Furnace is making an intermittent grating noise

[debodun]

I have a hot water baseboard heating system fueled by an oil furnace. It is heating okay, but sometimes when the furnace starts or shuts off, I can hear a grating sound. Doesn't happen all the time and sometimes it's not very loud and sometimes it sounds really loud. I had the furnace serviced last March when it stopped working and it was a bad flame sensor. Any ideas what's happening?

 

[jujube]

Could be the furnace's water pump getting ready to fail. How old is the system?

 

[debodun]

Could be the furnace's water pump getting ready to fail. How old is the system?

I don't know, but it's probably the original furnace and the house was built in 1995.

 

[Chet]

When I lived in the other house, the oil furnace flame thingy had to be adjusted just right or it made a noise when it started running, although I wouldn't call it grating.

 

[debodun]

My oilman was here today and I mentioned the noise. All he said was, "If it gives you any trouble, call me."

 

[Nathan]

You have an oil fired hot water boiler? Might be the draft motor making the noise.

 

[debodun]

You have an oil fired hot water boiler?

Sounds right. There's no hot water tank for the house. The hot water comes off a jacket of water inside the boiler, and let me tell you, it's scalding. Boiler temp set to 180F. I asked two people (a handyman in my church that looked at it and the fuel oil guy) if it could be set lower and they said there's no way to change it.

 

[Knight]

you could Google this

grating sound in oil furnace when starting up

and get a variety of suggestions.

 

[Geezer Garage]

You should be able to install a proportional mixing valve from your cold water supply line to your out going hot water line to temper/adjust your max domestic hot water temp. I would shoot for around 140 deg. There is always a way to achieve most things, you just need to find the right guy.

 

[Capt Lightning]

I had similar problems with my oil boiler and the noise got progressively worse. It was coming from the blower motor which seemed to have a bad bearing. It was almost as much to have this repaired as to buy a complete new burner (new version) , so that's what I did. Works grand.

 

[debodun]

I noticed that the damper is always stuck open. I've put it down so it's freely swinging many times but when I look again, it's in a horizontal position. I've observed it when the furnace is running and when it shuts off and nothing happens, but when the furnace turns on, damper flies up and sticks in that position.