Stop second stage from kicking in, noisy

[caslon]

I have a 886 sq. ft condo and live in So. California. 2 years ago I had a Carrier Performance series furnace installed, hallway closet. It's a 2 stage furnace. For the life of me, I cannot prevent the second stage kicking in during the last few minutes. I hate the way the second stage kicks in. It sounds like a freaking jet engine. I've fiddled with the thermostat to extend the interval between first and second stages so that the second stage won't kick in. It still does.

Look, I live in So. California. My small 2 BR. (one floor) condo heats up quickly.
I don't need and don't want that second stage to kick in. I don't care if it does it to be more economical.

My old thermostat was replaced back then (vintage 1986). It had just 2 or 3 wires (if I recall). I'm wondering if the new thermostats need an additional wire in order to have full functionality, maybe not.

Can I have a tech come in and change jumpers on the furnace to force the unit not to kick into the second stage? It's kind of ridiculous now, because the second stage only kicks in during the last 5 minutes anyways, and is very loud.

[HVAC dawg]

You should probably have a service call and speak directly with a tech regarding this.It probably won't $ too much and he might be able do it from the T -stat depending on what type of T-stat you are using.Your Efficient Equipment is meant to be, whether you care or not. You just don't tell it not to do what it should.DYU:troll2:

[caslon]

I read the t-stat manual and set the interval time between the first stage and when the second stage should kick in. I set it high enough a time that the second stage should not have kicked on.

[beenthere]

A good tech can take care of that for you, very easily.

[flange]

logic in the board sometimes can bypass the thermostat, and call for second stage after a time period or other reason. i know what I would do Let a tech on site take care of it.

[caslon]

logic in the board sometimes can bypass the thermostat, and call for second stage after a time period or other reason. i know what I would do Let a tech on site take care of it.

Ya,well great. A tech will come in with limited knowledge, say it can't be helped (to cover for his vast knowledge) and leave with my 45 bucks.

One has.

The idea that units board will override the thermostat setting makes the most sense to me so far.

This is the kind of problem techs don't like to deal with (seems to me). Their whole attitude thru the door is one of "leave it alone, it's meant to be that way". TRANSLATION: "I don't want to hassle with it". Pay me now.

And yes, the furnace is about 5 feet from my living room, and it really does make a roaring sound when the second stage kicks in. I'm not being fussy.

[BaldLoonie]

Could be already on a friggin' timer and coming on when not needed. If it were on a 2 stage stat, it sure wouldn't be coming on at the end of the cycle. '

A good tech can make it a single stage furnace firing only on low. I have a switch on mine to keep high off unless I want it. That's the trouble with oversizing a furnace :(

[SJProwler]

OP already stated it's on a 2 stage stat. Sounds like maybe it's optioned for timed staging instead of the 2 stage stat.

[caslon]

The t-stat is a Venstar T1900. I read the manual and believe I set it right to have the second stage not fire up. So, I'm thinking the unit itself is taking control (as was replied to). I'll have another tech come in, I suppose. I read the schematic of the jumper switches on the unit and don't feel confident myself to start fiddling with those.

I had read the t-stat manual....I set the interval on the t-stat (in minutes) before the second stage is to kick in. I set it way high enough (in minutes) thinking the unit would follow the t-stat settings. It didn't.

[sktn77a]

Do you have the installaton manual for the furnace? These issues should be detailed there - usually a dipswitch setting. Is the noise coming from the supply vents, the return vent, or the blower motor itself? The blower speeds may also be set up incorrectly. Check the installation manual.

[caslon]

It probably is just a dipswitch setting needed. Nothing in the user manual deals with messing with dipswitches on the unit, but I checked out the units dipswitch area and just am not sure how to definitively get the furnace to do what I want (changing dipswitch settings) without possibly messing up things.

The noise is from the actual jets. Whatever, it's like mellow and quiet during 1st stage (which I want continuously) and then it gets louder when it kicks into second stage. The actual gas jet(s) that heat the air kick into overdrive and the unit roars for the last 4 minutes or so. That also makes no sense to me. Kicking into overdrive for just the last few minutes. I set the t-stat to take care of that, so I thought. Wierd.

What pisses me off are that some techs seem reluctant to tackle the problem, whether due to skill or knowledge (more like genuine experience) or what. It's probably not your typical service call. But still...

[flange]

if you were able to figure out how that second stage were getting turned on, you might be able to turn it off. one guy posted he does it with a switch, does that maybe turn on a light for you? I cannot tell you exactly how to so it here, but think about what is written instead of getting upset at paying a fee.

[caslon]

I posted out of frustration that one tech didn't consider that. He basically told me to leave it like it is. $ please.

I posted to see if any here would say it can or can't be changed, before I go spending another $. Does that turn on a light for you?

[beenthere]

Stop using cheap companies.

That won't get a good tech to the door, let alone a good tech to work on your furnace/thermostat.

[Peztoy]

Are you hearing 2nd gas firing up or a higher speed fan? Be sure.

[caslon]

Are you hearing 2nd gas firing up or a higher speed fan? Be sure.

It's not a variable speed unit. The two 4 inch aluminum tublear "jets" get louder, one does anyways.
I don't know much about furnaces, maybe the unit calls for more gas too.

As far as me letting a tech look at it, ya. Who knows who they send out for repairs these days (just saying). Most are good, and this should be an easy one. It's AC/Furnace together.
Me figuring out the t-stat relation to the board dipswitch settings got me confused. The controls on furnaces these days are very efficient. Both jets fire at low, so it might be more complicated than one dipswitch.
There is no 1 dipswitch setting I could see where you just change that and it overrides everything. Maybe it's as simple as that.

Thanks for reading, anyways.

[HVAC dawg]

Are you hearing 2nd gas firing up or a higher speed fan? Be sure.

Agreed:angel:

[caslon]

One speed blower, not variable...except manually.
My t-stat program isn't being implemented by the units default programmed energy efficiency, maybe.

[hvacrmedic]

The furnace is likely still in the factory default "adaptive" mode. This allows it to work with a single stage t-stat, with the control board using algorithms to decide when to stage up or down based upon previous cycles. The maximum duration that low stage can run in adaptive mode is 16 minutes before switching to high stage. The furnace can easily be converted to operate exclusively in low stage by anyone capable of reading and comprehending the installation manual.

[caslon]

OK. Thanks. Makes sense.