"Mark" wrote in message
oups.com...
modelman wrote:
Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. It is well known that PWM systems generate strong
harmonics throughout the radio spectrum, resulting in radio
interference. However, properly designed PWM systems include filtering
and shielding to suppress the radio frequency currents from the wiring.

I contacted my installer, who is totally unfamiliar with the problem.
The electrician who was sent to my house to investigate the problem
also doesn't understand what's going on. I had to explain the
difference between an RF ground and dc or house ground to him.
Although everything appears to be well grounded from a dc perspective,
I suspect that portions of the system are radiating RF energy.

Several days ago I emailed Trane about the problem, but haven't
received any response.

Although there has been past discussion in this group about radio/TV
interference emanating from Trane high efficiency gas furnaces, I
haven't seen any definitive fix. Does anyone know if Trane has a fix
for this problem. Do they have a shielded cable and or rf filter kit
to suppress this noise? Since my system is under warranty, I won't
attempt any modiifcations to the system.

Has anyone experienced this problem?

Thanks.


Trane should be made to fix this and recall all the units that have
been installed. I can pick this interference up on a 2 meter receiver
in my car for blocks. The FCC should bust them if they don't fix it...

I cross posted this to some of the amateur radio groups.

Mark

with the punce gotcha do u hav anyting cognet two say?



--
Posted via a free Usenet account from http://www.teranews.com

Interesting discussion, folks....

As a controls engineer and High-Voltage electrician.... as well as
delving into HVAC control of late... here's my observations...

These manufacturers will always take the cheapest route possible and
damn the consequences. This is particularly true in power and control
systems.

A whole lot of manufacturers are moving toward PWM drives on their
blowers in particular. Many solutions are an 'on-board' frequency
chopper that is integral with the blower's motor.

These choppers are cheaply built and cheaply engineered. I suppose they
thought RFI and EMI would be insignificant due to the control being
mounted on the motor... but they're noisy as hell.

Suggestions: Replace the power cables with a shielded, VFD rated cable.
Belden makes a wide variety... I think they're called the VFD classic
line. Pay close attention the unit and cable grounding. Check to be
certain your house ground and neutral connections are only tied together
at the service entrance panel of your home.

My 2 cents...

Jake

"Jake" wrote in message
news:xB85h.54$xD.43@trndny08...
Interesting discussion, folks....

As a controls engineer and High-Voltage electrician.... as well as delving
into HVAC control of late... here's my observations...

These manufacturers will always take the cheapest route possible and damn
the consequences. This is particularly true in power and control systems.

A whole lot of manufacturers are moving toward PWM drives on their blowers
in particular. Many solutions are an 'on-board' frequency chopper that is
integral with the blower's motor.

These choppers are cheaply built and cheaply engineered. I suppose they
thought RFI and EMI would be insignificant due to the control being
mounted on the motor... but they're noisy as hell.

Suggestions: Replace the power cables with a shielded, VFD rated cable.
Belden makes a wide variety... I think they're called the VFD classic
line. Pay close attention the unit and cable grounding. Check to be
certain your house ground and neutral connections are only tied together
at the service entrance panel of your home.

My 2 cents...

Jake

As Jake said.... with the addition of....
Make sure that you have proper earth grounds for your power, and the HAM
rigs/shack. That will go a long way towards eliminating RFI. Make sure that
all the bonding screws in the furnace are clean and tight, make sure that
the furnace has a proper ground also.
When I put the shack together, I drove a seperate 8ft copper ground rod, and
silver brazed #6 solid copper to it, then silver brazed the wire to the
copper ground buss on the back of the bench. All equipment grounded.....no
problem.

de n6ojn

"clifto" wrote in message
...
MLD wrote:
Nice thought, but I went a bit down that road--I'm fuzzy about the
specific
details but for one reason or another the people that I spoke to didn't
give
me anything positive. Something about the generation of RF interference
not
applying to a product like a furnace.

Anything that generates RF inside the USA is regulated by the FCC. If your
cat's butt emits RF in the USA it's regulated by the FCC.

Wrong. If the cat's butt emits RF, it's regulated by the FCC. But, digital
equipment used only in transportation vehicles - busses, cars, aircraft -
and equipment used in appliances - HVAC equipment mentioned specifically -
are exempt from Radio Frequency Device regulations. The rule says "....are
exempt from the specific technical standards and other requirements
contained in this part. The operator of the exempted device shall be
required to stop operating the device upon a finding by the Commission or
its representative that the device is causing harmful interference".

As to harmful interference, just because the noise floor rises 20db for 5
seconds on a 50 kHz segment of 20 meters when a bus passes your house, it
isn't going to be considered harmful interference. As much as you might like
to think that it is, a detectable signal from your neighbors Air Conditioner
isn't going to be considered "harmful interference". A carrier that
obliterates a specific, used - as in "there's a repeater 3 miles away
running 200 watts on 444.600, and the carrier from the Carrier (or Trane)
nukes it" - frequency might result in a letter. Just " 'cause you can hear
it" ain't gonna cut it.




47CFR15.103

Hi again Mark,

I think Jake is on the right track, whatever the source of noise inside the
unit its the mechanism that radiates the noise that needs to be attended to.
In my case it was the external cables, choking them off with ferrite sorted
out my problem. To suppress the noise at source within the unit seems a bit
hard for me. I also suspect there may be more than one noise source in the
box.

73 Alan VK6BN


"Mark" wrote
Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM

Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

/s/ DD, W1MCE

Mark


Mark:

A quick check of the web turned up a site with posts dealing with the
same problem you are experiencing, it seems someone was able to make
some noticeable improvements in the rf interference generated--but not
totally eliminate... Just might be worth you time time to look, the
link I will paste is a long one, if it wraps you may have to copy and
paste both lines into the address bar of your browser and make sure
there have been no breaks, spaces, caused the whole link. Hope this
helps...

http://groups.google.com/group/alt.h...eb8ab594ac0781

Regards,
JS

Alan Taylor wrote:

Hi again Mark,

I think Jake is on the right track, whatever the source of noise inside the
unit its the mechanism that radiates the noise that needs to be attended to.
In my case it was the external cables, choking them off with ferrite sorted
out my problem. To suppress the noise at source within the unit seems a bit
hard for me. I also suspect there may be more than one noise source in the
box.

73 Alan VK6BN


"Mark" wrote

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM



Hi,
Then, shielding, choking, bypassing with caps come to mind. It's all by
trial and error. O'scope may come in handy.

Yes, the FCC not only has cognizance, but quite legitimately does not want
to see products throwing a lot of EMI out which cause you and perhaps your
neighbors to have reception issues. If I were at Trane handling Customer
Service and was threatened with FCC action, I would react.

Smarty


"clifto" wrote in message
...
MLD wrote:
Nice thought, but I went a bit down that road--I'm fuzzy about the
specific
details but for one reason or another the people that I spoke to didn't
give
me anything positive. Something about the generation of RF interference
not
applying to a product like a furnace.

Anything that generates RF inside the USA is regulated by the FCC. If your
cat's butt emits RF in the USA it's regulated by the FCC.

--
"A man's country is not a certain area of land, of mountains, rivers, and
woods, but it is a principle; and patriotism is loyalty to that
principle."
-- George William Curtis

Hi,
Then, shielding, choking, bypassing with caps come to mind. It's all by
trial and error. O'scope may come in handy.

Well that's my concern.
There are more and more of these kinds of units being installed
everyday.
We can't "home brew" a fix for all of them.
Someone needs to get to the FCC or to the manufacterer to fix this at
the source before it gets worse.

Mark

Noon-Air wrote:

SNIPPED

As Jake said.... with the addition of....
Make sure that you have proper earth grounds for your power, and the HAM
rigs/shack. That will go a long way towards eliminating RFI. Make sure that
all the bonding screws in the furnace are clean and tight, make sure that
the furnace has a proper ground also.
When I put the shack together, I drove a seperate 8ft copper ground rod, and
silver brazed #6 solid copper to it, then silver brazed the wire to the
copper ground buss on the back of the bench. All equipment grounded.....no
problem.

de n6ojn



As you describe your setup it does meet USA National Electrical Code. Your home
should have ONLY one earth connection, not two!

As you describe it, your house presumably has the electrical service panel
grounded to an 8 feet long ground rod where the service enters the house. You
seem to have added a second 8 feet ground rod to your home specifically for the
Ham station.

Check with a local electrician for specific compliance issues.

/s/ DD