Secondary pressure limit switch a good idea?

Big Al

After reading articles about boiler explosions still occuring with modern equipment, I'm a little spooked.

I've been looking over the electrical schematic for my Burnham Independence steam boiler. As far as I can tell, the only pressure limit switch is the Pressuretrol, with the backup safety device being the pressure relief valve. (Somebody please correct me if I'm wrong.) Are these Pressuretrol switches that reliable? I think I'd sleep better if there was a backup over-pressure switch in the circuit . . . maybe set at 3 psi, so it would never trip in normal operation, but could be tested without damaging anything.

I suppose I could install a second Pressuretrol, but that seems like an expensive way to do it. A simpler fixed-pressure switch would do the job. I suppose it will need a pigtail syphon or something like that to protect it, etc. Recommendations?

Any advice would be appreciated. Thanks in advance!

Al

Rich L.

Two safetys

Hi Al, We do only commercial and industrial work but everything we do has two pressure controls. The automatic pressuretrol and a second pressure limit with a manual reset. That way you know if it's out on the second, you,ve got a problem with the first.

Good luck, Rich L

Big Al

So, where can I find the details on a secondary switch . . . Make, model, etc. If I can find the right one, I'm confident that I'll be able to hook it up correctly.

Big Al

Found a Switch

OK, I spoke with an industrial steam guy I work with. He found me a like-new salvaged Honeywell L404C1147 manual reset pressuretrol and a pigtail syphon. I plan to tee it in with the primary pressure limit and wire it in series with the LWCO . . . which is also in series with the existing pressuretrol. I'll get some appropriate BX and fittings, and do it neatly.

Does this sound right? . . . or should I pipe it in someplace else, like on the header or main loop. I don't see any other appropriate tappings on the boiler, a Burnhamn I6.

Thanks,

Al

Mike2

Second Switch

When a problem arises due to a clogged pigtail, a second switch on that pigtail also fails.

martin

Exploding Boilers

Boilers exploding because of a sticking pressuretrol are probably quite rare, Usually it is from some sort of low water condition the sections get real hot and then it gets a fresh dose of water somehow, it expands exponenxially and no relief valve could handle it fast enough and somethings got to give. If you have a new independance you probably have a probe LWCO which should aleve your worries about a low water condion. I think if you would check out the boiler explosions most are from lack of routine maintanance. Kind of like some people and there kids just feed em and forget them.

Big Al

Thanks!

1) I'll be putting the switch in on a second pigtail, but probably teeing it into the same tapped port on the boiler, since I can't see any other logical place.

2) I have a float type LWCO and I check its function every week when I drain it a little and top off the boiler.

3) I like things safe. If the boiler was in a commercial or industrial setting, a second switch would be required. Why not at home? Since I can get a cut-off switch for free, why not put it in? I plan to set it for about 3 psi. That way I can run up the pressure and test it once in a while without causing any damage to my vents.

Sound OK?