HVAC Heating/Humidity issues

10 years ago

Moved into a new construction home in the lower hudson valley in NY. First Winter in this house. Having multiple issues with the HVAC system. Here are the specifics to help with understanding whats going on.

House is a 2 story colonial with 2 story foyer and great room. Total livable square footage is 4100 sq ft.

2 Tempstar LP units in the house: 1 in the basement for the first floor and in the attic for the second floor. In the basement, which is well insulated and unfinished, there is a humid-a-mist humidifier attached just above the coils with cold water line attached to this for on demand mist. The humidifier is controlled with a gain switch that is currently on 3second pulse and about 55% on the humidistat. The system has 2 return vents (18x48 each approx) on the first floor right above the basement unit and this return is right outside our kitchen and mudroom area, which is also near our great room, thus giving a draft when the heat is on.

In the attic, the system is also well insulated, but it is an attic and therefore, no humidifier attached to this. There is a return vent (16x16) right outside the master bedroom and one of our kids bedrooms. There is another return vent in the Master Bedroom right at the entrance to the Master Bath (also 16x16). The other 2 bedrooms are on the opposite end of the home with no return vent on that side.

Both furnaces/blowers are controlled with separate NEST 2nd gen thermostats, but it does not control the humidity level, just shows the level in the area of the thermostat.

We also have a direct vent LP Fireplace that we use intermittently in our Great Room with air pushed out from a blower on the inside and run the ceiling fan on reverse to bring down some of the heat.

The house has a good seal to it since it is a new construction, or so it seems at this point. The house is cooler than we would like and the humidity level is suboptimal. I have had the HVAC guy who installed the system (still under warranty with the builder) come by and look at why it is cold in our Master and all he did was close a vent in one room (has 2 ceiling vents in there) and shut the ceiling vents 50% or so in the other 2 bedrooms. The heat in the Master has improved somewhat and now is hotter, but lets see how this goes with the 2nd arctic vortex headed our way this week.

Our wood floor in the great room, foyer, dining room and kitchen are beginning to show gaps as is the molding. I am worried about the lack of adequate humidity in the house, especially on the first floor. The kitchen cabinets are also shrinking and the showing some non-stained areas due to this shrinkage. We wake up in the mornings with a dry mouth and noses and our skin is dry. I have bought a thermostat/hygrometer combo and to my surprise, the relative humidity in the different areas is hovering around 35%-40%, sometimes goes down to 30% as well.

Over the weekend, I bought a Sunbeam Cool Mist Humidifier and placed it upstairs below the outside return since there is no humidification system in the upstairs furnace. I also cranked up the Humid-A-Mist and over a matter of 10 days increased the gain to 4seconds and the humidistat up to 60%. Today I noted a pool of water in the basement about 5 inches wide with some moisture on the tape outside the vent - I called the HVAC guy and he just asked me to lower the gain and humidistat setting and use the blower fan 24/7 for the next 3-4 days to dry out the water that is probably in the vent in the basement where the leak is. This is just very frustrating.

I need help with figuring out how to more adequately control the humidity in the house and to more adequately control the heating without compromising the ductwork or the furnace/blower. Could the system be adjusted for more comfort for the family? Any expert opinion and experiences will be much appreciated.

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Comments (5)

mike_home
10 years ago
last modified: 9 years ago
Is your humidifier set up to turn on the furnace blower when the humidity level is low? If not then you should your HVAC contractor to do this. A better solution would be is to replace your Nest thermostat with a thermostat which can monitor and control your humidity levels. You want to measure and control the humidity in the interior of your house, not at the furnace.

Your house is not as tight as you think it is. Outside air leakage is the main contributor to low humidity. It has been unusually cold in our area this winter. This is aggravating the situation.

You have a large house and I am glad to hear you have two HVAC systems. Unfortunately the builder decided to install the upper floor furnace in the attic. This means a lower efficiency furnace (80% vs. 95%+) and no humidifier. Both furnaces should have been installed in the basement.

The one advantage of have an attic furnace is that you have complete access to all supplies and returns. The HVAC contractor should be making changes to the attic supplies and not closing vents. Go in the attic yourself and take a look on how the duct works is configured. If it looks like a mess to you then it needs to be redone.
energy_rater_la
10 years ago
last modified: 9 years ago
new construction doesn't mean an air tight house.
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Gurvy
Original Author
10 years ago
last modified: 9 years ago
I agree that the new construction does not mean air tight, but compared to older homes, new construction homes are tighter.

As for the humidifier, it is set to turn on when the heat turns on. I have asked the HVAC guy to install the humidistat component to the Nest, but his answer was that the humidistat needs to stay downstairs by the furnace. I obviously dont agree with that either and have placed a call to the manufacturer of the humid-a-mist to get their input on the issue.

I have gone up the attic with the builder personally and we did not find any issues with the ducts. SOme were kinked over trusses but they have the hard ducts inside insulation and were not really pinched.

I bought an infrared thermometer and the temp at the registers is about 20-30 degrees higher than in the "living area" (ie, 90 at the registers and 60 at the sofa). I think that additional registers may need to be placed in the upstairs bedrooms, but does anyone think that its a bad idea to do that? Isnt that just gonig to redistribute the same amount of air coming out of the furnace anyway?
mike_home
10 years ago
last modified: 9 years ago
"...but his answer was that the humidistat needs to stay downstairs by the furnace."

Did he explain why? I think he does not want to spend the money on running another wire and replacing the Nest thermostat. Did you ask for the Nest or was it his idea?

"Some were kinked over trusses but they have the hard ducts inside insulation and were not really pinched."

If you have flexible ducts then they are easily pinched.. Even a hard duct should not have a 90 degree angle without a curved transition elbow.

A large bedroom will need 2 - 3 registers. More registers will deliver and distribute more heat.

Put you hand up to the ceiling register when the heat has been off for a period of time. See if you feel and cold air drafts. If you do the duct work has not been sealed properly. Your duct work should have at least an R8 insulation.

Stay on top of the contractor. He is going to wait you out until the one year warranty has expired. Start documenting your requests and what he has done.
Gurvy
Original Author
10 years ago
last modified: 9 years ago
I asked for the Nest...he tried to sway me away from it, but it worked great in our previous home so moved them to this house. I just wanted to have the wire for the humidifier connected to the Nest right off the bat, but he said it was not the best thing to do. No other reason than that.

I'll go up to the attic again and take another look at them.

The registers in the ceiling have good amount of air coming through them. I even purchased one of those infrared temp gauges and I get about 80-90F coming out. Unfortunately in the actual living area where we sit, its colder. My kids have a room each that is about 13x12 feet with 1 ceiling register each and our master is 29x15 with 2 ceiling registers and 1 hi/lo register set up. Does that seem enough??

In our center hall colonial, the thermostat is in the hallway upstairs and think that it may need to moved to the master bedroom instead so it doesn't stop to prematurely before it warms the rooms up.

The inside of the ducts...i am not sure if they are flexible ducts or not, but will double check, but the insulation is R8.

I am going to have another HVAC company come in and give me a report on the system and see if it is adequately sized for the home, which I think is the real issue. Its builder grade, so I am sure he cut corners on it.

Any input into the humidifier system? Has anyone heard about the Humid-a-stat Previously we had the Honeywell system in the last home. Not sure if one is better than the other.