Overheat Again

[djblech]

My GW blew one of the pex lines that comes across from the garage to the basement last night. The water followed the drain tile that my pipes are buried in so I have 1" of water in the basement. I woke up once last night thinking the power was out, but the night light in the hall was on so I didn't go and check. Power was on this am so it was probably a just a momentary disruption. I don't know how this caused a pipe to burst, but this is getting old. At least 2 of my pumps were running without water for hrs. The temp on the stove this am was 212*, hot but not that hot. I don't know about the aquastats. They don't like the heat either. I'm sure the warm temps didn't help. I sure am glad I separated the wood boiler from the rest of the house with a hx. At least the rest of the house is still running fine on propane. This may be a forced shut down for the year because I know I don't have any antifreeze left.
Could have been worse.
Doug

 

[steam man]

You ain't the first person I have seen this happen to. The other was with a Greenwood also and one with a solar collector application. All using PEX. I would never use pex in a situation that could get exposed to abnormally high temps. Usually this happens during a power outage or a component failure. Using copper/steel pipe as much as practicable before converting to PEX would help dissipate some of the higher temps. A good failure analysis should always be done on any energy related system. Along with some pipe modifications I'm thinking some kind of passive thermal dump was in order for your application.

Mike

 

[b33p3r]

What happened to you has been on my mind over the winter. Unlike you I have no HX. My econo flows directly through my in house oil boiler. Thinking I was clever, I installed a pair of relays so if the temp of the WB drops below 150*, the oil boiler would automatically fire and I would have no want for heat or hot water. But what if I busted a water line and I didn't know it ? What would happen to the oil boiler in my house? No low water shutoff on the oil boiler. Would it over heat with the possibility of a fire?
So I'm thinking I'll remove the relays and just control the boiler firing with a manual on/off switch. That way if I bust a pipe outside, I'll recognize a problem with cold temps in the house. I can investigate and shut off whatever necessary before turning the oil boiler back on. Thougts are definately welcome.

 

[duane9835]

I take it your not running a battery back up???? It would have paid for itself by now!! I learned my lesson, trust me....

 

[heaterman]

A couple thoughts...

Do you have a functioning relief valve on that thing?

The GW was at 212 because it was at that point an open system and that's all the higher it will go.

No way the temp wasn't higher, a lot higher, than 212.

Did the pex itself blow or did it come off at a fitting?

 

[2.beans]

ive had my seton unsweat copper connections before i had a battery backup.

 

[Willman]

ive had my seton unsweat copper connections before i had a battery backup

Thats what is known as HOT!!

Will

 

[djblech]

It actually blew the pex right were it goes through the floor in the garage. I think the supply and return were touching right at the draintile that goes underground. I do have a pressure relief valve on the system right at the stove. I do not think it blew. I do not have a battery back-up, just a generator that I have to manually start and plug in. I also have a dump zone that is manually activated. I'm sure it was hotter than 212 because my heat exchanger is clean as a whistle now. Temps were in the 40* during the day 30* at night. I had only fired once in the morning and figured the hot water maker would take most of the heat. Power must have gone off a couple of hours into the burn. I need an alarm that goes off when the power goes off, then I could get the generator hooked up. One of the problems is that I am running 3 pumps in the garage and 2 in the house on separate electrical services. So even if the backup kept the GW and its 3 pumps running the house would not be calling for heat.
Doug