Furnace/power

Jim_22

Jim_22

Furnace with generator.

This isn't Steam/Hydronic related but I know someone here has an answer.

We had one hell of an ice storm here in Western New York last Thursday night with approx. 250,000 households losing power. I was out till Saturday afternoon, but with my generator we were fine. (cable still on and able to run TV and computer) As of today (Wednesday) 20,000 still out.
I tried to run my in-laws house with the same generator and thats when the trouble began. (nothing ever goes smoothly at the in-laws:-)
They have two Goodman/Nordyne 100,000 btu, 92+ gas fired residential furnaces, neither of which would run on the generator power. On call for heat, the draft blower would spin up and prove, hot surface igniter glow, and main burner would light, only to drop out instantly. Then the cycle would start again and again but fail to stay lit. When power was eventially restored both ran normally. Generator output is 120 vac, 60 hz, 20 amp. Polarity was correct. In talking to people over the last few days I found others with the same problems. I would like to find a way around this just in case it happens again. We had a similarly devistating ice storm in 1991 where some folks lost power for three weeks. At that time the weather forcasters said this kind of storm only comes about once in 100 years. Twelve years later I guess we should be clear now till 2203.

Any Ideas?

Jim

Unknown

Using the generator

the Furnace controls were probably not seeing a ground circuit. Once the burner lights it must prove its microamps back through a burner ground. Next time try connecting a seperate wire to the gas line from the generator.

Wayne_12

earth ground

The earth ground is missing. but not to the gas line. Drive a seperate grounding rod into the ground following electrical code. Frozen ground, may be able to find a copper/steel water pipe to use temporarily. Once the ground has thawed drive the grounding rod in and devise connections per code to be prepared in the future.

I agree, the hundred year cycles happen more often then every 100 years. We see the hundred year high water mark several times in the recent past.

Wayne_12

follow up, generators should always be grounded to earth grounding any time they are used. Something most users overlook.

Jim_22

Thanks

Thanks Timmie,
That makes sense. I'm going to give that a try so I can be prepared for NEXT time. Winter isn't over yet this year.
Thanks again,
Jim

Unknown

You still need to ground

the generator to the gas line. That is so that the electronics in the furnace can have a "chassis" ground. If you did this even if the earth ground is not connected it will work.

This is not a code violation as the code allows using the gas line for electronic component grounding as long as the voltage is Under 50 volts.

The fact is if you look at most gas valves today you will see some sort of ground symbol or connection on them for grounding. The failure to have a good "chassis" ground is what causes intermittent problems on electronic igntion systems.

When you are troubleshooting with a multimeter the gas valve becomes an excellent place to use for grounding on the 24 volt side of the transformer. Most systems today the "C" terminal on the transformer is chassis grounded. The "R" terminal is 24 volt "Hot" if you will. You should have 24 volts from "R" to ground and "0" volts from "C" to ground.

John Mills_3

OR

check polarity too!

Howard

Don't know much about NEC but...

I'd ground the chassis and the generator to the cold water pipe first. I wouldn't rely on the gas pipe for ground in case of a power fault. my $.02...


Howard Hansen Service Technician Extraordinaire

Unknown

Gas pipe is not

being used for power fault. The post had a problem with gas furnace not staying on, I assume everything elso worked.

The reason for the ground to the gas pipe is to insure that the electric ignition system on the furnace has a "chassis" ground.

The gas line can not be used for ground on 120 volt systems it is a code violation. So by the way is using the copper water pipe.

MURPH'

NEC CODE......

REQUIRES all new main services to be grounded to water line AND gas main with continueous line (no splices) #4 solid copper conducter to each. or you may run seperate lines to each. thats for 200amp could be (and is) larger for commercial (higher) applications !!

Murph'

Unknown

Murph what section of code?

Are you sure it doesn't say that all gas lines and water lines have to be bonded to ground in order to prevent electrical shock.

If it says that gas line is to be used for ground that will really affect the corrosion protection system used by utilities on their underground piping systems. Also the gas line is not a good ground anymore as many of them are plastic.

Mark J Strawcutter

\"bonded to\" vs \"used for\"

what is the difference between being "bonded to" ground and being "used for" ground?

Mark