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    Why ever buy a used boiler? For economic advantage, obviously. The motivations may vary widely, from a low budget fixer-upper owner project to a pro bono effort by a well-intended mechanic, but the risks and value results nonetheless remain the same.

    Our comments are purposely being limited to Weil-McLain Residential (Gas & Oil) Cast-Iron Water and Oil Steam Boilers, our specific area of expertise. Northern New England offers us particularly good insight into higher demand heating systems and their effects, with over fifty years of observed results. As people we all age differently and more or less graciously — similarly with boilers. A boiler’s age or appearance is incidental to its performance. Recently pulled 50 to 100 (yes, 100) year old cast-iron boilers still looking pretty good, yet you couldn’t afford to feed them.

    The age varies but 15 to 20 years is a fair economic life of a boiler, considering heat exchanger and combustion design efficiency progression over this period. Personally, we won’t consider using anything over five year old steam and ten year old hot water — and even then with an eagle eye. Furthermore we use our trade costs only in our consideration.

    First and foremost, there is a great potential difference in life cycle between a hot water and a steam boiler. Specifically:

    1. A hot water boiler operates at a much lower average demand temperature (usually up to 180-190°F) with no state change (boiling) involved.
    2. A steam boiler must operate at boiling (212°F) and significantly higher to distribute heat as a vapor. The state change (boiling) accentuates chemical actions within the water and ultimately will deteriorate the boiler castings. “Steamers” therefore must be considered separately from “Hot Water” Boilers. They just live differently!

    Similarly, so-called “Dry Base” Boilers must be disallowed under any conditions. Definition: A Dry Base Boiler is a design variant where the boiler sits over the combustion device (burner), as opposed to having combustion occurring within the boiler. (Picture it as a kettle sitting over the burner on your stove.) The easy way to tell is if the lowest (return) pipe enters the boiler above the burner level. Dry Base Boilers, particularly those fabricated from Steel Plate rather than Cast Iron have very limited life and are viewed within the heating community as “junk boilers” — sold on price alone, and are short-lived.

    The latter, more desirable and more common “Wet Base” Boiler has its lowest (return) pipe very near the bottom of the boiler and is intrinsically more efficient than the “Dry Base” Design. Combustion occurs completely within its heat exchanger castings. Getting down to the specifics in qualifying a used Weil-McLain Boiler (we are admittedly terribly opinionated), you must look beyond the seller’s story and get down to these facts:

    1. Determining the actual age of any Weil is relatively simple. Every Weil boiler has a “CP Number Label” affixed either on the front or left side of the enclosure. Weil Tech Service can tell you exactly when and what was made.
    2. A Gold Series Enclosure indicates a 1995 to Present build. A Blue (Presidential Series) with corresponding small label near top left front of enclosure indicates a 1985-1995 (approx.) build. Prior Blue or unlabeled boilers are just too old to consider.
    3. The new Weil-McLain Ultra Series Condensing Gas and Triple-Pass Oil Boilers are designer packaged with tan lower and black top control cabinetry. Introduced in 2005/2006 they are as pretty performing as they are appearing. Unlikely that these have regularly hit the used market yet, but you never know.
    4. We don’t deal with the pre-2005 Gas Boilers and therefore exempt ourselves from their discussion. Frankly, the jump from 80-83% of these to the 93-98% AFUE’s of the current Ultras just doesn’t make for used economic sense.

    Once you’ve determined that your “find” is a candidate, grab a Heating Mechanic and go — the same as you would for a car. His expertise should determine exactly what you are getting in terms of wear and tear, parts replacement and condition. Generally speaking:

    1. First look closely for leaks originating between the boiler “sections”. (Cast boilers are similar to a loaf of bread, i.e. a “crust on both ends and slices in the middle”, tied together with rods.) Seam stains, rust trails and debris are indicative. Walk away! This is a catastrophic condition on all boilers.
    2. Specifically on Steam Boilers remove the covering and look at the top of the boiler. If it has a rusty red to orange color, then it has been “cooked” (overheated, likely due to low water malfunction). It may be still running, but likely not for too long since its life has been severely compromised. Don’t walk but run away!
    3. Look for leakage around the immersion heater bolts, flange and/or blank-off plate. This is from poor maintenance with possibly some deterioration of the casting resulting. Crusty rusting with wet tracking throughout bolting — watch out!
    4. Determine that any other staining, etc. is from piping and related devices that leaked and tracked onto the boiler and not from within itself. Boiler water condition is important, too. Internal black “goo” is a no-no.
    5. Has the unit been scavenged for controls, valving, its burner swapped or missing? Most Weils come with (our preferred) Beckett AFG Burners, but Carlins and Riellos are offered options. Leaving a poor burner behind is not the worst of options if replacing with a new/newer unit.
    6. Steamers with an electronic auto water feeder and low water cutoff are much preferred. If controls stay behind or the unit has the older, cast, black McDonnell-Miller Low Water Cutoff, deduct significantly for it. They suffer immediately from poor maintenance.

    Q. Where do we shop for used boilers? A. Large Cities that have Natural Gas Service.

    There is a perpetual turnover of oil and natural gas conversions in the Northeast/Middle Atlantic Corridor. We use Greater Boston in our market but note that NYC/NJ is very active, supply and pricing-wise. There are smaller markets in Hartford, Providence and Albany but pricing is typically much higher. The rural areas are worst in our experience. Maine, Northern NH and Vermont are just out of touch with reality! Their asking prices are twice the Boston Area, and travel up to 400 miles to boot? No.

    Watch the Internet for the best deals. (Ebay is not very active for the used market.) Craigslist is fine, but be quick and be smart! The rural “PennySavers” are useless. Word of mouth within the trade is very good also. A short time between availability and closing the sale is paramount. Be there first and negotiate with cash in hand!

    Pricing? Just remember that the scrap value of $100/150 is the starting point. Anything above that is negotiable. You don’t care what they paid to have it installed; only what you can replace it for with an incentive to do so. Just how much risk can you afford? The top end would seem to be about $1000 for a very good, near new system — all considered, in our area. Example: We recently purchased a very large 2007 Weil-McLain Gold Steamer with Carlin Burner and Controls, documented used only one season for $1000, 40% of Trade Cost, 40 miles away. Mint Condition. It has been upgraded to the AFG and Electronic Water Feed System for about 60% of Trade. Beautiful System!

    We have just skimmed over this subject matter. A lot of detail is necessarily omitted.

    Whether you are buying a horse or a boiler, bring the expert with you. Also figure how you are going to get it home! Also, a deal is not a deal unless it matches your application. Ultimately you have to feed the horse, or your boiler. Do your homework first.

    Last Edit: 10/10/2012


    Plagued with a part of your home, a room, a heater that just doesn’t heat the way you might like it to?

    First let’s be assured your system is able to work as it was designed. Make certain that your baseboard registers, radiators, wall or toe heaters are free of lint, hair and objects placed immediately in front of them.

    1. You must take the trouble of removing the front covering and the movable damper off your radiation to expose the fins for a good cleaning. Use either a long bristled cleaning or a small diameter soft wire brush to completely remove all lint, hair, etc. between each fin. Reassemble with the dampers fully opened.
    2. Similarly remove the grilles or covers from heaters and do as above.
    3. Radiators are easier with a conventional dusting brush, but make sure it isn’t being used as a warming shelf. This will reduce efficiency.
    4. Did you note any fittings with a screwdriver slot or small cans with a stem cap on top at an end of your baseboard registers or near the top of your radiators? These are vents and must be opened until a steady flow of water is emitted. On the automatic “can types”, the vent cap (looking like a tire stem cap) must be removed and the stem depressed to confirm a water flow. Replace the cap and leave it very loose to allow air escapement in operation. If repetitive can venting is required or stem leakage is observed, replace them as faulty.

    Notes: If any vents don’t allow water flow or leak thereafter they must be replaced, probably by a technician (unless you know how to remove boiler pressure, or get wet swapping without doing so). If your baseboard radiation has no vents you have a newer system that requires “purging” at the boiler, and probably by a technician. (You must isolate each zone by closing valves and forcing water through each piped heating zone to force air out of that system area.)

    All of this is just to assure that we have a water-filled system and good radiation integrity, bringing us back to what your system was designed to do. Now we can detect system flaw(s) without guesswork.

    Switch on your boiler with all thermostats turned down or switched off. Turn up one thermostat and note the warm up of its zone radiation. Does all radiation warm up quickly along the piping flow direction and is evenly tempered? (Hold you hand near each register to sense.) A cooler radiation fin area denotes probable air entrapment. Vent or purge as necessary. Similarly with toe and wall heaters. Do their fans switch on after temperature rises significantly? If not, vent them again. Same? Read on. Balance the temperature of each room in the zone by leaving the radiation dampers or radiator valves in the coolest room(s) FULLY OPENED. Progressively close downward the warmer room(s) dampers or valves until the desired balance (or imbalance) of temperatures is achieved. If you can’t achieve the desired balance, adding radiation to the coolest room(s) may be required.

    Repeat this procedure with all zone thermostats and take notes as required.

    Please note that we have optimally tested each zone individually, and in succession. Now we must analyze the entire system in operation.

    If you have only one heating zone (one thermostat) in your home, the following discussion is probably moot if you noted no major issues in the system clean up and venting/purging.

    Circulators are the method of choice in modern hot water (hydronic) distribution. Every system must have at least one. They circulate heating water quietly and efficiently. The question becomes whether they are performing adequately.

    For any structure having more than one thermostat (zone) there are two circulation options:

    1. Each zone has a dedicated, thermostatically controlled circulator.
    2. A shared, single system circulator is used, with individual, thermostatically controlled zone valves switching each zone.

    Being the common distribution component to any hydronic (FHW) heating system, THE CIRCULATOR MUST MATCH THE TASK IT IS REQUIRED TO PERFORM! Whether it is the single System Circulator or the multiple, dedicated Zone Circulators it must move an adequate amount of heated water from the boiler through your radiation.

    The scenarios are therefore:

    1. One or more circulators dedicated and matched to their respective zones.
    2. One system circulator matched to boiler and/or total radiation capacity shared by all zone demands.

    The dedicated zone circulator scenario (No 1.) is by design self-regulated. (Radiant Heating zones must also be served by dedicated circulators.)

    By design a shared system circulator cannot be all things to all zone valved radiation zones at all times. The question really is whether it really matters during the course of normal operational demands. The answer is that it depends on the individual zone configurations, their size and content.

    Zone symptoms to look for:

    1. Baseboard and particularly radiator temperatures that decrease significantly as you move from the supply line (off the top of the boiler) pipe through the radiation sequence to the return line (going toward the bottom of the boiler). This can explain rooms that warm up slowly or always seem cool, even with radiation dampers or radiator valves fully opened.
    2. The kitchen kick space (toe) or wall heater that seems to vary in temperature output and sometimes runs cooler, short cycles.
    3. The large downstairs and/or upstairs zones that don’t warm as quickly as others during a cold start up (Programmed thermostat setbacks or a cold boiler restart from an emergency switch.)

    All of the above are symptomatic of low zone circulation conditions that can only be improved by qualifying each zone circulator(s) or system circulator size for zone valved systems. The sure check is to measure the temperature difference between the input (supply) and output (return) near the boiler of each zone with a thermometer or thermal crayons. The narrower the temperature difference the better, with a 20 degree drop being ideal.

    So, if you have a smaller house with similar zones and no significant symptoms, disregard this. Otherwise you may wish to consider a move to correctly sized circulators, remembering that the most often found issue with them being incorrect (too small) sizing. That little green Taco 007 Circulator that is used almost universally and sold at the local hardware or ‘box” store just can’t do everything everywhere.

    To summarize:

    Zone valves coupled to a correctly sized system circulator provide a viable, economical solution to a modestly sized, similarly zoned home. Their installation and repair costs are lower than circulators, but repair incidence varies with cycle times. The system circulator necessarily has a very high cycle time, reducing its longevity. A system circulator failure completely shuts down your heating system operation. Upgrade your Green and Gold Head Zone Valves to the new “energy green” Zone Sentry Valves for performance.

    Properly sized, dedicated circulator zones offer constant, efficient distribution. Dedicated circulators are a moderate cost additive yet are much less prone to failure.

    Improperly configured or piped zones are also a consideration, particularly with zone valves. The possible deviations are substantial and are therefore not included in this discussion, save to consider this possibility if the discussion scenarios do not correct your situation.

    Taco Service Notes:

    1. If you currently still have Taco “Green Head” Zone Valves in service, you may wish to upgrade them to the newer, interchangeable “Gold Head” Actuator. They are simple to change, merely a clockwise 1/16 twist of the head and they are off. Rewire per the prior Head.
    2. If you have any old style circulators (separate motor, coupling and pump assembly with oil fittings on the pump and on some motors) consider upgrading them to the newer “Wet Rotor Circulators”. They are a smaller, integral design that runs in the heating water. Far more efficient, reliable and service free. Made by Taco and others. Make certain to correctly size the substitute.

    Refer to the Blogs on our “Delta-T System™”. It is the final solution.

    Last Edit: 10/10/2012 pdm