Ladder Towel Rail or Radiator?

[TheScullster]

Hi all

This could be more involved than the subject header suggests!

I am refurbing 1970s bathroom and intend to replace the radiator. Currently there is a single panel convector rad installed 450 high 1000 long (Stelrad K1 type I think).

My questions are as follows:

1. I have installed an extractor and wonder how much the radiator size should be increased to compensate for the air removal.

1. Mounting the heating source vertically (as in a towel rail) would appear to be self defeating, as a proportion of the heat is being applied at the top of the room rather than at occupier level. The radiant heat effect felt by the bather must be partially lost. Has anyone felt a "loss of comfort" due to this vertical rather than horizontal trend? Should a ladder type radiator be oversized to allow for this?

2. Are Stelrad's ladder towel rails any good?

1. Bearing in mind the lack of head between the header tank and the top of any vertical radiator (Stelrad state minimum 600mm), do they function as well as a radiator? I am thinking particularly about water flow around and therefore heat distribution from the total surface.

2. Any good alternatives to Stelrad?

TIA

Phil

[Andy Hall]

You need to know the rate of extraction, which will be in the spec. of the fan. In practice it will be less of course, because of ducting but will give you a worst case.

You can then work on the basis of 0.36W of heat required to heat a cubic metre of air by one degree Celsius.

You just need to look at the manufacturer data. All of that is accounted for in the heat output. One factor is that the heat output will be reduced by putting towels over the radiator/rail of course.

.andy

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[Grunff]

0.36W - is that in one second?

[Christian McArdle]

That doesn't make sense. 0.36W is a measure of power, the heat required to raise the temp of a parcel of air is a unit of energy.

Christian.

[Andy Hall]

Just testing whether you were awake in the back.

At least I didn't throw chalk or the board eraser like one of my school teachers used to do. :-)

This is per hour.

So ventilation loss is given by

Ventilation loss = 0.36NV( Tai - Tao ) N is the number of air changes per hour V is the volume of the space (m3) Tai is the inside air temperature (k) Tao is the outside air temperature (k)

.andy

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[BillR]

[SNIP]

In my experience this is the biggest snag with the ladder types. Swmbo covers it with towels so no heat gets to room. Without towels its more than adequate to heat the bathroom.

[Colin]

0.36W/Hour/m^3 doesn't sound much... I must be missing something... Based on this couldn't I heat my whole house with a light bulb(?)

What would the calculation look like for a 50^m room?

Colin

[Christian McArdle]

50 x 2.4 x 24 x 1.5

Based on 2.4m ceiling height, 1.5 air changes per hour and -3C outside, 21C inside, you get:

50 x 2.4 x 24 x 1.5 x 0.36 = 1555W.

Obviously, it is unlikely to be -3C outside for any length of time.

At a more typical 10C, you get:

50 x 2.4 x 11 x 1.5 x 0.36 = 713W.

Should the losses calculated for your house be too large, consider sealing the house to reduce leakage and installing heat recovery ventilation. This is much easier to do on a newbuild than an existing structure, though.

Christian.

[Colin]

Thanks, that seems to make sense.

Colin

[Neil Jones]

For this reason I have bought the towel warmer with the biggest output I could find for my imminent batroom refit. It wasn't cheap, but hopefully it'll chuck out enough heat.

Neil

[Andy Hall]

I have seen accessories for ladder type towel rails which are pegs for robes and stand-off rails for towels. This would at least give some convection from the main part of the radiator.

.andy

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