We want to put a 'dual fuel' towel rail in our new shower room. As
far as I can see these are just about always a normal hot water CH
towel rail with an add-on electric heater (200 watt typically).

Is this the only type or are there more 'integrated' ones where it's
designed as a combined electric/CH towwel rail?

Whatever, does anyone have any recommendations or "don't do it"
comments for particular brands or models?


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Chris Green
·

On Wednesday, 21 August 2019 09:16:05 UTC+1, Chris Green wrote:
We want to put a 'dual fuel' towel rail in our new shower room.

Whatever, does anyone have any recommendations or "don't do it"
comments for particular brands or models?

I don't know what types your central heating or shower is, but I'm very happy with the "single fuel" towel radiators in my house. They are plumbed into the central heating primary side, before the diverter valve, such that they are heated whenever the boiler fires up, regardless of whether it's for heating the radiators or replenishing the hot water in the water storage cylinder.

So, for example, by the time we've finished a shower in the summer, the towel radiator has heated up to provide cosy warm towels, and to dry the towels again.

As I said, it works well for us. And there's no need for an electric element (which would need to be on a timer to heat up sufficiently in advance of you needing the radiator to be warm).

On 21/08/2019 13:48, Tim Streater wrote:
Andrew wrote:
On 21/08/2019 09:30, Tim Streater wrote:

Side note: towel rails should be white not chrome finish for best
radiation.

Matt black surely ?, but when draped with wet/damp towels only
conduction is relevant anyway ?

Black would look ugly and intrusive; the emissivity of a white finish
vs. black is small compared to how bad chrome is.

While it's a fact that metals have low emissivity, that's only true for
super-clean surfaces. It only takes 20 microns of any kind of oil,
finger grease, body fat, random airborne contaminants, etc, to raise the
emissivity significantly towards the 'black' end of the range - from
memory 0.2 for clean metals, 0.8 for the 20-micron contaminated surface.

It's why painted surfaces have high emissivity irrespective of the
colour, the radiation taking place more from the paint binder than the
pigment due to the '20 micron effect'.


--
Spike

On 23/08/2019 11:19, Spike wrote:
On 21/08/2019 13:48, Tim Streater wrote:
Andrew wrote:
On 21/08/2019 09:30, Tim Streater wrote:

Side note: towel rails should be white not chrome finish for best
radiation.

Matt black surely ?, but when draped with wet/damp towels only
conduction is relevant anyway ?

Black would look ugly and intrusive; the emissivity of a white finish
vs. black is small compared to how bad chrome is.

While it's a fact that metals have low emissivity, that's only true for
super-clean surfaces. It only takes 20 microns of any kind of oil,
finger grease, body fat, random airborne contaminants, etc, to raise the
emissivity significantly towards the 'black' end of the range - from
memory 0.2 for clean metals, 0.8 for the 20-micron contaminated surface.

It's why painted surfaces have high emissivity irrespective of the
colour, the radiation taking place more from the paint binder than the
pigment due to the '20 micron effect'.


It is a little known fact that the majority of heat generated by
'radiators' is not radiated.

It is convected.

It is another little known fact that heating things does not dry them.
It is heating the air moving past them so that it can carry away the
moisture, that dries them.

Now apply those facts to towel rails..




--
Climate Change: Socialism wearing a lab coat.

On Friday, 23 August 2019 12:04:15 UTC+1, The Natural Philosopher wrote:

It is a little known fact that the majority of heat generated by
'radiators' is not radiated.

It is convected.

It is another little known fact that heating things does not dry them.
It is heating the air moving past them so that it can carry away the
moisture, that dries them.

It does 3 things
1. It lowers the RH of the air, since maximum absolute water vapour content rises a lot with increasing temp. Ie it dries the air
2. It causes the air to move past the wet thing
3. Higher temp also increases rate of evaporation


Now apply those facts to towel rails..

If what you really want is towel drying, a small fan is far more effective, and not a total waste in summer.


NT