Types of Defects and Problems with Hot Water Heating Boilers - Hydronic Heating Systems, Loss of Heat, Noises, Leaks
What sort of defects should you look for when inspecting a heating system?
Unsafe conditions on the heating system such as signs of burn-out of the combustion chamber liner, unsafe relief valves, unsafe flue gas venting, fuel leaks, combustion gas leaks. Burn marks on boilers or furnaces, evidence of leaky or stuck pressure relief valves, evidence of tampering with the safety controls, abnormal heater control settings, evidence of chimney, flue, or flue gas venting defects, are all safety concerns.
Loss of heat - boiler or furnace won't operate, or system operates but heat is not produced in the living area - we provide a guide to diagnosing the reasons for "no heat" beginning
at NO HEAT - BOILER / FURNACE DIAGNOSIS. If your hot water heating system is running (the steam or hot water boiler is making noise and seems to get hot) but some of your radiators or baseboards are cold,
Improper Heating System Function: OIL BURNER NOISES, burn marks on the furnace or boiler, unreliability, inadequate heat distribution. Soot production by gas fired heating equipment is an immediate, serious hazard that risks potentially fatal carbon monoxide poisoning. Turn such equipment off and call for expert advice. Severe smoking and soot puffback from oil fired heating equipment is also dangerous and requires immediate action.
Improper heating system maintenance, such as failure to adequately clean and inspect the heating flue, furnace, or boiler, unsafe heating safety devices (e.g. relief valves), evidence of sooty, noisy operation, leaks in fuel, air, water. An example of an easy-to-spot clue that an oil fired heating system needs service and cleaning is illustrated
at DRAFT REGULATORS, DAMPERS, BOOSTERS
Heating system reliability - Unreliable heating systems or heating systems at or near the end of their useful life. Home inspectors and qualified heating inspectors should not give a heating system a passing grade just because heat is entering the building. The heating system needs to be safe, and sufficiently reliable that the owner can reasonably expect to leave the building without a likely loss of heat and related building damage. If a heating system has less than a year of remaining reliable and safe operating life, it is in unacceptable condition.
How to Diagnose Loss of Heat With Oil-Fired Hot Water Heating Systems
Does the heating equipment have electric power?: make sure that electrical power is on for all of the heating system components.
switches at the boiler, wall mounted boiler
switches at the stairwell down to the basement or utility room or in other areas, and check
the circuit breakers or fuses in the electrical panel.
Is there fuel for the boiler
? check the oil tank gauge; if the boiler or furnace is fired by natural or LP gas check that no one has
shut the supply valves.
If a system has been "shut down" and you don't know when or by whom this step was taken, beware of turning the heating system back on without an inspection and safety check by an expert technician.
If you're out of oil call your oil company and request an emergency delivery. Usually the delivery person will also need to enter the building to bleed air
from the oil lines in order to get the oil burner operating again.
Does the oil burner start but then shut off? Is the system "off on reset"? if so the red "reset" button will have popped up on the oil burner
control (or possibly on an electric motor operating the oil burner) and the system has an operating problem and needs service.
It may be possible to re-start
an oil burner that has turned itself off by pressing the red reset button ONCE.
If the system re-starts and runs acceptably, you can have heat while
waiting for the service technician but the system still needs inspection, service, and possibly other repairs before it can operate safely and reliably.
If you push the reset button and the burner does not start and keep running for five minutes or more, DO NOT try again as you may flood the system
with oil and make restarting difficult and dangerous. Also
see OIL BURNER INSPECTION & REPAIR
Boilers-Hydronic Heat: Is hot water water circulating?
Check the hot water circulator: Test to see if the circulator is operating Feeling the hot water distribution piping (Watch out it should be HOT!). Feeling the piping can indicate if circulator is running or not -- a quick change in temperature means the circulator works; slow change in temperature may occur if the circulator does not work but hot water is circulating by convection.
Check hot water baseboards: if some baseboards are hot and others cold, are they all on the same heating zone? If not, are all of the thermostats turned up? If some heating baseboards are hot and others cold
and we're sure that they're on the same zone, then the system is probably air-blocked.
A heating circulator pump is capable of pushing water around in the
loop of heating baseboard but is often not capable of overcoming a section of baseboard that contains a large bubble of air. It's necessary to remove such
air blocks. If air blocking has been recurrent a previous owner may have installed air bleeders at strategic points.
The bleeder can be opened slightly
and carefully, to permit air to escape. As soon as water starts coming out of an air bleeder valve it can be closed. Automatic air purge devices are available
and are usually installed right at the heating boiler but sometimes additional ones are needed at higher levels in the building.
Check hot water radiators or convectors: if some radiators or wall convectors are hot and others are cold, and provided that the individual
feed valves located at each of these devices is open (turned counterclockwise) the radiator or convector may be air blocked.
Usually an individual air
bleed valve is located on each of these devices. As we suggested above, if your hot water heating system is running (the steam or hot water boiler is making noise and seems to get hot) but some of your radiators or baseboards are cold,
Noises specific to an oil burner used at heating boilers or water heaters are discussed
at OIL BURNER NOISE SMOKE ODORS. Excerpts below focus on some of the most common heating system noises.
Noises during oil burner startup - a "bang" or puffback which blows soot into the room through the barometric damper or through other equipment openings: the oil pump may not be shutting down properly at the end of
an oil burn cycle, leaking incompletely burned oil into the combustion chamber. That oil ignites at startup causing a potentially dangerous puffback. Immediate service and repair are needed.
See OIL BURNER SOOT & PUFFBACKS
Noises during oil burner startup - a "rumbling" sound (which usually continues all during operation" or a "stumbling" sound in the combustion chamber probably indicates that the system needs inspection and cleaning very soon. Some noise is normal however, but the normal sounds tend to be more smooth and continuous.
See OIL BURNER NOISE SMOKE ODORS
Noises during oil burner shut-down - a stumbling or rumbling after the oil burner motor has stopped, indicate that oil is continuing to leak into the combustion chamber and risks a dangerous puffback - see "Noises during oil burner startup" above. Immediate service is recommended.
See OIL BURNER NOISE SMOKE ODORS
Noises of shrieks or grinding coming from the electric motor or oil pump on the oil burner or more rarely at a circulator pump mean that prompt service is needed - probably a bearing is failing.
Startup problems: noises and clues of puff back: if you see flapping at the barometric damper or if you see or hear vibrations in the system, prompt service is needed -
see OIL BURNER SOOT & PUFFBACKS.
Clanking heating system pipes or sharp snapping noises may be heard as a normal consequence of expansion of metals during the heating cycle. These noises can often be eliminated or reduced
by careful routing of piping and by allowing room around heating pipes for expansion, but probably not eliminated in the case of hot water baseboards.
Bubbling or rumbling heating system noises in hot water heating piping can be caused by air in the heating lines. If the amount of air becomes excessive the heating system may be unable to circulate hot water and extra steps to bleed unwanted air will be required.
See AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE
Hissing heating system sounds such as air escaping from
radiators or the piping where air bleeder valves are installed are normal but should be brief and uncommon. If you constantly hear air
hissing from radiator bleed valves double check that you understand what kind of heat you have - hissing from bleeder valves on steam
heat radiators as heat is coming up in the building is normal.
When observing evidence of leaks on a heating boiler, keep these points in mind:
Even serious leaks may never show up as "wet" spots: A boiler may be leaking but you may see no actual water: during the heating season the boiler may always be hot, causing small leaks on the boiler or on heating piping to simply evaporate. But such leaks will usually be visually very evident: look for a build-up of corrosion, green or white or other colored mineral salts, or look for rust or water stains on the equipment.
Internal heating boiler leaks: Some critical boiler leaks may be internal and not visible by simple inspection, such as a leak inside the boiler heat exchanger which may pass water into the combustion chamber. A service technician or a skilled home inspector should be able to spot evidence of these leaks.
Surface rust, light, superficial rusting, is generally repairable. Clean the area and fix the leak when the boiler is next serviced and monitor for any future leaks.
Exfoliation, or thick flaking rust on any boiler but particularly on a steel heating boiler is very serious, possibly not repairable, and risks loss of the boiler as well as sudden loss of heat in the building.
Leaks related to temperature or pressure: Some leaks occur only at peak operating temperature - e.g. at relief valve. On some heating boilers such as some cast-iron units, leaks may occur between boiler sections when the system is cold - on these models some technicians prefer to keep a little heat in the boiler year-round to avoid this problem. Leaks between boiler sections may be repairable but if left unattended can destroy the equipment.
A Catalog of Common Heating System Leak Points - Where to Watch for Heating System Leaks
Tankless Coil mounting plate - see rust stains below and around plate
Pipe fittings at face of coil plate - mineral salts
Leaks around bolt openings - suspect hidden damage
Leaks between sections of a cast iron boiler
Leaks at the circulating pump mounting flanges
Leaks at the boiler temperature/pressure relief valve. This leak may be very dangerous as corrosion from water passing through the valve may prevent its safe operation in an emergency. Prompt expert inspection and repair are needed. Watch for leaks below the valve's mouth or discharge pipe (a pipe should extend from the relief valve to a few inches from the floor) or watch for corrosion at the tip of the discharge pipe. Gently feel inside the tip of this pipe to see if it's wet. DO NOT TRY TO TEST or open or operate the relief valve itself.
Leaks at air bleeder valves - at the boiler or remote where such bleeders are placed on heating piping or baseboards or radiators
Leaks at radiator control valves
Leaks at poorly-soldered copper pipe fittings on finned copper baseboard heating systems
Leaks due to frozen and burst piping or in extreme cases, frozen and burst heating boilers themselves
How to Recognize & Diagnose Inadequate Combustion Air, Sooting, or Burn Marks at Oil-Fired Heating Systems
Lack of adequate combustion aircan be indicated by or can result in these heating system operating and heating system safety worries:
See COMBUSTION AIR
Improper oil burner system operation such as noises, rumbling, etc. discussed above.
See BOILER NOISE SMOKE ODORS for the conditions listed here.
Oil burner sooting or dirty operation (the photo at above-left) may be due to improper adjustment of the oil burner or draft, a blocked chimney, or other problems. Also
see DRAFT INDUCER FANS as their use may indicate a chimney, draft, or venting problem.
Burn marks on the boiler (photo at above right), furnace, or water heater, (these conditions may be caused by a blocked exhaust flue and inadequate venting).
Safety Warning: burn marks on a heating boiler or furnace (shown in our page top photo) can also be due to collapse or damage to the combustion chamber liner - a serious fire hazard needing immediate attention. Notice that in our photo at right, the brown burn marks around the oil boiler combustion chamber inspection port (that rusty round door above the oil burner) have been cleaned-off.
The presence of these burn marks does not necessarily mean that the oil burner backpressure problem remains - in this case the system has been cleaned and adjusted, but no one has re-painted the front of the boiler. But if you see fresh peeling paint or soot in such an area further investigation is needed.
That's why we recommend that after repairing a back-pressure problem at heating equipment the service technician should clean the boiler or furnace exterior - to remove confusing debris and to make it easier to see if the problem recurs.
Heating equipment located in a small utility room with no provision for combustion air intake. When the service technician adjusts the system she probably worked with the utility room door open, but when the service tech left the job he may have closed the door - completely changing the availability of combustion air for the equipment. We need about one square inch of un-louvered (unobstructed) combustion air intake per 1000 btuh of the oil fired heating boiler, furnace, or water heater.
See COMBUSTION AIR and
Smoke indoors,coming out of the heating equipment or its draft regulator.
See BOILER NOISE SMOKE ODORS for the conditions listed here.
Carbon monoxide or combustion gas and flue gas leaks: potentially, the production of carbon monoxide or other flue or combustion gases which escape into the building - potentially dangerous.
See CARBON MONOXIDE - CO
A Guide to Heating Equipment Malfunctions & Their Implications
Noises & soot buildup can lead to a potentially dangerous puffback which can damage the heating equipment and blow soot and smoke throughout the building.
Leaks on hot water heating systems are never acceptable, anywhere.
Leaking pressure/temperature relief valves need immediate attention and repair (Leaking relief valve could be due to water-logged expansion tank, improper control settings (temperature too high), improper automatic water feeder operation (pressure too high), or defective valve (leaky). True, you only have to report the valve.
Did you miss problems at the other components?)
Corroded relief valves also need to be test by a service technician and repaired or replaced as they may be unsafe and may fail to open when necessary
Relief Valves: Do not touch the heating boiler or water heater temperature or pressure relief valve - it may open and fail to shut down. A relief valve which does not work is dangerous since the system is missing an important safety device. Should an over pressure or over temperature condition develop for other reasons, the boiler could explode.
Corrosion on heating system parts: Do not pick at corrosion as you may start a catastrophic, un-stoppable leak requiring total system shut-down. Leaks left un repaired can destroy heating equipment.
Tankless coils for making hot water:
If there is different water pressure/flow observed in the kitchen in which the hot water pressure is significantly less than cold, even before examining the building's mechanical systems you may speculate that a tankless coil installed may be installed.
What other clues suggest that the local water supply may be hard in minerals and that there may be a risk of clogged piping?
When the water supply is high in minerals, the hot water pipes or tankless coils clog up before cold water piping. Is a water softener installed? Is there known "hard" water--have mineral deposits clogged the coil?
Are there "cleanout" plumbing fittings on the tankless coil piping? Does this suggest a history of clogging and acid-flush treatments?
A clogged tankless coil can be repaired or replaced.
How severe was that rust you observed at the tankless coil mounting plate? Severe rust may mean that the boiler must be replaced.
Examples of Heating System Defects with Important Implications
Lack of adequate combustion air can result in improper system operation, sooting, loss of heat, noises, smoke, and potentially, the production of carbon monoxide or other flue or combustion gases which escape into the building - potentially dangerous
Leaky oil at an oil burner ignition transformer: watch for back pressure in combustion chamber--watch out for blocked heating flue or blocked chimney - these would be unsafe, or the heater may be unreliable. An unreliable heater can lead to
frozen burst pipes and costly building damage. A blocked chimney could lead to a potentially fatal carbon monoxide hazard.
Leaks in hot water or steam (condensate piping) heating systems risk
Loss of heat, frozen pipes, related damage
Water damage to the building including rot or costly mold contamination
Unusual interior moisture conditions, noises, smoke, or odors during heating season--watch for blocked chimney or poor flue vent connections
Equipment recalls: Specific heating system problem brands Repco, Blueray etc.
[Do not confuse Repco™ heating boilers, which had fire chamber and other failures, with other products (REPCO pumps, REPCO controls, REPCO water conditioners, or water treatment that carry the Repco name. Those products are distinct from REPCO heating boilers and are produced/distributed by the R.E. Prescott Company. Further, we are unaware of any remaining warranty or replacement support for failed or antiquated Repco heating boilers.]
BLUE vs YELLOW COMBUSTION FLAMES - the Blueray history and blue flame vs. yellow flame combustion, flame color & combustion efficiency, & how oil competes with gas as a heating fuel.
Question: how to prevent the heat exchanger from overheating
(June 29, 2014) Anonymous said:
How I can prevent the heat exchanger from getting too hot and smelling like hot metal burning. Goodman heat exchanger and coil made of aluminized steel. How can we prevent the coil and heat exchanger from getting too hot.
Since you mention Goodman I am guessing you're asking about a heating furnace, not a hot water heating boiler (which is the subject of the article above).
If the heat exchanger on a warm air heating system is overheating then the fan limit switch is not working and the system is unsafe - and needs expert diagnosis and repair.
Check first for a common mistake such as a dirty air filter and reduced air flow through the system.
(Jan 4, 2015) Jackson said:
I have a residential gas boiler heating system that is not just whining, it's howling. It actually sounds like there are three or more howls going on at the same time and the noise is even throughout the house. The circulation pump appears to be running fine and the heat exchange is not cracked/broken. Any suggestions?
Start right at the boiler: if the noise is at or in the boiler I'd shut if off immediately as it may be unsafe.
If the nose is coming from piping check for a failing circulator pump motor.
also at HOWLING HVAC sounds from air conditioners, air handlers, blower fans, heat pumps, furnaces, duct systems & their motors
we include additional examples of howling sounds traced to heating or cooling equipment.
(Jan 6, 2015) Anonymous said:
Thanks DJF, here is an update.
Inspected the boiler again and decided to drain the water out to check how dirty it might be but it came out clear. Can't see any reason that it would howl. Put it together and howling has stopped. ?
I can only guess - which is mere arm-waving: that sometimes draining a system will move a bit of debris or dirt, changing an orifice through which water was running. I'd still be looking at circulators; also see if there's a correlation between howling at the boiler (other than you with laughter at this advice) and temperature or boiler on or off time or boiler pressure. Other howl points might be check valves, zone valves, even air bleeders or piping elbows.
Question: running water noise in heating baseboards
(Jan 8, 2015) Anonymous said:
I have baseboard hot water heating system. There are 3 zones. When any zone starts up you can hear the water running through the system. Is this normal?
If the water is noisy in the hot water heating piping I suspect the system has excessive air that is not being automagically bled out by air bleeders that we usually install at the boiler, at radiators, at baseboard zones.
Question: burning smells from heating boiler: suspect burn-off of oil coatings?
(Jan 15, 2015) MLizbeth said:
Hi, We've got a boiler mainly for hot water heating. (House is heated with wood stove.) Four days ago, out of the blue, the electric switch box on the front of the boiler started smelling like paint or like heated-up electric components.
My plumbing/heating man first said it had just overheated (from turning it on more often to run water through baseboards during this cold snap, so water wouldn't freeze in pipes).
But he checked it out at my insistence, and replaced the switch - he said it was, after all, damaged. But there is still a smell when the boiler goes on, i.e. it gets heated up. (He also bled out air that he said was in the pipes. Could be totally unrelated.) Smell dissipates until next time boiler kicks on. This all happened literally out of nowhere. I hate to bother him yet again with more phone calls but this smell shouldn't be the norm. What do you think?
Burning smells are not normal and should be fixed, including the cause not just the damaged part. For example backpressure in a combustion chamber can overheat nearby components.
Just be sure you distinguish between left-over odors from a prior problem and new smells.
(Jan 21, 2015) MLizbeth said:
Thanks for the good ideas. I had my heating/plumbing man check it out again, and he was surprised to find that the toggle switch was cracked inside. He replaced it. I wasn't surprised; I knew something had to be different. But it hasn't solved the smell, which is kind of petroleum-ish, a little like paint, not really a burning occurring anyway. (He and his assistant checked everything immensely thoroughly, which was reassuring.) The smell comes only from the toggle switch box on the front. I am thinking to have him simply replace that. Though there is no problem per se, to have that smell when it has never been there before should not be the case. Thank you again.
Indeed if the switch was overheating or arcing other components in the switch box may be burned; open, examine, replace. Use the email at our CONTACT link found at page top or bottom to send me some photos for further comment if you can.
(Jan 23, 2015) MLizbeth said:
Well, my plumbing/heating man along with his assistant were here, opened it, looked at it plus basically every last aspect of the system, checked out EVERYthing in my basement. Very kind and helpful! Everything was fine.
The one thing he mentioned that resonated with me was that components inside are given a light coating of oil, even the electrical wires inside. That could have overheated before the (cracked) toggle switch was replaced. I also spoke with my own oil company who helped me out with information and it looks like that is the solution to the mystery.
My husband has already called him, and he'll be replacing the whole switchbox and wiring. If I can get a photo that shows anything at all I will, but as of a couple days ago, visually, it was "picture perfect" and nothing to see other than what it should be. It appears that that oil coating just heated up. Strange the littlest things that can occur (that I a layperson would never have known of prior)! I appreciate the vast repository of information you have placed here for home owners to access, to become knowledgeable about their home systems. Thank you!
Bryan Jaicks said:
I have a gas boiler for a multi-zone hot water heating system in my big old house. It seems the boiler suddenly will not ignite when a thermostat calls it, and the boiler temp will go down to almost room temp, along with the pressure that goes down from a normal 20-30 to 10psi.
I can remedy the situation by making sure at least one thermostat is "kicked in", and then turning off and turning on the red service switch. Some times it takes a few tries, but eventually i hear the aquastat relay fire, and a ll the flames come on,
Questions & answers or comments about diagnosing problems with residential hot water heating systems: the heating boiler
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
R.E. Prescott Company, a producer of other REPCO™ residential and industrial products as well as a provider of design-build engineering services is at 10 Railroad Avenue, Exeter, NH 03833. Tel: 603-722-04321 or 888-786-7482. Trish O'Keefe from Prescott informed us (10/7/2009) that their company had nothing to do with the failed Repco heating boilers discussed at InspectAPedia.com. She wrote:
Our company manufactures & distributes residential water treatment equipment, including our Repco line of conditioners. We have a plumbing & heating supply dept as well. We are mistaken for the Repco Boiler company on a regular basis, most frequently in Oct. and Nov.
Any information you could give me on the other Repco company would be appreciated. We've assumed it is no longer in business, and we'd like to know that for sure. Many callers want to know where to get replacement parts and I would be glad to direct them if I knew...plus there's always a chance they might be interested in a Crown Boiler instead.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)