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Honeywell L4064B pull out tab for low voltage wiring (C) Daniel Friedman at InspectApedia.comLimit Control Breakaway Jumper Tab FAQs

Questions & answers about when to pull out or break off the Jumper Tab

Heating furnace limit switches often include a break-away or pull-out tab on the limit switch. These questions and answers add details about what to do with this tab on your limit switch.

These heating system articles answer questions about all types of building heating systems and describe how to inspect, diagnose, and repair heating system problems, how to cut heating bills, and heating system safety, heating system efficiency and heating trouble-shooting advice.

Page top photo: the "jumper tag" on a fan limit control switch.

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Q&A about the Breakaway Jumper Tab on the Furnace Fan Limit Control Switch

These questions and answers were posted originally

at FAN LIMIT SWITCH INSTALLATION & WIRING MANUALS - be sure to read details about the limit control and use of the break-away or pull-out tab that are given there.

Tip #1: About when to pull out the breakaway tab shown on a fan limit control at the top of this page,

see HONEYWELL L4064B LIMIT WIRING WHEN CONTROLLING LOW VOLTAGE - also see the 4064T

Tip #2: If the breakaway tab has been removed (to use the control for low voltage switching) and you wish you could put it back to use the control for line voltage you can see how to do so

at HONEYWELL COMBINATION FURNACE CONTROL TYPE L4064 WIRING HOOKUP

 

Also see our index to fan limit control switch questions & answers found at FAN LIMIT SWITCH INSTALLATION & WIRING FAQs

 

What to do with the break away tab on a replacement limit control

Honeywell L4064B low voltage installationHave an old furnace that works fine.

I'm concerned that the fan relay in the White Rogers control (Type 5A75-46, Style V2PIYZ) might fail. Does anyone know of a replacement? - On 2019-05-17 by John H

[When John purchased a replacement limit control he then asked about the breakaway tab on that switch.]

Reply by (mod) -

John a search of InspectApedia using the search box just above to look for FAN LIMIT SWITCH UNIVERSAL REPLACEMENT

finds FAN LIMIT SWITCH INSTALLATION & WIRING a

where you will find HONEYWELL L4064B, L4064R UNIVERSAL COMBINATION FAN & LIMIT CONTROLLER INSTALLATION MANUAL PDF] (2017) [*** A LIVE LINK to this PDF is on the page I cited above ***]

Honeywell 1985 Douglas Drive North Golden Valley, MN 55422-3992 customer.honeywell.com

This L4064B, L4064R limit controller is a universal replacement for older furnace fan limit controllers. Here is the difference between the L4064B and L4064R, excerpting from the document above:

These combination warm air fan and limit controllers are suitable for various types of forced air heating systems.

The controllers have 2 switches; one which opens the limit circuit if the plenum temperature exceeds the preset safety limit; it resets automatically.

The other switch turns the fan on and off.

The fan is turned on and off according to plenum temperature.

The L4064R has a special high temperature range suitable for gravity heating systems.

All models may be used as limit controllers by wiring only the limit side. Limit contacts are suitable for both line voltage and low voltage.

Watch out: For low voltage applications, the brass jumper must be removed.
...
Follow furnace or burner manufacturer’s instructions, if available.

Maximum element temperature is:

L4064B—350 ºF (177 ºC).

L4064R—250 ºF (121 ºC) above limit setting.

Maximum switch temperature is: L4064B,R—190 ºF (88 ºC).

by JW

Thanks -- The wiring seems to check out OK. Went ahead and replaced the Honeywell L4064B limit switch with a new one.

This switch has a break-away jumper in it. How do I determine if I need the jumper or not (already discarded the old switch) ? I have three wires running to the limit switch. Thanks again .

by (mod) - Handling the breakaway jumper or pull-out tab on a new fan limit control switch:

JW

Handling the breakaway jumper or pull-out tab on a new fan limit control switch:

I don't know which brand and model limit switch you've got but removing a breakaway tab on the Honeywell fan limit switch is for use with low voltage - that breakaway or pullout is explained in the article

FAN LIMIT SWITCH INSTALLATION & WIRING where you'll find installation instructions and manuals for fan limit controls.

 

New Honeywell Limit switch with the brass jumper broke off by mistake

I have a New Honeywell Limit switch with the brass jumper broke off by mistake, is there anyway I can use it by maybe putting a jumper wire between the red and black wire? On 2017-03-09 by Dave -

Reply by (mod)

Dave:

The company, wanting to avoid liability for a fire or injury will say no, buy a new unit, but I suspect if you can make an electrically-secure connection the switch will work fine.

At the top of this page we gave this tip:

If the breakaway tab has been removed (to use the control for low voltage switching) and you wish you could put it back to use the control for line voltage you can see how to do so

at HONEYWELL COMBINATION FURNACE CONTROL TYPE L4064 WIRING HOOKUP

Basically that involves simply adding a jumper wire at the control.

...


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