5 AM steam discharge

[allseason]

I did an inspection one week ago. Hydronic boiler with baseboards for heat. Seperate a/c with independent thermostat.

This morning my cell phone rings at 5:45 AM. It's the homeowner freaking out that her basement is full of steam and her smoke alarms are going off and I never turned off the heat and there is water all over the floor and she can't understand what is happening, OMG OMG OMG!

She wanted me to come over to see what the problem was, so I obliged and was on the property at 7 AM.

Turns out the TPR valve had discharged. She had enough common sense to turn of the service/emergency switch to shut the boiler down.

I know that I had returned the thermostat to 50 when I was done with the boiler at the original inspection as I only had it running for a short time, the day of the inspection it was 90 plus degrees. When I got to the house this morning the thermostat was at 50.

What can cause that boiler to discharge at rest? Bad TPRV,bad expansion tank? She's going to get a plumber to investigate after I told her I could not fix it (she asked me if I would).

[Terence McCann]

The boiler had to be firing to have steam vapor at the tprv. You can't have steam vapor from a boiler at idle.

It's most like flooded. Did you check the X-tank? A boiler should be able to heat the home without lifiting the tprv. Also, did you see if the boiler was firing with no call for heat? If you had the t/stat at 50 and the boiler was firing there is a control circuit problem.

[Jim Morrison]

Still, the high limit on the boiler should have shut the system down before the water in the boiler flashed to steam. Plus, there's no reason for the boiler to be firing in August anyway. One or more controls has clearly failed on this system.

[Terence McCann]

Still, the high limit on the boiler should have shut the system down before the water in the boiler flashed to steam. Plus, there's no reason for the boiler to be firing in August anyway. One or more controls has clearly failed on this system.

Not if the X-tank is full. You'll lift the tp/v then flash.

[Jim Morrison]

Agreed, but why was the boiler firing in August? No mention of a tankless water heater.

[allseason]

As I had said, I tested the heat 7 days ago by upping the thermostat, look for flame, heat to baseboards, then returned the tstat to 50. Today I show up and the tstat is at 50, same as it was a week ago, but at 5 am it blows off as per the owner. I suspect something has gone wrong between then and now, 7 year old Utica Boiler.

[Jim Morrison]

Indeed, forced hot water boilers shouldn't ever make steam, especially in August. Sounds like something relatively inexpensive went wrong to me. Nothing to lose sleep over.

[Darren]

Did the boiler have a water heater coil?

[allseason]

No, heat only. For some reason the TPR went off, I could see the evidence on the floor. I do not know if the steamy basement was a result of the hot water coming from the valve, I only have the word of the owner as to what went on at 5 AM. She said the smoke alarms were going off and the basement was full of steam, which I associate with high moisture in the air. The owner says "steam" which may have just been tons of moisture in the air, like a fog. When I got there the boiler was off and I had no intention of turning it on and recommended a plumber.