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Question:

Well, I spent most of the day waiting for a furnace repair.  High of 19F in Baltimore today.  Brrrrr.  It was 56F in the house this morning.  So the repair guy shows finally at 4:30.  The igniter had cracked, rendering it useless.  An easy repair and I got the last one on the truck. We chat while he works.  Turns out there is a flame rectifier in the unit. The flame heats a metal rod, which rectifies the A/C current going through it.  That sends a DC signal to the control board to let it know the unit is hot and working properly.  I thought it was pretty nifty. Ready to try one of those in yer next homebrew? Phil

Response:

Hi, Yup, it’s called HSI(hot surface ignitor) which is nothing but heating element made of Si composite driven by 120V AC. Seems like they burn out or crack rendering useless every ~5 years. When flame is established, the flame sensor senses it and all is well until set temp. is reached then fan stops running by settable delay(30 sec to 1.5 mins). The flame sensor needs light rubbing with emery cloth to clean off the dust/rust build up. Otherwise it can get sluggish. Usually control module has LED which gives off error code when something is not right. You count the number of LED blinking to get the code. Glad your furnace is back in business. My house has two gas fire places, one wall mount heat exchanger(mainly used as A/C in summer) as back up. Came from visits to SPCA, no suitable dog this time. Going back tomorrow after noon after noon mass. Tony – Hide quoted text — Show quoted text – > Well, I spent most of the day waiting for a furnace repair.  High of 19F in > Baltimore today.  Brrrrr.  It was 56F in the house this morning.  So the > repair guy shows finally at 4:30.  The igniter had cracked, rendering it > useless.  An easy repair and I got the last one on the truck. > We chat while he works.  Turns out there is a flame rectifier in the unit. > The flame heats a metal rod, which rectifies the A/C current going through > it.  That sends a DC signal to the control board to let it know the unit is > hot and working properly.  I thought it was pretty nifty. > Ready to try one of those in yer next homebrew? > Phil

Response:

> > We chat while he works.  Turns out there is a flame rectifier in the unit. > The flame heats a metal rod, which rectifies the A/C current going through > it.  That sends a DC signal to the control board to let it know the unit is > hot and working properly.  I thought it was pretty nifty. > Ready to try one of those in yer next homebrew?

I was going to say Mesa might try one in their next model (Quadruple Rectifier!?!), but after hanging in AGA for a few years, I’d wonder if it might be more appropriate in a Crate. Ooooh, am I gonna get *flamed* for this! Steve

Response:

Tony:

> Hi, > Yup, it’s called HSI(hot surface ignitor) which is nothing but heating > element made of Si composite driven by 120V AC. Seems like they burn out > or crack rendering useless every ~5 years.

It glows red and ignites the gas.  Quite a sight when you realize what you are looking at.  Looks like it’s made of material similar to the heating element in an electric oven. > When flame is established, the flame sensor senses it and all is well > until set temp. is reached then fan stops running by settable delay(30 > sec to 1.5 mins). The flame sensor needs light rubbing with emery cloth > to clean off the dust/rust build up. Otherwise it can get sluggish.

I watched the service guy do this to the flame sensor, so it’s good to know he knows his stuff. > Usually control module has LED which gives off error code when something > is not right. You count the number of LED blinking to get the code. > Glad your furnace is back in business.

Me, too!  And my family, too.  My house has two gas fire places, > one wall mount heat exchanger(mainly used as A/C in summer) as back up.

You live much further north.  Multiple heat sources make more sense. > Came from visits to SPCA, no suitable dog this time. Going back tomorrow > after noon after noon mass. > Tony

Animal shelters are hit and miss.  Eventually you’ll find a dog you like. Good luck. Phil – Hide quoted text — Show quoted text -> Well, I spent most of the day waiting for a furnace repair.  High of 19F in > Baltimore today.  Brrrrr.  It was 56F in the house this morning.  So the > repair guy shows finally at 4:30.  The igniter had cracked, rendering it > useless.  An easy repair and I got the last one on the truck. > We chat while he works.  Turns out there is a flame rectifier in the unit. > The flame heats a metal rod, which rectifies the A/C current going through > it.  That sends a DC signal to the control board to let it know the unit is > hot and working properly.  I thought it was pretty nifty. > Ready to try one of those in yer next homebrew? > Phil

Response:

>We chat while he works.  Turns out there is a flame rectifier in the unit. >The flame heats a metal rod, which rectifies the A/C current going through >it.  That sends a DC signal to the control board to let it know the unit >is >hot and working properly.  I thought it was pretty nifty.

Yeah, flame rectification is a neat trick. We’ve got it on our gas range, GE calls it "automatic pilotless ignition".  It sparks when you turn on the gas, the knob doesn’t need a "light" position, just turn it on however you like. Once the flame ignites, a small AC charge is recitifed and the ignition module senses the current flow and then turns out the spark. If the flame blows it, it starts sparking again all by itself. The downside is it isn’t perfectly reliable – a small flame or dirt on the tip of the electrode will cause it to fail to sense the flame sometimes. But it is a good idea and prevents a gas build up in the event of a flame-out condition. The physics of it are pretty interesting. Google up flame rectification effect for more discussion. I had to figure all this out when we bought the house and the range wouldn’t stop sparking. Had to change the module out – not cheap at about $100. — Dr. Nuketopia Sorry, no e-Mail. Spam forgeries have resulted in thousands of faked bounces to my address.

Response:

Tony this doesn’t have anything to do with HSI.  It’s just the flame sensor and is used with both direct spark & HSI.  Both may be operated by a variety of controllers from several mfg’s and their delays & etc. are also a whole ‘nother.  A flame sensor rod should never be cleaned with emery cloth and particles or light fouling have no effect on it. It just gets brushed or washed off.  FWIW the HSI unit you’ve confused it with is delicate though, and easily ruined if anything touches it during removal/replacement.  HSI can be particularly problematic in condensing-type (highly efficient) gas boilers (mine), for any moisture also wrecks it.  Good ol’ direct spark.  Easy to adjust. BZzzzzttt….FOOoooof. – Hide quoted text — Show quoted text – > Hi, > Yup, it’s called HSI(hot surface ignitor) which is nothing but heating > element made of Si composite driven by 120V AC. Seems like they burn out > or crack rendering useless every ~5 years. > When flame is established, the flame sensor senses it and all is well > until set temp. is reached then fan stops running by settable delay(30 > sec to 1.5 mins). The flame sensor needs light rubbing with emery cloth > to clean off the dust/rust build up. Otherwise it can get sluggish. > Usually control module has LED which gives off error code when something > is not right. You count the number of LED blinking to get the code. > Glad your furnace is back in business. My house has two gas fire places, > one wall mount heat exchanger(mainly used as A/C in summer) as back up. > Came from visits to SPCA, no suitable dog this time. Going back tomorrow > after noon after noon mass. > Tony > Well, I spent most of the day waiting for a furnace repair.  High of 19F in > Baltimore today.  Brrrrr.  It was 56F in the house this morning.  So the > repair guy shows finally at 4:30.  The igniter had cracked, rendering it > useless.  An easy repair and I got the last one on the truck. > We chat while he works.  Turns out there is a flame rectifier in the unit. > The flame heats a metal rod, which rectifies the A/C current going through > it.  That sends a DC signal to the control board to let it know the unit is > hot and working properly.  I thought it was pretty nifty. > Ready to try one of those in yer next homebrew? > Phil

Response:

- Hide quoted text — Show quoted text – > Tony this doesn’t have anything to do with HSI.  It’s just the flame > sensor and is used with both direct spark & HSI.  Both may be operated > by a variety of controllers from several mfg’s and their delays & etc. > are also a whole ‘nother.  A flame sensor rod should never be cleaned > with emery cloth and particles or light fouling have no effect on it. > It just gets brushed or washed off.  FWIW the HSI unit you’ve confused > it with is delicate though, and easily ruined if anything touches it > during removal/replacement.  HSI can be particularly problematic in > condensing-type (highly efficient) gas boilers (mine), for any > moisture also wrecks it.  Good ol’ direct spark.  Easy to adjust. > BZzzzzttt….FOOoooof. >Hi, >Yup, it’s called HSI(hot surface ignitor) which is nothing but heating >element made of Si composite driven by 120V AC. Seems like they burn out >or crack rendering useless every ~5 years. >When flame is established, the flame sensor senses it and all is well >until set temp. is reached then fan stops running by settable delay(30 >sec to 1.5 mins). The flame sensor needs light rubbing with emery cloth >to clean off the dust/rust build up. Otherwise it can get sluggish. >Usually control module has LED which gives off error code when something >is not right. You count the number of LED blinking to get the code. >Glad your furnace is back in business. My house has two gas fire places, >one wall mount heat exchanger(mainly used as A/C in summer) as back up. >Came from visits to SPCA, no suitable dog this time. Going back tomorrow >after noon after noon mass. >Tony

Hi, Even in owner’s manual mentions about cleaning flame sensor. I worked for Honeywell for ~30 years but learned a lot over the shoulder. I belonged to Systems division. Not controls. Most serevice techs, first thing they do is rubbing it with fine sand paper. I use emery cloth. HVAC control circuit is not much complicated sequential logic. Tony

Response:

> Tony this doesn’t have anything to do with HSI.  It’s just the flame > sensor and is used with both direct spark & HSI.  Both may be operated > by a variety of controllers from several mfg’s and their delays & etc. > are also a whole ‘nother.  A flame sensor rod should never be cleaned > with emery cloth and particles or light fouling have no effect on it. > It just gets brushed or washed off.  FWIW the HSI unit you’ve confused > it with is delicate though, and easily ruined if anything touches it > during removal/replacement.  HSI can be particularly problematic in > condensing-type (highly efficient) gas boilers (mine), for any > moisture also wrecks it.  Good ol’ direct spark.  Easy to adjust. > BZzzzzttt….FOOoooof.

– Hide quoted text — Show quoted text ->>Hi, >>Yup, it’s called HSI(hot surface ignitor) which is nothing but heating >>element made of Si composite driven by 120V AC. Seems like they burn out >>or crack rendering useless every ~5 years. >>When flame is established, the flame sensor senses it and all is well >>until set temp. is reached then fan stops running by settable delay(30 >>sec to 1.5 mins). The flame sensor needs light rubbing with emery cloth >>to clean off the dust/rust build up. Otherwise it can get sluggish. >>Usually control module has LED which gives off error code when something >>is not right. You count the number of LED blinking to get the code. >>Glad your furnace is back in business. My house has two gas fire places, >>one wall mount heat exchanger(mainly used as A/C in summer) as back up. >>Came from visits to SPCA, no suitable dog this time. Going back tomorrow >>after noon after noon mass. >>Tony > Hi, > Even in owner’s manual mentions about cleaning flame sensor. > I worked for Honeywell for ~30 years but learned a lot over the shoulder. > I belonged to Systems division. Not controls. > Most serevice techs, first thing they do is rubbing it with fine > sand paper. I use emery cloth. > HVAC control circuit is not much complicated sequential logic. > Tony

I dunno.  I’ve got a Carrier Weathermaker 8000 furnace.  The service guy cleaned the recitifier sensor with something.  I wasn’t looking at what he used, but it sounded mildly abrasive.  He sure looked like he knew what to do and he handled the thing very carefully..  Anyhow, furnace is working well now.  It was a balmy 37F today and the dog got a walk without her sweater..  Maybe the heat bill will go down some. Phil

Response:

> I dunno.  I’ve got a Carrier Weathermaker 8000 furnace.  The service guy > cleaned the recitifier sensor with something.  I wasn’t looking at what he > used, but it sounded mildly abrasive.  He sure looked like he knew what to > do and he handled the thing very carefully..  Anyhow, furnace is working > well now.  It was a balmy 37F today and the dog got a walk without her > sweater..  Maybe the heat bill will go down some. > Phil

Hi, Phil Identical one here in my house. One burnt out HSI is the only problem I had since it was installed new in my house when it was built in ‘94. It heats 3000 SF two story w/o any problem. My house is air tight R2000 spec. one. Cooling in summer(SHORT season) is done by a heat exchanger in the sun room. We’re getting out of the cold snap as well. By week end, it’ll be just over freezing mark. Tony

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