enough, and putting a shiny surface on a radiator will reduce its ability to radiate, hence why your kettle is typically silver and not black - it reduces heat loss.

FrankGrimes

I'm fairly certain that radiators actually convect heat and the name 'radiator' is misleading as a result.

I was in buying a designer rad in Heating Distributors in Finglas last week and the saleswoman said chrome rads reduce the BTU output by 10%.

By nature of their layout towel rads have siginificantly lower BTU output than a normal rad with the same external length and width. And with chrome it's lower again.

As Martin suggested, calculate your BTU requirements and work off that.

My bathroom is about 2.2 metre by 2.5 metre and is well insulated - we find that the heat from the chrome towel rad actually heats this room fine, but for a larger bathroom don't rely on it as a single source of heat.

I'd like to add an electric element to the chrome towel rad and have the ability to do this as the stud wall behind it is currently open (no slab yet) - what do I need to add (will get the electrician to wire it when he's wiring the extension this weekend) and do the element fittings come in chrome?

air

Yes the water to air heat transfer is primarily by convection on the outside of course, with some minimal radiation also.The colour difference still makes an impact on the heat transfer from the water inside the pipe to the air outside the pipe. Whatever the exact physics are, we are agreed that the chrome reduces the heat output, I have no hard figures on the actual reduction for two radiators that are identical except for finish.

beldin

As I said you can get combined ones. These have a radiator as well as some rails overhead to heat towels on.
http://www.bathroomstuff.co.uk/iqs/dbitemid.22/sfa.view/column_radiator_towel_rails.html

These have their output specified so use martins calculator and see if any of these would heat your room. I know tubs and tiles do some of them so maybe check what they have.

FrankGrimes

look nice if that's the style you're after, but very pricey.

I picked up mine which is a modern style chrome one (i.e. looks kinda like a ladder) and is quite large for €199 in Clondalkin Builder Providers there last year. That's an awful lot cheaper than I'd seen them in bathroom stores, but I thik B&Q might even be cheaper again.

Mellor

I still think the poorer performance of chrome rads is still more down to the shape and not the finish.
A normal and chrome rad with the same dimensions are NOT the same size/area.

tred

secman wrote:

I put one in a bathroom, plumber told me it would be sufficient to heat the bathroom. Unfortunately he was wrong, it looks great, but it is noticebly cooler compared to the rest of the house in the winter. As previously stated their purpose is to heat towels not bathrooms, found out the hard way!

my brother is in the plumbing trade. he told me you need to have a normal rad to heat the bathroom, and then with a towel rad, to dry the towels. if you have any decent size bathroom.

Endymion

Right; How rads work.

Rads radiate heat, which in turn heats the surrounding air, this heat rises, cooler air decends and is heated by the rads radiated heat. This sets up a convection current which heats the room. Due to both how towel rails are designed and how they are used, they have reduced surface area, making for reduced convection currents, which leads to less heat spreading through out the room. It's not that less heat is produced, it that it's not very well disipated throughout the bathroom. If it was, the towel rail would be useless as a towel rail.

Good rads have good air flow. Good towel rails don't

Ps ignore all comments about finish, the effect is insignificant to the level of being non existent.

Do-more

The other thing of course, is that towel rads normally have towels on them! It's like having a nice insulating jacket on your rad and the heat can't get out to heat the room.

Best combination I think is a nice towel rail and underfloor heating so your tutsey's are nice and warm when you step out of the shower.:D

air

I'd imagine that the majority of the heat transfer between the rad and the air is by conduction through the wall of the pipe, followed by convection in the surrounding air. I explicitly discounted the different usage patters - as I mentioned above, I was considering "two radiators that are identical except for finish". The radiative heating I'd imagine is pretty low as a proportion of total output but finish would have a big impact on this portion of the emission. For practical purposes in a radiator it could well have a negligible impact.

Endymion

air wrote:

I'd imagine that the majority of the heat transfer between the rad and the air is by conduction

Please do not take offense to what I'm about to say. It's been pointed out that I can be abrassive. But you are wrong, Look up what conductions is and you will see that you do not get conduction between two separate bodies. conduction is the transfer of internal energy from a region of higher temperature to one of lower temperature through means of stimulating adjacent particles in a body.

I explicitly discounted the different usage patters - as I mentioned above, I was considering "two radiators that are identical except for finish". The radiative heating I'd imagine is pretty low as a proportion of total output

I found this link, it agress with what iv'e said so far up thread.

but finish would have a big impact on this portion of the emission. For practical purposes in a radiator it could well have a negligible impact.

One of the first third level experiments I did was to test how well different finishes absorbed or reflected energy. yes theres is a different in finish, no its not major. Your understanding on how it affected heat transfer is also lacking. the inside of the towel rail is black, "good for absorbing radiated heat, the outside is shinny or white, good for reflecting heat into the room.

air

Carnivore wrote:

good for reflecting heat into the room.

Reflecting heat into the room? What are you on about? Surely you meant to say radiating, which a silver surface is definitely not suited to.

Furthermore what two seperate bodies are you talking about? I was referring to conduction between the inner surface of the radiator pipe and its outer surface?

Furthermore, your quote of me above amounts to quoting out of context, the abstract which you quoted appears to make no sense, whereas my complete sentence does make sense.

Mellor

Every object that gives out heat gives it out in all three ways, conduction, convection and radiation. The amount of each it gives out depends on the object.
Obviously you could set up certain situations where this wont happen, but this will not occur in the real world. Only in a lab book

cormac_byrne

Carnivore wrote:

you do not get conduction between two separate bodies.

Err Yes you do

see http://en.wikipedia.org/wiki/Heat_conduction
note the phrases

... So, when dealing with a multilayer partition ....

and

... When heat is being conducted from one fluid to another through a barrier ...

Technically radiators transfer heat from water to metal to air via conduction.
The heated air then travels around the room by convection. there is little or no radiation involved.

Mellor

cormac_byrne wrote:

Technically radiators transfer heat from water to metal to air via conduction.
The heated air then travels around the room by convection. there is little or no radiation involved.

The air is heated by conduction as well as radiation. And this warm air heats the room through convection currents.
Any hot surface radiates heat. Anything that gives out infa-red light/radiation.
As I previously said rads give out heat in all three forms.

cormac_byrne

Heat is given off when an object's thermal energy is transferred. Thermal energy (see below) can be transferred in three ways:

by conduction, by convection, and by radiation.

1. Conduction

Conduction Example (Game of Pool)

Conduction is the transfer of energy from one molecule to another. This transfer occurs when molecules hit against each other, similar to a game of pool where one moving ball strikes another, causing the second to move. Conduction takes place in solids, liquids, and gases, but works best in materials that have simple molecules that are located close to each other. For example, metal is a better conductor than wood or plastic.

Convection Example (A Radiator Emiting Heat)

2. Convection

Convection is the movement of heat by a liquid such as water or a gas such as air. The liquid or gas moves from one location to another, carrying heat along with it. This movement of a mass of heated water or air is called a current.

3. Radiation Radiation Example (Sun Bathing)

Heat travels from the sun by a process called radiation. Radiation is the transfer of heat by electromagnetic waves. When infrared rays strike a material, the molecules in that material move faster. In addition to the sun, light bulbs, irons, and toasters radiate heat. When we feel heat around these items, however, we are feeling convection heat (warmed air molecules) rather than radiated heat since the heat waves strike and energize surrounding air molecules.

---

Yes everything that's above absolute zero radiates heat, or emits infra red to put it another way.

Radiant energy is proportional to the fourth power of the absolute temperature of the source.

To get a significant amount of IR from an object it needs to be quite hot (generally glowing as per the examples light bulb and toaster above)

squire1

Wow, you learn something new every day.

OP. If you want to warm towels get a heated towel rail, that's what they do. If you want to warm the room get a radiator, that's what they do.:cool:

Endymion

Air; I'm tired replying to you. Shinny reflects heat, dull absorbs heat. The outside to the towel rail is shinny, so the outside reflects the rediated heat, the inside is dull so it allows heat to pass easily from the water to the steal.

cormac_byrne; Your link is broken, and I have my doubts that you understand any of what you just posted. Conduction requires the interaction of molecules, air molecules don't interact with the crome molecules, they don't bounce off each other in any significant way. I've read nothing in what you posted that suggested conduction exists between two seperate bodies. Heat transfer is therefore through radiation.

ps, don't quote wiki, and certainly never use it to contradict someone.

Pss the reason I don't think you understand what you quoted was the "Radiant energy is proportional to the fourth power of the absolute temperature of the source." coment. Thats a matierial specific comment.

Psss your definition of conduction is pretty shockly over simplified.

Mellor; It wouldn't be right to say that rads convect heat through a room. Convection is how heat is disipated throughout the room. But, meh, you seem to get the idea at least.

air

Carnivore wrote:

Air; I'm tired replying to you. Shinny reflects heat, dull absorbs heat. The outside to the towel rail is shinny, so the outside reflects the rediated heat, the inside is dull so it allows heat to pass easily from the water to the steal.

Again, reflects? Surely you mean radiates?
The latter half of your sentence above makes no sense - "the outsides reflects the rediated heat" - reflects it from where exactly? Fair enough if there is heat energy incident on the outside of the radiator from another source it could reflect it, the heat from within it would be radiating - not reflecting.
Your poor spelling, attitude and lack of any supportive sources - not even the wiki's you condemn, lead me to believe you dont have a clue. If something is "shockingly over simplified" then why dont you explain it in further detail?
Finally, how qualified are you to contradict anyone? Do you hold any qualifications of relevance in physics?

Endymion

air wrote:

Again, reflects? Surely you mean radiates?
The latter half of your sentence above makes no sense - "the outsides reflects the rediated heat" - reflects it from where exactly? Fair enough if there is heat energy incident on the outside of the radiator from another source it could reflect it, the heat from within it would be radiating - not reflecting.

Reflects the radiated heat. This is my third time saying it. Scource radiates heat, shinny layer reflects heat away from source. Ps look up what radiate means.

Your poor spelling, attitude and lack of any supportive sources - not even the wiki's you condemn, lead me to believe you dont have a clue.

Thats your opinion. Your welcome to it.

If something is "shockingly over simplified" then why dont you explain it in further detail?

Metals are good conductors due to the nature of their atomic bonds. "simple molecules" is really a moronic term you might use to explain something to children. Also the "bouncing off each other" idea is miss leading.

Ps I've allready given my definition of conduction.

Finally, how qualified are you to contradict anyone? Do you hold any qualifications of relevance in physics?

I recieved an A1 grade in leaving cert physics. Also as part of my general engineering course I've studied Thermodyanmics and Material science.

Mellor

Carnivore wrote:

Mellor; It wouldn't be right to say that rads convect heat through a room. Convection is how heat is disipated throughout the room. But, meh, you seem to get the idea at least.

Sorry is I wasn't clear enough, but I think you understand me. The room is heated through convection, and the air through conduction and radiation.

Fel this thread has got away from the original point. Towel rail rads not worse than regular one. They just do a different job. Also, a towel rad measuring 1200 x 1000 is not the same size as a regular rad 1200 x 1000, so all comparisments are skewed from the start.

Victor

Carnivore wrote:

Look up what conductions is and you will see that you do not get conduction between two separate bodies.

So how does the heat get from the metal heating element on a cooker to the metal saucepan?