HRV... is it worth it?

Forums › Home Workshop DIY › HRV... is it worth it?

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8

761 posts

Ultimate Geek

#1367903 17-Aug-2015 13:48

Our house had DVS installed by the previous owner. I assumed it was an old system as it only had a manual on/off switch (like a light switch) and a dial (potentiometer?). Air is sucked in from outside and deposited into the lounge and hallway.

We used it a few times but it made the house smell like roof dust. I changed the filters, and still: roof dust. Haven't used it since - do get some weeping windows. Have been meaning to get in the roof and tape everything up real good and leave it running for 2 weeks with a hope that it will clear things out. I'm a big fan of airing out a house but haven't seen the actual benefits of such a system myself...

Edit:- When I phone DVS they told me it wasnt that old of a system, just sounds like the previous owner went for a cheap version. We couldn't use the roof space as its to dusty/spidery. I don't like the idea of that anyway - fresh air is surely best?

jaymz

1133 posts

Uber Geek

#1367907 17-Aug-2015 13:53

When I first started hearing about HRV systems i looked into whether they would be any use for my place as it was a bit damp in winter time.

After reading that they basically just forced air from the roof into the house I checked out the temps in the roof during winter. I found that even in the middle of a warm day in winter, very little heat was to be found in my roof and this was due to it being concrete tiled.

After that, i decided against it. What was the point in putting freezing cold air into the house that i was trying to warm?

I then went about addressing the sources of moisture. I laid plastic on the ground under the house, installed a shower dome, removed the flued gas heater and installed a wood burner and installed a hefty layer of insulation in the roof.

By far, this was a better spend of money. only on very cold mornings do we have moisture on the windows, and that is with 5 of us in a 3 bedroom house.

As an extra, i also make sure windows are open during the day to allow air flow through the house and i run a dehumidifier (first time this year) on the controlled power meter and thus far this winter there has been no crying windows.

stefankrz

20 posts

Geek

#1367913 17-Aug-2015 14:05

I installed a positive pressure system in my previous house as it was a brick and tile 1950's house on piles in Auckland. Even with a dehumidifier running over night we would have crying windows all through winter but within a few days of installing the system the windows cleared up. The house felt warmer due to the reduced humidity inside and was easier to heat.

The system would ramp the fan up and down depending on the temperature in the house compared to the roof space, on the lowest fan speed you would barely notice any air flow. We found that we would manually turn the fan up to full on hot summer nights as it created a cool breeze through the night as the roof space cooled faster than the rooms

I have just bought a smartvent system to install myself in my new house. Quoted installation price from smartvent to install was $4500 but was able to purchase a 4 vent system and the summer option from Corys electrical for under half that after getting a discount from trade prices. Currently sitting in 2 large boxes in the garage waiting for me to install over the coming weekend(s)

bcourtney

652 posts

Ultimate Geek

Trusted

#1367916 17-Aug-2015 14:09

mdooher: Or in my personal opinion... Don't be so stupid as to put one off these overpriced fan in a tube in your house. Yes it will stop crying windows, but so what? do think that makes your house healthier?

The way to remove moisture form your house is to:

1 Bring in fresh air (at least 10% fresh)
2 filter it
3 remove the moisture from it
4 heat it (particularly if you removed the moisture by cooling it)
5 recycle about 90%
5 Allow the 10% overpressure air back out (recover heat from it for efficiency)

This is what I do, we never open our windows, never have crying windows, never smell the disgusting coal fires in the rest of the neighborhood and quite frankly do a lot less dusting (well my wife does)

We got a SmartVent PP system installed almost 2 months ago and are completely happy with the system and the results. I'm not sure I (and potentially others that have been happy with the product and/or similar products) appreciate the inference that I'm stupid for doing so.

We have a 1920's double-brick bungalow. Typical old character home with it's draughty quirks, 3.1m ceilings etc. We have a toddler that suffers from asthma that is aggravated in winter and I also suffer mild asthma that only crops up in winter times. We have two smallish dogs that we keep inside during the day too. Our kitchen, dining living area has been altered to be open plan. We've never really had a bad issue with dampness at all (no musty/mouldy smells etc) but definitely had issues with crying windows in winter. We don't have the benefit of someone being home during the day to be able to leave windows open. Being an old home, it wasn't really designed that well with regards to north facing living. We get all day sun but the open plan living side of the house is the east/south side of the house and the rooms on the north/west sides don't have great windows!

Putting "one of these overpriced fan in a tube" systems in our house has:
1. Almost completely eliminated condensation on windows, even on frosty nights. One small leadlight window still gets a minimal haze of condensation on the coldest nights but mainly due to the roman blind over it creating an almost airtight barrier that doesn't allow the fresh airflow to it when closed.
2. Noticeably clean and fresh smelling home when arriving there after work and having the two dogs in there all day - this has been a great bonus that we hadn't really thought about.
3. On the sunnier days (not necessarily cloud free days) we've noticed the house is definitely making the most of the 23-24 degree heat that is being generated in the roof space meaning we're using the heaters less and not needing them to be turned on until later in the evenings.
4. Waking up to our small bedrooms not smelling like people (and yes, the two dogs) have spent the last 8-10 hours sleeping in them!
6. The house feels noticeably drier too - you know that dry nose feeling when you've been to the Nevada desert or when you've been up skiing etc - that's been quite noticeable which would indicate to me that the house is drier. The odd occasion that we have to hang up clothes to dry inside on bad days (I know it's frowned upon) also provides a remarkable indicator as to how dry the air in the house is overall too as they dry within a few hours.
5. The greatest benefit has been health related. I went from using my inhaler on a daily basis to having used it twice since the system went in. My daughter however we've noticed a dramatic decrease in respiratory related issues and sleeplessness since the system went in. To me that trumps all of the other benefits by a long shot.

So overall we're really pleased with the "overpriced fan in a tube". The money spent getting someone else to install it was money well spent as I didn't want to be playing around in the ceiling space when my time is better spent doing other things. I also DO think it's made my house healthier.

mattwnz

20155 posts

Uber Geek

#1367917 17-Aug-2015 14:10

IMO these systems are just a bandaid way to help, but are not a long term solution. They also only work in certain types of houses. If you have a skillion roof, then you will be out of luck as they need and attic (unless you are pumping in air from outside but you need an attic to distribute pipes). The best solution is to get the house up to a modern standard, with decent insulation and double glazing and thermally broken frames.

shk292

2853 posts

Uber Geek

Lifetime subscriber

#1367929 17-Aug-2015 14:24

We had the HRV man call round a few years ago when we were looking at vent and heating options. Having done some research, I took the precaution of placing the outside thermometer of my weather station in the roof space, ready for his visit. So, on a "cold" (13C?) day in Auckland, he was expounding the virtues of HRV and all the lovely warm air that was going to waste in my roof space, that I should be pumping into my house. I pointed at the weather station - 13C in the roof space - why exactly do I want to pump that air into my house? I sent him on his way and spent the money on some heat pumps instead.
I am tempted by the true heat recovery systems, with a heat exchanger. But I think the best way to fix moisture on windows is double glazing. No-one (exaggeration) has heard of HRV etc in the UK, no-one has condensation on their windows, and everyone has double glazing - and it's generally a lot colder and moister there than here.

mdooher

Hmm, what to write...
1424 posts

Uber Geek

ID Verified

Trusted

Lifetime subscriber

#1367931 17-Aug-2015 14:26

bcourtney:
We got a SmartVent PP system installed almost 2 months ago and are completely happy with the system and the results. I'm not sure I (and potentially others that have been happy with the product and/or similar products) appreciate the inference that I'm stupid for doing so.

Fair enough studies show the more people spend on a product the happier they are with it, I believe its related to the placebo effect

We have a 1920's double-brick bungalow. Typical old character home with it's draughty quirks, 3.1m ceilings etc. We have a toddler that suffers from asthma that is aggravated in winter and I also suffer mild asthma that only crops up in winter times. We have two smallish dogs that we keep inside during the day too. Our kitchen, dining living area has been altered to be open plan. We've never really had a bad issue with dampness at all (no musty/mouldy smells etc) but definitely had issues with crying windows in winter. We don't have the benefit of someone being home during the day to be able to leave windows open. Being an old home, it wasn't really designed that well with regards to north facing living. We get all day sun but the open plan living side of the house is the east/south side of the house and the rooms on the north/west sides don't have great windows!

Putting "one of these overpriced fan in a tube" systems in our house has:
1. Almost completely eliminated condensation on windows, even on frosty nights. One small leadlight window still gets a minimal haze of condensation on the coldest nights but mainly due to the roman blind over it creating an almost airtight barrier that doesn't allow the fresh airflow to it when closed.
Great so the dampness in the house is now the same as the dampness outside and now you have God knows what being sucked in from your ceiling.. It doesn't meet NZ standard for air quality

2. Noticeably clean and fresh smelling home when arriving there after work and having the two dogs in there all day - this has been a great bonus that we hadn't really thought about.
Pretty sure you are correct there

3. On the sunnier days (not necessarily cloud free days) we've noticed the house is definitely making the most of the 23-24 degree heat that is being generated in the roof space meaning we're using the heaters less and not needing them to be turned on until later in the evenings.
University of Otago Study shows a maximum heating effect of 0.5kW, so I think it is the placebo effect again

4. Waking up to our small bedrooms not smelling like people (and yes, the two dogs) have spent the last 8-10 hours sleeping in them!
Again I'm betting that the system works well to do this

6. The house feels noticeably drier too - you know that dry nose feeling when you've been to the Nevada desert or when you've been up skiing etc - that's been quite noticeable which would indicate to me that the house is drier. The odd occasion that we have to hang up clothes to dry inside on bad days (I know it's frowned upon) also provides a remarkable indicator as to how dry the air in the house is overall too as they dry within a few hours.
Part placebo and partially because the amount the humidity level in your house now matches the humidity outside your house

5. The greatest benefit has been health related. I went from using my inhaler on a daily basis to having used it twice since the system went in. My daughter however we've noticed a dramatic decrease in respiratory related issues and sleeplessness since the system went in. To me that trumps all of the other benefits by a long shot.
Be very very careful with the filter, this system does not meet NZ standard for fresh air ventilation

So overall we're really pleased with the "overpriced fan in a tube". The money spent getting someone else to install it was money well spent as I didn't want to be playing around in the ceiling space when my time is better spent doing other things. I also DO think it's made my house healthier.

I think I'll stick with my system

Matthew

Sharesies

Trade NZ and US shares and funds with Sharesies (affiliate link).

scuwp

3885 posts

Uber Geek

#1367982 17-Aug-2015 14:54

mdooher:
bcourtney:
We got a SmartVent PP system installed almost 2 months ago and are completely happy with the system and the results. I'm not sure I (and potentially others that have been happy with the product and/or similar products) appreciate the inference that I'm stupid for doing so.

Fair enough studies show the more people spend on a product the happier they are with it, I believe its related to the placebo effect

We have a 1920's double-brick bungalow. Typical old character home with it's draughty quirks, 3.1m ceilings etc. We have a toddler that suffers from asthma that is aggravated in winter and I also suffer mild asthma that only crops up in winter times. We have two smallish dogs that we keep inside during the day too. Our kitchen, dining living area has been altered to be open plan. We've never really had a bad issue with dampness at all (no musty/mouldy smells etc) but definitely had issues with crying windows in winter. We don't have the benefit of someone being home during the day to be able to leave windows open. Being an old home, it wasn't really designed that well with regards to north facing living. We get all day sun but the open plan living side of the house is the east/south side of the house and the rooms on the north/west sides don't have great windows!

Putting "one of these overpriced fan in a tube" systems in our house has:
1. Almost completely eliminated condensation on windows, even on frosty nights. One small leadlight window still gets a minimal haze of condensation on the coldest nights but mainly due to the roman blind over it creating an almost airtight barrier that doesn't allow the fresh airflow to it when closed.
Great so the dampness in the house is now the same as the dampness outside and now you have God knows what being sucked in from your ceiling.. It doesn't meet NZ standard for air quality

2. Noticeably clean and fresh smelling home when arriving there after work and having the two dogs in there all day - this has been a great bonus that we hadn't really thought about.
Pretty sure you are correct there

3. On the sunnier days (not necessarily cloud free days) we've noticed the house is definitely making the most of the 23-24 degree heat that is being generated in the roof space meaning we're using the heaters less and not needing them to be turned on until later in the evenings.
University of Otago Study shows a maximum heating effect of 0.5kW, so I think it is the placebo effect again

4. Waking up to our small bedrooms not smelling like people (and yes, the two dogs) have spent the last 8-10 hours sleeping in them!
Again I'm betting that the system works well to do this

6. The house feels noticeably drier too - you know that dry nose feeling when you've been to the Nevada desert or when you've been up skiing etc - that's been quite noticeable which would indicate to me that the house is drier. The odd occasion that we have to hang up clothes to dry inside on bad days (I know it's frowned upon) also provides a remarkable indicator as to how dry the air in the house is overall too as they dry within a few hours.
Part placebo and partially because the amount the humidity level in your house now matches the humidity outside your house

5. The greatest benefit has been health related. I went from using my inhaler on a daily basis to having used it twice since the system went in. My daughter however we've noticed a dramatic decrease in respiratory related issues and sleeplessness since the system went in. To me that trumps all of the other benefits by a long shot.
Be very very careful with the filter, this system does not meet NZ standard for fresh air ventilation

So overall we're really pleased with the "overpriced fan in a tube". The money spent getting someone else to install it was money well spent as I didn't want to be playing around in the ceiling space when my time is better spent doing other things. I also DO think it's made my house healthier.

I think I'll stick with my system

What studies? Care to share the evidence that the filters do not meet NZ standards, as that is contrary to the manufacturers specifications.

Case by case basis for sure, but my experience has been pretty much the same as bcourtney's. Not having to mop up a couple of litres of water everyday from the windows, and have curtains replaced/cleaned every year was worth it alone. Our house is contemporary, but just missed out on double glazing. Rather a couple of thousand on this system, that 10x as much getting glazing retrofitted.

Lazy is such an ugly word, I prefer to call it selective participation

mdooher

Hmm, what to write...
1424 posts

Uber Geek

ID Verified

Trusted

Lifetime subscriber

#1367986 17-Aug-2015 15:07

scuwp:

What studies? Care to share the evidence that the filters do not meet NZ standards, as that is contrary to the manufacturers specifications.

This Study http://www.energywise.govt.nz/sites/all/files/heating-potential-ventilation-systems-may-2011.pdf

and this standard " Ventilation systems that draw air from the roof space and not directly from outside do not comply with ventilation standard NZS4303:1990 "Ventilation for acceptable indoor air quality" from here:http://www.energywise.govt.nz/your-home/ventilation/systems

Matthew

bcourtney

652 posts

Ultimate Geek

Trusted

#1368008 17-Aug-2015 15:36

mdooher:
scuwp:

What studies? Care to share the evidence that the filters do not meet NZ standards, as that is contrary to the manufacturers specifications.

This Study http://www.energywise.govt.nz/sites/all/files/heating-potential-ventilation-systems-may-2011.pdf

and this standard " Ventilation systems that draw air from the roof space and not directly from outside do not comply with ventilation standard NZS4303:1990 "Ventilation for acceptable indoor air quality" from here:http://www.energywise.govt.nz/your-home/ventilation/systems

I'll gloss over all the condescension and patronising comments in your initial reply to me. Your setup works for you and mine now works for me and my family with real world results. So we're both happy.

As for the Otago study - I don't think anyone nowadays installs ventilation systems for heating or cooling benefits as either can't be relied upon. The three different companies we had quote us on systems also all pointed this out during their sales pitches (granted we didn't ask HRV to quote). That study should be relied upon with a certain amount of caution too. It was done based on the recording of data from 4 x 10 day periods in 2008 in 3 houses in Dunedin only. Then Matlab was used to create a model to estimate the results in other areas of NZ. I understand the study and the results and absolutely agree you shouldn't rely on a ventilation system for heating or cooling, yet they definitely will provide it when conditions suit. Disclaimer - I have a Physics Degree from Otago specialising in Energy Management.

The fact is that on sunny winter day's we are getting a noticeable increase in temperature in the house. It's not a "placebo" effect either as we have thermometers that we use in the bedrooms as well as Heatermate and Effergy devices attached to our heaters that are showing real world data that backs up the fact that on sunny days the house is noticeably warmer inside and the heaters are coming on less because of it (the heaters are all set to come on automatically at certain times and maintain specific temperatures). The heaters are consuming less energy now that the ventilation system is in and this is most noticeable on sunny days. On overcast/cold/rainy days the heaters are also being used less than they used to even though the air in the house isn't initially any warmer than it used to be prior to, say, 5pm when the heaters are set to come on in the evening, and I can only assume (quite confidently) that this is due to lower humidity.

If my house is NOT drier than it used to be with fresher air than it used to contain through natural ventilation then I'm sorry but you can't explain away they dramatic decrease in respiratory issues by suggesting it's a placebo effect. In a grown adult that has spent the money on the system (me) then sure, perhaps (although I'm not NOT taking my inhaler just to justify the money I spent on the system!). But my 2 year old daughter?

sbiddle

30853 posts

Uber Geek

Retired Mod

Trusted

Biddle Corp

Lifetime subscriber

#1368013 17-Aug-2015 15:42

jaymz: When I first started hearing about HRV systems i looked into whether they would be any use for my place as it was a bit damp in winter time.

After reading that they basically just forced air from the roof into the house I checked out the temps in the roof during winter. I found that even in the middle of a warm day in winter, very little heat was to be found in my roof and this was due to it being concrete tiled.

After that, i decided against it. What was the point in putting freezing cold air into the house that i was trying to warm?

Concrete tiles is something I've wondered about as well. On a hot day the roof space can get warm, but on a cold winters day the roof space is cold and full of moist air. I'm not sure how forcing that air around the house can really help.

Clearly in a new house the roof space is well sealed and this issue isn't something you'd even question.

scuwp

3885 posts

Uber Geek

#1368196 17-Aug-2015 21:19

mdooher:
scuwp:

What studies? Care to share the evidence that the filters do not meet NZ standards, as that is contrary to the manufacturers specifications.

This Study http://www.energywise.govt.nz/sites/all/files/heating-potential-ventilation-systems-may-2011.pdf

and this standard " Ventilation systems that draw air from the roof space and not directly from outside do not comply with ventilation standard NZS4303:1990 "Ventilation for acceptable indoor air quality" from here:http://www.energywise.govt.nz/your-home/ventilation/systems

Thanks for the links. Interesting reading.

I didn't install the system for heating/cooling, although I may look at installing the summer vent kit in future just to keep the house fresher when locked up during hot days. So the first study is largely irrelevant for me. I wanted it for condensation mostly, and thus far is is 100% successful.

The filter comment was interesting. All it says is that it doesn't comply with the current building code which says the air must come from outside. If this were the only source of ventilation I can accept that, but as most houses have windows/doors that are opened from time to time weather permitting I am not losing sleep over the potential for carbon dioxide poisoning. Someone far cleverer than I may be able to quantify what this means but here is what SmartVent claim of their filters...possibly/probably even better than the air outside?

Medical-grade Filtration The high quality F7 filter captures 80 – 90% of 0.4 micron particles including dust, pollens, allergens and mould spores.

Lazy is such an ugly word, I prefer to call it selective participation

MikeAqua

7779 posts

Uber Geek

#1368597 18-Aug-2015 13:36

The positive pressure systems work on a sunny day by pushing warm dry air into the house from the roof space. They do reduce condensation and (while the roof space is warmer than the house) can achieve even background heating in a house.

They work really well somewhere like Blenheim which has clear still winter days and low humidity.

A much better system brings in dry cool air and exhausts warm moist air through an efficient air-air heat exchanger. These systems recover ~75% of the heat from outgoing air.

Smart Vent do such a system, which they installed in our previous house in Nelson.

It's fantastic system. Our experience was that: -

- The house was drier;
- Condensation disappeared;
- Objects like furniture and beds felt dry and warm;
- We ran the heats pumps 2 deg C lower but the house felt warmer;
- Mould in the bathroom disappeared;
- Allergies were better;
- Power consumption decreased; and
- The house felt nicer to be in.

No hesitation in recommending smart vent. Great guys to deal with.

Mike

BinaryLimited

796 posts

Ultimate Geek

Trusted

#1368611 18-Aug-2015 13:50

Just had the smartvent guy here today..
Quoted $4900....2 fans....7vents....apparently using my current(3vents) dvs vents isnt ideal?

Abit pricey...was only the basic system.
Evolve : +$925
Heat exchange : another +$1000

Hrv quoted me $5300....cash for $4300...

Binary Limited - Safe. Secure. Simple. ™
www.binarylimited.co.nz

bcourtney

652 posts

Ultimate Geek

Trusted

#1368615 18-Aug-2015 13:56

BinaryLimited: Just had the smartvent guy here today..
Quoted $4900....2 fans....7vents....apparently using my current(3vents) dvs vents isnt ideal?

Abit pricey...was only the basic system.
Evolve : +$925
Heat exchange : another +$1000

Hrv quoted me $5300....cash for $4300...

As a comparison, we had a SV04 single fan system with 5 outlets installed for $3220 through Smart Energy Solutions.

Not sure what the DVS system uses for ducting but the SmartVent system uses insulated ducts so perhaps that is why the said you could use the existing DVS ones?

Did you ask the SmartVent people to price match? From what I found it seemed to be a fairly competitive market and deals were there to be done.

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8