been fitted up by those somewhat wanting in experience, such as
connecting draw-offs from the return pipe in No. 2 system; result is
that the whole of the water in the tank having to be heated before
any hot water finds its way down the return pipe, it is naturally a
considerable time after the fire is lighted before hot water can be
obtained from the tap; connecting draw-offs direct from the tank,
result nearly as bad as connecting from the return; dipping or
trapping the flow pipe, causing circulation to become air-locked as
before mentioned; connecting the cold supply to the tank or cylinder
without forming a syphon (inverted) in the pipe, so permitting hot
water to find its way up into the cold-water cistern: result, loss
of heat and water lukewarm which should be cold; placing tank and
pipes in very cold situations, causing serious loss of heat, as
before explained. Another common error, or piece of bad work, is
connecting or screwing the flow pipe through the top of the boiler
so that it projects through the inner surface, as Fig. 130. Now when
the apparatus is finished it is, of course, before being charged
with water, full of air; when the water flows in, it expels the air
as it fills, but it cannot expel the stratum of air existing between
the lower edge of the flow pipe and the top of the boiler; this is
not noticeable when the water is cold, but when heat is applied and
steam is generated, the steam naturally wants to expand into this
space, but at the same time the air has no desire to be evicted, so
a struggle ensues, and the steam is eventually the victor; but the
struggle is fierce, and can be heard and felt in every part of a
building of moderate size. The trouble does not end here, for when
the position is gained, the steam has to pass away, when it has
gained sufficient strength to force its way back through the water
and up the flow pipe, and this is an unpleasant experience. Exactly
the same result is obtained if the rising main is screwed too far
through the top of cylinder or the expansion too far through the top
of tank--an air or steam chamber is formed in either case; these
pipes should be quite flush with or above the inner surface of the
receptacles they are screwed into. There is no more annoying or
alarm-producing error than this.
Still another error is in running the circulating pipes up a casing
containing other pipes without felting the former, or even without
separating them; the result of placing a hot pipe against a cold one
for several feet is obvious, and if a hot pipe is placed against
a soil (w.c.) pipe, the result is offensive; these errors are
commonly found. There are numberless minor errors to be met with;
to enumerate all would occupy much space and be of no real use to
the reader. Errors are not uncommon things in this work, and some of
them are of so extraordinary a nature as scarcely to be creditable.
An objectionable feature in an old apparatus is the small supply or
feed cistern fixed at the side of the tank, but this is now almost
totally in disuse, for it has at last dawned upon some one that it is
quite unnecessary; this feed cistern must have a ball valve or cock,
and, this is where the mischief lies, no reliance can be placed on
a ball valve or cock of any description; they are commonly a source
of never-ending trouble. We give this description, as there are some
people who still persist in the use of this secondary cistern.
Discoloured water is sometimes caused by the rust that is naturally
created in new work, and lasts but a short time, as the pipes get
covered internally with a very thin coating of lime, which then
prevents the water coming in contact with the metal of the pipe.
Water is discoloured to a greater or less extent if it is permitted
to boil very hard, as this agitates any loose sediment that is lying
in the tank, and the boiling is much like churning the water.
The water in the tank or cylinder should not be permitted to boil,
as it creates an unpleasant noise, and is a certain strain upon the
work, and answers no good purpose; it can be stopped by drawing a
quantity of water off, so causing cold to flow in, but the remedy
is to keep the boiler flue closed by the damper; if this does not
prevent the overheating of the water, there is the possibility that
the flue is out of order, or “leaks.” This can be tested by closing
all the dampers when fire is in working order, which in the ordinary
way would cause all the smoke to be discharged into the room; if this
is not the cause, there must be an improper exit for the smoke and
heat, and a loss is of course being sustained.
Coils and hot-water pipes for heating a small conservatory or chamber
are sometimes connected with the circulating service, or direct by a
distinct service from the boiler, but there are no especial rules to
be observed in using these, as there are only stop-cocks to be turned
on or off as the requirements demand.
It may now be useful to give a few hints to those having a new
apparatus fitted.
There is a rather old saying to the effect that the “best is the
cheapest”: this especially applies to hot-water work. It would be
waste of time and space to enumerate the evils of cheap work of
this description, as the list would be a very long one. The best
plan is to apply to a good firm (not necessarily a large one) who
makes somewhat a specialty of this branch (generally boiler or stove
manufacturers, or good plumbers and builders). They will provide an
estimate of cost with _detailed_ specification free of charge if the
distance is not great. The object of a _detailed_ specification is,
as probably the reader guesses, to know exactly what size, strength,
quality, &c., of boiler, cylinder, or tank; pipes, iron and lead;
cocks, &c., &c., that are to be used; and before finally deciding,
the purchaser should insist upon the efficiency of the apparatus
being _guaranteed_. Boilers are of many various shapes and sizes,
but the best form has been proved to be that with a good flue or
heating surface underneath, so as to present as much bottom or under
surface as possible to the flame and heat; the best surface is easily
determined by any one, by applying the heat to the top of a kettle,
and afterwards applying it at the bottom, and noting the difference
in results; there are many other perhaps better forms of boilers made
for heating purposes; but it must be remembered that the boiler for
hot-water supply must not be of complicated form inside, but must
be quite clear, offering every facility for removing the incrusted
deposit. Fig. 131 shows the common form of boiler used in kitchen
ranges; the size must be governed by the capacity of the range
itself, but it should have as great a width and length as possible,
to increase the bottom surface; and the flue should be as large as
the size of fire will possibly permit. A most important point is to
see that the boiler has a large manhole _easily accessible_.
[Illustration: 131. Common Boiler. 132. Improved Boiler.]
Experience has proved that the best material from which these boilers
should be constructed is wrought iron or copper; the wrought iron
should be of 5/16 in. or ⅜ in. substance, and copper can be of a
little less substance except the front where the external wear and
tear takes place (chiefly by the poker). The principal of these
remarks apply to independent boilers also, which, however, are
generally set in brickwork and are of larger capacity and strength in
proportion. Fig. 132 represents a more powerful form of boiler for
domestic purposes, and is found a very rapid heating and efficient
shape, in instances where a large number of draw-offs are in use,
or a coil or heating pipes are in connection. Care should be taken
to avoid boilers with narrow water-ways where the heat is applied;
there are occasionally made boilers with 2 projecting horns or cheeks
which occupy the place of the fire-bricks in the range firebox;
these narrow parts, which are subjected to almost the most intense
heat, will fur up solid and crack in 6 months with London water.
The advantages of a copper boiler are quicker heating, greater
durability, and greater expansion and contraction, which prevents the
incrustation adhering to the surface so firmly as it does inside an
iron boiler; and although a copper boiler is of greater first cost,
yet when worn out it is of almost sufficient value to purchase a new
iron one.
These boilers are recognised by several names, viz. “high pressure,”
“Bath,” and “circulating,” &c., boilers. The first term is generally
known.
Cast-iron high-pressure boilers have now gone almost entirely into
disuse on account of the unsatisfactory results experienced.
Safety valves have been generally treated of in an earlier part of
this chapter, but it might be impressed upon the reader that the
valve should be as near as possible or directly in the boiler; they
are sometimes put in the circulating pipes or in the cylinder or
tank, but this is away from the seat of danger; it would be a rarity
to hear of a cylinder or tank exploding.
The reason that cylinders are used when the No. 1 system is adopted,
and tanks with No. 2 system, is that the cylindrical shape is better
adapted to bear the greater pressure; otherwise a tank would answer
as well to all intents and purposes; to show the pressure-resisting
strength, a tank of ⅛ in. plate is tested and warranted to bear 5
lb. pressure to the square inch. This is equal to the cistern being
10 ft. above the tank, whereas a ⅛ in. plate cylinder is tested and
warranted to bear 25 lb. pressure to the square inch, equal to 50 ft.
In speaking of pressure by feet this alludes to the _vertical_ height
between the cylinder or tank and the cold cistern; it does not matter
what size pipe connects them. A cylinder or tank can generally be
depended upon to bear a little greater pressure than they are tested
to. There are 3 or 4 strengths made to meet the various requirements,
and the makers’ lists show what pressure they are tested to in lb.,
and every lb. can be calculated as equal to 2 ft. of vertical pipe.
The general sizes of tanks and cylinders for domestic purposes vary
from 30 to 60 gal. according to requirements; the disadvantage of too
large a tank is the time taken in heating its contents and completing
the circulation, and in some instances the space it occupies; tanks
of 100 gal. capacity are sometimes fixed in residences where there
are only 4 or 5 taps (hot water). This is much too large for any but
large mansions or for business purposes; for say 5 taps, including
bath, a 50 gal. tank or cylinder will be found large enough and will
admit of 3 baths in succession about 1 hour after lighting the fire.
The pipes or tubes commonly used are iron steam tube, galvanised
iron steam tube, iron gas tube, or barrel, and lead pipe; the two
latter, though commonly found, should be avoided as being totally
unsuitable for this work. Gas barrel is sometimes used on cheap work
and in small speculative property, and answers well, when no real
work is put upon it; but no respectable firm would undertake to use
it, as satisfactory results cannot be relied upon except under very
favourable circumstances.
Steam tube, commonly known as “red steam” tube on account of its
colour externally, is much like gas barrel, but especially strong
for engineering purposes, and the utmost reliance can be put in
it. Galvanised steam is the same quality tube, but galvanised to
prevent rust; this is much liked, and is absolutely necessary in some
districts where unprotected iron rusts at an alarming rate; but care
should be exercised to see that it is galvanised _inside_ as well as
out; preference, however, is on the side of the “red steam” as it is
considered that the tube is deteriorated in strength by the process
of galvanising.
Galvanised iron boilers are sometimes used, but the same remarks
apply as are given respecting galvanised pipes.
The best size of tube for ordinary domestic purposes is 1¼ in.
internal diameter for the circulation and 1 in. for the major portion
of the draw-off services; ¾ in. may be used for minor purposes, as
lavatory draw-off, &c. There are, however, many apparatuses being
fitted at the present moment with 1 in. circulation and ¾ and ½ in.
draw-offs, and even ¾ in. circulations are to be met with; but the
advantage of a good-sized pipe is the freer flow of water when taps
are opened, and most important its less liability of being stopped
or rendered unfit for use by incrustation; 1¼ in. tube has fully 30
per cent. more inner surface than 1 in., so that it would take a
third longer time to get a ¼ in. coating of deposit in a 1¼ in. tube
than it would in a 1 in., and when this thickness has accumulated,
the 1 in. tube requires renewing, whereas the 1¼ in. is fit for
still further service, so that it can be calculated that 1¼ in.
tube will last about double as long as 1 in. so far as incrustation
is concerned, and this incrustation, as the reader now knows, is
an important element requiring every consideration in almost all
districts.
When _circulating_ pipes have to be carried round angles, bends
(which are nearly a segment of a circle) should be used invariably,
and not elbows, unless absolutely necessary in rare instances. A
bend permits the water to circulate round the angle much more freely
than an elbow, as the turn in the latter is abrupt, and tends to
check the circulation; this only applies to the circulating pipes;
it should also be seen that connecting-pieces known as “connectors”
are inserted at intervals where they will be of practical use, as
they permit of a piece of pipe being removed without disconnecting
the whole service, as is so often necessary for a small repair or
inspection. A connector is a piece of the tube with the socket so
arranged that it performs the function of a union.
When an apparatus is being fitted up, it must be borne in mind that
the most perfect arrangement would be to place the tank immediately
over the boiler, and carry the pipes in a vertical line between them;
this can rarely, in fact, never be done, so it should be arranged and
carried in a manner as near this as possible; every angle and every
piece of horizontal pipe is objectionable, but regard must be had
for positions where the pipes or casings would be unsightly. Where
pipes _must_ be run laterally, they should if possible be given a
rise towards the cylinder or tank if only 1 in. in 5 ft., but more if
possible; these remarks only apply to circulating pipes.
The “flow” pipe should always proceed from the top of the boiler,
never from the sides or back (although this is often done), as it
will be understood that the heated water, wanting to rise, much
objects to starting along a horizontal pipe however short, and
another reason is that an air chamber will be formed in the top of
the boiler, and cause much annoyance already alluded to.
In No. 1 system the cylinder and circulating pipes cannot well be
placed in a cold position, but with No. 2 system ingenuity must be
exercised to carry the pipes and place the tank in as warm positions
as possible near to chimneys and not on outside walls, &c., if
possible; it is time well invested to cover the pipes and tank with a
non-conducting covering in any case for the reasons already stated.
Pipes should on no account be let into the wall and cemented over,
as, with the best work, investigation may at some time be needed, and
this would necessitate serious damage to the decoration of the wall
in question. On no account sanction the idea of carrying circulating
pipes outside the building, however well or carefully they are to be
cased or covered. These remarks apply also to the cold-supply pipe to
prevent failure in supply by frost. It is also necessary to see that
neither circulating pipe comes in contact with a cold-water pipe or a
soil (w.c.) pipe.
It will be noticed in the illustrations that before the cold supply
enters the tank or cylinder, it descends below its entrance level a
short distance, about 12 in., and rises up to the tank or cylinder;
this dip in the pipe is called a “syphon,” and prevents the hot water
rising up this pipe, as it must be understood that hot water _will
not_ circulate downwards.
The cold supply is usually of lead pipe ¾ in. internal diameter, but
lead pipe is quite unsuited for soft or pure water (distilled). The
same applies to lead cisterns, as this water attacks (oxidises) lead
vigorously, and lead pipe is not looked upon with favour for many
reasons. Iron is now often used for the whole apparatus, including
cistern, tank, &c. (excepting where copper is used for boiler or
cylinder). There is a marked advantage if the cold-supply pipe is 1
in. instead of ¾ in., for this reason, if two or three ¾ in. (usual
size) taps are opened at once, as commonly occurs, the flow of water
must be reduced at each of them if only a ¾ in. supply exists.
The advantages of draw-off services being “returned” have already
been explained, and cocks or taps have been treated upon. There are
numberless good cocks in the market, but of course the best are
subject to wear and tear; those with lever handles, known as plug
cocks, have to have the plugs reground in occasionally, and with the
screw-down cocks the sealing, generally of prepared indiarubber, has
to be renewed periodically; but money is well invested in really good
quality taps.
If after the apparatus is fitted and finished there are any leaks
noticeable, the purchaser should insist upon these being remedied
before the workmen finally leave; there is a common saying amongst
workmen that small leaks or “weeps” pick themselves up, i.e.
the aperture rusts up; very small leaks will pick themselves up
sometimes, but no reliance can be placed in this unworkmanlike way
of finishing, and it is commonly necessary to have the men in the
house a second time to remedy one or more obdurate “weeps,” which are
really defective joints.
Baths and lavatories are of very numerous variety; but a good feature
with a bath is to have the hot-water inlet near the bottom, so that
when the taps are opened this inlet quickly becomes below the water
level, and this prevents the steam rising as the water is discharged,
rendering the room unbearable if small; but this inlet _must not_ be
in any way connected with the waste outlet as it often is, as when
the water runs in it will bring back a portion of the last bather’s
soapsuds. A good feature in a lavatory basin is a flushing rim: the
rim of the basin is hollow and provided with a fine slit or aperture
which extends all round its lower edge. When the tap is turned, the
water is discharged into this rim, and from there flows into the
basin, through this aperture around the whole of its circumference;
this is of especial use to wash away sediment from the sides of the
basin after use.
Both baths and lavatories should have large supplies (hot and cold)
and large wastes, to fill and empty rapidly.
No. 2 system can, when desired, be converted into No. 1 system at a
moderate expense (about one-third the cost of a new apparatus); and
a range can be fitted with a high-pressure boiler in such a manner
that it can be used for low-pressure purposes first, and when the
high-pressure apparatus is fitted up it can be connected and started
to work upon the latter principle in 2 or 3 hours.
If two ranges are in proximity they can both be provided with
high-pressure boilers and the two services united, flow to flow and
return to return, and work the one tank or cylinder and apparatus,
either assisting each other or working independently. This is
oftentimes a very great convenience; the union of the services should
be as near the boilers as possible; no stop taps are needed (avoid
these whenever possible).
Twin boilers can sometimes be fitted to a range, and each used for a
different purpose, viz. one for hot-water supply, and one for steam
cooking, &c.
[Illustration: 133. Self-filling Apparatus.]
Fig. 133 represents the common form of self-supply or self-filling
apparatus as attached to low-pressure boilers in kitchen ranges. By
the term “low pressure” is meant open top or closed boilers that
are not usually filled quite full, and the draw-off is below the
water-level within them. _A_ represents the small supply cistern,
which is supplied from the general cold supply of the house; the
quantity and level of the water in this small cistern is regulated
by a ball valve _D_, as shown; this cistern is connected with the
boiler _B_ by a supply pipe _C_, usually of lead and ¾ inch internal
diameter, and provided with a “syphon” as shown, and for the purpose
described in cold supply to tanks, &c.; this supply proceeds from the
bottom of the supply cistern _A_ to the bottom or near the bottom
of the boiler _B_. There is a very common error in arranging the
apparatus so that the boiler fills up to about 4 in. from the top;
this is not high enough, it should fill up to within about 1½ in.,
this is ample room for expansion and boiling; if a 4 in. space is
left it means 4 in. for the flame and heat to act upon without having
water to protect it, and consequently it becomes destroyed. This does
not always produce a leakage, but it permits the smoke and soot to
enter and discolour the water. There is another still more common
form of error in this description of apparatus, and that is, failing
to draw from the upper part of the boiler where the hottest water is,
and where it first becomes hot; it will be understood from Fig. 133
that when the tap (if placed near the bottom of the boiler as usual)
is opened, a portion of the contents of the boiler flows out and a
supply of cold immediately flows in, to make good the loss. Now the
hot water being lightest, remains at the top of the boiler, so it can
readily be seen that it cannot be drawn, for it will not descend,
and the inflow of cold is right opposite the tap, therefore when the
tap is opened a small quantity of hot water is drawn, and then there
sets in a flow of cold water from the cistern, across the bottom of
the boiler, and out at the tap almost without disturbing the hot
water in the upper part of the boiler. There are two remedies; one
is to have the tap inserted in the upper part of the boiler (by the
manufacturer) when purchasing it; another is with existing ranges
to screw an elbow on to the end of the tap _inside_ the boiler, and
into this elbow to screw a short length of pipe to stand up to about
4 in. below the water-level, as in Fig. 134; this elbow and pipe can
be fitted by any one, as no jointing is required, and to fit it the
tap does not require to be moved in any way. The reason that it is
necessary to keep the end of the pipe so much below the water-level
is, that the ball valve by which the cold water is supplied is
smaller than the tap from which the water is taken, or, in other
words, the inlet is smaller than the outlet, and the level of the
water sinks or becomes lower in the boiler and cistern as you draw.
[Illustration: 134. Draw-off Tap.]
It cannot be too strongly impressed upon the reader that good work
executed by a good firm, although the expense is increased, is a
source of comfort and many advantages, and is “the cheapest in the
end.”