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Old 12-16-2010, 12:27 PM   #1
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Contractor installed HRV wrong I think


Since we moved into our new home in Sept I am having a tough time bringing down the humidity level in the home. I started looking at the manual for the HRV which is a Lifebreath RNC10 and noticed a few things that were different in the installation. It looks to be what is called a simplified installation where the stale air in and return air to home both come off the cold air return side. My installation is different as:

1) The stale air inlet to the HRV comes off of the HOT plenum, about 24" above the furnace where as the manual it is at least 40" upstream of the return out from the HRV and both are taken off of the return air duct.

2) The manual states that the HRV should be "interlocked" with the furnace so that when the air exchanger calls to run it starts the furnace blower.

I called the contractor and mentioned these differences and he said that this was how they had been installing the units for years. "Maybe I'm not running it right" with the digital controller" I was told. Maybe I'm not as the instructions are not the most straightforward. The unit seems to run allot, but according to my thermostat which also measures humidity I have between 50%-58% humdity in the house. The Digital controller is a Lifebreath RNC digital control part # 99-DX-01.

The contractor said that he wasn't familiar with this new controller and basically said that he knows the ducting is correct, If I wanted the system interlocked with the furnace he would need to have the electrician wire it that way, He has never seen it done like that before. I wanted to ask him if he actually balanced the system, (which I don't think was ever done) but I could sense he was getting irritated and wanted to brush me aside to the electrician.

How important are the above issues and are the installation differences the cause of my higher levels of humidity?

I feel confident that with a little help from the furum I can make the changes and do the work myself if it will make a difference. Or should I push to have the contractor do the work if he is truely out of the loop?

I should mention that their are some sour notes with the general contractor that came up toward the end of the building process. I know that both us and the general contractor would be happier if we didn't have to talk again.

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Old 12-16-2010, 03:16 PM   #2
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Contractor installed HRV wrong I think


Should not be off the hot plenum as it is wasting a lot of hot air/$$ and cold air/$$ in the cooling season, even with the unit shut off in the summer air will still flow thru it. Needs to be balanced properly with an expensive magnehelic gauge or it won't work properly/won't defrost properly/can cause a negative or positive pressure problem in your house. Sounds like he does not know how or has the proper tools or knowledge.

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Old 12-17-2010, 07:51 AM   #3
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Contractor installed HRV wrong I think


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Originally Posted by yuri View Post
Should not be off the hot plenum as it is wasting a lot of hot air/$$ and cold air/$$ in the cooling season, even with the unit shut off in the summer air will still flow thru it. Needs to be balanced properly with an expensive magnehelic gauge or it won't work properly/won't defrost properly/can cause a negative or positive pressure problem in your house. Sounds like he does not know how or has the proper tools or knowledge.
I'm confident I can re duct and balance it as I can borrow a 0-1.0" or 0-3"magnehelic from work. The wiring is where i'm confused, to interlock the two units. My furnace is a Carrier Infinity 58MVP080 and I am using an Infinity communicating T-stat which is connected to the ABDC terminals on the furnace board, not the 24V thermostat connection screws which is what the HRV calls out.

I'll scan a few images from the manuals and put them up.
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Old 12-17-2010, 09:05 AM   #4
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Contractor installed HRV wrong I think


So can I make the HRV connections to the 24V terminal screws on the furnace board in addition to the already having the tstat to the communicatinon connector or will the two conflict with each other?

If this is right, and both can be connected. Then when the HRV calls and closes sending 24V to the G terminal screw to start the fan which set of DIP switches would control the fan speed? would it be linked to the (CF) contunuous fan airflow DIP switches or (A/C) airflow DIP's? Without the furnace knowing what is connected to it, ie.. just a 24V trigger for fan call coming over the G terminal. What speed will it run at since it is variable speed fan? and which set of DIP's control that speed?
Attached Files
File Type: pdf 58MVP control board.pdf (56.3 KB, 107 views)
File Type: pdf HRV schematic.pdf (58.6 KB, 92 views)
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Old 12-17-2010, 03:43 PM   #5
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Contractor installed HRV wrong I think


I do REALLY high end Lennox stuff comparable to what you have there but have not seen yours yet. Need advice from a Carrier Pro.
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