Down the HVAC rabbit hole
Hi all,
New member here (home owner). I found the forum by listening to the HVAC school podcast. I am farm kid with a PhD in physics and propensity to figure things out in my own but smart and humble enough to know when to ask for help. Some might call me cheap. But I am value oriented but will gladly spend what it takes to do the job correctly but I need to see that my choice makes finical sense.
Short version:
Locations Wilmington NC, 2300 hdd and 2200 cdd. Lots of humidity. Average RH is higher than New Orleans and Miami in July August and December.
1968 ranch 2000 sq ft upstairs (open concept) with 1100 sq ft walkout basement with Insulated glass double car garage door.
Current system is a 2009 Trane 16 seer package heatpump with 10 kw resistive strips
Basement was finished after all the ducting was installed and renovated to add 500 sq ft after the Trane unit was installed.
We heat with wood most of the time. Big insert in the basement fireplace. Medium stove upstairs. We can burn 2 full cords of softwood if I don’t run the heatpump much and we get a couple cold snaps. It would be nice not to have to rely on it during the cold snaps.
I want the all the duct work completely replaced so we can finish the basement remodel. It is really leaky. I’m have a hard time deciding how far go with respect to the HVAC equipment. If replacing all the ducts, should I replace the entire unit (I think it’s premature and we gotten by for 10 years so I’m not really ready for the cost of a completely new system).
I have a one of kind house that but it looks like every other 1960s ranch from the front. Our market is very diverse. The beach homes on one side and very rural Southeastern North Carolina in the other 3 directions. Hurricane Florence brought a lot of contractors and I think a lot stayed but not for the right reasons. As a story I had a friend building his own home that in the space of 12 months had to fire every single contrator he hired for cause. He was build a near passive house/net zero house. Consequently he took a leave from his job and did it all himself.
I’m pretty sure I want to add a whole house dehumidifier. Reducing the latent load on my system and adding insulation seems like I would be OK keeping my 3 ton unit. Summers are getting warmer and longer. Cold snaps would be really cold in the house if we didn’t have wood stoves. Last one I just turned the system off at night as it was running all night and not holding 65 degree set point. House got down to 58 in the mornings. It would warm up during the day I could hit my 65 set point. Just plugged a space heater in the when we wanted to heat a room we were in and gave all the kids an extra blanket. (This was pre woodstoves).
So I am looking for recommendations. here are my options always open to consider more.
1 (just fix the leaks and kick the can down the road) it would be cheap. And when the package unit needs replaced I could redo everything at that time.
2. (Replace all ducts keeping the 3 ton trane package unit. ). I really feel like the 3 ton unit is now undersized for heating. I’ve tried to do my own manual J but have never be able to figure out out to enter my half finished walkout basement with insulated two car glass garage door. How do size new ducts?
3. (Add a whole house dehumidifier). This option just seems to make sense to me and probably will happen in conjunction with the other options
4. (Add a mini split to supplement capacity). Upstairs or down or both single or dual head unit(s)
5. (Replace it all). At minimum I want a two stage system and would really like variable speed compressor. I just don’t see how it would save me any money. We don’t use more than 1200 kWh during peak summer times. And heat with wood now.
6. Something else?
Thanks for getting this far. The version is below
Evan
Long read with lots of details.
It is time to replace all of my ductwork that is original to the 2000 ft.² ranch house built in 1968. Since it was built the entire 1100 square-foot basement has been added as condition living space. this includes a two car garage that has now been transformed the living space with an insulated 17 foot wide glass garage door. The ductboard duct work was hacked up when 500 sq ft of basement were finished in 2000. As a consequence of our recent renovation. Several runs were removed, two feeding the now open concept upstairs 1000 sq ft kitchen living room dining room.
The current equipment is a 2009 trane package heat pump 16 XL 3 ton unit. 10kw of resistive heat. the blower has been replaced in the last five years. I have the unit set in comfort plus mode that runs on the first stage with reduced air capacity for the first five minutes before ramping up to 80% for 8? Minutes then on two stage stage two if the temperature is not satisfied. Currently set at 350 cfm per ton. The unit cannot hold setpoint at the thermostat location in a hallway if the outside temperatures are above 98°. Heating is not that great and we heat with wood most of the time anyway.
The ductwork is very leaky (I measure temp and humidity in the crawl space and you can see the exact cycle times of the hvac unit.) it runs through an unconditioned crawlspace on 1/2 of the house. a significant portion of the single main floor air return (7’ from thermostat) air return in the crawlspace is not insulated.
The crawlspace needs new insulation vapor barrier and or complete encapsulation but I am currently in a flood zone that will change in the next two years as new flood maps will be drawn after a stormwater project to remove our house from the flood zone.
We live in Wilmington North Carolina 3 miles from the coast. Average August September and December relative humidities are greater than New Orleans and Miami. We run stand alone dehumidifiers on both levels. Dumping once every 10 days when ac is running to once every day or two when ac is not. Monitoring indoor RH we run 55% when ac is on. Now it’s 65% no ac or dehumidifiers run this week. Generally if it get to high I turn on the ac for an hour. But house is 72 degrees this morning so I will run dehumidifiers.
Attic insulation is original loose fiberglass. 4” -6” inches. I am trying to air seal as best I can and have made decent progress. I am considering adding 1000 sq ft of R30 batt on top of loose fiberglass (after I complete my air sealing).
So what’s the best choice moving forward. I know timing is not great to for this project and I can likely put it off for some time. But I don’t want to wait too long on the duct replacement as I am under strict orders to finish the basement project ASAP.
That was long. Thanks for read to this point. My wife is done listening to me talk about this.
Evan
Hi all,
New member here (home owner). I found the forum by listening to the HVAC school podcast. I am farm kid with a PhD in physics and propensity to figure things out in my own but smart and humble enough to know when to ask for help. Some might call me cheap. But I am value oriented but will gladly spend what it takes to do the job correctly but I need to see that my choice makes finical sense.
Short version:
Locations Wilmington NC, 2300 hdd and 2200 cdd. Lots of humidity. Average RH is higher than New Orleans and Miami in July August and December.
1968 ranch 2000 sq ft upstairs (open concept) with 1100 sq ft walkout basement with Insulated glass double car garage door.
Current system is a 2009 Trane 16 seer package heatpump with 10 kw resistive strips
Basement was finished after all the ducting was installed and renovated to add 500 sq ft after the Trane unit was installed.
We heat with wood most of the time. Big insert in the basement fireplace. Medium stove upstairs. We can burn 2 full cords of softwood if I don’t run the heatpump much and we get a couple cold snaps. It would be nice not to have to rely on it during the cold snaps.
I want the all the duct work completely replaced so we can finish the basement remodel. It is really leaky. I’m have a hard time deciding how far go with respect to the HVAC equipment. If replacing all the ducts, should I replace the entire unit (I think it’s premature and we gotten by for 10 years so I’m not really ready for the cost of a completely new system).
I have a one of kind house that but it looks like every other 1960s ranch from the front. Our market is very diverse. The beach homes on one side and very rural Southeastern North Carolina in the other 3 directions. Hurricane Florence brought a lot of contractors and I think a lot stayed but not for the right reasons. As a story I had a friend building his own home that in the space of 12 months had to fire every single contrator he hired for cause. He was build a near passive house/net zero house. Consequently he took a leave from his job and did it all himself.
I’m pretty sure I want to add a whole house dehumidifier. Reducing the latent load on my system and adding insulation seems like I would be OK keeping my 3 ton unit. Summers are getting warmer and longer. Cold snaps would be really cold in the house if we didn’t have wood stoves. Last one I just turned the system off at night as it was running all night and not holding 65 degree set point. House got down to 58 in the mornings. It would warm up during the day I could hit my 65 set point. Just plugged a space heater in the when we wanted to heat a room we were in and gave all the kids an extra blanket. (This was pre woodstoves).
So I am looking for recommendations. here are my options always open to consider more.
1 (just fix the leaks and kick the can down the road) it would be cheap. And when the package unit needs replaced I could redo everything at that time.
2. (Replace all ducts keeping the 3 ton trane package unit. ). I really feel like the 3 ton unit is now undersized for heating. I’ve tried to do my own manual J but have never be able to figure out out to enter my half finished walkout basement with insulated two car glass garage door. How do size new ducts?
3. (Add a whole house dehumidifier). This option just seems to make sense to me and probably will happen in conjunction with the other options
4. (Add a mini split to supplement capacity). Upstairs or down or both single or dual head unit(s)
5. (Replace it all). At minimum I want a two stage system and would really like variable speed compressor. I just don’t see how it would save me any money. We don’t use more than 1200 kWh during peak summer times. And heat with wood now.
6. Something else?
Thanks for getting this far. The version is below
Evan
Long read with lots of details.
It is time to replace all of my ductwork that is original to the 2000 ft.² ranch house built in 1968. Since it was built the entire 1100 square-foot basement has been added as condition living space. this includes a two car garage that has now been transformed the living space with an insulated 17 foot wide glass garage door. The ductboard duct work was hacked up when 500 sq ft of basement were finished in 2000. As a consequence of our recent renovation. Several runs were removed, two feeding the now open concept upstairs 1000 sq ft kitchen living room dining room.
The current equipment is a 2009 trane package heat pump 16 XL 3 ton unit. 10kw of resistive heat. the blower has been replaced in the last five years. I have the unit set in comfort plus mode that runs on the first stage with reduced air capacity for the first five minutes before ramping up to 80% for 8? Minutes then on two stage stage two if the temperature is not satisfied. Currently set at 350 cfm per ton. The unit cannot hold setpoint at the thermostat location in a hallway if the outside temperatures are above 98°. Heating is not that great and we heat with wood most of the time anyway.
The ductwork is very leaky (I measure temp and humidity in the crawl space and you can see the exact cycle times of the hvac unit.) it runs through an unconditioned crawlspace on 1/2 of the house. a significant portion of the single main floor air return (7’ from thermostat) air return in the crawlspace is not insulated.
The crawlspace needs new insulation vapor barrier and or complete encapsulation but I am currently in a flood zone that will change in the next two years as new flood maps will be drawn after a stormwater project to remove our house from the flood zone.
We live in Wilmington North Carolina 3 miles from the coast. Average August September and December relative humidities are greater than New Orleans and Miami. We run stand alone dehumidifiers on both levels. Dumping once every 10 days when ac is running to once every day or two when ac is not. Monitoring indoor RH we run 55% when ac is on. Now it’s 65% no ac or dehumidifiers run this week. Generally if it get to high I turn on the ac for an hour. But house is 72 degrees this morning so I will run dehumidifiers.
Attic insulation is original loose fiberglass. 4” -6” inches. I am trying to air seal as best I can and have made decent progress. I am considering adding 1000 sq ft of R30 batt on top of loose fiberglass (after I complete my air sealing).
So what’s the best choice moving forward. I know timing is not great to for this project and I can likely put it off for some time. But I don’t want to wait too long on the duct replacement as I am under strict orders to finish the basement project ASAP.
That was long. Thanks for read to this point. My wife is done listening to me talk about this.
Evan
source https://hvac-talk.com/vbb/threads/2243351-Ducts-need-replacing-and-system-recommendations-I’m-down-the-HVAC-rabbit-hole?goto=newpost
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