LWCO Replacement

zbase · June 2013

I have a mid 80s Burnham boiler with what is probably its original McDonnell & Miller 67 LWCO. Now that summer is here, I will be replacing that, along with the pigtail and pressuretrol.

I am looking on the PexSupply site, and see a few different models, and am wondering which is the correct replacement. The first link below is the one I am thinking I should get, which seems the same as the second one, but does not have manual reset. What is manual reset?

The third one comes up when I search for the BC-1 version, which is what is listed in my boiler manual, though not on the LWCO itself. Seems as though this is the Burnham listed replacement, but may actually be the same thing?

Also, the pictures in the first two show the ball valve on the opposite side on where mine is (on mine, the site glass is on the right looking at the ball valve handle). Can that just be moved to the other side?

Thanks for any help... I have read many posts on the site over the last year, which convinced me to insulate the steam pipes that had been stripped years ago. I bought Dan's book 'We Got Steam Heat', which I found to be very helpful in trying to, at least basically, understand what how my steam heating system is working. I know I still need to do some work with the venting, which is next on the list.

Here are the LWCO links I am looking at:

<a href="http://www.pexsupply.com/Mcdonnell-Miller-149400-67-Float-Type-Low-Water-Cut-off-Steam">http://www.pexsupply.com/Mcdonnell-Miller-149400-67-Float-Type-Low-Water-Cut-off-Steam</a>

<a href="http://www.pexsupply.com/Mcdonnell-Miller-149700-67-M-67-Float-Type-Low-Water-Cut-off-w-Manual-ResetSteam">http://www.pexsupply.com/Mcdonnell-Miller-149700-67-M-67-Float-Type-Low-Water-Cut-off-w-Manual-ResetSteam</a>

<a href="http://www.pexsupply.com/Burnham-80160517-McDonnell-Miller-67-BC-1-Low-Water-Cutoff-152026">http://www.pexsupply.com/Burnham-80160517-McDonnell-Miller-67-BC-1-Low-Water-Cutoff-152026</a>

Jamie Hall · June 2013

Either of the regular

ones should be OK. They are, after all, pretty simple gadgets -- two switches (one for the feed, one for the burner). I haven't looked to see, but I should think you could rotate the ball valve.

The manual reset is just that: if it hits the low water cut off, it won't turn back on when you (or the feed) refill the boiler. It has to be manually reset to get the burner to turn back on. Most larger applications have two LWCOs; the regular one -- which incorporates the feed and is automatic -- and another one set lower, in case something goes wrong with the upper one. That one is manual, so that someone actually comes and looks at the situation and, hopefully, finds out what's wrong. Sometimes the double setup is required by code, sometimes not -- but I've always liked having it on bigger boilers.

zbase · June 2013

The one I have

on there now then is automatic... there is no manual reset. I do not have an automatic feed on the boiler, so I don't see the advantage in having the manual reset. Thanks.

zbase · June 2013

Here is

a pic of the current setup. I didn't notice this before, but when I took this picture, I realized the bottom of the pressuretrol is actually level with the waterline. Should that be higher? Is it ok for the pigtail loop itself to be below the waterline?

This may be a good time to redo that piping there and add a low pressure gauge....

Jamie Hall · June 2013

Mostly yes...

Ideally the pressuretrol should be higher than the water line. A good bit higher. Also, ideally the pigtail should be above the water line. And yes, this would be a lovely time to do a little simple repiping and adding a low pressure gauge!

Rod · June 2013

Bronze Pigtail

Hi- It looks like your present pigtail is steel so you might want to change this to one made of brass/bronze as these are less likely to corrode and plug up.You should be able to get one at your local heating supply store or from McMaster Carr www.mcmaster.com/ on the internet. I get mine from McMaster Carr as they have a large assortment of configurations. You also might want to add a bronze pipe union below the pressuretrol as this allows you to remove the pressuretrol and blow out the pipe/ pigtail without having to disconnect the pressuretrol wiring.

- Rod

Steamhead · June 2013

If that were my boiler

I'd remove the #67, remove the plug in the boiler directly behind the #67 and put a probe-type LWCO there. That would eliminate those moving parts and it would not need weekly blow-downs.

The gauge and Pressuretrol could go on the upper sight glass pipe.

Hap_Hazzard · June 2013

The 149400 is the right part

You do want the automatic reset. If you have low water, the reset will allow it to cycle. You'll hear the burners going off and on and realize something's wrong, and you can fill it up so you can stay warm while you hunt for the leak. You don't want low water to make you lose heat in the dead of winter, especially if you're away for a few days.

You want to get the pressuretrol as high as possible. When you replace the pigtail, get a straight one and lose the 1/4" elbow. That will give you another 3-4".

That LWCO is an old one. The newer ones have a yellow blow-down lever on the ball valve, not that green spoke handle. (The ball valve with the yellow handle on yours is a separate valve.) The flange for the blow-down valve has four evenly-spaced bolts so you can mount it four different ways.

But Steamhead is right. You should really ditch the paperweight and put a probe-type LWCO on there. They're inherently more reliable and cheaper too. I recommend the Hydrolevel Safgard 400, but any 24-volt residential steam primary cutoff should work for you. You'll need to redo the trim piping, but that's easy, and we can help you if you need it. The hard part's going to be getting that plug out, but you can do it.

LWCO Replacement

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