MIKE CREEGAN, Somersworth, N.H.

A. A short answer to a long question: Why not? Make yourself a guinea pig and try it. If it works, fine; if not, there is no harm done. One wonders just how much is the ``main ingredient,'' but it still is worth trying. Just don't mix it with ammonia and/or bleach; there is no reason that you would, but it's just a standard warning against mixing various materials.

Mike Creegan of Somersworth, N.H., asked if he could use trisodium phosphate (TSP) to keep his flue clear of creosote, since the main ingredient of his powdered-type chimney cleaner cleaner was TSP. The latter is less epxensive, so why not, he asked. He uses a wood-burning stove regularly.

The handyman answered, why not indeed. Even if it doesn't work, no harm done.

Not necessarily, said W. Troy Couch, vice president of Combustion Improvers Co. of Newport, N.H., makers of Anti-Creo-Soot, a creosote control for wood-burning stoves.

``TSP is derived from phosphoric acid, and is therefore strongly alkaline and potentially corrosive to some surfaces.

``The use of 100 percent TSP would probably introduce far more of the chemical than the chimney cleaner, with more drastic results, but possibly more deleterious side effcts.

``The long range effect of TSP-based treatments on . . . metal chimneys is not known, but the corrosive aspects are commonly known.

``Powdered-type cleaners and other `old time' remedies are the dinosaurs of the wood-burning scene, still available because they are cheap. . . . Most of these products are, happily, only history.''

Couch recommended wood-burners use Anti-Creo-Soot, a spray product introduced by his company in 1982. ``It is water-based, safe, nontoxic, nonflammable, noncorrosive. It can help extend the life of metal and masonry chimneys by dispersing acidic creosote and soot formations.''

Couch added that Anti-Creo-Soot does not claim to eliminate the need for chimney sweeping and inspection. Chimneys should be swept regularly, he added.

Couch also mentioned a relatively new product, Anti-Carbon Spray, a carbon and soot remover for gas logs.

Thank you, Troy Couch.

So, the handyman suggests that Mike Creegan use a product other than TSP as a chimney cleaner. Short-time use of TSP probably will cause no harm, but as Couch points out, long-range use could be bad for any kind of chimney.

Q. I removed some brick from an old chimney in my circa-1890 house. Some of the brick is common brick, but seems fairly hard. Can I use it for a patio?

M.M., Newburyport

A. Generally, even common brick is acceptable for use on a patio, because it is fairly hard. But if you have any so-called salmon brick (it is the color of salmon), do not use it on the patio; it is very soft and will crumble in a few months. The rest of the brick should stand up for years; if some of the bricks crumble, you can always pick up the debris and replace them with a hard brick such as a City Hall paver, which is very hard and will last for 100 years or more.

Q. A vine is growing up the outside of my chimney, right to the top. I was told to take it down because the vine holds water against the brick and mortar, hastening their deterioration. Doesn't the chimney get too warm for water to stay?

LESLIE GLYNN, Waltham

A. I think you can leave it in place, although it would be wise to cut it a few feet down from the top, to keep it from overwhelming the top of the chimney. While constant water against mortar may promote decay of the mortar, it would take a long, long time to do so, and it will not hurt most bricks. Your theory about the chimney being warm enough to evaporate some of the water is valid, but it does not apply when the burner is not on, which is perhaps four months out of the year.

Q. My chimney is set against the side of the house until it goes above the roof. I discovered the waferboard sheathing behind the chimney is wet, and I can put my finger right through the board. I took off a 1 x 1 trim at the joint between chimney and siding, and the sheathing is wet in most places behind the chimney. What can I do to dry it out and prevent it from getting wet again?

RICHARD ALBA, Winchester

A. It sounds as if the flashing where the chimney meets the roof is defective, and allowing water into the space, wetting the sheathing. And, possibly, the bricks are porous and allowing water to go right through them. If the bricks are porous, you can seal them with a masonry sealer. And, finally, that 1 x 1 trim may be leaking water to between the chimney and the siding as well.

So, to try to dry out the sheathing, cut an opening in the sheathing in the attic. That might allow enough air circulation to start the drying process. And, check the flashing against the chimney and have it fixed, if indeed it is leaking. Of course, you also should replace that decayed sheathing.

That 1 x 1 trim may just be resting against the brick and the siding, leaving plenty of gaps for water to get into. So, install a new trim, but make it, say, a 1 x 2 and notch one edge so that it matches the face of the siding (clapboards or shingles); that way it will fit snugly against the siding for a tighter fit. Caulk the chimney and the siding before installing the 1 x 2 trim and see what happens. But I would do that only after the sheathing has dried out; if you install the trim (on both sides of the chimney) before everything dries out, it will take that much longer, if ever, to dry out.

One more problem: The water may be coming from inside the house; water vapor inside makes its way through the wall and sheathing, where it condenses into water. Hope that that is not happening, because the cure is difficult; you have to stop that water vapor from condensing.

Thinking about it, another possible fix is to install that 1 x 2 trim tight against the siding, but keep it, say, 1/4 inch from the brick. This gap will allow air circulation, which is badly needed; any water that gets in should evaporate because of that extra air circulation.

Q. My chimney sweep told me my old clay flue liner is cracked with some holes, and suggested installing a stainless steel liner. Is this necessary? I recently converted from oil to gas.

JOHN STASIOWSKI, Wellesley

A. One might argue that it is not absolutely necessary, but there are two reasons why a new liner should be installed. One is that it will cure the crack-and-hole problem in the present liner, and also because a stainless steel or aluminum liner is essential when using gas to heat the house. Gas produces 2 cubic feet of water vapor for every cubic foot of gas burned; this water vapor combines with soot and other pollutants in the chimney to form an acid that can deteriorate a chimney and/or its liner quickly.

Q. I would like to cover a concrete block chimney with brick. How can I do it?

M.L.A., Wrentham

A. That's quite a question, because it's not just a matter of attaching brick to the concrete block; in fact, that is impossible. First important requirement, if the chimney goes up the side of the house, is a brick shelf at the bottom of the chimney, underground. This brick shelf must have its own footing so that the brick can be set on it. And that requires digging down to the bottom of the chimney, installing a concrete footing around the chimney and starting brick from there. That footing should be 6 to 12 inches wide and 12 inches thick.

That is difficult enough, and even harder, in fact impossible, to put brick on the fourth wall of the chimney where it goes above the roof. It is also impossible to put brick around a chimney that is in the middle of the house, going through the roof. I suggest one of two other things that do not require all of the above: New England Brick Master, which puts a veneer of a bricklike material on the chimney. Or, parge the concrete blocks, which is a method of applying a coat of mortar or stucco on the concrete block. Be sure to put a bonding agent on the concrete block so the mortar or stucco will stick.

Q. The downdrafts in my chimney are so severe that you can hear them roaring, four of them feeding four flues. Needless to say, they carry that burnt-wood smell with them, at least into the fireplaces. I try opening the windows to reverse the drafts, without success. How can I reverse those downdrafts or at least keep that odor from coming down into the fireplaces?

S.D., Plymouth

A. A chimney cap might help. Another way to do it is to put a piece of plywood tight over the firebox opening. A draft-inducer fan at the top of the chimney also will make a difference. Covering the top of the flue with a solid cover will definitely do it for that flue, but do this only if the flue is not used. The problem, and solutions, have been discussed on these pages all year long. But Ed Grant of Beverly has what he calls a foolproof way of preventing those downdrafts, and wrote us all about it. His situation is different because he has a wood stove partly set into a fireplace, but his problem was the same: downdrafts causing what he called a terrible stink.

The original damper was removed when the stove was installed, wrote Grant, and a blank plate fastened over the flue space. The stove is connected to the flue by a 6-inch stove pipe.

``When we get an air inversion, usually during wet weather, the outside air becomes heavier than the inside air; I get that awful stink!''

Grant used to burn wood to get rid of the odor, but that was not practical in warm weather.

``My solution is simple, and it works great for me. ``I found an old kerosene lantern. I cleaned it up, bought a gallon of kerosene and found it to work. I placed two firebricks on the ashes at the bottom of the stove. I put the lantern on the bricks, closed the top door and opened the front door, lit a crumpled up newspaper, put it in the stove and closed the door. In a few minutes, the draft was up the flue. I opened the door and lit the lantern. No smoke, no mess, no stink. After a few minutes, the top of the stove gets a little warm, but never hot.

``If it gets cold outside, I can take the lantern out and get a fire going in a few minutes. My lantern holds enough kerosone to run for 24 to 30 hours. I found kerosone at a rental store near my home. I run the lantern with just an inch-high flame, which works for me just right.

``I hope some of your readers can benefit from my experiments.'' Thank you, Ed Grant. While your situation with a stove is different I don't see why your solution wouldn't work in a fireplace. There may be some loss of heat from the house with this treatment, but it also might be worth it to get rid of that smell!

Q. Why do chimney liners always seem to get wet all the time? Under the flashing around the chimney in my attic, it is all black and wet. I have oil heat.

RICHARD ALBA, Winchester

A. The weakest point in a roof, unless it is more than 20 years old, is the flashing, which can leak if it isn't done right. Done right, it will resist all kinds of battering. That wet black area below the flashing in the attic may be condensation, where the wood and the flashing material are coldest, and water vapor is building up in the attic and condensing on those cool surfaces. Result, the black mildew. You can clean the mildew and kill it with a solution of 1 part bleach and 3 parts water. It's a good idea to do that because mildew left in place can cause decay of wood, shingles, and anything else prone to decay, and that is just about everything.

To help keep the mildew away, ventilate the attic more by installing vents. The best system is a ridge vent in conjunction with soffit vents, a continuous 2-inch-wide louver on the soffit, the underpart of the roof overhang. This will allow water vapor to escape the attic before it builds up enough to condense.

Flue liners get wet the same way: condensation on a cool surface. If you have gas heat, the situation can be worse because burning gas produces 2 cubic feet of water vapor for each cubic foot of gas burned. That's a lot of water vapor. But whether you have gas or oil heat, there is not a lot you can do. With oil heat, the situation may not be so bad when the heat is on, because the flue will warm up and dry out. And at least even with gas heat, the fumes and water vapor go up the chimney before they condense.

Q. I have a mid-1700s house, and am trying to be true to its history and style. I made one mistake when I had my massive center chimney, which was disintegrating, completely rebuilt. The mistake was using modern common brick, and now a large part of the interior brick looks like a Stop & Shop wall. Is there any way I can antique the brick? I was thinking of whitewashing, then wiping it off.

DON BRADBURY, Medway

A. I have no idea how to antique bricks except as you described, but whitewash is really passe. I doubt if you can find any, and it is difficult to make with many exotic chemicals. Besides, it washes off in weather. But you can try substituting latex paint or solid latex stain for the whitewash. Put it on, let it sit 5 to 15 minutes, and scrub. Or, thin it down with water, apply, and wipe off.

Q. When I had a concrete cap put on the top of my large, three-flue chimney, the contractor took off a band of concrete that went all the way around the chimney at the top, and did not put up a new one. Now, water runs off the cap and directly down the four sides of the chimney. I am afraid that running water will stain the sides of the chimney. Should the border or band be put back?

JACK OLSON, Framingham

A. The band is mostly decorative, but it also acts as a drip edge to prevent just what you are concerned about. Have the contractor put up a new band. Such a band does not have to be very thick (half to a full inch will do), nor is there an arbitrary rule as to how deep it should be.

In Revolutionary times, the band served one more purpose. It created the opportunity for a black-and-white chimney. The chimney was painted white and the band black. This was called a Tory chimney, and it was a secret sign that Loyalists occupied the house. If the band was proportioned correctly, the black-and-white chimney had a certain class to it. It was good looking, and kept those massive chimneys in perspective.

Q. The mortar is deteriorating in my chimney that comes up through the roof, but only from the roof up. I was told that it should be rebuilt from the roof up; another company said it would stucco the outside. Rebuilding is expensive. Are these the only things that can be done?

DON HOY, Weymouth

A. Not necessarily, particularly if only the mortar is deteriorating. That is what mortar does, exposed to the weather over the years. I don't think rebuilding is necessary. The stuccoing referred to is really parging, applying a layer of mortar or concrete to the brick. That is possible, and a lot less expensive than rebuilding.

Another thing that can be done is repointing. Not inexpensive, but worth finding out about. Repointing is simply chipping out the old mortar to a depth of at least three-quarters of an inch, and inserting new mortar. If the bricks are in good condition, the repointing will last 20 years or more. It might cost about as much as the parging.

Q. A lot of soot has washed out of the bottom door of my chimney in the basement, staining the floor. How can I prevent that? I have oil heat.

C.R., Quincy

A. Chances are there is a goodly buildup of soot at the bottom of the chimney; this could happen even with oil, if the chimney was not checked for a number of years, and rainwater came down the chimney to wash some of the soot out the cleanout door and onto the basement floor. Open the door and check. Be very careful, because that soot could spew out and fluff around in a draft. Call a chimney sweep if you are reluctant to open the door.

As for the soot on the floor, just sweep it up, put it into a paper bag and throw it into the trash. Clean the stain with a strong solution of Spic and Span and water.

Q. I had my two chimneys rebuilt, and now one is taller than the other. The originals were the same height. How can I even them out?

M.C., Walpole

A. The only legitimate way is to add a course or two of brick to one of the chimneys to make the match, which would be quite an accomplishment because it is covered with a concrete cap. This cap would have to be removed and a new one built after the chimney is extended.

There is another possibility. If the difference in height is small, you might be able to add concrete to the low cap, making it a little thicker to make the match.

And still another way is to install a stainless steel chimney cap (different from the concrete cap), on each chimney, with one of the steel caps a little higher or lower, so you would at least fool the eye.

Q. My chimney needs attention; the top bricks look loose. I know I need someone to check it, but who? What is the difference between a chimney man and mason?

MARY WHITTEMORE, Winchester

A. Let's put it this way: Most masons are also chimney men, because very few masons do not also work on chimneys. Not all chimney men are masons. So, you have to find a mason who has done and does chimney work. The bricks sound as if they need repointing, which entails digging out the old mortar and inserting new mortar. If a lot of the bricks are loose, it may require rebuilding the chimney from the roofline up, also the work of a mason.

Q. A chimney sweep told me I need a chimney cap, and a stainless steel one 13 by 26 inches would cost $175 installed. Is that excessive, and why would I need a cap in the first place?

MICHAEL ROSS, North Attleborough

A. That price for a relatively large stainless steel cap is not excessive. As to why you need a cap, that is a good question that the sweep should have answered. A chimney cap is needed for two basic reasons: to prevent rainwater from coming down the chimney into the fireplace (or at the bottom of any other chimney), and to prevent entry by critters. There is a third reason why you might need a cap: to increase the draft of the chimney.

So, if yu have none of these conditions -- water in the chimney, problems with animals, or a bad draft -- you don't need a cap, in the handyman's opinion. In fact, sometimes if you have water in the chimney, a cap is not necessarily a cure. That is when the flue liners (clay tiles) that normally stick out through the top of the chimney by about 2 inches, come up only flush with the top. If that is the case, windblown water can get into the chimney more easily. If the liners stick up about 2 inches, that is enough to stop that windblown rain and will reduce or eliminate the water in the chimney.

Q. I have to put liners in two chimney flues, each 45 feet high. One man suggested stainless steel liners for $4,500. Is that high? What about putting in poured concrete liners?

TOM KANE, South Boston

A. The $4,500 comes to $50 per foot, but I don't think that is exorbitant. The poured concrete flue is equally good, and probably is close to the same price. I personally would opt for the stainless steel liners.

Q. I am having a chimney built of concrete flue blocks. I know it has to sit on a footing, but how deep should the footing be? Should the blocks go up against the shingled wall, or should the shingles be cut out for the blocks? Should brick ties hold the chimney to the wall?

DON MAYER, Halifax

A. The footing should be below the frost line (the maximum depth that ground freezes in winter), which is generally 4 feet in New England, to prevent heaving of the structure.

The chimney can go directly against the wall shingles, but it would be better and neater to cut out the shingles and let the chimney butt up against the sheathing. That way, you can caulk along the edge for a smooth, waterproof joint, preventing water from getting between chimney and sheathing. Brick ties won't hurt, either, added stability to the chimney. Brick ties are metal strips, one end of which is mortared into the joints between the blocks, the other nailed to the sheathing.

Q. After I had six fir trees removed from near my house, I had big downdrafts into my wood stove. It's amazing how much air came down the chimney. I have a chance to put in one of those wind direction chimney caps for $115. Would this eliminate the downdrafts?

JOE WALSH, Braintree

A. Yes, I believe it will, because the vane of the new cap will keep the opening away from the wind, something that a standard chimney cap might not do.

It is amazing what air and water can do; people, not necessarily you, are often skeptical of the many weird things they can do. But it's a fact of life, and we can be thankful that there are things out there to handle almost anything water and air can do.

Q. Water is getting into the fireplaces of my brand new house, some in the fireplace on the first floor, and more in the fireplace on the second floor. It's a lot of water, not just a little drip. What can I do? Can I seal the bricks?

FRANK MARCHICA, Sudbury

A. I doubt if sealing the bricks will do much good because they are not old enough to become saturated with water, which can happen with old bricks -- they're more absorbent than new ones -- and prolonged soaking. Besides, sealing the bricks with an ordinary masonry sealer can trap water inside the bricks, making matters worse. If you do want to seal the bricks, use a sealer that will waterproof bricks on the outside, but allow water vapor to pass through. One such sealer is Chimney Saver Water Repellent, sold by the Chimney Chap, Ken Keithly, 4 Trout Farm Lane, Duxbury, MA 02332, or call (508) 585-5321.

The water is more likely to be coming in directly down the chimney. To correct that, install a stainless-steel chimney cap. Also, check the clay flue liner that lines each flue (opening). It usually sticks up beyond the chimney top by about 2 inches. If it doesn't, blown rain can get into the chimney much more easily. If the liner does not stick up, you can cut a section of flue liner to do so.

While you're at it, check the top of the chimney itself. It should have a concrete cap on top, slanting down from the flue liner to the edge of the chimney itself, acting as a water shed. For some weird reason, the cap may be level, or sloping into the flue, encouraging the intake of water. If so, the builder should fix it.

Q. I have to replace the vent pipes to my power-vented water heater and boiler, but they cost $450 each. I don't want to do that too often. Could I install an insulated chimney instead for both units?

ROGER FRUGGERIO, Salem

A. I have never heard of the power vents wearing out or deteriorating, but I suppose they could, just as an auto exhaust system corrodes and needs replacement. You should be able to install an insulated chimney, but I would suggest one for each appliance. And check first with the person who installed the power-vented appliances. An insulated chimney is very expensive, but at least it should last longer than the power vents. You can put it up inside or outside the house. For gas, a special stainless-steel or aluminum chimney is recommended.

Q. How do I know if my chimney is blocked and needs cleaning? I have oil heat.

A.A., Randolph

A. You'll know that the chimney is blocked when you smell oil smoke in the house and basement. It is toxic and you'd have to move fast to avoid being asphyxiated.

With oil heat, the chimney does not get seriously dirty, and does not need cleaning often. However, an oil fire can build up ashes and debris in the bottom of the chimney, below the smoke pipe. If that happens, and the smoke pipe gets blocked where it enters the chimney, you could have a serious problem. This is because an oil burner runs under pressure and will not shut down if the smoke pipe or chimney is blocked, resulting in fumes backing up into the basement and the house. If you were burning wood or coal, a blocked smoke pipe or chimney would shut down the fire, after a lot of smoke.

So, have a chimney sweep check the bottom of the chimney, by opening the ash cleanout door. If there's a buildup of ash or debris, it can be removed.

Q. I have three flues, one for the fireplace, one for a stove and one for the furnace. The pilot light on the gas furnace keeps getting blown out from the downdraft from the flue. How can I prevent that?

JACK HILLIER, Mattapoisett

A. You could devise a baffle around the pilot light, or better yet, have the gas company, or whoever tends your furnace, do it. Or, perhaps install an electronic ignition system. A stainless-steel chimney cap on top of the guilty flue might also reduce or eliminate downdrafts.

Q. I had my chimney extended to meet the building code. It contains one flue, and is now extending 9 1/2 feet above the roofline. Should it be braced?

J.Z., Rockport

A. A brick chimney on a proper, level foundation could last several hundred years, but being pretty thin (with only one flue), 9 1/2 feet above the roof and in Rockport (windy, huh?), I suggest bracing it, if only for your peace of mind.

Q. I installed a wood stove last fall. The chimney man said he would paint the chimney with two coats of a sealer called Chimney Saver that is 100 percent breathable, to keep the chimney from leaking, at a cost of $225. The man told me that the sealer, being breathable, will not trap moisture in the brick. Is all this worth it?

BERT BOUCHARD, Danvers

A. If the chimney is not leaking, there is no need for the sealer. If rainwater is entering at the top of the chimney and is dripping on the stovepipe, sealing will not work; you need a chimney cap. The sealer helps only if the water is making its way through the brick; that can cause all sorts of mysterious leaks.

Q. The mortar in my chimney is coming out, but there are no leaks. One man said he would repoint the chimney (chip out old mortar and insert new) for $625, another said he would rebuild the chimney from the roofline up, for $1,250. Are those prices reasonable, and if so, which way should I go?

GINA VILLA, Milford

A. Both prices are reasonable, I think. If the bricks are intact, and not spalling or chipping off in any way, then repointing, if done right, is the way to go. If some or a lot of the bricks are deteriorating, then rebuilding from the roofline up, with new bricks, would be best.

Q. I had my chimney repointed; there were bricks falling out, and I finally found a company that did it in a week, all new mortar and the bricks put back in place. Trouble is, the masons were sloppy, getting all kinds of mortar on the face of the brick. When I asked the mason if he could apply muriatic acid to clean off that excess mortar, he said that would be at an extra cost. Is acid the only way I can get rid of the mortar?

I might do it myself, except the chimney that goes through the roof is very high and I really don't relish the idea of doing it. And I'd like it done before it's too late.

AN UPSET CALLER

A. Very interesting. There was a day when workmen cleaned up their mess; in other words, a repointing job included the acid treatment; just as many years ago a whisker trim went with a haircut. Not any more. I am confident that some companies will include acid treatment, but I suppose the added cost in some cases is part of the contemporary work ethic.

You paid a pretty penny for the repointing, but I don't think it will be terribly expensive for the acid treatment. So go ahead and have it done. But time is not a factor; you can treat with acid two days or 200 years after the job; the acid attacks the lime in the mortar and will be effective at any time.