Tapping for Pressure Relief

Ok... So I am wondering something.

on my EFM the 3/4" tapping that is shown in the manual for the pressure relief. Appears to have never been used. So I once again have a plug that is STUCK. like my return plug. It looks like someone tried to get it out at one time as the edge of the corner is already broken off.

Which brings me to my next question.

There is a 1/2" tapping near the front of the boiler, in front of the supply tapping.

Can I use this 1/2" tapping and bush UP to the 3/4" pressure relief valve? Will this matter? I'm guessing that is what the previous owner did. seeing how the plug appears to be pretty much locked in there.

so its use that 1/2" or take my hand at getting ANOTHER plug out. this one is in a much worse spot to get at easily...

Mark

This isnt really a good answer to your question but may be of some help.

On that 1300 we put in the shop there were a few plugs that were stuck. And I mean STUCK!... Dorked around with them till we rounded them all off. Heated with the oxy-acetylene and everything we could think of. Ended up drilling them out (they are cast; and are soft) and after drilling was able to get a hacksaw blade through the hole. Filed two grooves in each hole, while being careful not to cut into the threads. then we were able to use a chisel to knock them around and make them collapse on themselves and pull them out.

Maybe this could work for you.... and maybe you have even tried this by now. As far as weather you can use that other tapping.... ill let that to the experts!

good luck
Tyler Hall

as long as you put it as close the boiler as you can before the first valve and the vessel would be protected from overpressurization

You gotta have a 3/4 tapping. Law (and safety) says so. If you ever had a serious problem, the 1/2 inch would not spew enough pressure to keep it from going boom. A 3/4" barely does the job!

Freddy are the 1/2" PRV's meant for hot water tanks? I've seen them both listed at a couple of online plumbing supply houses.

The safety valve on a hot water heater senses both temperature and pressure. A boiler safety valve senses pressure only. They are different.

The 1/2" PRV's are for domestic hot water coils of boilers. They do not have a tank, just the coil in the boiler and the pipes that go to a mixing valve then to the domestic water. Because there is no tank involved, the 1/2" has enough capacity to dump if needed.

I am with freddy
Drill out the cast plug.
Then use a easyout to remove the stuck plug.
Run a 3/4 tap in the hole to straighten out the threads.
Most the time just drilling it out will cause it to come out on its on.
BDD

Thanks for the info Yanche and Freddy. You guys might make a plumber out of me yet.

Thanks guys for your info!

another fun job ahead.

I have no doubt that drilling it out will absolutely not loosen it up if the last one was any indication! HEHE.

out comes the hacksaw, sawzall etc... Oh boy...

Ohhh, to be fly on your shoulder and get to watch.

Using left handed drill bits sometimes makes easy work of drilling out stuck threaded things. I've found the masonry impact drill motors do the best. The impact shock helps get things turning. Harbor Freight sells a small set of left hand drill bits. Buy a second set if you plan on using an impact drill motor. Broken bits are a given. I just grind new points on what's left.