Help with Carrier Infinity new system

GiuseppeMNovember 16, 2011

Hi guys, I'm still in the process of building my house and finally the HVAC system is running. This is my setting:

Area 1

Air Conditioner: 24ANA160A003

Evaporator Coil: CNPVP6024

Furnace: 58MVC120F10020

Area 2

Air Conditioner: 24ANA160A003

Evaporator Coil: CNPVP4824

Furnace: 58MVC120F10020


Zoning Interface SYSTXCCUIZ01-B


What's happening is that on a day that the system doesn't call for AC nor heating I've noticed that the indoor humidity level on the thermostat is around 65% even if set to 50%. I've asked the contractor why the system is not dehumidifying and he said it's because I don't have the heating part working yet (these are gas furnaces and I don't have a gas meter yet). Is that correct? I thought the Infinity system had its own advanced dehumidification system, i didn't think it would rely only on reheat.

Second question...the mechanical engineer designed the system that handles the basement and first floor with Return Damper on both supply and return, but now the contractor didn't install the one on the Return. Maybe not having a closed damper in the basement return (when it calls for it, I guess spring and summer are likely) is not a good idea because there wouldn't be recirculating air)

Will the remote sensor in the basement call for dehumidification constantly?

What do you guys think?

I'm attaching the schematic of my systems.

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Do you have two furnaces and two AC condensers? If true, the models numbers show you have 240,000 BTU for heating and 10 tons of cooling. You must have a very big house!

I noticed Area 2 has a 4 ton coil. I don't think this is a correct match with the 5 ton condenser. You should ask the HVAC contractor about this.

The AC must be running in order to dehumidify. The coil must be cold in order to remove moisture from the air. The furnace does no dehumidification. The relative humidity will drop as the temperature rises, but not by 15 percentage points. I am surprised the HVAC contractor could not explain this.

I don't understand why you need dampers on the returns. It is better to have as much return air as possible. Your units are the large and need a lot of return air. It makes no sense to limit it with a damper.

    Bookmark   November 16, 2011 at 8:00PM
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Thanks Mike, I've just noticed the condenser #2 is 24ANA148A003, and the furnace #2 is 58MXB060F10016.

Does this system have a dehumidification system when the thermostat doesn't call for AC? I thought the Infinity line had an advanced dehumidification system.

The comment I made about the return damper is because the unit #1 covers basement and first floor, and the basement has its own controller, I think it would be good to recirculate the air but in the summer the basement is always cooler so I would have the supply damper closed but the return open?

Also I forgot to mention that I have a return in each room and a main return on the main level and one in the basement.

    Bookmark   November 16, 2011 at 8:51PM
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The 58MXB furnace is a Comfort series. As far as I know it is a single stage furnace without a varible speed fan. It will not dehumidify without the AC on. I don't understand why the contractor would match this furnace with the 2 stage Infinity condenser. You have a top of the line condenser with a low end furnace. It seems wasteful to me.

I personally think it is a good idea to draw cool air from the basement in the summer providing you have good humidity control. This is how I have set it up in my house. I can maintain a humidity level of 40-45% during the most humid days.

    Bookmark   November 16, 2011 at 9:29PM
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Yes that doesn't sound right, the whole system was supposed to be an Infinity System but I'll double check tomorrow morning.

One issue I have is that I tested the unit on High Fan Speed and is loud, really really loud. I see in one of the details from the engineer that they were supposed to have insulation inside the return duct but the contractor didn't install the special duct. Also during a storm the basement got some water and the furnace was 2" under water. I recently opened the second panel (the one that has screws on) and the whole interior has corrosion on it, like oxidation. Also all the ducts are really dirty because during construction they didn't cover the vents even thought the system was off, so one day I just started taping them all but it was too late, I don't know what to do...

    Bookmark   November 16, 2011 at 10:04PM
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Is this a brand new furnace? I hope whatever happened to it does not void your 10 year parts warranty.

My Infinity furnaces are very quiet. I have the 60,000 BTU sizes. If yours are loud, then I suspect a problem with either the furnace or the duct work. My suspicion is your duct work is undersized. Muffling the sound with insulation is not the right solution.

Ask the "engineer" what is the static pressure reading when the furnace is on high. He can get this information from the Infinity controller.

    Bookmark   November 17, 2011 at 9:00AM
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I will check the message on the controller when they come next time, thanks for all the info, it definitely sounds more like a turbulence sound rather than mechanical sound.

And yes it's a brand new furnace...

    Bookmark   November 18, 2011 at 9:40AM
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Boy your furnace looks like crapola, how old is it? Do you do maintenance on it? No wonder you are having probs.

    Bookmark   November 18, 2011 at 10:29AM
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If you had flood damage, does your homeowner's insurance cover the damage? If so, this unit should be replaced in my opinion.

    Bookmark   November 18, 2011 at 4:05PM
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heatseeker and weedmeister the system is brand new in a new construction home, just recently turned on.

The builder is responsible for the 2" of water in the basement and I'll have to have a talk with his HVAC contractor tomorrow morning...

    Bookmark   November 18, 2011 at 6:30PM
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Ok Mike so I checked the values and the are:

Furnace Status:

Heat Stage: OFF
Airflow CFM: 1848
Inducer RPM: 0
Blower RPM: 1243
Static Pressure: 0.79
Lockout Timer: NONE

The sizes of the ducts are:

Supply to 1st floor: 22x12
Return from 1st floor:22x12
Supply to basement:20x14
Return from basement:20x7

    Bookmark   November 20, 2011 at 10:10AM
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The static pressure is high. Ideally it should be at 0.5. The blower is operating at 1243RPM. The manual lists 1300RPM as the maximum. I think this is the source of your noise.

What the demensions of the filter and it is a 1 inch or 4 inch?

What is going on about condition of the furnace? You need to address this first.

    Bookmark   November 20, 2011 at 5:44PM
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Well right now I have a temporary 25"x20"x1" pleated Merv 8 but the engineer and the contractor know that we are planning to use a 4" Lennox Healthy Climate 16 Media Air Cleaner.

Is that going to raise the pressure?

Regarding the condition of the furnace, are you talking about the corrosion you see? They think it's all fine, but the fan was under water as well as some of the boards.

Also now the heating has been running for 2 days and the humidity didn't drop at all, 58% in the house but set to 45%

Also the heating has been running for the past 2 days but the humidity level on the controller said 65% but it was set to 50%.

I checked the sticker on the units to see if they installed what the engineer specified but it doesn't seem like they did.

Area 1

Evaporator Coil: CNPVP6024
Furnace: 58MVC080F10120 instead of 58MVC120F10020

Area 2

Air Conditioner: 24ANA160A003
Evaporator Coil: CNPVP4821 instead of CNPVP4824
Furnace: 58MVC060 instead of 58MVC120F10020

    Bookmark   November 20, 2011 at 7:43PM
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If this were my new house, then this is what I would do:

1. Ask the contractor for the heating/cooling calculations and the duct sizing and an explanation of how he came up the sizes.

2. A list of the model numbers of all the equipment which will be installed (furnaces, coils, condensers, etc.).

3. Replace the flood damaged equipment with new equipment which has been correctly sized.

    Bookmark   November 21, 2011 at 10:57AM
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"the fan was under water as well as some of the boards. "

Replace it.

This is like buying a flood-damaged car at full price.

If it looks like this now and it is 'new', what do you think it's going to look like 20 years from now?

    Bookmark   November 21, 2011 at 4:22PM
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