Photograph of  a modern oil-fired heating boilerOil Heat Service Repair Snags & SNAFUS
Why does the same stuff keep breaking?

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Heating system service snarls and snags:

This article describes examples of how fixing a broken control or part on a heating system may have addressed the root problem. Sometimes it's helpful to look at junk left in the boiler or furnace area by the other guy.

Clues can tell us that something is causing a control or part to break more often than it should.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Four Cute Examples of Service SNAFUS Blamed on "Bad Heating Controls or Equipment"

Aquastat primary control showing its thermal sensor (C) Daniel FriedmanIt is important at the outset of a series of examples of incomplete HVAC system diagnosis & repair that I'm no smart guy.

Any old timer with lots of experience can recite plenty of cases like these in which through persistence and perhaps paying attention, s/he finally got to the bottom of an irksome problem.

[Click to enlarge any image]

The few HVAC diagnostic successes I can report of my own were all achieved through training by Mike Guido, asking true experts like Dave Ferris, or through the generosity of more experienced service techs like Bob from Bottini Oil.

Oh, and of course the manufacturers like Beckett who publish regular service tips are invaluable too - for those who read.

Poor thermal sensor contact on an aquastat: I encountered a service tech who refused to use the manufacturer's recommended thermal conductive paste, arguing that it creates a goopy mess.

I think he was just lazy and BS'ing me. I figure if the manufacturer says to do something - they know what their product needs for successful performance..

The installer typically bends the flexible copper tubing so that she or he hopes the sensor will remain in good contact with the walls of the sensor well that in turn is immersed in the boiler water.

In my photo (above left) you can see the temperature sensor poking out of the back of this aquastat. Once the control has been installed, it would be a real pain to disconnect everything just because some smart ass wants you to clean out the sensor well and put some thermal conducting paste on the parts. You'd have to disconnect a bunch of wires that were tough to fit into jammed working space in the first place.

Given that the poor service tech has been told to complete twelve heating service calls in one day, you can't blame his reluctance to mess around or to "gild the lilly" if that's how it seems.

But unfortunately, bad thermal contact with the sensor can generate erratic aquastat control behavior

Oil burner ignition transformers, dead and alive (C) Daniel FriedmanLeftover busted ignition transformer: at a service there was a little gift left by the previous fellow - you can see it along the right side of my photo: an extra ignition transformers over in the corner.

Dead. The heating service tech, responding to a no heat call, quickly traced the problem to bad ignition spark, checked the ignition transformer, found it "weak" and replaced it.

Bingo. Heat restored. This could become a regular event, about every year or two.

I took a look at the burn marks on the face of the boiler, checked the draft over the fire and in the breech, found backpressure in the combustion chamber - nobody was cleaning this hard-to-clean boiler. Another clue you may find at some jobs is evidence of a history of inadequate draft (barometric damper taped shut BAROMETRIC DAMPERS) or failiure to adequately clean the heating system or the chimney. The absence of a test port in the breech tells you nobody was even measuring the draft!
See CHIMNEY DRAFT & Performance

The backpressure sent high heat back up the burner tube and melted out tar from the transformer. You could see blobs of tar inside the blower assembly, on the floor, and on the lower back corners of each of the dead transformers.

Pile of dead tankless coils (C) Daniel FriedmanWe were taught about this at oil burner school, thanks to Mike Guido.

Pile of tankless coils: I came a cross a surprising collection of clogged and sometimes holed tankless coils. The owner had spent a fortune replacing them every year; an acid wash didn't seem to give any lasting relief.

The cost to install a water softener was actually lower than the cost to replace all of those coil assemblies.

Pile of busted circulator pump assemblies: at a service call that taught me a lesson on this score I found another pile of detritus: several hydronic heat circulator pump assemblies over behind the boiler.

Sometimes the circulator motor was replaced, sometimes the impeller assembly.

Circulator pump mount (C) Daniel FriedmanBut the whole shebang looked cockeyed to me - the circulator pump motor bracket hung down at an angle towards the floor.

Somebody, not a trained technician, kept replacing parts but installing them in a bad support. The down-pressure on the drive shaft of the motor or impeller was causing bearing wear and parts failure.

The fix was to replace the whole assembly with a new set of parts that lined up properly.

No more busted circulators.

Reader question: reset button keeps popping - Honeywell R8182D replaced three times

My Honeywell R8182d 1111 Aquastat keeps tripping the red safe button. This is the third aquastat unit installed. Each one seems to last about 5 years and quit.

I installed a new aquastat control about two weeks ago. It worked fine for just two days. I then went away for four days. When we returned the Beckett oil burner afg was off.

I re-set the red button, the system ran for a couple of days, and went off on safety-reset again.

At this point I called a local oil burner service and they sent their best expert. He said everything checked out ok, installed a new oil filter, new nozzle.and new photo cell [cad cell]. everything, he says everything at my heating system is perfect.

Not so.

Again the system worked for two days then stopped - off on reset. ( I go for cancer treatment 5 days a week)

If i knew what to replace I would. I'm concerned about the heating season. We use the furnace for heating our hot water ,Utica external 40 gal tank, (not tankless). can you help with your expert advice? thank you, J.& J. 8/24/2013


Unless the control was itself mis-wired or improperly installed, it seems more likely to me that there is an underlying operating problem with the heater that the control monitors. It sounds to me as if the service tech has not found the condition that is causing the system to trip off. If the service tech opines that the heating system is "running perfectly" when s/he leaves the job, the there must be an intermittent problem source or intermittent change in site conditions that cause the burner to malfunction. See

Other examples would be debris in the fuel, an improperly installed or unsafe chimney, downdrafts at the chimney, a combustion air supply defect etc. A simple example that I've encountered is inadequate combustion air for an oil burner enclosed in a small utility room. The service tech measures draft with the door to the room open - finds it fine, then leaves and closes the door - air-starving the system.

Reader Follow-up:

This is the 3rd unit installed over 19 years. I installed the last one myself, it's pretty hard to mis-wire the unit ,it's pretty simple. That was the first thing i check.also i took a photo, i,m not new to this furnace, the first time i had a service guy set it up. the furnace was working properly for about 5 years them replaced the R8182d unit for over a total of  20 years .

I have checked everything you suggested, everything . I changed the filter and drained off about 2 gal of oil to check for anything. i change oil filter twice a yeas , also the nozzle, and cleaned the small amount of soot  in the ribs with a wire brush. with a flash light you can see the bottom ,and when you shine the light in the nozzle area you could see the light up to the top. the furnace sit's in a 1900 sq.ft basement with no restrictions.  Draft is fine.

This is the first time this i'm having this problem. in my mind could I have a defective unit? maybe i could back up here for a minute. the first unit did the same thing red button kept popping, replaced by service person ,and it worked for almost 5 years. then this one started to do the same, changed that one and it lasted about the same. now the 3rd unit did the same and i have this problem. it's frustrating ! if i knew what to replace i would. when a service guy says everything ok ,now what.

if you have anymore ideas please e-mail me . i hope i answered your questions  or concerns
thanks again for you help and reply - J & J J. 8/16/2013


I think it's time to talk with the service manager at your heating company, ask for an experienced service tech, explain the recurrent problem and that clearly the prior calls didn't find the trouble. I would not keep shot gunning or just "replacing parts" before figuring out what is actually wrong with the system operation.

If you were having just one system outage showing up as a popped reset button about once every five years I'm not sure I'd rush to assume the problem is the primary control itself. Especially after the primary control has been replaced at five year intervals, I suspect other system operating problems.

And your case, when the problem of system keeps going off on reset after the primary control, nozzle, and filter have been replaced, then most likely the problem is elsewhere.

But even though wiring itself may seem simple, there are service and diagnostic steps that you cannot do without proper training and equipment; you can't measure draft, smoke, CO2, oil line pressure, voltage, for example.

There are usually more ideas or things to check when diagnosing a heating system control problem - we never give up. At OIL BURNER INSPECTION & REPAIR we have published a troubleshooting flow-chart that includes other things to check when an oil fired boiler or furnace is off on reset. You might also want to check the general no-heat diagnostic procedures at DIAGNOSE & FIX HEATING PROBLEMS-FURNACE.

Based on your information so far, here are some off - the - cuff suggestions to check

Reader follow-up: defective new control blamed for aquastat problems

it was a defective new control.   received another new control working great for over a month. J&J J 11/14/2013

Reply: good news, but check for installation or site conditions that are affecting control life

Thanks so much for the feedback - I have run into the "defective new part" problem from time to time, and used to hit it more when I worked on my own car or truck - you could go back to the same supplier four times and get four bad parts - since at that individual supplier, all of their parts came in the same shipment, from the same production run, with the same snafu. 

I would give some thought to whether or not site conditions or installation details are affecting control life at your heating system. Over five years the chances that all of the controls from the supplier came from the sam batch seem low. Possible, if they're using substitutes or copies and not OEM.

I'm not asserting that this is the problem in your case, but just food for thought: an example more subtle installation error than mis-wiring is failure to establish adequate contact between the aquastat's temperature sensor and the surface of the sensor well into which it is inserted.

If you have no heat,

You can also continue your heating boiler diagnostic procedures with the articles at the "More Reading" links at the bottom of this article headed under

If your heating system is fired by an oil burner, you can go directly to those diagnostics

Gas burners are discussed

Piles of Steam Boiler Condensate Return Pumps

Busted condensate pumps tossed in a corner (C) Daniel Friedman Steam condensate return pump system (C) Daniel Friedman

Vassar College, in Poughkeepsie, NY used to heat buildings across the street from the college campus by piping steam all over the place. In fact some of those remote buildings may still be on steam heat. In any event, a large, disseminated steam heat system requires one or sometimes many condensate collection and pumping stations like the one shown at above right and still in use.

On entering a home a couple of blocks off campus and stumbling down to my favorite room I first saw those two condensate pumps in a dark corner of the basement (above left). It was dark - my flashlight and then my camera flash lit up the carnage.

What the heck? Then I spotted the condensate return system at above right. Those pump motors are heavy as heck - nobody wants to carry them out to the truck, and nobody much goes down in this basement anyhow.

One wonders - three condensate pump? Over how long?


Continue reading at DIAGNOSE & FIX HEATING PROBLEMS-BOILER or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

HEATING SERVICE SNAGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

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.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman