The first street mains laid down more than 30
years ago are still in use and generally in good
condition. It is apparent that the maintenance
work is less on the hot-water-distribution system
than on the steam system. Our data, however, are
not sufficient to give definite figures. On the steam
system the condensate lines were at first laid in
copper pipes welded together. The welds proved
to be a weak point requiring considerable maintenance. For the last about 25 years steel pipes has
been used also for condensate lines with satisfactory
FIG. 6-Warm Wafer Installation.
The largest size of street mains used in 400 mm
(16 in.) diameters. In other towns in Denmark
larger mains, up to 600 mm (24 in.) diameter are
in use. '
The warm-water system at present extends out
to about 3 km ( 1.86 miles) from the plant. This
distance cannot be increased very much without
installing booster pumps in the system.
The cell-concrete insulation mentioned later
has been very satisfactory. It is, of course, necessary that the duct and pipes are dry, which means
that the drainage system must be effective.
A measure of the conditions of the system is
the maintenance costs and the losses. The annual
maintenance costs for the whole district heating
system has as an average for the last two years
been 6,800 kroner per km pipe line ($1,586 per
mile) with a downward tendency. The heat losses
in the system determined as the difference between
the heat bought from the power plants and the
heat paid for by the customers has f0r the last
two years been 12. 7 per cent based on heat sent out.
(Continued in July Issue)
FLORHAM PARK, N. J.
On a 675-acre site Esso Research and Engineering Company is building an office building,
prototype building, service building, two gatehouses and a sewage treatment and disposal
plant-the initial construction of a modern
research center. All heating, air conditioning,
power and communication lines are run underground. Over 500 tons of Gilsulate will be used
for insulating and protecting the underground
BUFFALO, N. Y.
A laboratory has solved the problem of
increasing hot water volume without adding
costly heating installations by installing mixers
to existing steam and cold water lines. Style
D Steam and Water Mixer, made by the Powers
Regulator Company, Skokie, Ill. was used. It
automatically mixes water and steam to deliver
water at any temperature desired by the user.
In the laboratory, the mixer combines cold city
water with WO..lb steam to provide water averaging 14'0 F, but can also provide water at
temperatures as low as 50 F and as high as
Mrs. Elva B. Webb
Office Secretary, l-l.D.H.A.
August 1939 to September 1957