Old oil furnace fan/limit and Iron Fireman controls cross reference

Reply

  #1  
Old 02-26-11, 10:05 PM
D
Member
Thread Starter
Join Date: Jan 2011
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
Old oil furnace fan/limit and Iron Fireman controls cross reference

I have an old fan/limit control (plenum mount) on my oil furnace that I'd like to cross reference to something new, just in case. Minneapolis-Honeywell, It's got a mercury tilt bulb switch, range of 50-200. The old number on the plate is L420A1X3, it's round in shape. Controls the fan only. I'm guessing 1940's vintage.

Second, I have an Iron Fireman model A111 made in Portland OR, same vintage, range of 50-450(!). Anyone care to hazard a cross reference to this one? I'm guessing this is an overheat control? I presume the MH is the 'primary' fan control as it has a summer fan setting, and the IF is in essence a back-up to overheat on the burner or some sort of redundant control? Not sure I'm perfectly clear on the set-up but I'm up for the education. This is all on a retrofit slag/coal burner.

I do not have a cad set-up on the burner (White-Rogers 611-31 E11 instead) FWIW.

All are working fine and the old furnace is still operating exceptionally well, but after 60-70 years one might want to plan for eventualities...!

And thanks for info from a previous post regarding a Sundstrand/Suntec replacement pump. All worked out just fine.
 

Last edited by dsbur; 02-26-11 at 10:44 PM.
  #2  
Old 02-27-11, 03:02 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 0 Votes on 0 Posts
Frankly, the fan control switch you have using the mercury switch is highly reliable ---- more reliable than a new switch using a mechanical switch to turn the fan on.

I'd leave it as it is.
 
  #3  
Old 02-27-11, 07:15 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 14,359
Received 32 Votes on 30 Posts
The old mercury switch, as S/P said, is a far better control than today's mechanical switches but if you want something on hand for a replacement, maybe a Honeywell L4064 would fill the bill. It is a combination fan & limit but can be used for either purpose.
Model
 
  #4  
Old 02-27-11, 09:11 PM
D
Member
Thread Starter
Join Date: Jan 2011
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
My best guess so far was one of the 4064's also. They appear to be pre-set and I'd just have to match up the depth.

The little mercury tilting bulb works fine but there's a fine wire that leads to one of the ends and I just can't help but think one of these days it's going to fail.

Just so I understand, my old MH is the fan control and the IronFireman is what you would call the limit (shuts the pump off on an overheat, like if the fan failed). The MH is a mechanical switch, ancient but pretty simple also.
 
  #5  
Old 02-27-11, 11:53 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 0 Votes on 0 Posts
I've never seen the wire fail or that part wear out.


I'd consider your worry to be objectively groundless, but perhaps you can't sleep at night. That would be a good reason for changing it out or having a spare.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: