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Warm air boilers and heating systems...
....were very trendy in the large housing estates built in the 1970s and
1980s, but have been largely superceded by water-filled radiator systems these
days. A surprising number of warm air systems still exist though, and a
significant proportion of my work is servicing and repairing them. (I hold the
right certificates to competently and legally work on domestic gas-fired warm
air heaters).
Most people who live with warm air heating seem to actually like it. A well
designed system is quiet, warms the house very quickly and the absence of
radiators makes room layout much easier. On the other hand, some people report
problems with draughts, dust being wafted around the house, and problems with
temperature control. Draughts are caused by incorrect system design or
incorrectly set air outlet grills, dust should be removed by an air filter
(sometimes missing) and poor temperature control can be improved by cleaning the
filter(!) or having proportional control instead of an on/off room thermostat.
Most people with well-designed warm air systems really like them. Most other
people have already taken their warm air out and replaced it with a 'proper'
radiator system!
Maintenance of warm air...
... can be a problem. Faults are generally easy to trace and fix but few Gas
Safe Register bods
are inclined to try as most do not have the (compulsory) 'warm air' qualification.
Sadly when faced with a warm air system there is a tendancy for some technicians
to condemn it and advise the
customer to replace it with a conventional radiator system rather than admit it
is an appliance for which they are not qualified. This is appallingly unprofessional in my opinion but I encounter customers
from time to time who have had this problem. For example I was contacted a while
ago by a new customer whose warm air heater had been (incorrectly) disconnected
from the gas supply and labeled as dangerous by another gas engineer. This chap
then helpfully provided a quotation of £3,000 to fit a new boiler
with radiators. I re-connected the gas supply, serviced and and tested the warm
air system and found nothing wrong with it. The water heater attached to it was
dangerously sooted up but this was easily repaired and both appliances are now
back in use and operating safely.
The customer was so pleased he wrote this
letter thanking me.
There IS a problem with warm air heating in general though. It relates to
'ventilation'. Most warm air heaters are 'open flued'. This means they have a
'chimney' type flue to remove the burned gas, or products of combustion. For the
open flue to work correctly and safely it is of critical importance to have a
ventilation grill to outside air that lets fresh air IN to replace the flue gas
going OUT (up the chimney flue), and to provide oxygen for combustion. If a
correctly sized ventilator to outside does not exist then the warm air heater is
potentially dangerous to use, and many installations I encounter do NOT have
such a ventilator.
A ventilator was almost always fitted as part of the original installation
but users fail to appreciate the significance or importance of the ventilators
and have them blocked up to get rid of the draught they sometimes create. The
original ventilators are often installed through windows or door panels and are
lost when double glazing is installed and/or new doors replaced. This is
DANGEROUS!
If you invite me to service or repair your warm air heater I am obliged by
law to carry out a set of four safety checks and one of them is checking for
adequate ventilation. If I find your installation has inadequate ventilation I
am obliged to issue a Warning Notice and take action to ensure the installation
is made safe. This can come as a bit of a shock when you were expecting me to
can service or repair your appliance, and protestations from householders that
'it's been like that for years' carry no weight. I have no choice. It is a legal
obligation on all gas installers to carry out the safety checks and 'make safe'
any installation that presents a risk to an occupier.
A further drawback to warm air heating is inflexibility. The system is
designed as a whole and cannot be easily extended at a later date if, for
example, the house is extended. When a house with warm air heating is extended
it usually makes sense to abandon the warm air heating and fit a conventional
wet radiator system.
Hot water with warm air heating...
...is not the same as with a water-filled central heating boiler. Either a
hot water cylinder with electric immersion heater or an 'ascot' style gas-fired
instantaneous water heater can be used, but the best option is the 'Janus' water
heater accessory which fits inside the warm air heater casing. This is a
miniature gas boiler designed to heat just a hot water cylinder (and bathroom
towel rail if needed), and they work very well.
Page last edited 03/01/09.
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