Loud Pinging Noise in Baseboard Heat, Pilot Won't Stay On

[BenderHeel]

We recently moved into a house and are running the heat for the first time. It's a gas-powered hot-water heat system with a single-loop design.

(1) When the heat turns on -- and especially in the middle of the night when I'm slepping -- there's a loud pinging-type noise in the baseboard heat of our bedroom. It's similar in sound to if you flicked your finger off of the wall. Our boiler self-purges air bubbles, so it shouldn't be related to excess air in the system that would have to be bled. I know that the copper tubing expands and contracts a bit when the water heats or cools, but I'm hoping that I can do SOMETHING to stop the pinging so that I can sleep through the night rather than being awakened everytime the heat comes on. Can anyone help me trouble-shoot the problem?

(2) Our pilot light wouldn't light at all, so we called in a plumber, who replaced the wire sensor (the name is escaping me) that goes into the pilot light, but that didn't solve it. So he then replaced the gas valve, which seemed to do the trick because the pilot lit and the system worked for 5 days. The system worked last night (because it woke me up with the pinging...) but then the pilot went out this morning. I re-lit it, but don't want to have to keep re-lighting. The plumber said he can't think of anything else that might be causing this. Our hot water heater is about 6 feet away and its pilot stays lit, so it shouldn't be a sudden drop in gas pressure from the gas provider or even a draft. Any thoughts on this one?

Many thanks for any advice, tips or guidance!

[jnaas2]

Normally when the system heats up it can cause some noise or if the air seperator isnt working properly it can cause noise to. What temperature is your water operating at, and make sure that the flame isnt going out on a high temperature limit, and if the thermocouple isnt directly in the flame of the pilot light it will not work right. Also the pilot assembly could need to be cleaned, they can get dirt, rust and the flame will be to small, some can be adjusted to get a larger flame on the pilot light

[BenderHeel]

Okay, I'm having more problems with the pilot light going out.

It has worked with no problems for about a week, but this morning when I checked our house thermostat, it was a few degrees lower than the temp on which it was set, so I knew the pilot was out again.

I went down to our "wonderful" Peerless gas boiler, and re-lit the pilot light. It probably stayed lit for about 5 minutes and went out again. I re-lit again, and, once again, maybe after 4 minutes, it went out again. I checked the position of the thermocouple, and it's in the path of the pilot flame, which is pretty big as is.

Can anyone think of what the heck could be causing the pilot to go out so often? Again, I wouldn't think that it's a sudden -- and often -- drop in the gas pressure since it doesn't effect our hot water heater, which is about 6 feet away. Our plumber has pretty much given up and says that he can't think of anything. Any ideas or suggestions would be greatly appreciated.

[BenderHeel]

To add to my above post, I called my gas provider to check on the input pressure, but that department is closed today for Veteran's Day. I also did my best to clear the pilot orifice with a bread tie to knock of any ash or debris. I'm not sure how successful that was since the tie didn't go that far into the orifice and I couldn't get a good angle (I did this clearing attempt without taking anything apart).

After my clearing attempt, I re-lit the pilot, and it stayed lit for approximately 11 minutes on this first "test" before going out again.

When I attempted to re-light the pilot, it took a few attempts while holding the button for at least a minute each time.On the third attempt, I held the button for 1:30 minutes, and it lit.

The second "test" run lasted only 8 1/2 minutes though.

Any thoughts on why the pilot keeps going out?

[HayZee518]

all I can think of is the flame detector isn't in the flame enough or the pilot flame isn't high enough to properly generate the 750 millivolt signal to the pilot valve. inside the main gas valve is a very small and sensitive electro magnet. the flame detector generates the above value of volts and keeps the pilot valve open. check your furnace draft. if it is too strong or there is a back draft, it could be blowing out the flame.

[BenderHeel]

HayZee -- This may seem like a stupid question, but what exactly is the flame detector? Is that the thermocouple? If it's the thermocouple, it's definitely in the flame, as I see it getting red-hot and it appears to be mid-flame. The width of the pilot flame, I would guess, is about one inch, so it would seem to be big enough, although I readily admit that I don't know what the correct width/size should be.

Regarding draft, I don't feel anything inside the system, and it's not a particularly windy day here. Also, the pilot orifice appears to have almost a "hood" to it, which would seem to block a down draft (?).

For what it's worth, I re-lit the pilot but kept the boiler off. So far, the pilot has stayed lit for 27 minutes and counting. I'll update my post to let you know whether the pilot is staying on with the system turned off, which might help diagnose where the problem lies.

[HayZee518]

ok, just the fact that it stayed lit without the main burner on suggests that the thermocouple [millivolt generator] is working properly. next I would examine the air venturi for the burner. it is an adjustment for the flame for best efficiency air/gas ratio. too much air you'll get yellow/orange flame tips, too blue and you're burning raw gas. also when the main valve opens you get this whoosh through the venturi tube which can blow out the pilot flame.

[HayZee518]

natural gas and propane flames have distinct colors. natural is like a aquamarine blue in a deep blue outer cone. propane is a light blue in a deep blue outer flame. natural and propane gives off orange to bright yellow in too much air.

[BenderHeel]

We should have natural gas through PGW (Philadelphia Gas Works). I'm not aware of us having propane.

The flame seems to be blue with a bit of orange on the outer "wings", so it's not a total yellow or total blue. If there is a bit of orange, does that signify that there's too much air? If so, would that explain why the pilot cuts out when the system and burners are running?

If I turn on the system, there's definitely the "whoosh" sound as the burners ignite, but the pilot and burners stay on -- in my "tests," they stayed on for 11 minutes and 8.5 minutes. So it doesn't seem like the whoosh from the new gas valve opening is blowing out the pilot since it remains on for a period.

Should I still try to adjust the flame? How easy/hard is that to do? Any other ideas? Since it seems like it cuts out when the system is running, could it be related to improper or blocked venting? For what it's worth, we have a CO detector in the basement, but it hasn't gone off.

Thanks again for the feedback and advice!

[HayZee518]

if the thermostat is satisfied then the main burner will cut off. if the aquastat limit reaches its set point then the burner will shut down. to adjust the flame air loosen a little phillips screw or hex head sheet metal screw on a round sleeve and move the sleeve in or out while watching the flame. when you think you've got it tighten the screw. when the burner shuts down watch how the flame goes out, the pilot should stay lit. if you consult a plumber tell him exactly what you observed.

[BenderHeel]

I understand that once the thermostat meets its set temp, the burners will shut down -- but in our situation the burners and the pilot are going out.

I'm going to turn the system back on this afternoon and try to watch it until it burns out. It might be akin to watching a pot of water boil, but I'm going to try to do it and get more info to try and diagnose this frustrating problem.

Edited to add: I turned the heating system back on. The burners fired up as they should. However, the burners and the pilot light went out after only being on for 6.5 minutes! What the heck is causing the pilot and burners to go out when the system is supposed to be on?! For what it's worth, the circulator continues to run once the burners and pilot go out.

Further edit: I re-lit the pilot again, and both the pilot and burners shut down again at the 6.5 minute mark. When it went out, it sounded almost like a switch went off, sorta the sound you make when snapping your fingers. Anyone?

[HayZee518]

check the aquastat. it may be a snap action switch. can you send me a copy of the wiring diagram? tmierzwa@twcny.rr.com

[BenderHeel]

Without doing anything else to it, the system is working fine today. When the burners go out, the pilot stays lit.

I had an HVAC guy out today, and he thinks that the problem might be a draft caused when the burners go out, sucking out the pilot light as well. We don't have a chimney cap and our terra cotta chimney liner has seen better days, so he thinks that the pressure created is sucking the pilot out when the burner goes out. I'm going to have the chimney capped first and see where that takes us.

[HayZee518]

I think I did mention the chimney draft about 5 posts before but you said it wasn't the problem, so I guess I was on the right track to begin with. if there is no or very little wind above your chimney the hot gases go straight up and out but if there is any "good" wind its like you blowing across a soda bottle the air goes down into the stack. goodbye flame.

[BenderHeel]

Would a chimney cap help? He also mentioned a new liner for the chimney that might help balance the pressure of the exhaust; our current terra cotta liner has seen better days.