Such great information! I run a ventilating dehumidifier with merv 16 filters on inside and outside returns going into my A/C return which also has a merv 16. The main issue I deal with is my oversized A/C. It took a while for me to get it all working well to maintain humidity properly. The other thing I learned is exactly as you said. I needed more fresh air than I thought was needed to maintain healthy VOC levels. Close to all of the air on my ultra 70 is outdoor air. Very little is recirculated. I had to figure all this out because I couldn’t sleep in our new home. I was left to commission since the HVAC company who installed didn’t know how! With the fresh air going 24/7 I sleep and dream very well and get rested. I think people miss out on a lot of quality of life not monitoring IAQ.
Corbett, so glad to have more of your videos to watch again. I am extremely interested in why you said you would not run dedicated supply ducts for your ERV if you were to do it again. You started to say it makes weird things happen, could you explain more? The reason I am on your page so much is to figure out the BEST way to do things. Like John said after you, running separate ERV supply ducts seems like the most controlled way to do it.
More time, more materials, more clutter, and you can get rings of dust around the terminals over time- even MERV13 only grabs 85% of particles >1 micron.
thanks guys. a lot to unpack there, and so much of the issues are familiar even tho hvac is pretty rare here. back drafting fireplaces has hit the news here due to heat transfer systems (poor mans hvac) sucking the air out of the room (because almost none tells them to install returns). quite common for them to fit ventilation into the return but our ducted heat pumps typically have the filters at the return grill. turn the heat pump off and the ventilation blows the dust off the filters. lack of commissioning systems, lack of design work etc. hack jobs to combine the ventilation. even with passive houses, big dollar exterior sliding doors that span most of the house and a cheap budget recirculating range hood. i swear they only build passive houses for the name. erv's being used but no dehumidifier or even humidity gauges to tell you if its to humid. plenty of sales people selling things, but no one making the systems work properly.
I’m poor right now so I open a window. Problem solved. 😂 I have a 5 ton split single stage 92% AFUE natural gas furnace. I have remote sensors throughout the house measuring temp, humidity, AQ that I monitor and depending on the situation I control the HVAC with my ecobee app and track energy consumption with a sense energy monitor. I have to manually do everything that was a talking point/topic. Fortunately everything that was spoken of today I already knew having followed the passive house movement the building science forums etc since 2013. I’ve been slowly modernizing and repairing a drafty cape (the most difficult style of retrofit to seal!) for the past ten years. Still my #1 Poor Handyman’s tip of the day… open a window!
I have found co2 builds up really fast in my house. So I monitor it in the main rooms and open my furnace fresh air vent whenever it starts to rise. Without monitoring I would not have known this. Monitoring air quality is really important since every family uses their house differently.
I decided on the airthings system. The larger units now allow you to plug in a power supply and it becomes a wifi hub for all the battery Bluetooth only airthings devices. But at $250 they are not cheap. Once it’s connected to a power adapter and wifi it can trigger automation. I’m using Alexa and ifttt (which costs money) to do all my automation. It’s working well. I have it turning fans on and of and controlling the fresh air damper.
@todd5963 Mine was original to the house in 1995. It is a Columbia CVP SRRD. It is 24 v. I decided to not bother trying to directly make it WiFi controlled I just did it by making the 120v source for the 24v power supply a wifi wall switch. It is a spring return damper. So I turn off the WiFi wall switch and it closes. I turn on the wifi wall switch and it opens. It has worked great.
what testing / studies have been done on ERV's vs HRV's about the medium porosity and potential to bring bacterial/viral contamination through the transfer medium with the humidity/moisture transferred? Or even just timeline to become clogged / not transfer moisture anymore. Thanks
I have an HRV now and consider to replace the core or whole unit to ERV since the winter time like today with -10°C outside and 20 innside the air humidity is around 24% and petting my dog the sparks are flying all the time.. it is much too dry. It would be better in my basement to dry out instead
I have worked mostly in commercial/ industrial HVAC so mostly maintenance. We were fortunate enough to have engineers on staff who hand the larger picture. We had over 8 million square feet under a/c plus 2-4 million square foot just heating 5 cafeterias and hundreds of machines/computer cooling units at least 30 rest rooms 4 active very large boilers . Residential experience is limited . The VENTILATION part of HVAC is the most neglected discipline of the entire industry. I have found very few residential technicians that are proficient in that field. The tight housing being built is problematic . Most residential ac or heating have little to none ventilation capabilities. 5 areas areas that need ventilation attention badly crawl space,bathroom s , kitchen, fireplace s nonconditioned spaces . Each of then have intermittent needs for ventilation each with different levels of makeup air needs . My take is ventilation should almost be considered a separate field for design purposes. With “code” tightening the air exchanges required far more attention should be placed on the design /maintenance requirements of air exchange . The KISS keep it simple stupid principle is a must to raise awareness and skill needed to keep systems clean and safely operating. One of the most problematic aspects of ventilation is systems maintenance is neglected . The more complex the the system the more susceptible to poor maintenance issues.systems the more Industrial ventilation systems is mediocre at best and residential ventilation systems often are neglected until they fail completely or burn out, because almost nobody thinks about them. We spend more time and money to seal the building. Then proceed to poke holes into it and spend more time/money to clean/control the air in/out so we can breath again. More money/time to run/ maintain it (madness I say)😅
In tight homes (say 1.5 ACH50), there seemed to be shunning of gas furnaces and fireplaces. I assume that this is due to backdrafting being a serious threat. But, what about high efficiency sealed combustion furnaces? or sealed combustion wood stove fireplaces? Any known issues with these in such tight homes? Thanks for the excellent deep dive!
Thanks Math- you CAN do that, but when the home has such tight tolerances most ppl shy away from combustion- also, efficiency/sustainability also generally is attractive to performance folks.
Just my opinion but it’d be more practical to have the exhaust fan switch split so that it also turns on simultaneously a matching CFM intake fan piped from the exterior as close as possible to the exhausting unit. Mainly just because an “air pressure” switch sensor it’s prone to delay or even not activating at all say in the situation a window or door is open to the outside. An electrical split at the switch is the most resilient solution, and that’s important with any type of gas range/appliance.
Don’t forget NOx. You can live in a drafty home with no ventilation and CO2 is marginally dangerous, but if you’re living in a tight house with no ventilation NOx can kill a person pretty quickly.
ERV instead of bathroom exhaust fans in Florida remodel. Guys I am trying to do a tightish remodel of a 50yr old Florida block home. I am air sealing everything I can. New AC unit, and ducts with a dedicated dehumidifier with fresh air intake. I was about to order a couple of high end Panasonic bath fans, but I am torn with the idea to skip them and install an ERV. I could pull air at a lower volume from baths and bedrooms and dump back into the AC return. Any input would be great. Thank you
It will end up being a MUCH higher volume overall, James, because you’re running all the bathrooms 24/7. I do not advise this unless you get so airtight that you cannot use bath fans without severely depressurizing the home.
Please please please please do another deep dive. I love listening to you and John and hvac school. So much value!
Such great information! I run a ventilating dehumidifier with merv 16 filters on inside and outside returns going into my A/C return which also has a merv 16. The main issue I deal with is my oversized A/C. It took a while for me to get it all working well to maintain humidity properly. The other thing I learned is exactly as you said. I needed more fresh air than I thought was needed to maintain healthy VOC levels. Close to all of the air on my ultra 70 is outdoor air. Very little is recirculated. I had to figure all this out because I couldn’t sleep in our new home. I was left to commission since the HVAC company who installed didn’t know how! With the fresh air going 24/7 I sleep and dream very well and get rested. I think people miss out on a lot of quality of life not monitoring IAQ.
Corbett, so glad to have more of your videos to watch again. I am extremely interested in why you said you would not run dedicated supply ducts for your ERV if you were to do it again. You started to say it makes weird things happen, could you explain more? The reason I am on your page so much is to figure out the BEST way to do things. Like John said after you, running separate ERV supply ducts seems like the most controlled way to do it.
Corbett, I second this. Can you explain more why wouldn't do dedicated ERV ducts? What are the "weird things" that happen?
More time, more materials, more clutter, and you can get rings of dust around the terminals over time- even MERV13 only grabs 85% of particles >1 micron.
I want one of the HVAC Illuminati Crew t shirts!
thanks guys. a lot to unpack there, and so much of the issues are familiar even tho hvac is pretty rare here.
back drafting fireplaces has hit the news here due to heat transfer systems (poor mans hvac) sucking the air out of the room (because almost none tells them to install returns).
quite common for them to fit ventilation into the return but our ducted heat pumps typically have the filters at the return grill. turn the heat pump off and the ventilation blows the dust off the filters.
lack of commissioning systems, lack of design work etc. hack jobs to combine the ventilation.
even with passive houses, big dollar exterior sliding doors that span most of the house and a cheap budget recirculating range hood. i swear they only build passive houses for the name.
erv's being used but no dehumidifier or even humidity gauges to tell you if its to humid.
plenty of sales people selling things, but no one making the systems work properly.
I’m poor right now so I open a window. Problem solved. 😂 I have a 5 ton split single stage 92% AFUE natural gas furnace. I have remote sensors throughout the house measuring temp, humidity, AQ that I monitor and depending on the situation I control the HVAC with my ecobee app and track energy consumption with a sense energy monitor. I have to manually do everything that was a talking point/topic. Fortunately everything that was spoken of today I already knew having followed the passive house movement the building science forums etc since 2013. I’ve been slowly modernizing and repairing a drafty cape (the most difficult style of retrofit to seal!) for the past ten years. Still my #1 Poor Handyman’s tip of the day… open a window!
I have found co2 builds up really fast in my house. So I monitor it in the main rooms and open my furnace fresh air vent whenever it starts to rise.
Without monitoring I would not have known this. Monitoring air quality is really important since every family uses their house differently.
What type of monitor do you have? I'm in the market and hate to pick a generic one on Amazon. Thx
I decided on the airthings system. The larger units now allow you to plug in a power supply and it becomes a wifi hub for all the battery Bluetooth only airthings devices. But at $250 they are not cheap.
Once it’s connected to a power adapter and wifi it can trigger automation. I’m using Alexa and ifttt (which costs money) to do all my automation. It’s working well.
I have it turning fans on and of and controlling the fresh air damper.
@@ecospider5Thanks! I'll look into that one. Appreciate all the details
@@ecospider5 ok that is cool. Is your fresh air damper Fantech? We are looking at that model for kitchen hood make up air and dryer.
@todd5963
Mine was original to the house in 1995. It is a Columbia CVP SRRD. It is 24 v. I decided to not bother trying to directly make it WiFi controlled I just did it by making the 120v source for the 24v power supply a wifi wall switch.
It is a spring return damper. So I turn off the WiFi wall switch and it closes. I turn on the wifi wall switch and it opens. It has worked great.
what testing / studies have been done on ERV's vs HRV's about the medium porosity and potential to bring bacterial/viral contamination through the transfer medium with the humidity/moisture transferred? Or even just timeline to become clogged / not transfer moisture anymore. Thanks
I have an HRV now and consider to replace the core or whole unit to ERV since the winter time like today with -10°C outside and 20 innside the air humidity is around 24% and petting my dog the sparks are flying all the time.. it is much too dry.
It would be better in my basement to dry out instead
Solid idea
Backdrafting the fireplace is fun. House smells awful and if you happen to be near it when it happens.... just yay...
Should you ever install a large 4” filter box on an ERV? Or always go with the smaller internal factory setup?
As long as you check the tested filter pressure drop at the ERV’s airflow
I have worked mostly in commercial/ industrial HVAC so mostly maintenance. We were fortunate enough to have engineers on staff who hand the larger picture. We had over 8 million square feet under a/c plus 2-4 million square foot just heating 5 cafeterias and hundreds of machines/computer cooling units at least 30 rest rooms 4 active very large boilers .
Residential experience is limited . The VENTILATION part of HVAC is the most neglected discipline of the entire industry. I have found very few residential technicians that are proficient in that field. The tight housing being built is problematic . Most residential ac or heating have little to none ventilation capabilities. 5 areas areas that need ventilation attention badly crawl space,bathroom s , kitchen, fireplace s nonconditioned spaces . Each of then have intermittent needs for ventilation each with different levels of makeup air needs . My take is ventilation should almost be considered a separate field for design purposes. With “code” tightening the air exchanges required far more attention should be placed on the design /maintenance requirements of air exchange . The KISS keep it simple stupid principle is a must to raise awareness and skill needed to keep systems clean and safely operating.
One of the most problematic aspects of ventilation is systems maintenance is neglected . The more complex the the system the more susceptible to poor maintenance issues.systems the more Industrial ventilation systems is mediocre at best and residential ventilation systems often are neglected until they fail completely or burn out, because almost nobody thinks about them.
We spend more time and money to seal the building. Then proceed to poke holes into it and spend more time/money to clean/control the air in/out so we can breath again. More money/time to run/ maintain it (madness I say)😅
☝️ everything this guy said! Preach!
In tight homes (say 1.5 ACH50), there seemed to be shunning of gas furnaces and fireplaces. I assume that this is due to backdrafting being a serious threat. But, what about high efficiency sealed combustion furnaces? or sealed combustion wood stove fireplaces? Any known issues with these in such tight homes? Thanks for the excellent deep dive!
Thanks Math- you CAN do that, but when the home has such tight tolerances most ppl shy away from combustion- also, efficiency/sustainability also generally is attractive to performance folks.
Is there a range hood or bath room fan that provide it own makeup air with possible a pascal pressure differential switch or would this not function?
Just my opinion but it’d be more practical to have the exhaust fan switch split so that it also turns on simultaneously a matching CFM intake fan piped from the exterior as close as possible to the exhausting unit. Mainly just because an “air pressure” switch sensor it’s prone to delay or even not activating at all say in the situation a window or door is open to the outside. An electrical split at the switch is the most resilient solution, and that’s important with any type of gas range/appliance.
The purpose of ventilation is to remove high concentration of CO2 out of house. Other than that is just sale pitch
Don’t forget NOx. You can live in a drafty home with no ventilation and CO2 is marginally dangerous, but if you’re living in a tight house with no ventilation NOx can kill a person pretty quickly.
Look up sick building syndrome
ERV instead of bathroom exhaust fans in Florida remodel.
Guys I am trying to do a tightish remodel of a 50yr old Florida block home.
I am air sealing everything I can.
New AC unit, and ducts with a dedicated dehumidifier with fresh air intake.
I was about to order a couple of high end Panasonic bath fans, but I am torn with the idea to skip them and install an ERV.
I could pull air at a lower volume from baths and bedrooms and dump back into the AC return.
Any input would be great.
Thank you
It will end up being a MUCH higher volume overall, James, because you’re running all the bathrooms 24/7. I do not advise this unless you get so airtight that you cannot use bath fans without severely depressurizing the home.
If I find someone in the central Florida area to do a blower test before I install the bath fans, what numbers would be where it would be beneficial?
Home is 1750 sq ft. Single story block construction
Can you @ John