We get sick a lot in the winter because were indoors more so that HRV or ERV is a help those appliances will make a world of a difference especially when it’s too cold to go outside
Steve, as you say, condensation on the windows can be an indicator of insufficient ventilation, but I'd say, more often it is due to very badly insulated windows. As an example, we have a window which always has condensation on it, even when humidity is below the ideal humidity range (under 30% rel humidity). In this case it just means that the windows interior surface temperature is below the due point, probably below 10deg C in our case (I wouldn't be surprised if it was close to freezing during the coldest parts of winter). The dilemma is now, use an HRV to dry out the air inside to uncomfortable levels (dry lips, itchy skin) and have no condensation, or leave it a bit higher and risk condensation (and potentially mould growth).
Good Morning Hans-Jorn! Thanks for you note. Good to hear from you again. In my experience, most windows in heating climates are sealed double-pane units that deliver decent (though not great) insulation values. And while it's true that the higher the insulating value of windows gets, the less likely window condensation is to form. But given the current state of typical window technology I've found that condensation is still a useful indicator of indoor air quality. That may change over the decades as windows get better, but for now typical windows are still a good yardstick. Poorly insulated windows would prompt one to install an HRV even sooner, and that's not a bad thing. Interestingly enough, a whole house of really bad windows (i.e. windows that leak plenty of air) often prevent window condensation because they allow so much moisture to escape naturally. Of course no one wants this, but it is an example of poor windows solving the indoor air quality problem in a round-about way. In my tests, indoor relative humidity levels of about 40% to 50% is the threshold of comfort for most people in winter. Anything more than this also triggers window condensation in most standard, double-pane windows at anything colder than about -5ºC to -10ºC. Anyway, just some thoughts and experiences! Thanks for watching. Steve
Hi Alex! For some reason there was no reply button under your comment, so I had to start a new one . . . All your questions are great, and I'll give you a quick answer for each: 1. A 2 story home only needs one HRV. Our house is 3 stories and one unit does a fine job. 2. HRVs are usually installed in basements because the space there is at less of a premium. They can be installed anywhere in a home, though, as long as the space is heated. Intake and outgoing ducts should be place to force air to travel throughout the house. At our place we have fresh air output duct on the second floor and stale air intake on the floor below. This forces circulation throughout the building. 3. HRVs come in different sizes, based on the size of building you're ventilating. I hope this helps. Please let me know. You'll find lots of other good stuff about tools, homesteading, power tools and construction at stevemaxwell.ca. Drop by for a visit. I've got a big tool giveaway happening now. Bye, Steve
Very interesting. I don't have forced hot air (combo baseboard and radiant) no condensation on windows. Would I still need a HRV. I do have two a/c units 2.5 ton each. would I need 2 HRV?
Hi Ken, Thanks for commenting and watching! One HRV can work fine, even in a home with no ducts. I know this from experience, and it all comes down to where you locate the stale air intake and fresh air ports. Do you like in a cold climate? Where it gets down to, say, at least 5 degrees below freezing? If you do and there's no window condensation, then you almost certainly have enough natural air leakage to keep indoor air at a good quality level. I hope this helps. Please let me know. Bye for now, Steve
My house seriously needs something like this bad because we always get sick in the winter in Virginia it’s recommended to go for ERV because of the warm humid summers in the cold dry winters
Hey Steve, I noticed your video though very informative, did not touch on the subject of proper installation and placement of an HVR in a typical home. Would a 2 story house require 2 units? Is there a particular area of the house that the unit should be installed in? Do HRV's come in different sizes? ---Alex
On a slight tangent but related to energy exchange; my roof space is well insulated, (R3.2) and the roof is iron. It gets very hot in summer in the roof space. Would this effect an HRV unit? Secondly could I use the hot air in the space to feed a heat pump connected to the hot water cylinder? This might help such a heat pump work more on its heat pump cycle in winter as I would anticipate that the roof space would still be warmer than the ambient air temp outside even if a small amount of sun fell on the iron roof.
David, when we spec HRVs or ERVs, we generally recommend HRVs in heating dominated climates and ERVs in cooling dominated climates (in the southern states). HRVs don't transfer moisture, and running an HRV too high (too many air changes per hour [ACH]), can dry out your house below comfort levels (below 30% real humidity). The solution is to slow the air rate down. You only need about .3 ACH and at that rate an HRV will generally keep the indoor humidity at a comfortable level. In the south (cooling dominated climate) you want to avoid bringing too much humidity inside and therefor the transfer of humidity from the incoming stream of air onto the outgoing exhaust air works well. Lastly, I hear arguments for both sides, but this is what we recommend when designing Zehnder ComfoSystems.
I know im responding pretty late but the erv or hrv has a built in filter system. Usually the filters are Hepa filters. Think of an exhaust fan that also pulls in fresh air or in your case bad air from outside and then filters it immensely and conditions or heats from your hvac system.
Would it not take forever to get your investment back buying an HRV in energy savings compared to a normal intake or exhaust fan? Over a maybe 20 year period it might save energy, but I think it would take a LONG time to get your investment back.
Not about saving money. It is about comfort and health. Going from no hvac to a ducted central unit will never pay for itself either, but it sure is more confortable. While I am not an advocate for hrv/erv I am for ventilation to maintain a positive pressure through other means. Not because it will pay for itself though, but because it is healthier. #housesdontneedtobreath #peopledo #moisturekillshouses #electrifyeveryyhing
Low intelligence people think that science = whatever is trendy. It doesn’t even OCCUR to them that something can be necessary, without being mainstream and popularly talked about. The reality is, IAQ matters. It’s not the ONLY thing- healthy eating matters too. But for brain health especially, and to prevent allergies, IAQ matters
Well presented.
TONS of good advice, so that the home owner can make up his/her own mind.
this guy has some pro sales skills
I know 😂 I felt like I was listening to an audio book or something
We get sick a lot in the winter because were indoors more so that HRV or ERV is a help those appliances will make a world of a difference especially when it’s too cold to go outside
Steve, as you say, condensation on the windows can be an indicator of insufficient ventilation, but I'd say, more often it is due to very badly insulated windows. As an example, we have a window which always has condensation on it, even when humidity is below the ideal humidity range (under 30% rel humidity). In this case it just means that the windows interior surface temperature is below the due point, probably below 10deg C in our case (I wouldn't be surprised if it was close to freezing during the coldest parts of winter).
The dilemma is now, use an HRV to dry out the air inside to uncomfortable levels (dry lips, itchy skin) and have no condensation, or leave it a bit higher and risk condensation (and potentially mould growth).
Good Morning Hans-Jorn!
Thanks for you note. Good to hear from you again.
In my experience, most windows in heating climates are sealed double-pane units that deliver decent (though not great) insulation values. And while it's true that the higher the insulating value of windows gets, the less likely window condensation is to form. But given the current state of typical window technology I've found that condensation is still a useful indicator of indoor air quality. That may change over the decades as windows get better, but for now typical windows are still a good yardstick. Poorly insulated windows would prompt one to install an HRV even sooner, and that's not a bad thing.
Interestingly enough, a whole house of really bad windows (i.e. windows that leak plenty of air) often prevent window condensation because they allow so much moisture to escape naturally. Of course no one wants this, but it is an example of poor windows solving the indoor air quality problem in a round-about way.
In my tests, indoor relative humidity levels of about 40% to 50% is the threshold of comfort for most people in winter. Anything more than this also triggers window condensation in most standard, double-pane windows at anything colder than about -5ºC to -10ºC.
Anyway, just some thoughts and experiences! Thanks for watching.
Steve
I suffer from allergies and the air quality in my home is not too good. Thank you for this.
Hi Alex!
For some reason there was no reply button under your comment, so I had to start a new one . . .
All your questions are great, and I'll give you a quick answer for each:
1. A 2 story home only needs one HRV. Our house is 3 stories and one unit does a fine job.
2. HRVs are usually installed in basements because the space there is at less of a premium. They can be installed anywhere in a home, though, as long as the space is heated. Intake and outgoing ducts should be place to force air to travel throughout the house. At our place we have fresh air output duct on the second floor and stale air intake on the floor below. This forces circulation throughout the building.
3. HRVs come in different sizes, based on the size of building you're ventilating.
I hope this helps. Please let me know.
You'll find lots of other good stuff about tools, homesteading, power tools and construction at stevemaxwell.ca. Drop by for a visit. I've got a big tool giveaway happening now.
Bye,
Steve
Hi Steve!
Who said there's no reply button? xD
Very interesting. I don't have forced hot air (combo baseboard and radiant) no condensation on windows. Would I still need a HRV. I do have two a/c units 2.5 ton each. would I need 2 HRV?
Hi Ken,
Thanks for commenting and watching!
One HRV can work fine, even in a home with no ducts. I know this from experience, and it all comes down to where you locate the stale air intake and fresh air ports.
Do you like in a cold climate? Where it gets down to, say, at least 5 degrees below freezing? If you do and there's no window condensation, then you almost certainly have enough natural air leakage to keep indoor air at a good quality level.
I hope this helps. Please let me know.
Bye for now,
Steve
My house seriously needs something like this bad because we always get sick in the winter in Virginia it’s recommended to go for ERV because of the warm humid summers in the cold dry winters
Hey Steve,
I noticed your video though very informative, did not touch on the subject of proper installation and placement of an HVR in a typical home.
Would a 2 story house require 2 units?
Is there a particular area of the house that the unit should be installed in?
Do HRV's come in different sizes?
---Alex
On a slight tangent but related to energy exchange; my roof space is well insulated, (R3.2) and the roof is iron. It gets very hot in summer in the roof space. Would this effect an HRV unit? Secondly could I use the hot air in the space to feed a heat pump connected to the hot water cylinder? This might help such a heat pump work more on its heat pump cycle in winter as I would anticipate that the roof space would still be warmer than the ambient air temp outside even if a small amount of sun fell on the iron roof.
Air purifier and ventilation both works.
I wish you had touched on ERVs. I still am confused about when I would want an ERV vs. and HRV.
David, when we spec HRVs or ERVs, we generally recommend HRVs in heating dominated climates and ERVs in cooling dominated climates (in the southern states). HRVs don't transfer moisture, and running an HRV too high (too many air changes per hour [ACH]), can dry out your house below comfort levels (below 30% real humidity). The solution is to slow the air rate down. You only need about .3 ACH and at that rate an HRV will generally keep the indoor humidity at a comfortable level.
In the south (cooling dominated climate) you want to avoid bringing too much humidity inside and therefor the transfer of humidity from the incoming stream of air onto the outgoing exhaust air works well.
Lastly, I hear arguments for both sides, but this is what we recommend when designing Zehnder ComfoSystems.
Your website is no longer up..😮
Good video
What about if the "fresh air" is in a dense urban area like London and you'd just be making the air quality worse
I know im responding pretty late but the erv or hrv has a built in filter system. Usually the filters are Hepa filters.
Think of an exhaust fan that also pulls in fresh air or in your case bad air from outside and then filters it immensely and conditions or heats from your hvac system.
interesting friends of mine have this problem I will pass this info on, my 165 year old home doesn't suffer from this lol
Would it not take forever to get your investment back buying an HRV in energy savings compared to a normal intake or exhaust fan? Over a maybe 20 year period it might save energy, but I think it would take a LONG time to get your investment back.
Not about saving money. It is about comfort and health.
Going from no hvac to a ducted central unit will never pay for itself either, but it sure is more confortable.
While I am not an advocate for hrv/erv I am for ventilation to maintain a positive pressure through other means. Not because it will pay for itself though, but because it is healthier.
#housesdontneedtobreath
#peopledo
#moisturekillshouses
#electrifyeveryyhing
Just open your doors and windows. Let air out.. the more the better.
My home needs this bad . I get laughed at when I mention the air quality being dangerous to my health
Low intelligence people think that science = whatever is trendy. It doesn’t even OCCUR to them that something can be necessary, without being mainstream and popularly talked about. The reality is, IAQ matters. It’s not the ONLY thing- healthy eating matters too. But for brain health especially, and to prevent allergies, IAQ matters