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The furnace is natural gas. The old one is still working as we speak undamaged. It appears too risky to guess at the orifice and flame characteristic even with a photo if I send one. Maybe I should just leave it alone.
What's the risk of continuing to use a 30 yr old pilot burner?
What's the risk of continuing to use a 30 yr old pilot burner?
None
Then, I think I'm done. Thanks again for your help. It's much appreciated.
Glad you got it going. Stay warm.
Do you think I should replace the limit switch with a universal replacement? Its 30 years old. The insertion length is 10-3/16"
If the limit is defective replace with the same basic temperature cutoff.
How can I tell if it is defective?
Test it and see when it operates. Then look on the furnace for the operating temps. You just asked if you should replace it cause it was 30 years old. I guess it must be working since you were only going to replace it because of age.
Its working. I was just thinking of preventive maintenance.
Red, I'm sorry if I missed the post on these 5 pages, but did you ever get the proper rotation blower wheel or are you running the wrong one backwards? Because of the blower housing design, running the wrong wheel in the right direction still won't be as efficient as the proper wheel. You will get turbulance at the blower outlet. I think that would have been the first fix I tried before increasing the blower speed.
Missouri:
I bought a ccw wheel and was shipped a cw. I reversed the motor rotation.
If I understand you correctly, by reversing the motor rotation you're saying that I am going against the design of the blower housing, and won't get the proper cfm. Is this correct?
Yes. You have diminished air flow because of this, how diminished would depend on the blower output design... the more open the output of the blower, the less the effect would be.
I would agree with you, except that the blower housing is symmetrical, typically u-shaped from the side view, but rectangular at the top interface with the inlet. So there are no indications from the housing design that air blowing cw or ccw would make any differences as long as it passes upward over the heat tubes.
What do you think?
If your description is accurate, then I tend to agree with you. If blower housing design doesn't dictate the air flow direction, you are correct. Duly noted.
My take is the replacement blower has less blower blade surface area and so it is not "paddling" as much CFM as the original.
Thanks anyway. I'm always open to ideas.
That's probably accurate. And if the blower wheel doesn't fill the opening completely, there is an issue with turbulance at the edges of the wheel.
The blower wheel is the same width as the original, but the diameter is 1/2" larger. I couldn't find an exact universal fit.
I would be very careful of replacing blower motor with a higher RPM motor,, the fast it blows the cooler the needed air will be by the time it gets to your living areaQuote:
Originally Posted by Red-z
It was deliberate. The air was too hot at the register. I've replace the motor and it's now ranging between 100-120 F.
But I will have to see how it performs at the coldest day in January.
Thanks for the thought.
I would be most concerned about the life span of the blower motor. If the blower motor is not sized to the blower wheel you can cause the motor to over amp which can lead to failure.
The blower wheel is rated to 1750 rpm and the motor is running 1625. The 1625 rpm motor amp is 5.4. The 1075 rpm motor is 7.4 amps.
I do have a question for everybody between an old blower wheel and a new one: If the blower wheel diameter and width is the same, the number of blades the same, the rotation the same, and the motor shaft is long enough to mount the blower wheel, what difference would there be if the new blower wheel has a convex hub if the original has a concave hub?
Quote:
Originally Posted by Red-z
Every blower wheel has a rate of transfer. This rate is based upon testing by the manufacturer at various speeds in various style housings. One wheel can have many listed rates of air movement and safe speeds depending upon the load imposed by the cage it is placed in. Cage manufactures if different from the blower wheel manufacturers will also post this type of information or have it available for end users like major equipment manufacturer and there engineers. In order to find that information you will need to contact the manufacturer of the wheel/cage combination or visit there website if a website is available.
Engineers design equipment for a specific purpose and with specific goals in mind. Any modifications especially with HVAC equipment usually end in disaster by reducing the life of the equipment or creating a hazard. Heat exchangers are especially prone to damage as we have proven in our testing at the university. Manufactures have us test the equipment for failures under stress. Usually there is a 15 to 25% safety margin built into equipment till damage starts to occur. If for example a heat exchanger is taxed at 125% of its rated value for 5 minutes with 5 minutes cool down time no damage may occur but is taxed 15 times at this value some damage is noticeable (usually warping out of spec.) If the initial testing is at 125% for a 15 minute cycle at 15 times for this value the damage becomes much more severe and this goes on and on testing wise till total failure. This way if some idiot decides to modify there equipment to over fire for example they can cover there boxer shorts in a court of law. Even if the unit is returned to all stock parts before the investigation a
metallurgist can tell the values at the time of failure so there can be no coverup. Modern science is a wonderful thing and matching that with computers just makes it awesome.
It is a dangerous game we sometime play and in many respects just plain stupid since common sense tells us better. I try to follow the Do NO Harm policy. Try to repair as best as possible but Do NO Harm to the equipment that could cost human life.
The John Wayne attitude towards repair can be dangerous.
Actually there is no difference in air flow, all else being equal. Concave positions the hub closer to the motor. Convex positions the hub further from the motor.
That's it.
Thanks for your help.
hvac1000:
Why didn't you just say "I don't know". We're not addressing heat transfer gradients across the heating tubes, nor harmonic frequencies of blower wheel blades. This IS common sense.
I think you're twisted in your shorts again.
Since you are such a professional on air flow why did you ask the question to start with. In all your posts which started with blower running backwards till now you were the one with the cocky answers not me.
Example
I wouldn't be surprised if the rear wheels on my car were running backwards, too. I'll see if the supplier shipped me a CW instead of a CCW blower wheel.
To help you all I mentioned was the possibility of the unit running in reverse. Looks like that upset you because you could not figure out the problem yourself.
Example
You were right about something being backwards.
Looks like I helped you there. But that first cocky answer was a tip off to me exactly what type of personallity you have.
Example
I reversed the rotation on the electric motor to coincide with the wrong wheel, and its working much better.
I also mentioned that possibility in my post back to you.
It continues on and on with you asking questions and getting the best answers possible but you do not want to hear the truth all you want to hear is people agreeing with you and the methods you are using to modify your furnace.
If you are unhappy that is a shame. If you do not want to listen to the many helpers we have on this board that is OK in my book also. The John Wayne attitude you show towards the correct answers you have been given is a prime example of a person who always has to have his own way and that is probably how you try and run your life. That is just wonderful also but my last message to you was meant to make you think about what you are doing or have already done to your furnace. If the furnace was working correctly you would not have posted here to start with.
Good luck with your furnace since I believe you will need it when the real cold weather hits.
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