You’re a very good teacher. I would highly recommend everyone oversize dehumidifier/humidifier by 20% minimum. The new systems will automatically actuate when needed.
Great info Corbett! As a follow-up video, could you address the expense associated with humidity control and how much energy is saved by a) building air tight in both hot/humid and cold climates, and b) using an ERV vs an HRV in both climates as well? I did some math in a GBA forum post and I’d like to see if my calculations are anywhere close to what you come up with (I would trust you more than me). Thanks!!!
Great video especially explaining the delta grains method of sizing. This works great in a home like yours. 1. I will say that pressure driven infiltration due to duct leakage and improper room pressure balancing will increase the amount of humidity and dehumidification needed. These problems need to be addressed if possible at the same time. But for those reasons, it’s ok to aim a little high in sizing hums and dehus as long as you don’t go crazy. 2. In my volunteer work designing high occupancy places of worship with lots of ventilation I created a worksheet to calculate the unmet latent load in order to size the dehu needed during full load and part load conditions and it even takes into account the de-rating of the dehu due to actual indoor conditions and duct friction. You might like it, I can send it to you. 3. If you need help installing that Aprilaire, I’ve put several in. With your low crawl, there might not be a natural steam tube rise between the humidifier and the duct connector and you might need to do a funky p trap. As always, thank you Corbett!
Tim- in a "whole house" set up, do you link the dehumidifier to the central blower (i would think so as the dehumidifier fans aren't sufficient to overcome most homes stays pressure in ducts without it) where do you install the intake and output from the dehumidifier ? aprilaire and Sante Fe have several options. I assume tapping into the return duct is obvious answer for intake, but what about where you dump the dehumidified air ? if you return the air prior to the central blower/HVAC coil, you are not exploiting your HVAC latent capacity, but if you return it to the output of the HVAC (his supply sducting) you end up fighting the central blower ops worse/?
@@johnwhite2576 Santa Fe/ Broan (same parent company) recommend a dedicated return but ducting into the Hvac return plenum is acceptable. Since the dehu makes hot air, it shouldnt supply back into a single room. It absolutely can duct back into the supply duct as long as supply static isnt over 0.3" wc, theres a backdraft damper in the dehu supply and theres room downstream in the supply duct before the first branch for good mixture.
Great video. Wish you guys were on SI units already rather than half way. :) Principal factor determining Δg/kg in a tight house: * with HRV are external loads. This is equivalent to 0% efficient ERV, or a leaky house * with no ventilation (suffocation) are internal loads. Equivalent to 100% efficient ERV. * with typical ERV, external load >> internal load. Therefore sized based on ventilation rate based on delta grams of water / kg of air method, upsized for realistic capacity. And noting ERV halves the ventilation impact on latent heat or humidity. ERV Latent heat efficiency typically ~60% Zehnder ComfoAir Q600 ERV ~ 68%. BROAN ERV250 ECM ~ 55% As latent efficiency improves I assume the principal factor will eventually shift from external to internal loads.
Love the channel, another very informative video. Is my understanding correct that as a whole house dehumidifier cannot be oversized? In other words if it helps arrive at the desired level of humidity fast, then that relative humidity is consistent throughout the entire building (assuming we'll sealed). Thanks
Good info, agree with your math. With your sizing though, you may want to reconsider. Sizing both to the extremes when neither are the primary. HVAC isn't sized to the extremes either. Oversizing is going to happen, this may not matter with humidifier. Dehumidifier, unless it modulates will cause issues.
One little point about humidifiers. There are several types in the market. My experience is that when you actually want to control humidity, you need an electrode humidifier, like the aprilaire model referenced in the video. Other types either require heat to operating to add moisture the air or are drastically less effective when the heat is not running. Bypass, fan assist, mist type, might take the edge off but really not gonna work very well. Disclaimer: My design day is like 8degrees if you live in a place where your design day is in the 20s then maybe you can get away with crappy humidifiers.
Thanks for the video. I have a dehumidifier that dumps into my return to the air handler. Where would be best to add an ERV? In-line with the dehumidifier, or before the dehumidifier, or after the dehumidifier in your opinion? My dehumidifier only moves about 140cfm (sante fe Ultra 70). It is currently set up to pull in inside and outside air, mix it, and push it into the return. I'm going to be planning for an ERV and was wanting your fact based opinions. Thank you so much!!!
Fantastic video mate. Can a portable dehumidifier placed in the hallway work for multiple rooms simultaneously whose doors are open and connected to the hallway? Will it work that way? Assuming the four or five connected rooms are ranging from 8 to 16 sq.m and it can dehumidify multiple rooms at the same, how large a dehumidifier do I need?
Damn, this video should have been longer. Oh well, watch this instead: How to Craft a Home Ventilation System with Modular Components from Aprilaire th-cam.com/video/006AntQSqIA/w-d-xo.html
Do ERVs also transfer some humidity, and if so, would this affect the delta target during the winter? And where do considerations like moisture from showers, cooking, breathing, etc come in, or are these sufficiently negligible so as not to be a concern?
Hello 👋 great video You did mention about a website were you can take out the map from everywhere in the world and it will give you the “ load” your looking for to design HVAC … what is the website adresse ?
How did you calculate the 120 Gr/Lb (outside) number? You stated this number right after determining the outdoor temperature of 80.4 & dew point of 73.3. There is another number on the chart (HR 128.5). Do you convert this number? Thanks!
@@HomePerformance OK thanks, looking it up online, some calculators ask for the RH number with the temp to find GPP. I see now that each Dew Point is directly correlated with a GPP # on the chart.
Would you say that most homes in the south have some sort of mold growth in them, since many families have their thermostat temperature set below the outdoor dewpoint temperature, during the summertime?
Maybe I missed that but how to you account for your ERV? Should nt you add a delta to external humidity due to ERV for your calculations? Say external humidity is 20 RH but ERV brings in air at 25 RH. This should allow to decrease and maybe eliminate the need for humidifier in a super tight home.
ok corbett- whats better in the summer for getting your 150 com per hour you need in your house - dehumidification- a ventilating dehumidifier OR an ERV ??
An ERV will not replace a dehu. Anyone in a house this tight needs both. Can’t use a vent dehum for positive pressure, because then my bathrooms would need exhaust fans, which would mean disaster.
Dear Sir, how can I contact you regarding a solution for our house in Barcelona by the sea? The house has been built in 1900, we made a complete refurbishment, 2 years after we are having massive issues with humidity. Looking forward to hearing from you, sincerely yours, H
Would love to help you H, but I’m on a 3 month hiatus to finish our tv series. If you can wait til October, magnifico, if not there are others I can refer you to at: BuildingPerformanceWorkshop.com
Any dehumidification from a comfort cooling system is a coincidence. Learn about Sensible Heat Ratio, in the home and the evaporator. Corbin gets a B on this presentation. Residential related HVAC products and product data would NOT make the cut in commercial environments and applications. Always hire a pro to measure the installed performance capacity of any HVAC system *airflow, refrigeration, SHR, dew point, IAQ, etc.
Wait. What if all my rooms are zoned And tightly foamed. Exterior and interior walls all foamed. As if each room is a separate house. Each with thier own thermostat. each a return and supply. I want to keep some rooms at 80 with just a ceiling fan. And maybe install the in wall dehumidifier units. Has anyone explored that route? For larger homes. 4/5000sqft
You’re a very good teacher.
I would highly recommend everyone oversize dehumidifier/humidifier by 20% minimum. The new systems will automatically actuate when needed.
Great info Corbett!
As a follow-up video, could you address the expense associated with humidity control and how much energy is saved by a) building air tight in both hot/humid and cold climates, and b) using an ERV vs an HRV in both climates as well? I did some math in a GBA forum post and I’d like to see if my calculations are anywhere close to what you come up with (I would trust you more than me). Thanks!!!
Crazy how much chemistry is involved in understanding this.
Great video especially explaining the delta grains method of sizing. This works great in a home like yours. 1.
I will say that pressure driven infiltration due to duct leakage and improper room pressure balancing will increase the amount of humidity and dehumidification needed. These problems need to be addressed if possible at the same time. But for those reasons, it’s ok to aim a little high in sizing hums and dehus as long as you don’t go crazy. 2. In my volunteer work designing high occupancy places of worship with lots of ventilation I created a worksheet to calculate the unmet latent load in order to size the dehu needed during full load and part load conditions and it even takes into account the de-rating of the dehu due to actual indoor conditions and duct friction. You might like it, I can send it to you. 3. If you need help installing that Aprilaire, I’ve put several in. With your low crawl, there might not be a natural steam tube rise between the humidifier and the duct connector and you might need to do a funky p trap.
As always, thank you Corbett!
Rock on Tim- let’s do a video on your calcs for worship spaces, comparing catholic and Pentecostal!
@@HomePerformance lol I think we both know which ones gonna produce more occupant sensible/ latent loads.
Maybe we could make the Caths feel more guilty about particle count
Tim- in a "whole house" set up, do you link the dehumidifier to the central blower (i would think so as the dehumidifier fans aren't sufficient to overcome most homes stays pressure in ducts without it) where do you install the intake and output from the dehumidifier ? aprilaire and Sante Fe have several options. I assume tapping into the return duct is obvious answer for intake, but what about where you dump the dehumidified air ? if you return the air prior to the central blower/HVAC coil, you are not exploiting your HVAC latent capacity, but if you return it to the output of the HVAC (his supply sducting) you end up fighting the central blower ops worse/?
@@johnwhite2576 Santa Fe/ Broan (same parent company) recommend a dedicated return but ducting into the Hvac return plenum is acceptable. Since the dehu makes hot air, it shouldnt supply back into a single room. It absolutely can duct back into the supply duct as long as supply static isnt over 0.3" wc, theres a backdraft damper in the dehu supply and theres room downstream in the supply duct before the first branch for good mixture.
Great video! Appreciate the myth busting at the beginning, and showing the math throughout!
Thx JJ
Great video. Wish you guys were on SI units already rather than half way. :)
Principal factor determining Δg/kg in a tight house:
* with HRV are external loads.
This is equivalent to 0% efficient ERV, or a leaky house
* with no ventilation (suffocation) are internal loads.
Equivalent to 100% efficient ERV.
* with typical ERV, external load >> internal load.
Therefore sized based on ventilation rate based on delta grams of water / kg of air method, upsized for realistic capacity. And noting ERV halves the ventilation impact on latent heat or humidity.
ERV Latent heat efficiency typically ~60%
Zehnder ComfoAir Q600 ERV ~ 68%.
BROAN ERV250 ECM ~ 55%
As latent efficiency improves I assume the principal factor will eventually shift from external to internal loads.
Thanks Vahid!
Love the channel, another very informative video. Is my understanding correct that as a whole house dehumidifier cannot be oversized? In other words if it helps arrive at the desired level of humidity fast, then that relative humidity is consistent throughout the entire building (assuming we'll sealed). Thanks
Correct, and thanks for following
Good info, agree with your math. With your sizing though, you may want to reconsider. Sizing both to the extremes when neither are the primary. HVAC isn't sized to the extremes either. Oversizing is going to happen, this may not matter with humidifier. Dehumidifier, unless it modulates will cause issues.
One little point about humidifiers. There are several types in the market. My experience is that when you actually want to control humidity, you need an electrode humidifier, like the aprilaire model referenced in the video. Other types either require heat to operating to add moisture the air or are drastically less effective when the heat is not running. Bypass, fan assist, mist type, might take the edge off but really not gonna work very well.
Disclaimer: My design day is like 8degrees if you live in a place where your design day is in the 20s then maybe you can get away with crappy humidifiers.
Agree. Atomizing are not effective. And electric element steam is an energy hog. In my old industrial hvac days we worked on ultrasonic humidifiers.
Ultraaonics create tons of particles- vid coming soon
@@HomePerformance i did not know that! I worked on these at the Civil Rights museum in Greensboro!
Great info! I enjoyed this thanks!
Excellent!
Thanks for the video. I have a dehumidifier that dumps into my return to the air handler. Where would be best to add an ERV? In-line with the dehumidifier, or before the dehumidifier, or after the dehumidifier in your opinion? My dehumidifier only moves about 140cfm (sante fe Ultra 70). It is currently set up to pull in inside and outside air, mix it, and push it into the return. I'm going to be planning for an ERV and was wanting your fact based opinions. Thank you so much!!!
Fantastic info coming from an engineer in TX!!
Hey thanks brother!
Fantastic video mate. Can a portable dehumidifier placed in the hallway work for multiple rooms simultaneously whose doors are open and connected to the hallway? Will it work that way? Assuming the four or five connected rooms are ranging from 8 to 16 sq.m and it can dehumidify multiple rooms at the same, how large a dehumidifier do I need?
Thanks for the info! There is a lot of different types of humidifier. What are the differences in them?
Damn, this video should have been longer. Oh well, watch this instead:
How to Craft a Home Ventilation System with Modular Components from Aprilaire
th-cam.com/video/006AntQSqIA/w-d-xo.html
@@HomePerformance Just watched it. A lot of good info. Thank you
Do ERVs also transfer some humidity, and if so, would this affect the delta target during the winter? And where do considerations like moisture from showers, cooking, breathing, etc come in, or are these sufficiently negligible so as not to be a concern?
Hello 👋 great video
You did mention about a website were you can take out the map from everywhere in the world and it will give you the “ load” your looking for to design HVAC …
what is the website adresse ?
Ashrae-meteo.info
How did you calculate the 120 Gr/Lb (outside) number? You stated this number right after determining the outdoor temperature of 80.4 & dew point of 73.3. There is another number on the chart (HR 128.5). Do you convert this number?
Thanks!
If you know two numbers, you can glean the third. Used the wheel calc like on the others.
@@HomePerformance OK thanks, looking it up online, some calculators ask for the RH number with the temp to find GPP. I see now that each Dew Point is directly correlated with a GPP # on the chart.
Would you say that most homes in the south have some sort of mold growth in them, since many families have their thermostat
temperature set below the outdoor dewpoint temperature, during the summertime?
Maybe I missed that but how to you account for your ERV? Should nt you add a delta to external humidity due to ERV for your calculations? Say external humidity is 20 RH but ERV brings in air at 25 RH. This should allow to decrease and maybe eliminate the need for humidifier in a super tight home.
It’s addressed in the dehu section, yes
@@HomePerformance ok so the size of the humidifier can also be decreased by roughly 50% with an ERV?
I wouldn’t assume the latent efficiency, but if the manufacturer shares that data then yes. Can’t hurt to upsize though.
ok corbett- whats better in the summer for getting your 150 com per hour you need in your house - dehumidification- a ventilating dehumidifier OR an ERV ??
An ERV will not replace a dehu. Anyone in a house this tight needs both. Can’t use a vent dehum for positive pressure, because then my bathrooms would need exhaust fans, which would mean disaster.
Have you ever consulted on HVAC design for let’s say a Greenhouse or Indoor Vertical farm?
Yes, and a cheese cave and several schoolies and a hobbit house! Send me more weird stuff, it’s my soul food.
@@HomePerformance Perfect! Strawberry Farm in the desert, coming your way soon!
Note that the video talks about other videos that are being linked, but no such links are actually showing up.
Thanks for the heads up Brad, fixing that today
Dear Sir, how can I contact you regarding a solution for our house in Barcelona by the sea? The house has been built in 1900, we made a complete refurbishment, 2 years after we are having massive issues with humidity. Looking forward to hearing from you, sincerely yours, H
Would love to help you H, but I’m on a 3 month hiatus to finish our tv series. If you can wait til October, magnifico, if not there are others I can refer you to at:
BuildingPerformanceWorkshop.com
@@HomePerformance thank for your prompt response. Good luck with the TV series. Best, H
🤣🤣🤣 Sometimes I'm an idiot." 🤣🤣🤣
At first glance I read *humanity control* was gonna say you can’t even trust your friendly building science guy anymore these days smh
One liquid pint equals 16 fluid ounces.
😮 okay I feel like an idiot
This would be so much easier in metric 😂
Maybe so
Any dehumidification from a comfort cooling system is a coincidence. Learn about Sensible Heat Ratio, in the home and the evaporator. Corbin gets a B on this presentation. Residential related HVAC products and product data would NOT make the cut in commercial environments and applications. Always hire a pro to measure the installed performance capacity of any HVAC system *airflow, refrigeration, SHR, dew point, IAQ, etc.
Not knowing ACHnat makes this calculation a crap shoot.
Correct
Wait. What if all my rooms are zoned And tightly foamed. Exterior and interior walls all foamed. As if each room is a separate house. Each with thier own thermostat. each a return and supply. I want to keep some rooms at 80 with just a ceiling fan. And maybe install the in wall dehumidifier units. Has anyone explored that route? For larger homes. 4/5000sqft