Wiring

Nycwrenchturn

How do you wire 67 McDonnell miller manual reset on steam boiler . 24 volts and primary lwco is prone type 400

Nycwrenchturn

Can I just bring power to terminal 1 and 2 and then terminal 4 breaks my Tstat?

Jamie Hall

It doesn't require power. The terminals are plain switches, and it is wired in series will all your other safeties.

Mike_Sheppard

It depends on how it’s wired with your boiler. And if it’s controlling a feeder or not.

It would be best to consult the manual.

Nycwrenchturn

Manual stinks it only shows reg 67 not manual reset . Primary is controlling feeder I just need it to turn burner off

Nycwrenchturn

So which terminals do I run the limits through ?

Nycwrenchturn

Terminal 3 is the manual reset button . Then there is terminal 1 2 and 4

Do I just run a limit through 1 and 2 and call it a day

Nycwrenchturn

?? Anybody ??

DanHolohan

I don't think you can do manual reset with the 67.

JUGHNE

The 2013 M&M catalog shows a 67-M part number 149700, 67w/manual reset.

I don't think the wiring would be any different with manual reset unless you want to connect an alarm to notify of boiler hard lock out.....not a bad idea sometimes.

Nycwrenchturn

I have a 67 that’s manual reset . Normal terminal 3 isn’t there anymore it’s where reset button pushes in . Can I just run my Tstat for boiler through terminals 1 and 2 ?

Jamie Hall

There is no wiring diagram in the manual? Odd. Well, if not, the principle is this: 1 and 2 are the terminals for the float switch. Normally closed. You want to wire it in series with your pressuretrol(s) and the other LWCO you mentioned. Sometimes -- but not always -- the thermostat is in this loop. More commonly, the thermostat goes to T-T on the burner control, and the safeties (of which this is one) are on another loop -- but there are a variety of ways to hook things up.

The important point is that this is a safety control, and must be in series with all the other safeties on the boiler -- however that is done on your setup.

Zman

It is a simple double pole, single throw switch.
1-2 and 3-4 will make or break simultaneously.
If you are trying to disable the t-stat, what you are proposing will work fine. Most boilers have a string of safeties wired in series. typically your safety switch would be tied into that.

JUGHNE

I was taught years ago that a switch is determined to be labeled as NO or NC when it is on the shelf or still in the box without any outside influence applied.
So I would say you are looking for normally open contacts and when the float is up in the water the switch would be closed for "normal operation". Loss of water would put the switch in the dry mode, as if still in the box or on the shelf, and the contacts would open shutting down the burner.

The main thing is that during water loss or blow down the LWCO will shut down the burner. And even if the water returns to normal the burner will NOT restart until you manually push the reset button. It should be tested with the burner running.

EBEBRATT-Ed

Yes you can have a manual reset #67. It just has a manual reset switch instead of the normal switch a #11 switch or a #11m I believe.

With either switch you wire terminals 1 & 2 in series with you thermostat, operating controls and other safeties, those are the low water cutoff terminals

MAKE SURE ALL YOUR SAFETY'S WORK AFTER MAKING WIRING CHANGES.

Terminals 3 & 4 are use for operating a feeder or for an alarm. You can't use a feeder with a manual reset so that is why terminal 3 is missing