How To Build a Fireplace

The flue is, of course, a very impor­tant factor. Its cross section should be at least one-tenth of the area of the front opening of the fireplace. A flue having an area greater than one-tenth of the area of the finished opening is not objectionable, but one having less dooms the fireplace to unsuccessful operation.

The flue should be lined with a fireclay flue lining properly bonded together and to the masonry of the chimney. The area of the flue should be maintained for the entire height of the chimney and not contracted at the top. All turns and bends should be as gradual as possible, with no angle more than 30 degrees from the vertical. And every fire­place should have its own flue. Never connect any other heating apparatus to a fireplace flue.

The chimney should project at least three feet above any flat roof and two feet above the ridge of a hiproof.

In the table below are shown all the essential dimensions needed in the construction of a successful fire­place. The dimensions are worked out on a basis of the width of the fireplace opening. Slight variations in this dimension will alter the other dimensions somewhat, but the pro­portions may be easily worked out.

The throat of the fireplace is that portion between the top of the firebox and the smoke chamber. It should always be as wide as the fireplace is wide and from four to five inches in depth. By the use of a Majestic Fireplace Damper and Throat combined, this detail of construction is automatically and satisfactorily taken care of, for each damper is properly and scientifically designed to meet the re­quired conditions.

The back edge of the damper should always rest on the forward edge of the smoke shelf. The joint between the dam­per and the bottom of the smoke shelf should be tightly sealed with mortar so that it is impossible for flames to get to the flue, except through the damper throat.

The smoke chamber is that portion of the fireplace immediately above the throat or damper. A great deal of care should be used to see that pro[x*r dimensions are maintained, that the front of the wall is not drawn in so abruptly as to interfere with the rising smoke, and that all sur­faces are smooth and free from large pro­jections.

The bottom of the smoke chamber is called the smoke shelf that is, the por­tion of the smoke chamber between the damper or throat and the back wall of the smoke chamber. It is absolutely essential to provide a smoke shelf, because in every flue there is what is known as a back draft. Back draft is caused because the front wall of the flue is warmer than the back wall when the fire is burning, and the gases Missing upward along the front wall create a suction down the back wall, resulting in a down draft of outside air. When this down draft meets the smoke shelf, it is deflected by the damper valve plate and carried up again with the rising gases from the fire.

The smoke shelf should be the full width of the throat, never less than eight inches deep, and it may vary from this dimension to 12 inches or more, depend­ing upon the depth of the fireplace itself. See illustration.

In building a successful fireplace, there are at least six things that must receive attention. They are the flue or chimney, smoke chamber, throat, firebox, hearth, and mantel. Of the six, the least impor­tant, from the standpoint of construction, are the outer hearth and mantel. To be sure, they are the parts that give the fire­place a decorative effect; but they are not essential to the operating efficiency of the installation.

After the selection of the design for the mantel, the next important step is to de­termine the size. Too small an opening restricts the amount of heat thrown into the room. The average fireplace is from 30 to 40 inches in width between the jambs. The height of the fireplace and the depth of the fireplace from front to back do not vary to the same extent as the width of the fireplace. The table on page 44 will show you the proper proportions.

The shape of the firebox is important. Its sides should be splayed, that is, drawn in toward the back at an angle of about 15 degrees with the front, or about three inches for every foot. The back of the fire­place should be vertical for a distance of approximately ten inches; then drawn for­ward to a point where the damper rests upon the masonry. This arrangement pro­vides for throwing more heat into the room.

The ash dump should be placed directly below the fire or the inner hearth so the ashes may be worked through it to the ashpit below. A door to the ashpit at the level of the basement floor will make it easy to remove the ashes.

Flue Size

Flue size for the ordinary fireplace, en­closed on three sides, can be estimated by rule-of-thumb methods as an area proportionate to the size of the fire­place opening.   However,  cross  drafts

and  other  problems  encountered   in

multi-opening fireplaces must be over­come by a stronger draft, and therefore larger flues are required. Since the fire­place opening size can vary not only vertically and horizontally, as in a sin­gle opening, but also by the number of sides open (two, three, four, or a complete circle), the flue must vary in proportion. Suggested flue sizes for different styles of fireplaces are listed elsewhere in these instructions.

General

Inspect the damper, making sure the valve plate is undamaged and free to operate, Check to see that the pull chains are securely fastened to the valve, with the "C" pull hanging from the side that opens above the damper body and the "O" from the valve side that opens down into the dome. Test the tension adjusting bolt I see dia­gram I and readjust if necessary for proper operation. Tighten the nut against the tension arm to hold the tension bolt in the set position.

Installation

Lay up the fireplace according to your plans until the desired opening height is reached i see specifications). The damper is now set in place, taking ad­vantage of any built-up masonry sides as supporting ledges for the damper flanges. Any projecting corner should be supported by a suitable post of ad­equate strength. With the damper per­fectly level, accurately measure and cut the post to the length needed and set in place. Now pad the corners of the damper body with the ½” glass wool provided, and continue laying up the masonry. Keep bricks and mortar at least ½” away from the damper to allow for expansion and contraction of the metal.

Smoke Shelf

The flue tile should never be set di­rectly above the damper opening, but should be offset to one side. A smoke shelf, horizontal with the top of the damper, should be provided to impede and deflect downdrafts. It should be located directly beneath the flue tile, on any of the four sides of the damper. Actually, eight positions for the shelf and the chimney above it) are avail­able, since the damper can be reversed. The smoke chamber above the damper and the shelf should be generous in size, high enough not to impede the move­ment of the damper valve, and should be corbelled steeply to meet the bottom of the flue lining. For a smooth surface and better draft, the walls should be given a coat of cement mortar. From this point on, the mason should fol­low the best recommended practices for good chimney construction.

In searching for more striking and individual types of fireplaces for the modern home, designers have reached back to the most primitive eras for new ideas. From the old fire pit dug in the middle of a native hut has come the modern room-center fireplace, a circular or rectangular hearth which is hooded over but open to view on all sides. Other old European peoples, such as the Scandinavian, have contributed to the new designs in many different forms. Instead of having one open face, in what we might call the familiar, conventional fireplace, these modern units now have two, three, or four sides open in an amazing number of variations.

But with these new designs have come new problems in construction. The fact that two or more sides are open allows cross drafts to pass through the fireplace, a problem which can only be overcome by creating a stronger draft up the flue. Also, the increased area of the multi-open-ings requires an increase in the size of the throat and in the flue area.

To answer these and other problems of construction. Majestic has developed the universal Smoke Dome a combination building form, throat, and damper that assures construction free from operating com­plications. Where narrow or double dampers have proved unsatisfactory, these wide and deep units provide the proper throat area and a smooth, unobstructed dome that funnels the smoke to the flue under most adverse conditions.

The high sides of the dome, sloped to exactly engineered proportions, allow rapid laying of masonry in this important area and save hours of the mason’s time. The pivoted damper valve, operated by pull chains with "O" and "C" pendants, gives ample opening for full draft, holds at any degree of opening by means of a foolproof tension bar. and closes tightly against the flanged top when the fireplace is not in use.

In using a Majestic Smoke Dome, flue liner tiles are never placed directly above the damper opening but are offset in any of eight posi­tions, as described in the installation instructions. This provides for a smoke shelf of masonry that stops chimney downdrafts and shunts them into the updraft area.

Note:  These instructions are for a raised hearth, using the raised hearth accessory.

Step 1. Frame the opening, preparatory to in­stalling a Majestic Thulman Fireplace the U/L approved unit that has built in clearance permitting it to be butted against combustible surround.

Step 2. Set into framed opening the 12" high base of a Majestic Thulman Fireplace. Note that it is provided with brackets to support a raised hearth.

Step 3. This shows the front view of the open­ing with the Majestic Thulman Fireplace base set into position ready for receiving the primary unit.

Step 4. Now place the Majestic Thulman Fire­place on the base, which was previously set in position, extending behind  the wall.

Step 5. Rear view, showing the unit in place. Note that no other housing or covering needs to be placed around it — and with built-in clearances other objects or construction can be butted against it.

Step 6. You’re now ready to set into place the semi-fabricated marble or black glass facing panels, or surrounds, on a Majestic Thulman Fireplace. Other non-combustible materials of user’s preference can be used for facing.

Step 7. Raised hearth pan is placed in posi­tion. The Majestic Thulman Fireplace is now ready for final finish of room wall.

Note: Installation of the complete chimney and chimney top is equally simple, especially with the easy-to-follow instructions that are fur­nished with each Thulman Fireplace package.

The chimney top housings described here make possible many different arrange­ments of fireplace and chimney flues ter­minating in the same "double" housing or in separate housings (See diagram of arrangements on opposite page). Each housing is available in simulated brick finish of off-white, red or sun-tan color, baked on in modern ovens for permanence. Add the letter "W". "R", or "T" re­spectively to model numbers below for color desired. All housings are 54" high.

STANDARD T-l   HOUSING

The standard square housing is 18" x 18" and is used for separate fireplace and fur­nace flue installations, or where it is not feasible to locate both chimneys together.

DELUXE  T-2   HOUSING

This 18" x 36" deluxe rectangular housing is used where the furnace chimney is lo­cated directly in back of the fireplace chimney. It can also be used for double Thulman Fireplace installations—one below the other or back-to-back—or to house a single fireplace chimney and create a more massive appearance. Centerline of two chimneys should be located 18" apart.

DELUXE T-4 HOUSING

A really massive chimney. 18" x 54", usable in place of any of the other top housings but offering greater leeway in that the distance between chimney center-lines is 36".

DELUXE  T-101   HOUSING

For a more massive appearance, this 18" x 27" rectangular housing for a single chimney is used in place of the standard T-l housing.

DELUXE T-3  HOUSING

This is an   18" x45"  deluxe  rectangular housing and can be used in any installa­tion where the T-l. T-101. or T-2 might apply, for a massive appear­ance with only one chimney or with  two chimneys  27" apart on their centerlines.  It can be used where a furnace chimney must pass up on eith­er side of the fireplace casing.

DELUXE TOP  HOUSINGS

May be installed so the long dimension is parallel with, or at right angles to. the roof ridge. Stated distances be­tween flue centerlines must be maintained, if used for both furnace and fireplace chim­neys. The diagrams on oppo­site page show possible arrangements.