HRV... is it worth it?

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

BinaryLimited

791 posts

Ultimate Geek

Trusted

# 177860 16-Aug-2015 17:52

Hi all

Thinking of getting hrv....we live in an old home..no double glazing....
Is it really worth getting HRV or is it all just hype?

Anyone here recently got HRV installed? Anything you could recommend or to watch out for?

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

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503 posts

Ultimate Geek

# 1367540 16-Aug-2015 17:55

One person supports this post

Just remember its a fan in a box..... But it does work very well and keeps the moisture out by forcing the dry air down.

andrewNZ

2122 posts

Uber Geek

# 1367542 16-Aug-2015 17:56

4 people support this post

NO. Positive pressure ventilation is a scam.

I have just unplugged the one in my house (installed by the previous owner) and my house is now a LOT warmer with no noticable increase in condensation.

Location: Dunedin

BinaryLimited

791 posts

Ultimate Geek

Trusted

# 1367546 16-Aug-2015 18:01

shrub: Just remember its a fan in a box..... But it does work very well and keeps the moisture out by forcing the dry air down.

Take it that the dry air comes from the roof,therefore i need to make sure insulation in the roof is 100%?

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

BinaryLimited

791 posts

Ultimate Geek

Trusted

# 1367547 16-Aug-2015 18:02

andrewNZ: NO. Positive pressure ventilation is a scam.

I have just unplugged the one in my house (installed by the previous owner) and my house is now a LOT warmer with no noticable increase in condensation.

How old is your home? Single or double glazing? Do you open doors and windows(even tho the moist air comes from outside too...)...

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

RunningMan

5525 posts

Uber Geek

# 1367550 16-Aug-2015 18:16

One person supports this post

BinaryLimited:
shrub: Just remember its a fan in a box..... But it does work very well and keeps the moisture out by forcing the dry air down.

Take it that the dry air comes from the roof,therefore i need to make sure insulation in the roof is 100%?

Ceiling insulation will make zero difference to the air in the roof space. All it's doing is sucking air from outside and blowing it through the house - it's that simple.

andrewNZ

2122 posts

Uber Geek

# 1367551 16-Aug-2015 18:17

Single story 80's house 140 sq/m single glazing in Dunedin.

If you have issues with moisture, you need to address the source. If you have your heart set on a ventilation system, get a real balanced pressure system that has a heat exchanger. I'll be installing one of these in the short to mid term.

Positive pressure has been widely proven to provide no heat recovery. I'd go a step further and say they cost you a lot in heat loss because they are pulling in cold air and pushing out warm air. Newer systems than mine have the option of a tempering heater to take the chill off the air coming in, which is a ridiculous band aid.
Imagine buying a car with a fuel leak, and being told for an extra x dollars you can get a fuel can the same colour as your car.

A real system can retain 90+% of the heat already in your home.

Location: Dunedin

ockel

1674 posts

Uber Geek

# 1367552 16-Aug-2015 18:17

have you considered Unovent as an alternative?
I had HRV in my previous house. I wouldnt rush to put in my current house (cost of install + maintenance vs benefit)
But I know people who have positive pressure ventilation systems that are happy with HRV.

dusty42

111 posts

Master Geek

# 1367558 16-Aug-2015 18:26

Really useful if you struggle with dampness, and you will find a dryer home is easier to heat.

The air will only ever be the temperature of your roof cavity - at night it can be like an air conditioner forcing chilled air into your home.

In a couple of homes where I've had these type of systems I tend to turn them off at night, and run them only during the day. One DVS in a flat I had was the world's most basic system with the only fan control in the roof - dumbest thing ever. Eventually plugged it into a digital timer to turn it off at night.

shrub

503 posts

Ultimate Geek

# 1367566 16-Aug-2015 18:39

With the new HRV systems they they have sensors that will turn fans to very low/off when the roof temp is lower than the house temp. It all depends on the installer that does the setup some are rough as and the systems are not programmed properly it will not work.

andrewNZ

2122 posts

Uber Geek

# 1367573 16-Aug-2015 18:51

shrub: With the new HRV systems they they have sensors that will turn fans to very low/off when the roof temp is lower than the house temp. It all depends on the installer that does the setup some are rough as and the systems are not programmed properly it will not work.

My system has that, and I've ensured it is programmed properly. It doesn't help much at all.

Location: Dunedin

overkill

222 posts

Master Geek

# 1367580 16-Aug-2015 19:00

2 people support this post

We have the DVS equivalent type of system and wouldn't buy a house without one in the future. If we turn ours off, we get the "crying" windows within a couple of days. Is it worth it, I would say yes due how fast our house heats up, no crying windows etc....that is the hype 'sold' with these systems, certainly works for our home.

"Setting the Standard in Quality and Commitment"

Wade

2212 posts

Uber Geek

# 1367584 16-Aug-2015 19:06

We are in a 15yo brick & tile, heat pump, single glaszed, basic hrv system, they all work in well together

In the cooler months you can use the afternoon heat to preheat/maintain the house temp meaning less effort required by heat pump

In the summer months the HRV provides a most pleasant amount of air movement in the bedrooms making getting to sleep on those warm nights just that little bit more pleasant

At the price of a HRV system i wouldn't go there, i think i would investigate a proper ducted heating/cooling centralised system in

PoHq

411 posts

Ultimate Geek

# 1367601 16-Aug-2015 19:57

One person supports this post

Add me to the list of VERY satisfied customers.

We had crying windows in a couple of rooms. All completely gone with 2 days of our DVS system installed and not been back since.

If the air in the roof is to cold or indeed to hot for your chosen temperature the fan slows to a crawl. I've been in the roof to check it when this happens. It's almost impossible to hear it it's going that slow but even at the slow speed it's enough to clear condensation.

Just remember it's a ventilation system. NOT a heating system. Using heat from the roof to warm your house at certain times of the year is just an added bonus.

mentalinc

1715 posts

Uber Geek

Trusted

# 1367604 16-Aug-2015 20:17

Has anyone tested the humidity before and after install a system?

Lots of people say they don't get the crying windows anymore, but is that because of the air flow that is created? or due to a real decrease in the humidity in the house?

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michaelmurfy

Mr Snotty
8763 posts

Uber Geek

Moderator

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Lifetime subscriber

# 1367605 16-Aug-2015 20:28

HRV - don't go near them, they're expensive, pushy and actually not that good.

DVS on the other hand are good - they are not pushy for an installation and are very professional to deal with. Maintenance is mostly done yourself (and it is easy) and it is also easy to upgrade or add new zones. I've been in 3 houses with them and are about to get one installed in our current house. They're not at all a placebo and I've found in 100% of cases they work very well (and you really notice this when you turn them off).

Michael Murphy | https://murfy.nz
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