Canadian Money Forum banner
1 - 20 of 29 Posts

·
Registered
Joined
·
4,891 Posts
Discussion Starter · #1 ·
we have a Venmar Constructo 2.0 HRV air exchanger. First time I've had a house with an AE.
Does everyone just turn it on & forget it? any fiddling with it on a day to day basis?
 

·
Registered
Joined
·
14,986 Posts
You need to clean/replace filters periodically. You may want to increase/decrease the percentage of time it runs or fan speed depending on various factors (say, for a party with many guests or the weather vs electricity usage).
 

·
Registered
Joined
·
70 Posts
we have a Venmar Constructo 2.0 HRV air exchanger. First time I've had a house with an AE.
Does everyone just turn it on & forget it? any fiddling with it on a day to day basis?
I have almost the same unit and installed it myself and have had it for about 4 years. First thing, HRVs and air exchangers are different, air exchangers are simpler machines that swap out the air, HRVs do change the air but retain heat and remove moisture through the process. HRVs are primarily used in colder climates. If your house is sealed tight it removes the moisture (especially in the winter) while retaining some of the heat. It also removes the polluted air in your home, house air can be pretty polluted from breathing, cooking etc. it's kinda crazy actually. My HRV has a wall unit I installed, it detects the moisture in the home and turns the unit off and on - I don't really use it that way except during the winter. It has high, low and a cycle setting. I also setup a furnace interloc so the HRV turns on the furnace fan automatically when it starts. My old house had a very simple HRV and I used a simple outlet timer to turn it off and on.

You want to calculate how long it will take the HRV to replace the air in your home, mine is about 8 hrs. About once a week in the summer on cooler nights I'll flip it on before bed and flip it off in the morning. The house stays fresh that way.

In the winter I tend to run it more often, almost daily either with the humidity detection from the wall control or just turn it on during the days, I monitor the humidity so it's not too dry or damp in the house. I measure the humidity on each floor.

I also run a dehumidifier in the basement. I really love the fresh air and controlling my humidity. My unit tells me when to clean the filter, there is an error on the wall unit but it's rarely actually dirty. I find that when the power blinks in my area it causes the unit to stick on and it must be powered off to reset it. Mine is not hardwired. Lastly when you clean the unit (filter etc) they can be tricky to reassemble, pay close attention and take pics. Mine has a couple filters and plastic cube in the center.

Hope that helps!

Si~
 

·
Registered
Joined
·
2,342 Posts
Informative post @Simon Says. We installed central air and an HRV earlier this summer to our well built but not well sealed mid 1950s home. It is well constructed for its time but the building envelope is not the same as a newer home. The climate I live in is fairly dry and air quality in general is good. I presume our unit will have to work harder to maintain a constant interior environment in comparison to a newer home. Is there anything we should be mindful of in operation or maintenance beyond what you've posted until we replace the windows and add insulation to the attic?
 

·
Registered
Joined
·
1,863 Posts
We have an HRV in our home. We didnt put bathroom fans in and instead rely on the HRV kicking in high gear when needed to get rid of moisture.
Ours is set up to run 40 mins off/20 mins on. There is an override when the inside humidity goes above some amount (I think it's 50%), it stays on 100% of the time. But there are certain times of year that is quite pointless in that the external humidity is higher (at the same temp), which means the humidity would never drop inside the house.
 

·
Registered
Joined
·
4,891 Posts
Discussion Starter · #6 ·
I have almost the same unit and installed it myself and have had it for about 4 years. First thing, HRVs and air exchangers are different, air exchangers are simpler machines that swap out the air, HRVs do change the air but retain heat and remove moisture through the process. HRVs are primarily used in colder climates. If your house is sealed tight it removes the moisture (especially in the winter) while retaining some of the heat. It also removes the polluted air in your home, house air can be pretty polluted from breathing, cooking etc. it's kinda crazy actually. My HRV has a wall unit I installed, it detects the moisture in the home and turns the unit off and on - I don't really use it that way except during the winter. It has high, low and a cycle setting. I also setup a furnace interloc so the HRV turns on the furnace fan automatically when it starts. My old house had a very simple HRV and I used a simple outlet timer to turn it off and on.

You want to calculate how long it will take the HRV to replace the air in your home, mine is about 8 hrs. About once a week in the summer on cooler nights I'll flip it on before bed and flip it off in the morning. The house stays fresh that way.

In the winter I tend to run it more often, almost daily either with the humidity detection from the wall control or just turn it on during the days, I monitor the humidity so it's not too dry or damp in the house. I measure the humidity on each floor.

I also run a dehumidifier in the basement. I really love the fresh air and controlling my humidity. My unit tells me when to clean the filter, there is an error on the wall unit but it's rarely actually dirty. I find that when the power blinks in my area it causes the unit to stick on and it must be powered off to reset it. Mine is not hardwired. Lastly when you clean the unit (filter etc) they can be tricky to reassemble, pay close attention and take pics. Mine has a couple filters and plastic cube in the center.

Hope that helps!

Si~

good info simon. thanks!
Not being too scientifically- inclined.....I wonder just how effective these machines are in colder, damp(humid) areas, like here in St. John's, where outside humidity is almost always above 75-80% (a lot of time 100%!) ?
Aren't you continuously just dragging cold, damp outside air into the house.....?
 

·
Registered
Joined
·
14,986 Posts
good info simon. thanks!
Not being too scientifically- inclined.....I wonder just how effective these machines are in colder, damp(humid) areas, like here in St. John's, where outside humidity is almost always above 75-80% (a lot of time 100%!) ?
Aren't you continuously just dragging cold, damp outside air into the house.....?
Cold air can't hold very much moisture, so even in cold climates with high humidity, once you warm up the outdoor air it has low relative humidity.
 

·
Registered
Joined
·
7,182 Posts
good info simon. thanks!
Not being too scientifically- inclined.....I wonder just how effective these machines are in colder, damp(humid) areas, like here in St. John's, where outside humidity is almost always above 75-80% (a lot of time 100%!) ?
Aren't you continuously just dragging cold, damp outside air into the house.....?
The new ones are designed to use the temperature of the outgoing air to adjust the temperature of the incoming air by running them next to each other. Not sure how effective they are say in a Canadian winter when temperature differences are so extreme.

I think we could improve on this a lot. For example having the incoming air run through a line underground would warm/cool the air. For humidity I don't know if they combine those. My HVAC has humidity control using smart thermostats etc. I assume it uses the AC in the summer and adds humidity to try air in the winter
 

·
Registered
Joined
·
14,986 Posts
There is an excellent wikipedia entry on humidity. Here is the article and the pertinent chart.



100% humidity air around 0C can hold about 5g of water per kg of air. Air that is 20C can hold about 15g of water per kg. So if you take 100% humidity air at 0C and warm it to 20C, it can only have 5g of water out of a possible 15g, so it will only be about 33% relative humidity.

This is how air conditioners remove humidity from air, by the way. ACs cool the air, and since cold air can only hold so much water, much of it condenses on the heat exchanger. When that very cold air mixes with the warmer air in the rest of the home it averages out to a lower relative humidity.
 

·
Registered
Joined
·
1,075 Posts
Mine triggers on high speed fan on a humidistat mounted in the exhaust air side of the air to air heat exchanger.

Find we only need it in the winter, as unless like last week in southern ontario.Most of the time at least one window is open a bit once the furnace is not needed.

We rarely run a/c 24 hours a day.
More often open the house up at 7pm, and close at 7am and a/c triggers itself on about 1-3pm on a warm day.

House is circa 1967, but we have tightened envelope over time.

-new windows
-exterior steel clad doors
-second floor 2" thick seam taped foil faced rigid insulation under replacement siding
-foam seal through holes in back of electric outlets as part of dealing with aluminum wire connections.-
-better basement joist header insulation and sealing.
-lock top fire place damper and foam plug that goes into the heath opening once it is cold.
-insulate and better seal the attic access hatch.

I find I need to prime the water trap after it has sat idle over the summer. Otherwise some air bypasses through the trap.

Compared to high eff nat gas furnace the intake air pre warmer is all electric, and can run up the electric bill if you don't watch it, so we watch and sometimes shut the hrv off if the moisture source is just transitory.
 

·
Registered
Joined
·
7,182 Posts
this is the one I have

View attachment 23469
Notice how it has that drain hose? That means it impacts humidity somehow

Notice how it has multiple intakes and exhausts? It's running the fresh air next to the old air to warm/cool the fresh air which would also impact humidity with temp change

Again google is your friend. Have you even opened the owner's manual? I owned one of these and it had 3 settings - Off, Normal, Max.
 

·
Registered
Joined
·
1,897 Posts
The science needs to evolve. There needs to be one system that exchanges and dehumidifies the air. Currently we have whole house dehumidifiers (WHD) with fresh air intake and HRV's / ERV's. Some combine the two. We need one system. HRV's are useless in the summer, especially when one is using them as their only exhaust vents. Adding warm fresh moist air into a cold basement is a recipe for condensation, mold, etc. WHD's with fresh air intakes don't exchange air, don't recover lost heat, etc. Most HVAC techs are lost and wouldn't be able to balance a complicated system. Ask questions in Ontario and you'll likely get many blank stares.

Regardless of climate one system should be developed that can exchange / filter air, recover lost heat and add dehumidification. All while working in harmony with forced air heating and cooling - balance.
 

·
Registered
Joined
·
7,182 Posts
Ask questions in Ontario and you'll likely get many blank stares.

Regardless of climate one system should be developed that can exchange / filter air, recover lost heat and add dehumidification. All while working in harmony with forced air heating and cooling - balance.
What do you expect from a group that rents hot water heaters

I've watched some youtube videos for simple things home builders can do to improve efficiency. A lot of it costs next to nothing but takes the extra time

I realized most things are designed to look appealing and that's it
 

·
Registered
Joined
·
4,891 Posts
Discussion Starter · #16 ·
Notice how it has that drain hose? That means it impacts humidity somehow

Notice how it has multiple intakes and exhausts? It's running the fresh air next to the old air to warm/cool the fresh air which would also impact humidity with temp change
not sure what you imply mp3.....yes, I notice those things....are they good or bad?
& yes, I've read the manual...several times...
 

·
Registered
Joined
·
7,182 Posts
Does everyone just turn it on & forget it? any fiddling with it on a day to day basis?
Yes I just turn it on & forget. Unless outside air is too humid or too cold anyways

So basically it's useless for 11 month of year in Newf land? 😂

Actually I find them useful. Just needs more planning like routing the air intake underground imo
 

·
Registered
Joined
·
113 Posts
The science needs to evolve. There needs to be one system that exchanges and dehumidifies the air. Currently we have whole house dehumidifiers (WHD) with fresh air intake and HRV's / ERV's. Some combine the two. We need one system. HRV's are useless in the summer, especially when one is using them as their only exhaust vents. Adding warm fresh moist air into a cold basement is a recipe for condensation, mold, etc. WHD's with fresh air intakes don't exchange air, don't recover lost heat, etc. Most HVAC techs are lost and wouldn't be able to balance a complicated system. Ask questions in Ontario and you'll likely get many blank stares.

Regardless of climate one system should be developed that can exchange / filter air, recover lost heat and add dehumidification. All while working in harmony with forced air heating and cooling - balance.
There is a good line of HRV/ERV from Zehnder which was pretty much state of the art when we built a house 5 years ago. We installed one of the Zehnder HRVs as part of the Passive House building standard to control air flow between inside and outside. This gives you something close to what you describe for one system. But the 'system' is the whole house not an add-on unit for retrofit. I keep ours going 24/7 365 to ensure lots of fresh air since the house is basically airtight. When it's cool outside in the summer we open windows of course. The Zehnder HRVs have a 'night cooling' feature to close a damper so fresh air bypasses the heat exchanger when outside temp is cooler than inside temp so that helps a bit.

To your point about science needing to evolve. The building science, construction details and qualified products are out there. The building codes need to improve though for new builds and until that happens this will remain a niche technology for enthusiasts. The cost added to a new home build is reasonable about 10% overall, but it's a struggle to find trained builders and tradespeople who are invested in efficiency. But they are out there for sure.
 

·
Registered
Joined
·
7,182 Posts
To your point about science needing to evolve. The building science, construction details and qualified products are out there. The building codes need to improve though for new builds and until that happens this will remain a niche technology for enthusiasts. The cost added to a new home build is reasonable about 10% overall, but it's a struggle to find trained builders and tradespeople who are invested in efficiency. But they are out there for sure.
Yea it's a shame

There's lots of good youtube videos on it and looked like no-brainer stuff to do. The cost would easily pay itself off over the life of the house. It was impressive how much less demand was on the HVAC

For builders who need to compete and sell houses it's just not worth it short term. Reality is consumer decisions are based on superficial things
 

·
Registered
Joined
·
113 Posts
For builders who need to compete and sell houses it's just not worth it short term. Reality is consumer decisions are based on superficial things
Exactly right. I'd guess that an ultra-low energy house package (like passive house) would be about number 10 on a list of top 10 items buyers want in a new house. We need an HGTV channel with some cool dudes to make it more popular.
 
1 - 20 of 29 Posts
Top