Electrical Outdoor Heating Overview
Outdoor heating systems have been becoming more and more popular in commercial settings over recent years, and are in increasing demand following the introduction of the ban on smoking in enclosed public places, which has resulted in a pressing need for comfortable outdoor spaces where smokers can indulge their habit in peace.
Energy
As businesses consider their energy bills and also their carbon emissions, the
choice of heating system is likely to be an important one over the long-term,
affecting the success of the outdoor area, their energy bills, and also the
cost of maintenance. It is highly possible that many businesses that have
bought in haste, will be repenting at leisure, and will be revisiting their
options over the coming months, creating more business opportunities for
electrical contractors.
Choosing
For convenience in a commercial setting electric radiant heating is likely to
be the method of choice, as there will be no gas cylinders to order, store or
change. In addition, selecting a wall mounted electric heater will ensure
that no valuable floor space is wasted and that public safety is optimised
because the heaters can be mounted well out of reach. There are, however,
significant differences between the kinds of electric radiant heaters
available and major differences in their efficacy in an outdoor setting. The
principle of radiant heating is well known, and there are important
differences between long wave emitters and medium or short wave emitter quartz
lamps. For example, the radiant efficiency of a short wave infrared heater is
up to 96 per cent, and that of a medium wave heater around 40 per cent.
Electric infrared energy travels outwards in straight lines from the heat
source, diffusing over distance, and is directed into specific patterns by
optically designed reflectors. For successful comfort heating, there must be
reasonably even levels of heat throughout the area to be heated. Proper
mounting heights of the individual heaters, accurate heater spacing, reflector
beam patterns, and heat wattage must all be specified to generate the
appropriate heating levels.
The heat of the moment
The ban on smoking in enclosed public spaces has meant that businesses are
looking at outdoor heating to help create a comfortable environment in which
to smoke. Short wave high intensity quartz radiants work like sunshine and
have a warming effect the instant the heaters are switched on. Short wave
heaters warm people and objects within the beam rather than the air, resulting
in a pleasantly fresh rather than stuffy environment, whereas long and medium
wave heat has comparatively poor heating characteristics, especially when used
outdoors, as it relies on heating the air and does not penetrate the skin to
warm up the person. In addition for long and medium wave heat the heat is
susceptible to air movement and so is not directional. In reality, a medium
wave filament, which only heats up to around 900oC, is more suitable for
curing and drying processes than for outside heating applications, although
cheap heaters with medium wave filaments can be purchased as exterior heaters.
Long wave heaters are most
suited to heating inside areas where a low level of heat is required and it is
acceptable for the heaters to be in use for some time to pre-heat the area
before it is occupied. Ceramic plaque heaters fall between medium and long
wave, heating up to around 500oC but, again, are of little use for al fresco
heating as they warm the air rather than penetrating through it and warming
the individuals in the vicinity.
Short wave lamps
Short wave halogen heat lamps consist of a tungsten filament heated by the
passage of an electric current to a temperature of some 2,200oC. At this
temperature most of the emission is in the short wave infrared band.
The moment that they are switched on, a warming effect can be felt, so the heaters only need to be switched on when the area is occupied and when the ambient temperature dictates that heating is needed. 92 per cent of the energy used is converted to heat within seconds of the heater being switched on - the remainder is converted into light as a by product of the process, giving a cosy and welcoming glow that adds to the ambience of the area. For heating applications a ruby sleeve or gold dichroic coating encloses the halogen heat lamp, to filter out the intense white light and provide an aesthetically pleasing warm glow.
What to look for
When selecting short wave band electric quartz heaters, it is important to
consider the place in which they will be mounted. As a rule, ordinary lamps
should only be mounted horizontally and will quickly burn out in a vertical
position. If you need to mount heaters vertically, check with the manufacturer
that it offers lamps suitable for this purpose, specify which you need at the
time of ordering, and always look at the lamp inside the heater.
A quartz linear heater should always have a highly reflective, long lasting reflector which directs a focused energy beam on an area as required. A special benefit of the adjustable beam direction is that high intensity radiant heating can be provided at low level even though the heater is mounted at a high, safe level. Look for heaters with a dedicated reflector, not ones relying on the surface of their extrusion to reflect heat back. The method of extrusion production leaves draw marks on the surface and it is usually not of mirror quality so cannot act as a true reflector. It is merely a cost saving measure for the manufacturer, and one which will impact both on the heater's performance and on its life span. It is essential that the parabola shape of the reflector is accurate and the lamp is placed in the correct focus within the reflector in order to obtain maximum heat output. The lamp should be mounted in such a way to dissipate heat away from the ceramic on the lamp towards the heater body, which in turn will act as a heat sink. Specify heaters with side reflectors as they keep the heat away from the critical part of the lamp and significantly improve the output of the heater.
Necessary features
Some heaters for outdoor use are marketed with a high ingress proof (IP)
rating, for example, IP65. Before paying extra for it, consider whether it is
really necessary for the specific application. Many heaters in a patio area
will be installed under an awning or umbrella, which in itself provides
protection. Even if they are not under cover, IP24 is usually a sufficient
rating for permanent outdoor installation. If a heater has an IP65 rating,
check whether it can be re-lamped. In a heater with a wire guard, the wiring
is normally such that the heater will either need to be stripped down for re-
lamping or returned to the factory, which is both expensive and inconvenient
as the heater will be out of service for some time. Equally, don't be too
keen to secure a bargain. Beware cheap copies of quartz patio heaters - the
old adage 'you get what you pay for' applies to patio heaters as it does to
most things in life. Cheap heaters usually use ordinary glass which does not
allow heat to pass through efficiently and can shatter under the heat duress.
The component parts give poor heat output and an inadequate lamp life of
around 12 hours rather than 1,100 - 7,000 hours, depending on the heater
model, of a good quality product.
Some patio heaters are available with a glass front guard which has been specially designed for the purpose, as opposed to those where a heating element has been placed in a floodlight fitting, and the result is both better heat output and extended lamp life. Because these types of heaters have been designed and engineered for the purpose, they require minimal maintenance, typically a quick wipe of the front glass to ensure optimum heat transfer.
Cost savings
The running costs of good quality electric quartz radiant heaters are around
nine pence per kilowatt hour and there are ways to ensure that costs are kept
to a minimum without compromising on comfort. As we have seen, the efficient
nature of short wave heaters mean they can be left switched off when the area
is not in use - some manufacturers offer other
cost saving measures such as PIR detectors, coin slot operation, and
controllers which can provide on/off or proportional power inputs. Creating a
convivial outdoor area that can be used
year round inevitably requires an efficient heating solution in the UK and in
much of northern Europe. A little research into the available options now
will ensure that the heating system used will be both cost effective and
thermally efficient for a long time to come, and that the customer is a happy
one.
Biography
Pete Rana is managing director of electric quartz heating specialist Tansun,
which was set up in 1982 and is now the UK's leading manufacturer and exporter
of electric quartz radiant heaters. Pete is highly active in his local
business community and he has received a string of regional and
national awards for his success, including the government's Trade Partners UK
small business export award. In 2003 he was awarded an MBE for his services to
business and export.
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Shadow Fatboy 2.4kW Mega Heat Electric Patio Heater
From £409.19 inc. VATFrom £340.99 + VATProduct Features:- Large Parabolic Reflector
- 2.4kW Heat Output
- Remote Option Available
- Wall and Stand Mountable
-
Shadow II 1.5kW & 2kW ULG+ Electric Patio Heater
From £364.31 inc. VATFrom £303.59 + VATProduct Features:- Ultra Low Glare Plus Technology
- Slimline Design
- Inbuilt Variable Remote Option
- Vertical Mounting Compatible
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Heat Outdoors Empire 3kW ECO Carbon Infrared Patio Heater
£599.99 inc. VAT£499.99 + VATProduct Features:- Tower Heater.
- Awesome vertical design.
- Up to 3kW heat output.
- Variable Heat Remote control.
-
Shadow Sidekick Grande 2kW Portable Infrared Heater
From £287.99 inc. VATFrom £239.99 + VATProduct Features:- 2kW variable heat output
- Unique hexagon grill design - facilitates 360° dispersion of heat
- Remote control operated
- Fully waterproof - IP65 rated