Troubleshooting a Hot Water Boiler
OK, lot's of folks have furnaces but lots also have hot water heating systems using boilers. And boilers are a very different animal. Although they provide some of the most comfortable heat using "radiant heat" they have several uncommon parts like a tridicator (see photo), an expansion tank, an aquastat and the list goes on.Although some boilers use ignition systems similar to a forced air gas furnace, boiler systems are more complex and have their own issues, like noisy pipes, inconsistent heat, leaks and other fun stuff to deal with in the winter.
But I've got it all explained for you in the tutorial Troubleshooting a Hot Water Boiler complete with diagrams, and troubleshooting tips.


Comments
Thanks Bob! I’ve got a system with caste iron radiators and baseboard combined. My big issue in the winter is fear of freezing if I go away and the power fails )or the oil line freezes, etc. What kind and how much and where do you add antifreeze? Is there another alternative short of compleat system drainage?
Hi Sam,
Putting anti-freeze in a boiler system can be done but is not really recommended. It adversely affects the system’s efficiency and equipment lifespan and is a maintenance headache. You can read many opinions about it here: http://inspectco.com/PDFS/How%20to%20add%20Antifreeze.pdf
Would be a lot easier just to have someone check on your house periodically when you’re away.
Regards,
This is interesting. We have a different problem. Our furnace/boiler is of course for our heat and also for our hot water. Periodically there is no hot water (and in the winter sometimes no heat). We just flick the on/off switch and it starts up and begins creating both. Just trying to figure out the cause.
K, I have the EXACT same problem right now! It took 5 flicks of the switch this morning to get it to kick back on. I am trying to troubleshoot it as well…
Aaron, we had our gas company come out and they said there were loose wires in the aquastat – so for now we hope that was the problem.
flicking the switch causes vibration and the wires can slip into place –
good luck
Well loose wires in the aquastat wasn’t the problem. No hot water again yesterday. Any helpful hints are appreciated. Thanks.
My hot water base boards are making strange noises when the heat is on. Does this mean I have air in the lines, and if so, how do I remove the air.
I have boiler with 3 zone manifold. When zone 1 & 2 are open and zone 2 (second foor ) closes it sends shock through out the house with pipes banging. Please advise possible solution.
Ok, big question…
I have no heat in my hot water system it’s a 2 zone and feeds 16 rooms on one floor. The boiler heats the water just fine but no heat in the base boards. The feed line is hot until the just before the first room. The return line is cold. I have followed all the steps in these artical but still no heat.
Here is what I have done so far.
1 – Flushed all base boards. got some air in doing so. Still no heat.
2 – Flushed the boiler, got some air in doing so, still no heat.
3 – Pump is working, can hear it. Just replaced 6 months ago.
4 – expantion drained.
5 – zone switches are working.
I still have no heat.
3 – Help freezing here….
Regards, Jim
my boiler has had several problems. circulator pump and aquastat to name a few. now the pipes bang and the service people tell me bleed bleed bleed with no results. it helps for while then returns hope you can help
My boiler occassionally starts a “sighing” noise. We have a bungalo with all radiators on main floor only. You can hear this noise in the radiators (cast iron from 1950’s). I have drained excess water from the expansion tank and the sound occurs on startup. There is also a groaning sound on occassion that may last for 10 minutes and then goes away. Please help.
just installed new hot water heater, had to replace shutoff valve also, so i turned off main water. must have gotten air in lines zone 2 makes a gurgling sound now when water flows thru. how can i get air out
Here is a link on how to drain your system and recharge it.
http://homerepair.about.com/od/plumbingrepair/ss/drain_plumb_sys.htm
My house seems to take forever to heat up. What is normal for gas hot water heat? I have a two story townhouse with only one thermostat per floor. I usually leave the top floor at 60, but I will warm up the bottom floor to 70 or 72. I usually leave it at 62 at night or during the day when I’m gone. When it gets cold out (anywhere between 20 and -30 degrees F) it will take about 5 hours or more to warm the bottom floor from 62 to 70. Sometimes it never seems to get above 68 even though the thermostat is at 75 or 80. Do I just need to keep my thermostat higher at night and while I’m at work?
when the furnace comes on i hear girgiling in the lines.with no pressure in the furnace.
I have a m-80 boiler unit and the thing shuts down on flame failure. It starts with white smoke, runs for a couple seconds and the shuts down. We cleaned the fuel system, and are setting the electrodes at 1 nickel thick, 1/2 nickel wide in front of and above the nozzle.
hi, bob nice to know you, i have litlle problem in my boiler, my boiler type is combination fire and water tube, i using full condensat for FWB, my alkalinity and TDS, pH very low,and un stable what your suggestion, thanks
Hi,
I live in a 5-story apartment building, It uses a boiler for hot water. I live on the 4th floor. All my neighbors seem to have hot water just fine. I have to let my water run for about an hour before it gets hot. Then other times, it gets hot right away. Do you happen to know what the problem might be? My maintenance man doesn’t seem to know what the problem is>
Thank you in advance
sincerely,
Isabel
had a dripping pressure relief valve, found excess water in expansion tank, So I replaced the exspansion tank pressure relief valve and the water feed valve to cover it all, when I started to fill the unit the water blew out of thwe new pressure relief valve wanting to flood the area, checked this many times same sitaution and all with the boiler switch turned off, could the new pressure relief valve(30 psi rated) be defective?
My circulating motor will run for 15 sec. and shuts down and it will kick back on and run again for 15 sec. and shut down. It will do this for about 20 to 30 min. then it will run until it reaches the thermostat temp. I have wired the motor direct and it does the same thing run 15 sec. and shut down. I have also tried a different motor and does the same thing.
Sounds silly I know, BUT do boilers have filters that need changed regularly?
Single mom with no clue..
Thanks!