HRV home ventilation 'vs' the Air Movement Solutions system -

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k9yne

3 posts

Wannabe Geek

#63467 27-Jun-2010 22:30

Hi all, how is everyone?
i'm new to this forum and was just wondering if anyone has any information on the "HRV" home ventilation system compared to the "Air Movement Solutions" system - how they stack up against each other and which is the better of the two.
Any help or info would be much appreciated

Thanks

p.s. are they worth the investment? or am I just buying into the advertising hype?

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19282 posts

Uber Geek
Inactive user

#345885 27-Jun-2010 22:40

I thought you would be checking out their websites

Regs

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Snowflake

#345897 27-Jun-2010 23:26

if its reviews you're after, http://www.consumer.org.nz/ has a report on hrv's and other systems (for members only). if you're after opinions then there are bunch of old threads on the HRV and DVS etc on geekzone http://www.google.co.nz/search?hl=en&q=hrv+or+dvs+site%3Ageekzone.co.nz&aq=f&aqi=&aql=&oq=&gs_rfai=

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k9yne

3 posts

Wannabe Geek

#345898 27-Jun-2010 23:40

yes i have checked their sites out, i was more after the opinions of people that have either system

but thanks

k9yne

3 posts

Wannabe Geek

#345900 27-Jun-2010 23:42

ok cool thanks for the link

wmoore

510 posts

Ultimate Geek

#345916 28-Jun-2010 05:42

Firstly there a two main types of systems.

1) Positive Pressure Ventilation. These are normally a fan in the ceiling space, which blows dry air down into rooms that have vents. Brands that use this method include DVS, Moisture master, Healthaire, and HRV
(which is a brand name and nothing to do with Heat recovery ventilation)

2) Heat Recovery Ventilation. They have a heat exchanger, fresh air in brought in from outside and stale air steam etc is extracted from the house back into the exchanger, which then produces fresh air to blow into the house again. Cleanaire.co.nz are the main player in this system.

"In the end, it's not the years in your life that count. It's the life in your years." -
-- Abraham lincoln

Jaxson

8044 posts

Uber Geek

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#345952 28-Jun-2010 09:47

You mentioned two types, HRV and air movement systems.

I assume you mean heat transfer by the second one. Yes this can work well for moving heat from one room to others but in my opinion this only works well when you have a wood burner. You need a lot of heat in the first room to still deliver warm enough air into the second room to actually do anything.

The ducting is insulated apparently but it's really just marketing hype as it's insulated to 0.3 - 0.6 R which is next to useless. When it's cold in your roof space you will lose heat along the duct, more the longer the duct is. If you are aware of this you can make it work well, but you need hot air going into it, not just warm from a small heater or heat pump.

The HRV type should not be considered for heating at all if this is what you are after. They are ventilation products to reduce smells and humid/moist air. When you need heat, your roof space is cold and you are just transfering very cold air into your house and pushing out the air you have already heated. Not very economical but yes it will reduce condensation, as long as you don't mind paying more for heating.

The better option if you do need to reduce moisture levels is the heat exchanger type wmoore mentioned above. As well as making you have rangehoods and bathroom fans first and that they are ducted to the outside etc. You can't seem to buy the parts for the heat exchanger type yourself though, they seem to be company installs only.

akia

489 posts

Ultimate Geek

Trusted

#345989 28-Jun-2010 11:25

We have installed the Smart Vent system. We had both HRV and DVS come through and althought Smart Vent was a little more expensive it was what all the electricians and techies were getting installed in their house.

http://www.smartvent.co.nz/

Asmodeus

1015 posts

Uber Geek

#346024 28-Jun-2010 13:05

I haven't heard many good things about HRV and would avoid. You'd be better off getting a heat pump if applicable

Handsomedan

7304 posts

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Subscriber

#346038 28-Jun-2010 13:53

We have an HRV system and have had for several years.

It's good for reducing dampness, slightly cooling the house in the summer evenings and keeping a flow of "fresh" air going through the house.

Personally, I wouldn't invest in one again though. It just didn't do what they hinted at, which is to heat the house using the "free warm air in the ceiling and distributing it through out the house, giving you a warmer, drier home"...

It's just a really expensive and cheaper-to-run dehumidifier that needs the filter replacing every two years at the cost of a couple of hundred bucks.

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Jaxson

8044 posts

Uber Geek

Trusted

#346051 28-Jun-2010 14:40

Handsomedan: It just didn't do what they hinted at, which is to heat the house using the "free warm air in the ceiling and distributing it through out the house, giving you a warmer, drier home"...

Most people get drawn to these types of devices in winter, due to cold and moisture problems/condensation on windows/mould etc. These devices do not do both and that's where they are a bit misleading.

They WILL push out the humid air from your house, so this is a plus. However, with it goes the warm air you just paid to heat. (It is more efficient to heat dryer air though, so technically it's a slight plus too). If you have lots of money for heat then you will have a dryer home with this product.

They WILL NOT however heat your house in winter. Maybe the transition months but not when it's cold outside. When you need heat the most their statements are rubbish. Your roof is now freezing (as the iron is not insulated, it's the middle of the night so no solar gain, and you're pumping that cold air into your house.

A wood burner draws air into it to carry the smoke up the chimney. This brings fresh air into the home (actually causes drafts) through cracks around windows/doors etc. This replaces the air in the room too, so does the same thing, but for free.
Actually that's a great way to think of it, an HRV system is like a draft you pay to make as you run the fan. I bet that's not such a great marketing angle.

Similar with heat pumps though. They are most efficient when the outside and inside temperatures are similar. This 300% efficient advertising doesn't stack up when you're aiming for 20 degrees inside and it's 4 outside. Hasn't stopped the government pushing to have these installed and people lapping them up.

oxnsox

1923 posts

Uber Geek

#346103 28-Jun-2010 17:20

Good point on drafts Jaxson

You can get heat transfer systems from Bunnings/Mitre10 if you just want to move the dry air around. But proper installation is important with these. Too often folk put the intake close above the fire, where the fire is actually drawing the air from, so tis not the best location to get the warmest air and most efficient install/solution.

A bit of research and they are good value as $$$$ (yes thousands) less than HRV/DVS and the likes.

scuwp

3888 posts

Uber Geek

#346131 28-Jun-2010 18:51

Don't have one, but did heaps of research when we were looking at buying one. Heres some of my random conclusions:

1. The heat component in any (HRV/DVS) system is basically a waste of time. Think blowing cold air over a 100w light bulb. If you want heat then put in a heat pump or fireplace

2. "positive air pressure" is a flash was of saying its a fan that blows air around the room

3. Can be good for condensation but as for the rest of the claims as far as air quality etc is concerned its a bit of a stretch on reality

4. By the time you select all the 'add ons' the system requires to actually be effective the price doubles

5. I the case nof HRV once they have your details they will hound you forever

Comments I have found posted are mixed - If you can find someplace to actually go see in operation for yourself that would be worthwile.

Google it - You could read for days!

Best of luck

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

manta

249 posts

Master Geek
Inactive user

#346200 28-Jun-2010 23:26

I did considerable research with HRV v DVS to reduce condensation and increase warmth in our rooms upstairs.

Neither will heat your house in winter unless you install an in-line heater; expensive to fit and to run.

They will reduce condensation by taking outside air and putting it into your rooms, the outside air genrally being less humid than the air in the house.

My solution was to retro-fit double glazing in all the rooms upstairs which keeps the rooms much, much warmer and to open the odd window a fraction to replace the humid air in the house with drier air from outside - it just hasn't come though the roof space.

For us the double glazing option worked out slightly more expensive than HRV and less expensive than DVS and I am delighted with the results; warmer rooms with no condensation. I am very glad we didn't go for a ventilation system, but everyone's home and requirements are different.

DVS clinched it for me when they admitted that unless you actually shut the system down at night all their system does in blow cold air into your house and they recommended increasing the amount of heating in the house at night. Seemed crazy to me to pay a large sum of money to get cold air blown into your house and then pay more money to heat it up again!

wmoore

510 posts

Ultimate Geek

#346224 29-Jun-2010 07:37

If you are installing a PPV system make sure that your roof space is not damp. Because you don't want cold damp area being blown about. The other thing is to make sure the rooms aren't too airtight, If your windows have ventilation slots these need to be open, or make sure you have your windows safely ajar. This allows the old damp air to escape. If the room is to airtight, then the damp cold air, will just go into the walls and over time will rot your walls. This was found to be happening overseas.

"In the end, it's not the years in your life that count. It's the life in your years." -
-- Abraham lincoln

redjet

299 posts

Ultimate Geek

#346240 29-Jun-2010 09:40

We put in an HRV system just over 16 months ago and have to say it's well worth the money. As others have suggested you don't buy one of these for heating your home - it's really to keep it free from moisture. It's basically an extremely efficient dehumidifier. We've got really good heating and insulation but as a result had really bad crying windows and we were getting damp and mould in wardrobes which has completely gone after installing the HRV. Our house also smells at lot fresher.

I'm not sure what one poster was on about HRV hassling you forever - we haven't heard from them since the initial installation. If you have bad moisture/condensation problems then you'll either have to get a portable dehumidifier or a HRV/DVS type of solution. Adding more insulation to your home will just make matters worse. We also looked at DVS and they were also good but HRV gave us a better deal. Just don't go for the extras and you'll be fine.

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