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When to use HRV?

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Deal Addict
Jan 6, 2015
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When to use HRV?

So I've been hearing people say turn on HRV in winter, and in summer turn it off vs. vice versa. Is there any benefit in the summer time to turn the HRV on? Wouldn't that bring in humidity into the house, something you don't want, thus making the A/C run harder?
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Deal Addict
Dec 17, 2007
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Alliston, ON
You want to run your HRV from fall to spring. You are correct in your reasons for not running it in the summer. Some don't agree with that, but the HRV does not dehumidify the hot humid air in the summer time. If you had an ERV, then you could run it in the summer
Deal Fanatic
Dec 19, 2009
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It is called a heat recovery ventilator which means it recovers some of the heat exhausted from the house by warming the incoming air it replaces. If they wanted you to use it in the summer it would be called a CRV (cool recovery ventilator).
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Feb 8, 2014
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This thread :facepalm:
Not the OPs fault, the fault lies in the misinformation and lack of knowledge out there.
pootza wrote: It is called a heat recovery ventilator which means it recovers some of the heat exhausted from the house by warming the incoming air it replaces. If they wanted you to use it in the summer it would be called a CRV (cool recovery ventilator).
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
Just like insulation helps keep your house cool in summer as well as keep in the heat in winter. People insulate to save on heating bills but it also saves on your cooling bills.

The HRV should be used year round. It is the ying to (more) airtight construction's yang. 1000ppm of CO2 affects cognition.
In fact in Rand McNally they wear hats on their feet and hamburgers eat people
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Dec 17, 2007
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Quentin5 wrote: This thread :facepalm:
Not the OPs fault, the fault lies in the misinformation and lack of knowledge out there.
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
It does not equalize temps.
It transfers some of the temp from the outgoing air to the incoming air, it works best when there is a larger difference in those temperatures. It also does not dehumidify the incoming air, therefore running it in the summer when humidity is high in Ontario is going to make your house feel much warmer and cause your a/c to run more to combat it and the higher humidity. If you're going to run it in the summer, do it on cooler days when the humidity is lower.
If you had an ERV (which is what should be installed in newer homes, vs the cheaper HRV) then you can run it in the summer as it does a better job of pulling the moisture out of the hot summer air.
Deal Fanatic
Dec 19, 2009
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Quentin5 wrote: This thread :facepalm:
Not the OPs fault, the fault lies in the misinformation and lack of knowledge out there.
pootza wrote: It is called a heat recovery ventilator which means it recovers some of the heat exhausted from the house by warming the incoming air it replaces. If they wanted you to use it in the summer it would be called a CRV (cool recovery ventilator).
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
Just like insulation helps keep your house cool in summer as well as keep in the heat in winter. People insulate to save on heating bills but it also saves on your cooling bills.

The HRV should be used year round. It is the ying to (more) airtight construction's yang. 1000ppm of CO2 affects cognition.
That's right, bring in that 100RH air to support the festering of mold spores so your children can breathe them all in and die at an early age of respiratory problems.

I have a 850sqft house, 8 ft ceilings with a basement and live alone. If I don't go outside or open my windows, how long before my house reaches the 1000ppm of CO2?
Deal Addict
Dec 14, 2011
2004 posts
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London
We were confused at first when we moved into our new home in June. The HRV was on and running. We asked the builder how to use it and he just referred us back to the little reference card that was stuck in the unit. Confusing. Finally read through the complicated big manual and figured out to turn it off. Still not sure how to use it properly since there appears to be so many settings 20/40, 40/20, continuous, etc. I'm not convinced this thing will actually help at all other than exchange fresh air into my supposedly 'tight' house.
Deal Addict
May 23, 2009
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Hmm....Maybe I should consider an ERV. How much does it cost to install one? What is a good brand?

My indoor CO2 goes past 1000ppm a couple of times a week in the summer. Exterior air is usually too hot and/or humid that I don't bother opening windows so I just wait till I turn on the range hood for cooking which drops it down to an acceptable level.
Somehow it stays acceptable in the winter which probably shows my house is a little leaky and able to self regulate the air exchange when the temperature differential is greater.
Deal Fanatic
Dec 19, 2009
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bubuski wrote: Hmm....Maybe I should consider an ERV. How much does it cost to install one? What is a good brand?

My indoor CO2 goes past 1000ppm a couple of times a week in the summer. Exterior air is usually too hot and/or humid that I don't bother opening windows so I just wait till I turn on the range hood for cooking which drops it down to an acceptable level.
Somehow it stays acceptable in the winter which probably shows my house is a little leaky and able to self regulate the air exchange when the temperature differential is greater.
Buy a couple of plants and you'll be fine.

And when you turn on your range hood to exhaust that air where do you figure the replacement air comes from to replace it ... IT COMES FROM OUTSIDE, yes that hot, humid outside air.
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Feb 8, 2014
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A few articles on HRVs
http://www.greenbuildingadvisor.com/blo ... ion-system
http://www.greenbuildingadvisor.com/blo ... hrv-or-erv
schade wrote:
Quentin5 wrote: This thread :facepalm:
Not the OPs fault, the fault lies in the misinformation and lack of knowledge out there.
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
It does not equalize temps.
It transfers some of the temp from the outgoing air to the incoming air, it works best when there is a larger difference in those temperatures. It also does not dehumidify the incoming air, therefore running it in the summer when humidity is high in Ontario is going to make your house feel much warmer and cause your a/c to run more to combat it and the higher humidity. If you're going to run it in the summer, do it on cooler days when the humidity is lower.
If you had an ERV (which is what should be installed in newer homes, vs the cheaper HRV) then you can run it in the summer as it does a better job of pulling the moisture out of the hot summer air.
Its a device that allows heat transfer between exhaust air from house to air coming in. In winter this means heat from house air going out preheats cold air coming in. It does not have 100% efficiency so the fresh air is not quite room temp. In summer hotter air coming in gets cooled by conditioned air going out. Hence the fresh air is cooler then outside air, once again not 100% efficient. Think of it as two metal pipes in physical contact when there is a temperature difference, they start equalizing in temp. This principle is now an HRV works. The laws of thermodynamics don't disappear because we have wrong beliefs.

pootza wrote:
Quentin5 wrote: This thread :facepalm:
Not the OPs fault, the fault lies in the misinformation and lack of knowledge out there.
pootza wrote: It is called a heat recovery ventilator which means it recovers some of the heat exhausted from the house by warming the incoming air it replaces. If they wanted you to use it in the summer it would be called a CRV (cool recovery ventilator).
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
Just like insulation helps keep your house cool in summer as well as keep in the heat in winter. People insulate to save on heating bills but it also saves on your cooling bills.

The HRV should be used year round. It is the ying to (more) airtight construction's yang. 1000ppm of CO2 affects cognition.
That's right, bring in that 100RH air to support the festering of mold spores so your children can breathe them all in and die at an early age of respiratory problems.

I have a 850sqft house, 8 ft ceilings with a basement and live alone. If I don't go outside or open my windows, how long before my house reaches the 1000ppm of CO2?
Oh please, if you want to be a moron and believe stupidity that your business, but telling other people garbage to protect your ego is despicable.
In an older home the air exchange uncontrolled, variable and much higher then most HRVs. So much for preventing mold. :facepalm: Also uncontrolled and often bidirectional air leakage is more likely to lead to mold in hidden walls. The controlled and measured air delivered by HRVs is enough to dilute contaminants, vent CO2, provide oxygen and does not pressurize or depressurize a house. HRVs often have filters and can even be HEPA filtered, so in fact the air is of better quality then opening a window. So you give a free pass to uncontrolled ventilation which is randomly over or under ventilated, and tell people to breathe polluted air because your ego is at stake. :facepalm:
An HRV does have a slight efficiency penalty, but its lower then high uncontrolled leakage and is better for your house and health then depending on leaky construction.
Of course your not going to accept any of this and keep peddling stupidity. Your welcome to prove me wrong.

Drakestar wrote:We were confused at first when we moved into our new home in June. The HRV was on and running. We asked the builder how to use it and he just referred us back to the little reference card that was stuck in the unit. Confusing. Finally read through the complicated big manual and figured out to turn it off. Still not sure how to use it properly since there appears to be so many settings 20/40, 40/20, continuous, etc. I'm not convinced this thing will actually help at all other than exchange fresh air into my supposedly 'tight' house.
Thats the point, to exhaust stale air and bring in fresh air at constant rates. HRVs need to be set at flow rates for the house when they are isntalled, intake/exhaust rates set at ASHRAE 62.2. The actual ventilation rates needed are under debate, but no one in the field will argue that random and constantly changing rates are superior to measured ones.
ERVs are more expensive and often unreliable, i've heard many stories of them not operating correctly but if you want to spend the money do lots of research and read all the reviews you can before picking a model. I would personally stick with the HRV. One of the links above explains more about ERVs and where they may be useful.
Also most builders resent HRVs because they add cost and need to be calibrated :rolleyes:
bubuski wrote:Hmm....Maybe I should consider an ERV. How much does it cost to install one? What is a good brand?

My indoor CO2 goes past 1000ppm a couple of times a week in the summer. Exterior air is usually too hot and/or humid that I don't bother opening windows so I just wait till I turn on the range hood for cooking which drops it down to an acceptable level.
Somehow it stays acceptable in the winter which probably shows my house is a little leaky and able to self regulate the air exchange when the temperature differential is greater.
In winter the stack effect removes air out your attic through light fixtures, gaps in the ceiling, attic hatch and any other cracks or holes at the top of the structure. This brings in cold air, often from the basement gaps which keeps your CO2 down. This can introduce large amounts of radon to the indoors if the levels in the soil are high. The neutral pressure plane usually keeps the cold air coming in from the basement gaps, this is a more complicated concept.
The stack effect is surprisingly strong and in winter this lowers your indoor humidity. Humidifiers on furnaces are actually considered bad for the structure of the house (except hardwood floors). Stack effect heat loss is somewhat good in your case, just enough to lower CO2, but is bad for your attic (if high enough to deposit moisture on underside of roof sheathing, (mold/rot), and is a double whammy on heating cost, hot air lost and ice cold air brought in. Its also variable, the colder the temp the higher the effect, so the highest bills are on the coldest days, a -10C day may cost X dollars a day and -20C may cost 2.5X (numbers not exact) because of the multiplying nature of the stack effect. Also most houses are insulated with fiberglass or cellulose which are air permeable, which do not inhibit the stack effect. In building science we say build tight and ventilate right.
pootza wrote:
bubuski wrote: Hmm....Maybe I should consider an ERV. How much does it cost to install one? What is a good brand?

My indoor CO2 goes past 1000ppm a couple of times a week in the summer. Exterior air is usually too hot and/or humid that I don't bother opening windows so I just wait till I turn on the range hood for cooking which drops it down to an acceptable level.
Somehow it stays acceptable in the winter which probably shows my house is a little leaky and able to self regulate the air exchange when the temperature differential is greater.
Buy a couple of plants and you'll be fine.

And when you turn on your range hood to exhaust that air where do you figure the replacement air comes from to replace it ... IT COMES FROM OUTSIDE, yes that hot, humid outside air.
A couple of plants will save you, the rate of air pollution and CO2 removal is undetermined and varies on species and size, and your plants will raise the humidity your so scared of, but they are superior to an HRV because you disagree with decades of research and development.
Oh, and your contradicting yourself, your correct that exhaust fans bring in outdoor air, yet you oppose HRVs that help mitigate this hot/cold loss and is better then a mechanical device meant to ventilate correctly.
If you want to believe nonsense thats your business, screwing other people over is stupid. I see more insults and denials coming in reply to this post, because your smarter then building scientists who devote their lives to this field. :facepalm:
In fact in Rand McNally they wear hats on their feet and hamburgers eat people
Deal Expert
Aug 22, 2011
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Quentin5 correct.
I run my HRV all year round with the timer set to 20min on, 40min off.
The incoming air will be heated/cooled by the heat exchanger at whatever the temp your basement is at and then distributed via the furnace (if it's interlocked with the furnace).
Deal Addict
Nov 30, 2011
1161 posts
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HRM
foodyforlife wrote: So I've been hearing people say turn on HRV in winter, and in summer turn it off vs. vice versa.
This is a good "How To" video:
Deal Addict
Jan 6, 2015
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westcoastyvr wrote:
foodyforlife wrote: So I've been hearing people say turn on HRV in winter, and in summer turn it off vs. vice versa.
This is a good "How To" video:
SO the video for spring/summer he said HRV doesn't run, that's the jist that I got.
Penalty Box
Nov 23, 2012
1451 posts
266 upvotes
Toronto
Quentin5 wrote:
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
Just like insulation helps keep your house cool in summer as well as keep in the heat in winter. People insulate to save on heating bills but it also saves on your cooling bills.

The HRV should be used year round. It is the ying to (more) airtight construction's yang. 1000ppm of CO2 affects cognition.
Do I need to send you a link for the definition of equalization?
If the HRV made the outside air and inside air it sucked in then it would equalize. It may make the temperatures delta less but it doesn't make them the same does it?

PS. I couldn't edit through all your blather to show the guy you are quoting but simply you are wrong and doubling down on it.
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Feb 8, 2014
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tungustungus wrote:
Quentin5 wrote:
Nice try, but it equalizes temps between intake and exhaust so it does cool incoming air.
Just like insulation helps keep your house cool in summer as well as keep in the heat in winter. People insulate to save on heating bills but it also saves on your cooling bills.

The HRV should be used year round. It is the ying to (more) airtight construction's yang. 1000ppm of CO2 affects cognition.
Do I need to send you a link for the definition of equalization?
If the HRV made the outside air and inside air it sucked in then it would equalize. It may make the temperatures delta less but it doesn't make them the same does it?

PS. I couldn't edit through all your blather to show the guy you are quoting but simply you are wrong and doubling down on it.
So you can't "blather" yourself some reading comprehension?
I'd mock you but the challenge is gone Face With Tears Of Joy
In fact in Rand McNally they wear hats on their feet and hamburgers eat people
Penalty Box
Nov 23, 2012
1451 posts
266 upvotes
Toronto
Quentin5 wrote: So you can't "blather" some reading comprehension?
I'd mock you but the challenge is gone Face With Tears Of Joy
?
I couldn't edit your blather, that means I tried to go through all the text of your blather and could not easily get all those quotes separated out so the thread would show correctly.

Admitting you were wrong seems to be quite the challenge for you.
I suppose that by giving up in failure you have left the challenge behind. Oh well.
Newbie
Mar 18, 2012
62 posts
25 upvotes
Winnipeg, MB
I'm going to answer this question simply. An hrv is there to exchange air in your house. It exhausts air from your house and brings in fresh air from outside. I recommend a Carbon and uv light filtration system be paired with the hrv to keep the air in your house as clean as possible.
Deal Addict
Jan 6, 2015
2860 posts
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Toronto, ON
RHarrison wrote: I'm going to answer this question simply. An hrv is there to exchange air in your house. It exhausts air from your house and brings in fresh air from outside. I recommend a Carbon and uv light filtration system be paired with the hrv to keep the air in your house as clean as possible.
But by definition HRV means heat recovery ventilator. So the question is do you bring humidity from outside the house inside, during the summer? And make the a/c work harder to cool that warmer air coming in?
Deal Expert
Aug 22, 2011
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foodyforlife wrote:
RHarrison wrote: I'm going to answer this question simply. An hrv is there to exchange air in your house. It exhausts air from your house and brings in fresh air from outside. I recommend a Carbon and uv light filtration system be paired with the hrv to keep the air in your house as clean as possible.
But by definition HRV means heat recovery ventilator. So the question is do you bring humidity from outside the house inside, during the summer? And make the a/c work harder to cool that warmer air coming in?
By the time that humid air gets through the heat exchanger core, mix with the cold a/c air in the furnace, it's negligible.
As stated, I've been running an HRV all year round and there's no drawback and air quality is much better, as the system also exhaust the inside air.
Penalty Box
Nov 23, 2012
1451 posts
266 upvotes
Toronto
vkizzle wrote:
foodyforlife wrote:
RHarrison wrote: I'm going to answer this question simply. An hrv is there to exchange air in your house. It exhausts air from your house and brings in fresh air from outside. I recommend a Carbon and uv light filtration system be paired with the hrv to keep the air in your house as clean as possible.
But by definition HRV means heat recovery ventilator. So the question is do you bring humidity from outside the house inside, during the summer? And make the a/c work harder to cool that warmer air coming in?

By the time that humid air gets through the heat exchanger core, mix with the cold a/c air in the furnace, it's negligible.
As stated, I've been running an HRV all year round and there's no drawback and air quality is much better, as the system also exhaust the inside air.
It is not negligible. ERV is better. run em all year

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