Furnace RF Noise
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I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level. Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject.
John K7JLT John K7JLT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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John, beware of any furnaces (or ACs) with variable speed motors. Some are RF quiet; some are not. There are three potential sources of RF leakage I have personally experienced:
1) Variable speed inducer motor - this is a small motor used on higher efficiency furnaces to provide draft air to the combustion changer. Some manufacturers have a kit that MAY reduce or eliminate the noise from this motor. 2) Variable speed blower motor - this is the large motor used to move air through the heat exchanger and into the duct system. I have a 3/4 HP variable speed motor in one system that is dead quiet; I also have a 1 HP version of the same motor from the same motor manufacturer in another system that is very noisy. The engineer that designed the motor confirmed that in the 1HP version it was difficult to manage RFI emissions. 3) Variable speed condenser fan motor - this is the motor on the outside compressor/condenser unit. Some manufacturers use a variable speed motor running at a fixed speed for this application. The one I have is very noisy. --- Chuck, AE4CW -----Original Message----- From: John K7JLT [mailto:[hidden email]] Sent: Saturday, February 27, 2016 18:03 To: Mailman <[hidden email]> Subject: [Elecraft] Furnace RF Noise I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level. Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject. John K7JLT John K7JLT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email]
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Chuck, AE4CW |
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Carrier air conditioning offers an add on filter IF the consumer complains.
The same may hold true for other appliance mfger's. Why not just purchase a 20 amp Corcom metal can filter and install it with the furnace. I soldered the metal can of the filter to the inside of the metal furnace housing. Jim W6AIM -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Chuck Catledge Sent: Sunday, February 28, 2016 12:05 PM To: 'John K7JLT'; 'Mailman' Subject: Re: [Elecraft] Furnace RF Noise John, beware of any furnaces (or ACs) with variable speed motors. Some are RF quiet; some are not. There are three potential sources of RF leakage I have personally experienced: 1) Variable speed inducer motor - this is a small motor used on higher efficiency furnaces to provide draft air to the combustion changer. Some manufacturers have a kit that MAY reduce or eliminate the noise from this motor. 2) Variable speed blower motor - this is the large motor used to move air through the heat exchanger and into the duct system. I have a 3/4 HP variable speed motor in one system that is dead quiet; I also have a 1 HP version of the same motor from the same motor manufacturer in another system that is very noisy. The engineer that designed the motor confirmed that in the 1HP version it was difficult to manage RFI emissions. 3) Variable speed condenser fan motor - this is the motor on the outside compressor/condenser unit. Some manufacturers use a variable speed motor running at a fixed speed for this application. The one I have is very noisy. --- Chuck, AE4CW -----Original Message----- From: John K7JLT [mailto:[hidden email]] Sent: Saturday, February 27, 2016 18:03 To: Mailman <[hidden email]> Subject: [Elecraft] Furnace RF Noise I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level. Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject. John K7JLT John K7JLT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Jim,
The Corcom line filter may help (it did help "some" on my blower motor but did virtually nothing for the condenser fan motor), but it does nothing to prevent RF energy from escaping via the multiple control and sensor lines that exit a typical furnace enclosure. To prove that, I removed every control and sensor line from the furnace enclosure and "hot-wired" the internal control board to run the blower at full speed. Thus isolated, the RFI from the blower motor was completely contained and not visible on the spectrum display nor audible on the radio. So, the solution is that EVERY wire that exits the furnace enclosure must by filtered or bypassed. Since all these lines carry low-voltage DC, a simple bypass capacitor on each line will work. --- Chuck, AE4CW -----Original Message----- From: Jim Bolit [mailto:[hidden email]] Sent: Monday, February 29, 2016 10:28 To: 'Chuck Catledge' <[hidden email]>; 'John K7JLT' <[hidden email]>; 'Mailman' <[hidden email]> Subject: RE: [Elecraft] Furnace RF Noise Carrier air conditioning offers an add on filter IF the consumer complains. The same may hold true for other appliance mfger's. Why not just purchase a 20 amp Corcom metal can filter and install it with the furnace. I soldered the metal can of the filter to the inside of the metal furnace housing. Jim W6AIM -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Chuck Catledge Sent: Sunday, February 28, 2016 12:05 PM To: 'John K7JLT'; 'Mailman' Subject: Re: [Elecraft] Furnace RF Noise John, beware of any furnaces (or ACs) with variable speed motors. Some are RF quiet; some are not. There are three potential sources of RF leakage I have personally experienced: 1) Variable speed inducer motor - this is a small motor used on higher efficiency furnaces to provide draft air to the combustion changer. Some manufacturers have a kit that MAY reduce or eliminate the noise from this motor. 2) Variable speed blower motor - this is the large motor used to move air through the heat exchanger and into the duct system. I have a 3/4 HP variable speed motor in one system that is dead quiet; I also have a 1 HP version of the same motor from the same motor manufacturer in another system that is very noisy. The engineer that designed the motor confirmed that in the 1HP version it was difficult to manage RFI emissions. 3) Variable speed condenser fan motor - this is the motor on the outside compressor/condenser unit. Some manufacturers use a variable speed motor running at a fixed speed for this application. The one I have is very noisy. --- Chuck, AE4CW -----Original Message----- From: John K7JLT [mailto:[hidden email]] Sent: Saturday, February 27, 2016 18:03 To: Mailman <[hidden email]> Subject: [Elecraft] Furnace RF Noise I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level. Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject. John K7JLT John K7JLT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email]
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Chuck, AE4CW |
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Chuck,
Excellent point! My design team in the Philippines did a variable speed power supply (4-6 kW range) where we also had to design a simple common and differential mode AC filter that was an available option if any "ham guys" (it was referred to as the "ham guys" filter in our communications with the customer) raised a noise issue with the power supply. I only dealt with the power supply and not the full system during the design process, but there were a number of communications as it related to system radiated emi. Jim W6AIM . -----Original Message----- From: Chuck Catledge [mailto:[hidden email]] Sent: Monday, February 29, 2016 8:22 AM To: 'Jim Bolit'; 'John K7JLT'; 'Mailman' Subject: RE: [Elecraft] Furnace RF Noise Jim, The Corcom line filter may help (it did help "some" on my blower motor but did virtually nothing for the condenser fan motor), but it does nothing to prevent RF energy from escaping via the multiple control and sensor lines that exit a typical furnace enclosure. To prove that, I removed every control and sensor line from the furnace enclosure and "hot-wired" the internal control board to run the blower at full speed. Thus isolated, the RFI from the blower motor was completely contained and not visible on the spectrum display nor audible on the radio. So, the solution is that EVERY wire that exits the furnace enclosure must by filtered or bypassed. Since all these lines carry low-voltage DC, a simple bypass capacitor on each line will work. --- Chuck, AE4CW -----Original Message----- From: Jim Bolit [mailto:[hidden email]] Sent: Monday, February 29, 2016 10:28 To: 'Chuck Catledge' <[hidden email]>; 'John K7JLT' <[hidden email]>; 'Mailman' <[hidden email]> Subject: RE: [Elecraft] Furnace RF Noise Carrier air conditioning offers an add on filter IF the consumer complains. The same may hold true for other appliance mfger's. Why not just purchase a 20 amp Corcom metal can filter and install it with the furnace. I soldered the metal can of the filter to the inside of the metal furnace housing. Jim W6AIM -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Chuck Catledge Sent: Sunday, February 28, 2016 12:05 PM To: 'John K7JLT'; 'Mailman' Subject: Re: [Elecraft] Furnace RF Noise John, beware of any furnaces (or ACs) with variable speed motors. Some are RF quiet; some are not. There are three potential sources of RF leakage I have personally experienced: 1) Variable speed inducer motor - this is a small motor used on higher efficiency furnaces to provide draft air to the combustion changer. Some manufacturers have a kit that MAY reduce or eliminate the noise from this motor. 2) Variable speed blower motor - this is the large motor used to move air through the heat exchanger and into the duct system. I have a 3/4 HP variable speed motor in one system that is dead quiet; I also have a 1 HP version of the same motor from the same motor manufacturer in another system that is very noisy. The engineer that designed the motor confirmed that in the 1HP version it was difficult to manage RFI emissions. 3) Variable speed condenser fan motor - this is the motor on the outside compressor/condenser unit. Some manufacturers use a variable speed motor running at a fixed speed for this application. The one I have is very noisy. --- Chuck, AE4CW -----Original Message----- From: John K7JLT [mailto:[hidden email]] Sent: Saturday, February 27, 2016 18:03 To: Mailman <[hidden email]> Subject: [Elecraft] Furnace RF Noise I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level. Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject. John K7JLT John K7JLT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Chuck - AE4CW
I completely eliminated blower noise from my new Bryant furnace with type 31 snap on ferrite beads on the control lines. Two 1/2 inch beads on each line with 3 turns through each bead as close to the cabinet exit as possible. Took the noise from S7 to my usual -125 dBm band noise level. No need for a line filter.
73, Brian, K0DTJ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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On Mon,2/29/2016 2:29 PM, Brian Hunt wrote:
> I completely eliminated blower noise from my new Bryant furnace with type 31 snap on ferrite beads on the control lines. Two 1/2 inch beads on each line with 3 turns through each bead as close to the cabinet exit as possible. Took the noise from S7 to my usual -125 dBm band noise level. No need for a line filter. Remember that the number of turns required will depend on the frequency(ies) where there is RFI. 3 turns peaks more or less around 10M. If you have noise below that, you'll want more turns (a lot more for the lower bands like 80 and 40). 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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