trane install problem

[in-trane-ing]

installer called me today couldnt get new trane 90% two pipe system to fire. had pressure switch failure. walked him thru a few things and we got it fired by pulling the intake air pipe. dont understand why,both intake and exhaust pipes are new, and each total 70' total length w/90s added into that total. installation manual allows 100'. gonna call trane in the morning but woul like to hear any of your ideas on this
thanks,
scott

[adamhvac]

What size pipe did you use?

[sandpipertech]

That's what she said

[in-trane-ing]

3" pipe. h/o had same problem with old furnace. Called trane and they are stumped, they are coming out to look. Ill let you all know what the verdict is
Thanks

[markco]

Was the pipe stored outside prior to install? It could be plugged from birdnest, or debris, and installers didn't notice an obstrution before they put it in.

[sinsee]

3" pipe. h/o had same problem with old furnace.

Here is a big clue.....I assume you are also using existing pvc flue.

[allstar08]

If the old furnace had the same problem it should make it easy to find. It has to be something in the pipe, or the way it was installed.

[tinmantu]

Make sure the vents are correct, then use a magnhelic gauge to test the pressure switch. With that length of a run, it may be as simple of a fix as a high altitude pressure switch. I live at around 3000 feet and was having a problem with one during a low pressure storm system. Called Trane and they said I was on the border line, they sent out a different one and it worked. Went back a few days later and just for giggles tried the old one after the system moved out and it worked fine.

[kellyr24]

Make sure the vents are correct, then use a magnhelic gauge to test the pressure switch. With that length of a run, it may be as simple of a fix as a high altitude pressure switch. I live at around 3000 feet and was having a problem with one during a low pressure storm system. Called Trane and they said I was on the border line, they sent out a different one and it worked. Went back a few days later and just for giggles tried the old one after the system moved out and it worked fine.

DITTO!

[in-trane-ing]

Was the pipe stored outside prior to install? It could be plugged from birdnest, or debris, and installers didn't notice an obstrution before they put it in.

cut pipe to look for obstructions but found none,
thanks

[in-trane-ing]

Here is a big clue.....I assume you are also using existing pvc flue.

new pipe

[in-trane-ing]

Make sure the vents are correct, then use a magnhelic gauge to test the pressure switch. With that length of a run, it may be as simple of a fix as a high altitude pressure switch. I live at around 3000 feet and was having a problem with one during a low pressure storm system. Called Trane and they said I was on the border line, they sent out a different one and it worked. Went back a few days later and just for giggles tried the old one after the system moved out and it worked fine.

never heard of this but something to look into, but not sure if that is it because when they did get it to fire w/ the pipe on the burners wouldnt like right due to starvation of combustion air. I havent heard if Trane has showed up yet to the job. Ill let you all know when I find out
Thanks again

[KCProTech]

What about running the last third of pipe in 4 inch diamater
How many 90's? Were they long radius?

[fixhvacr]

A short radius elbow is equivalent to 10' of 3" pipe. A long radius is equivalent to 6' of 3" pipe. Do you still come up with your 70'?

[in-trane-ing]

4 long radius 90s figured at 5' each so w/ your formula 74' I have not seen the install yet but im sure im gonna end up w/ this one. Install dept always turns there problems over to service

[docholiday]

Make sure the vents are correct, then use a magnhelic gauge to test the pressure switch.

Absolutely.

I find it hard to believe TRANE is sending a factory guy out without someone at least giving up actual pressure measurements. What is your pressure and what is the switch rated at?

Look, by pulling the fresh air you actually would decrease the negative pull on the furnace's HX, not improve it. However if your vent is restrictive, you may have hit full blower curve on the inducer indicating something is wrong with either a sag, an obstuction, short sweeping ells, or simply too long. You may also be trying to vent into a head wind.

[heatingman]

Many installers today dont look at instructions. I would guess that if all the piping is new, then the problem is how the piping terminates, IE exaust to close to intake, causing reduced pressure differential to satisfy the pressure switch.

[sandpipertech]

Is it possible that on the new installation a screen of some sort was added to the end of the flu pipe. I've had a install crew put a screen on that did not allow enough air to flow out and kept kicking out the pressure switch.

[markco]

Is it possible that on the new installation a screen of some sort was added to the end of the flu pipe. I've had a install crew put a screen on that did not allow enough air to flow out and kept kicking out the pressure switch.

A good point sandpipertech, but if they haven't fixed it by now, theyr'e probably froze to death......this thread is 1 1/2 years old.