Questions & answers about recognizing heating boiler defects & operating problems to start troubleshooting,

This article series explains how to recognize & diagnose problems with residential heating boilers, including loss of heat, heating boiler noises, leaks, odors, or smoke, and high heating costs.

FAQs on How To Recognize Heating System Defects

These questions & answers about our complete list of heating boiler operating defects were posted originally at BOILER OPERATING PROBLEMS - be sure to check out that defect catalog.

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?

Reply:

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.

See AIRBOUND HEAT SYSTEM REPAIR

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?

Reply:

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.

See HEATING SYSTEM ODORS

(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.

Reply:

ML

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!

Question: boiler won't ignite - thermostat troubles

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,

Whats wrong here? is it the aquastat relay?

Reply:

Bryan, check out the diagnostics at

OIL BURNER WONT RUN

and also check for a thermostat wiring problem at

THERMOSTAT WON'T TURN ON

Question: water leaking at boiler top

(Nov 11, 2015) Anonymous said:
leaking water on top in 35036106 model

Reply:

Dry everything off, wipe clean, then inspect with care to see exactly where the leak source originates. I can't guess nor advise from an open ended question; It's like saying A is bigger than something or other. What's A and what's something or other. ?

If you have no heat and need help diagnosing the cause,

see HEATING LOSS DIAGNOSIS-BOILERS - forced hot water heating baseboard, radiators, convectors, radiant heat

or HEATING LOSS DIAGNOSIS-FURNACES - forced warm air heat

The photograph at page top shows a heating boiler which is burning through it's steel outer jacket - this condition is a potential fire hazard and requires immediate inspection and repair.

There is probably a combustion gas leak at this heater. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

If you don't know whether your heat is provided by a furnace (hot air) or boiler (hot water)

see HEATING SYSTEM TYPES

On 2017-11-01 by (mod) - 400,000 Btu steam boiler. It keeps kicking out on low water.

Jim

It sounds as if the water feeder on your steam boiler does need service or repair.

depending on the type of water feeder involved, it may be that yours has not gotten the frequent cleaning or flush out that some theaters require.

OR the condensate return line is clogged and slow in returning water to the boiler - look for flooding after water has been added.

On 2017-11-01 by Jim Wanko

I have a 400,000 Btu steam boiler. It keeps kicking out on low water. It has a self feeder in the water line. If the boiler is low should it not energize the feeder to fill? Should the unit need to have water added more than one time a day if not leaking somewhere?

On 2017-04-28 by (mod) - boiler cannot change from low to high combustion during auto mode.

Wildon

Perhaps if you give me the boiler manufacturer brand, model, serial number, I can give a specific answer; most residential boilers do not have different firing modes.

On 2017-04-28 by Wildon

My boiler cannot change from low to high combustion during auto mode. What is the problem here

On 2017-02-25 by (mod) -

Sorry I can't make out what's happening from your e-text. Broiler? Oven cooker?

On 2017-02-25 by Joy

I had a bathroom replaced new pipes etc.... Now the broiler is giving off a substantial amount of heat is that the sign of a leak?

On 2017-01-08 by (mod) - If the boiler and its heating piping are leaking, the heating system may have become air-bound

Steward:

If the boiler and its heating piping are leaking, the heating system may have become air-bound. Search InspectApedia.com for AIRBOUND HEATING SYSTEMS to read details.

If the ONLY leak is at the mouth of the boiler drain, a temporary fix is to install a plastic or brass hose cap over the valve mouth. But if the system is airbound you'll need to bleed out air.

On 2017-01-08 by Stewart

Gas boiler has very slow leak out of lowest red faucet. Heat is not coming thru to first level of home BUT the pipe from the boiler is very hot anyway?

On 2013-02-27 by peter moore

my condensing boiler makes a winding noise only when my heating
is on but not when my hot water is on what is the problem thank you

On 2013-02-19 by Bill Marston

Mid-atlantic urban rowhouse 1960s HW radiator heating system. Sudden onset of vibration shaking almost grinding noise in one-half of radiators in 3 story house. Water pressure seems OK AFAIK. Radiators still producing (some, same?) heat as before.

B&G circulating pump & main HW distr pipes all vibrating as well. **apparently fresh metal shavings or grindings or scrapings, small like less than a mm, cover the smaller end of that pump.

I worried that perhaps pump had lost lubrication(?) and was grinding itself to death, so I followed metallic electr feed from the pump up to a switch - I turned off the switch, stopping the pump and of course the flow, I guess. HELP.

Pump is the ONLY new component of this system, which is the same as it was when we bought this early-1800s house 30+ years ago. It was installed when a street gas leak brought inspectors to everyone's basement, and our was shut down for a code compliance failure of some kind... about 2005(?) and have no record of HVAC mechanic who did that upgrade work. WHO should I call? Just anybody?

On 2013-01-13 by alex morrison - combi-boiler has stopped working and its flashing with a IE 19 error

my combi-boiler has stopped working and its flashing with a IE 19 error and there is no pressure on the gauge any ideas

On 2013-01-01 by Anonymous

relief valve is leaking

On 2012-11-09 by (mod) -

Marion
Look for a defective or misadjusted water feed valve, or a bypass valve left open. Also check for leaks.

On 2012-11-09 by (mod) - signs of an air - bound heating system

Walter see our articles on methods to diagnose and repair an air bound heating system. Also look for a valve or zone valve stuck shut.

On 2012-11-09 by mario

Why does it keep filling the water fill tube

On 2012-10-13 by james d

you turnn it on and it works reaches temature an swiches off when it trys to restart it trips ie the orange reset button is on ,you could press it ten times and it will trip straight away but realy strange is let it cool for 15/20 min it will fire up no problem and work grand

On 2012-03-11 by (mod) - Triangle Tube water heater failure

Annette, you asked the question below at our page titled "Hot Water Heater Selection, Inspection, Diagnosis, & Repair Guide" - search our website to find that page and see our detailed answer.

Also you may want to take a look at Triangle Water Heater's own troubleshooting guide. If you can't find it by searhing their website for those terms "SERVICE TECHNICIAN’S TROUBLE SHOOTING GUIDE
FOR THE TRIANGLE TUBE INDIRECT FIRED WATER HEATER" then let me know and we'll dig up a [copy on file as /plumbing/Triangle_Tube_Troubleshooting dot pdf ]

On 2012-03-09 by Annette

I woke up one morning to foamy and smelly hot water. I called my heating and a/c guy and he told me my TT TR45 was releasing antifreeze into my hot water.

The HWH was only 9 yrs old and still under warranty but the company wanted the unit back to check what happened (they would not admit their product was faulty). My plumber was sure the HWH was the problem and we replaced with a new Triangle Tube model (they no longer make TR45....wonder why...) since we were sure it would be covered under warranty.

Now, Triangle Tube said the chamber had collapsed and it was not their product's fault but ours!! They said the outside pressure (from the boiler) made the chamber collapse

. I'm so mad at them!! We did NOTHING new or different to make the pressure change! I wouldn't even know what to do to make the pressure change!
I was wondering if anyone here knows what could have made this happen that Triangle Tube is trying to cover up. Please help!
Thank you in advance!

On 2011-12-03 by David

When i put the heat on an grinding noises comes from the boiler and adiators.

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.

Reply:

Anon

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.

Details begin at FURNACES, HEATING

Question: howling residential gas boiler

(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?

Reply:

Jackson

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.

At HOWLING NOISES in BUILDINGS and

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. ?

Reply:

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.

...

Continue reading at BOILER OPERATING PROBLEMS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see - questions & answers about our list of boiler operating problems that help troubleshoot hot water or steam heat

Or see these

Recommended Articles

• AIR-BOUND HEATING SYSTEMS
• BOILER INSPECTION GUIDE
• BOILER NOISE SMOKE ODORS
• BOILER OPERATING PROBLEMS
• BOILER OPERATING STEPS
• CIRCULATOR PUMPS & RELAYS
• GAS BURNER FLAME & NOISE DEFECTS
• GAS BURNER SOOT CAUSE & CURE
• GAS BURNER PILOT LIGHT PROCEDURE
• GAS FIRED HEATING BOILER PROBLEMS
• HEAT WON'T TURN OFF
• HEAT WON'T TURN ON
• NO HEAT - BOILER
• NOISE, HEATING SYSTEMS
• OIL BURNER INSPECTION & REPAIR
• PRESSURE & TEMPERATURE SETTINGS, CONTROLS
• RADIATORS
• RELIEF VALVES, BOILERS
• RESET SWITCH, CAD CELL RELAY
• STACK RELAY SWITCH
• THERMOSTATS, HEATING / COOLING
• WATER FEEDER VALVE, HYDRONIC BOILER
• ZONE VALVES, HEATING

Suggested citation for this web page

BOILER OPERATING PROBLEM FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

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