My new furnace plus tankless install with pix!

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Originally Posted by SJProwler

Here's what they did with my return and the filter box for my new install. Maybe something similar would work well for your application without a huge modification. Perhaps the pros can comment on it.

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Something like that would have worked well before they changed the drop. I believe Beenthere was the first to suggest it in post #21 in this thread.

However, your post did make me think of something. If they didn't destroy my old drop, perhaps that could be a cost effective way of making the return better. Take off the new, put back the old, add a filter box horizontally, and a new transition where the filter box is now. I'll call tomorrow and see if that is still a possibility. No doubt I'll have to pay a few hundred dollars for the modification, but that is perhaps a small amount among the five figures I've got into a total rework of the basement infrastructure.

What price happiness anyway?

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Originally Posted by commerce48

Thanks, I'm going to run that by my plumber. Is the newer composite material you are referring to on the gas company side of my house? I could call my gas distributor, Vectren, for an answer if so.

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I have been seeing the utilities use pex type gas piping for burial in the street/branch runs.

I've even done burial with plastic for grills and generator installation.

Just for fun, I fired up the AC for a few minutes (20 degrees outside). The controller reports 800 CFM and .56 static. That's not so bad, right?

I only run the AC for perhaps 10 days a year. Seems like programming for 350 CFM per ton would be OK, and those 10 days are indeed humid. That would drop the static back point one.

Also, one other bit of data that I forgot about. Because the installers had to fabricate a new return drop and come back the next day, the furnace return was wide open. They place a half inch green plastic mesh in front of the return - it looked like it was probably packing material. It wasn't as open as a fiberglass filter, but you could see through the mesh-like structure. The reported static was very similar to the new installed return and filter at .21 at 483 CFM and .42 at 700 CFM.

I welcome any feedback related to whether I should pursue return modification with this new info, either a new L or turning vanes.

Wait until you really use the A/C. Running it when its 20 outside means that you didn't have much humidity inside for the coil to get wet.

Even at .7" wet. Thats safe to operate it in cooling mode.

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Originally Posted by beenthere

Wait until you really use the A/C. Running it when its 20 outside means that you didn't have much humidity inside for the coil to get wet.

Even at .7" wet. Thats safe to operate it in cooling mode.

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Thanks. I did forget about wet coils. It's 37% RH currently inside, and I only ran the AC for a couple of minutes.

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I beleive you still have to tell it to run the pump at certain periods as well as tell it whether or not you want hte pump running during a call for hot water. The pump will then cycle periodically based on the temperatures of the water in the storage tank if enabled for that time period.


THe contractor was wrong on he larger furnace blwoer. A larger blower and furnace doesn't help distribute air better. Air distribution at proper velocities is proportional to pressure drop in that pipe and the free area of the ductwork and grills. At higher velocities (undersized ductwork) you will get some other effects from the mass movement of the air in certain duct configurations.

Ultimately, smaller is better and longer run times will give you more even temperatures. If the ductwork upstairs is undersized, you will never get even temperatures, but a larger furnace WILL ALWAYS make temepraure imblance worse, not better due to shorter run times.

In most furnaces you can get a larger blower on the 80k BTU size anyway. With the Carrier Performance series (TP5) both the 80k and 100k are 4 ton blowers and can both handle a 4 ton AC.

That being said, you hame is probably large enough where the difference between between a 80k and 100k on low stage isn't that big of a deal and si still an improvement from your old system. But it still disapointing to see furnaces oversized for the wrong reason.


Also, that furnace has the ability to dehumidify on demand (slow the airflow for better moisture removal). I'd look into getting an improved thermostat or adding a dehumidistat to help with that. It can also slightly increase run times which will help with temrpature differences in the home. The better thermostats will also control the humidifier in winter and can even contrl it based on outdoor temprature toprevent frost and condensation on windows.

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That blower has 5 fixed speeds... or rather power settings (constant torque motor). You select the speed usign hte chart in the data sheets and by measureing staticpressure or airlfow. The furnace control board if wired for it, will slow the blower when there is a call for dehumidification. THsi si becomming a standard feature on msot all furnaces and airhandlers since dehumidificaiton is as or more important to comfort than cooling the air. In a larger, well insulated and sealed home in mild northern climates with a lot of shade and a cool roof design, you don't even need AC sicne the average daily temperpature rarely gets above 70F. It's not a true vairable speed, but it is a high efficincy blower motor and does have selectable speeds. It also will compensate some for a dirty air filter and higher static pressure.

One difference that can be noticeable. Low heat on the 80k is about 1050 CFM. On a 100k it's 1325 CFM. SO with 30% more capacity, you require 30% more air. That's still a little less airflwo than yoru old furnace, but still more than you need. That can be the difference between nearly silent and even heat or noisy and drafty. On my upstairs system in my home, that 80k BTU unit was very noisy on high stage, my 60k, especially after some more ductwork improvements is just barely audible on high stage and silent on low stage. Actually the inducer and burner, even located in the attic, is louder than the sound of the airflow.

I think a few pros on here have mentioned that they've never ever seen a undersized furnace. Consider than in Iowa where I am the desing temrpature is 0F. So at 35F, I only need 50% capacity. SO on a larger home with a lot of mass, if the average daily tmerpature is at least 35F, meaning if the high temperature is 42F and the low is 28F that day, a furance 1/2 the size of a properly sized one would run almost continously and depending on how much mass the house has, would probably only fall behind by maybe 1-2F in the early morning. Lets say I need a 80k BTU furnace. IF i installed at 60k BTU furnace, worst case, the average daily temp gets to lets say 10F. So

The Carrier Edge thermostat will do dehumidification I believe.

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