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Old 12-08-2011, 04:24 AM   #91
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Is this old Furnace Able to be Serviced?


By opening up the pulley. The belt spins at a slower RPM, which in turn spins the blower will slower.

A 2" motor pulley turning an 8" blower wheel is a 4:1 ratio. So a 1725 motor on that set up would only be turning the blower at 431RPMs.
A 3 " motor pulley would be 646 RPM.

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Old 12-11-2011, 02:57 PM   #92
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Is this old Furnace Able to be Serviced?


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max'd 1725 RPMs on that new one if it is little noisey and the belt is flush up to the top of those sheaves on the motor 1/4 to 1/2 turn to drop the belt a little down into the sheave won't kill to much air and quiet it up try it to test the difference...nice job save a ton of $$$.any chance of getting an amprobe on the wires see wh the amps are with the panels up see how close you are to the tagged amps....tip...wire tie the wires and green ground off the motor base from vibration....have a good holiday
Thanks for the tip. I opened up the pulley a bit and just like you said, the RPMs dropped a bit and so did the noise. The current dropped a bit too. I also, tied up the wires to get them off of the base. I'm not sure what the difference is since they are still vibrating because they are mounted to the motor but since you have the experience, I just do what is suggested.

Motor with Wires Tied Up


Current Measurement
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Old 12-11-2011, 03:33 PM   #93
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Is this old Furnace Able to be Serviced?


You can probably open that pulley another full turn, and get the amp draw down to around 3 or 3.5, and then check temp rise.
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Old 12-11-2011, 03:41 PM   #94
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Is this old Furnace Able to be Serviced?


Biggies suggested turning that split pulley one 1/4 or 1/2 turn out.

My questimate looking at your your picture says that this split pulley has been slowed down a lot more than that.
You will get a quieter sound but the operating temp of your furnace will be probably be 10 -12 degrees hotter than it was. That means a loss of efficiency and a harder wear factor on old parts and the exchanger.
Depends on what your priorities are.
I would still try a steel split pulley so you'd get some quiet at the same temp that this unit has been running with for 45+ years.
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Old 12-11-2011, 08:10 PM   #95
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Is this old Furnace Able to be Serviced?


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Biggies suggested turning that split pulley one 1/4 or 1/2 turn out.

My questimate looking at your your picture says that this split pulley has been slowed down a lot more than that.
You will get a quieter sound but the operating temp of your furnace will be probably be 10 -12 degrees hotter than it was. That means a loss of efficiency and a harder wear factor on old parts and the exchanger.
Depends on what your priorities are.
I would still try a steel split pulley so you'd get some quiet at the same temp that this unit has been running with for 45+ years.
I wasn't exactly paying attention to what I read from biggies and I was thinking that he meant 1/4" to 1/2" instead of 1/4 to 1/2 turn. Nevertheless, this what is what it looked like before. I remember the belt was riding low in the pulley and I didn't realize that there was a reason for that. I think were the pulley is now is similar to what I had before. I will check it out to see if tweaking it changes things much. I was happy to reduce the current draw of the motor because I did not replace the old wire in the controller and I am a little concerned about the ancient insulation melting if the current is too high. My next weekend project will might be to salvage my old steel pulley and to clean it up.

VC
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Old 12-11-2011, 08:24 PM   #96
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Is this old Furnace Able to be Serviced?


Sorry didn't read this till tonight..i took it the belt was up on the pully flash with the tops of the sheaves and you had vibration i ment a 1/4 turn to 1/2 turn from the loosening the allen key flat whats the amp tag on the motor.tightening the wires up was to get them off the frame base....sure they will vibrate from the motor run but not on the base....your never going to actually change a motors speed as in hi/med/lo with a sheave adjustment it's only to take slight rpms and amps off.where was the belt in the sheave before the adjustment..main part of the belt is the V part where you want the sheave to make a good grab..flush up is always a good place to start then drop it down is flush up the actual speed selected for the unit is somebody else to kick in with on that one..Question whats with the AC millivolt reading

Last edited by biggles; 12-11-2011 at 08:33 PM.
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Old 12-12-2011, 12:13 AM   #97
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Is this old Furnace Able to be Serviced?


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Sorry didn't read this till tonight..i took it the belt was up on the pully flash with the tops of the sheaves and you had vibration i ment a 1/4 turn to 1/2 turn from the loosening the allen key flat whats the amp tag on the motor.tightening the wires up was to get them off the frame base....sure they will vibrate from the motor run but not on the base....your never going to actually change a motors speed as in hi/med/lo with a sheave adjustment it's only to take slight rpms and amps off.where was the belt in the sheave before the adjustment..main part of the belt is the V part where you want the sheave to make a good grab..flush up is always a good place to start then drop it down is flush up the actual speed selected for the unit is somebody else to kick in with on that one..Question whats with the AC millivolt reading
I think its adjusted to a nice speed now. It's a bit quieter and drawing a little less current. The AC milivolt reading is actually equivalent to the same reading in amps. My buddy loaned me his amp clamp to connect to my fluke meter. The instructions said to put the fluke on the milivolt range and the reading that is read on the display is actually the current in amps. I'm not sure how it works but my bud is an electrical engineer and I just take his word for it.
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Old 12-12-2011, 06:30 AM   #98
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do you get the same numbers in the milli amp setting never saw that meter used like that reading amps....just wondering what was the amp rating on that new motor

Last edited by biggles; 12-12-2011 at 06:32 AM.
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Old 12-12-2011, 01:05 PM   #99
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do you get the same numbers in the milli amp setting never saw that meter used like that reading amps....just wondering what was the amp rating on that new motor
If you put it on the milliamp setting, the Fluke meter gives an error. The amp clamp that we were using converts voltage to current based on the inductance measured on the hot line. I could measure it in series on the amp setting to get a more accurate reading.
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Old 12-12-2011, 02:03 PM   #100
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Is this old Furnace Able to be Serviced?


30 yrs in the industry never saw that did milliamps on thermocouples testing..but line amps....always used clamp type amp probes....see how much i don't know..... work looks mint
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Old 12-12-2011, 02:12 PM   #101
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Is this old Furnace Able to be Serviced?


Hey Biggles
What circumstances had you milli amp testing a thermocouple instead of dcmv?
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Old 10-25-2012, 01:07 AM   #102
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Is this old Furnace Able to be Serviced?


Hi Guys,

Another year has gone by and my beast of a furnace is still churning away. I had my HVAC mechanic buddy inspect it and he said that he was amazed at what great shape it is in. He came over to try to sell me a new one but said that he will gladly help me service this one.
I've noticed that the gas valve sticks when the cold season first starts. Even last year, towards the end of the cold season here in the SF Bay Area, I noticed that the heat would not come on sometimes. I would then go down to the basement and tap on the gas valve in the position that I have shown here.

A couple of quick taps and the gas valve opens. My mechanic said that he would replace the gas valve for me but I need to find it or specify it and he would install it. He is only about 40 years old and like most union trained youngsters, only works on modern equipment. I was wondering if any of the oldtimers or experts here have a suggestion of gas valve that will replace mine.

Last year when I first posted photos of my furnace, I had to explain that this furnace was not pumping carbon monoxide into my house. I have a commercial grade CO monitor that gets calibrated on a regular basis and I'm certain that it is not pumping carbon monoxide into my house. I realize that those who were concerned with me being exposed to CO were just trying to let me know the dangers but I have determined that the a CO leak is not occurring at this time and to make sure, I have the commercial grade CO monitor running 24 x 7.

Any help or advice about a replacement gas valve would be appreciated. Thanks in advance, VC
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Old 10-25-2012, 04:15 AM   #103
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Is this old Furnace Able to be Serviced?


http://www.pexsupply.com/Weil-McLain...oilers-PFG-6-7

The above valve will work. You can search for Thermopile gas valves and come up with a fair number of links.

How big is your house again. thats a huge furnace for an area that I thought had a some what warm climate.
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Old 10-25-2012, 05:34 PM   #104
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Is this old Furnace Able to be Serviced?


OK, I'm pleading laziness for not going through 7 Pages of postings again.

Beenthere.. What made you think the gas valve was thermopile driven?
Just asking because of the amount of 6 & 12 volt transformers that I've seen attached to dinosaurs, not to mention the look of the extra limit load through that gas valve.
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Old 10-25-2012, 07:00 PM   #105
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Quote:
Originally Posted by beenthere View Post
http://www.pexsupply.com/Weil-McLain...oilers-PFG-6-7

The above valve will work. You can search for Thermopile gas valves and come up with a fair number of links.

How big is your house again. thats a huge furnace for an area that I thought had a some what warm climate.
Thanks for the tip. I didn't realize that thermopile can generate 24VDC. Are you sure the suggested valve will work with thermopile supplied voltage? $300 is a lot to spend to know for sure.

My house is around 2000 sq ft. This heater brings the house from cold to warm in about 2- 3 minutes. Not efficient, but damn comfortable.

Thank in advance, VC

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