HVAC help needed...Boiler seemingly having issues

So I'm not home from work for 20 minutes before SWMBO calls me in the basement because the floor is wet under the boiler. The leak appears to be coming from the relief valve and the insulation on the pipe to the expansion tank has melted, leading me to believe the system is allowing itself to run too hot. The temp is showing over 220 at the moment, with pressure around 20 psi. I've only seen a drip or two out the relief valve pipe and what's on the floor seems to indicate it is diminishing, however I'm still somewhat concerned. Need I be?

Other potentially relevant info: Hot water heating system (obviously), Burnham boiler installed circa 1990, it's an oil burner, definitely old but serviced earlier this fall and given a clean bill of health, aquastat set at 190/170/120 HI/LOW/DIFF. Nothing that I'm aware of has changed recently that might cause this. We did get an oil delivery today, for whatever that's worth, and do seem to be going through an awful lot of heating oil, around 250 gallons a month.

I'm certainly no HVAC expert and will probably end up calling a pro out one way or another, but I just wanna know 1) whether or how concerned I should be 2) any basic steps to troubleshoot and 3) whether this could be a potentially simple repair.

I'd get it looked at right away. Water temp sounds high to me.

https://heatinghelp.com/systems-help-center/what-is-the-right-pressure-for-a-hot-water-heating-system/

"Typical pressure for a residential boiler serving a two story home would show 12 psi cold, and less than 30 psi hot. Over 30 psi boiler pressure will cause the pressure relief valve to open.

Typical operating temperature settings on a boiler call for a Low temperature (boiler cut-in) between 120 and 160 °F.

Typical operating temperatures on a hydronic boiler call for a high temperature (boiler cuts off) of 180-200 °F.

If we set the boiler upper temperature too high over 200 degrees F. we're at risk of spilling at the pressure temperature relief valve.

If we set the boiler upper limit too low, there may be no relief valve problem but under some conditions we may reduce the operating efficiency of the boiler and heating system, thus increasing heating costs."

• See more at: http://inspectapedia.com/heat/Heating-Temp-Pressure-Settings.php#sthash.WLwJBmm7.dpuf

Figure out how to turn it off before it goes all Three Mile Island on you.

I recommend looking into replacing it. Pushing 30 years old it's just going to start nickle and dimeing you.

Likely a low water problem. Check the water feed valve, the strainer may be plugged and starving the system.

Grizz wrote: I recommend looking into replacing it. Pushing 30 years old it's just going to start nickle and dimeing you.

Yea, unfortunately we've known this prospect has been on the horizon since day 1 in the house. I'm hoping to at least eek a couple more years out of it. We could stomach the cost of a replacement now, but I would be far from happy about it.

I'll look into the feed valve.

I'm probably just gonna get the thing looked at if it's still showing symptoms tonight. I have neither the knowledge nor the time to deal with this myself at the moment if it's anything beyond the most basic of repairs.

Thanks for the help all.

Our boiler at the theater consistently leaks because the pressure valve is full of gunk.

20 psi shouldn't push the valve open. I can usually get mine to quit leaking for a week by tapping on it with a crescent wrench.

Ours is (or I should say was... it was removed when we put in rooftop 3-ton units) set for 30 psi and 230 degrees, mostly due to the long runs of pipe between the boiler and the radiators. I think it was a 35 psi valve.

In reply to curtis73:

So I'm 2/2 this week on issues that GRM has suggested percussive adjustment as a potential fix

I wouldn't be so concerned about it, and probably just chalk it up to an old leaky valve, were it not for the melted insulation on the pipe. That tells me that something is suddenly getting hotter than it previously was and worries me a bit. Probably keep an eye on it the next few days and see what happens.

Relief valve is suppose to relieve at 30psi, but they stick and often take much more to pop the first time they are asked to do so. Once they pop, they usually continue to drip because the rubber washer held by spring pressure against the seat rips instead of releasing cleanly. The main reason they get called into action is the pressure/expansion tank has sprung a leak in the rubber bladder that separates the boiler water and the pressurized air. Tap on the tank. The side that screws in should have water in it and should thud. The other side with the schraeder valve should have air in it and should ting. If both sides thud, then you need a new tank. The fill valve should fill the boiler to a preset pressure of 12 to 14 pounds. Anything above that and either the fill valve is overfilling, or the expansion tank doesn't have a large enough air space to accommodate the expanding water as it heats up. Set your high limit around 175 and the low limit 20 below that. The only reason to have it higher where you live, would be if you have a gummed up internal tankless water heater. and you need every bit of heat transfer you can get to make hot water in January. If it continues to heat above 200, then I'd replace the aqua stat control.

Furious_E wrote: In reply to curtis73: So I'm 2/2 this week on issues that GRM has suggested percussive adjustment as a potential fix I wouldn't be so concerned about it, and probably just chalk it up to an old leaky valve, were it not for the melted insulation on the pipe. That tells me that something is suddenly getting hotter than it previously was and worries me a bit. Probably keep an eye on it the next few days and see what happens.

Bigger hammer?

But yeah... melted stuff points to other problems

Well, I've been checking on the heating system several times daily and the problem seems to have gone away - no more discharge and the temperature and pressure have been back to normal. Weird, but I guess I'll leave well enough alone for now.