Ventilation Question (2018)

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Networkn
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#2084273 5-Sep-2018 12:19

Hi.

Interesting. I called SV to talk to them more about positive vs balanced. After some faffing around with someone who was not much better than the guy who came out, they put me through to a guy who apparently is the design engineer, who compiles the stats for the councils and a bunch of other stuff that led me to believe he knew what he was talking about. He understood my concerns but was adamant the positive system would be the worthwhile solution for us. His reasoning (not word for word):

1) New houses are ones built on the 2012 spec for insultation and other revised standards. There have been subsequent updates in 2014 and 2016 which are even more stringent. Those houses are airtight.

2) 2006 is a newish home, but still very leaky, unless they are designed well well overspec.

3) 2006 home will leak air and make a full HRV system not as effective as they are designed to be.

4) In an balanced system in our house config, the ducting runs are very long. There is a lot of pressure lost.

5) I am unsure if I got this exactly right, but air changes more frequently in the positive pressure system.

Neither will cool my daughters room or wifes office which are side by side, very much, but the summer kit in the positive pressure system is going to reduce temps slightly, he estimates 2-5 degrees, but it isn't possible to know easily in advance of installation.

He thought 8K for the balanced system was likely due to huge insultated ducting requirement and thought it was likely to cost slightly less with SV but not much less.

Thoughts?

Amosnz

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#2084293 5-Sep-2018 13:03

I self installed a SV Synergy 250S a few years ago (their codes have changed now). I got it through Corys/ Mastertrade through a friends account for about ~4k on a good discount (incl extra room, core bypass, summer vent). They are a pain to install but not that difficult if you have a normal roof space. The heat exchanger isnt huge, but we have good access.

Our house is an 80's build 240sqm brick house (Taranaki) with quite long runs and it made a massive difference to condensation. In one bedroom (with 2 external walls) we had water pooling in a deep alu window channel that would never evaporate, but over time with the ventilation it disappeared and didnt come back. A few weeks ago I was up in the roof checking something and accidentally bumped the ducts off the heat exchanger (i didnt realise at the time but i must have leant against them getting through a gap), the next morning we had very wet windows in the dining room and knew something was up, so went back up, saw the problem and fixed it. The next morning had nothing on the windows again.

The only aspect of it I probably expected more from is using the heat recovery for actual heating, but this fault is more with my expectation that anything else. If you start with 30 deg temps in the lounge, duct 6m to a heat exchanger (insulated ducting loses roughly 1 deg every 3m), get 75% recovery from the heat exchanger then duct another 6m to a bedroom, the air you a putting in the bedroom is roughly 19 deg.

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hadenkose

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#2084302 5-Sep-2018 13:20

Sounds like you spoke to the right person at SV. As I said in my previous post, I'm really happy with my SV Evolve PP system, with added summer feature in our 2014 built home. Not sure any other system offers the temperature and humidity sensors that SV provide.

tdgeek

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#2084305 5-Sep-2018 13:25

Amosnz:

I self installed a SV Synergy 250S a few years ago (their codes have changed now). I got it through Corys/ Mastertrade through a friends account for about ~4k on a good discount (incl extra room, core bypass, summer vent). They are a pain to install but not that difficult if you have a normal roof space. The heat exchanger isnt huge, but we have good access.

Our house is an 80's build 240sqm brick house (Taranaki) with quite long runs and it made a massive difference to condensation. In one bedroom (with 2 external walls) we had water pooling in a deep alu window channel that would never evaporate, but over time with the ventilation it disappeared and didnt come back. A few weeks ago I was up in the roof checking something and accidentally bumped the ducts off the heat exchanger (i didnt realise at the time but i must have leant against them getting through a gap), the next morning we had very wet windows in the dining room and knew something was up, so went back up, saw the problem and fixed it. The next morning had nothing on the windows again.

The only aspect of it I probably expected more from is using the heat recovery for actual heating, but this fault is more with my expectation that anything else. If you start with 30 deg temps in the lounge, duct 6m to a heat exchanger (insulated ducting loses roughly 1 deg every 3m), get 75% recovery from the heat exchanger then duct another 6m to a bedroom, the air you a putting in the bedroom is roughly 19 deg.

It's not a heating solution. the idea is to remove dirty warm damp air through the exchanger to outside, and bring in cool clean air which will warm up by the exhaust fins and also remove moisture. They do that very well. However, the clean, dryer air is cheaper to heat

Amosnz

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#2084311 5-Sep-2018 13:37

tdgeek:

Amosnz:

The only aspect of it I probably expected more from is using the heat recovery for actual heating, but this fault is more with my expectation that anything else. If you start with 30 deg temps in the lounge, duct 6m to a heat exchanger (insulated ducting loses roughly 1 deg every 3m), get 75% recovery from the heat exchanger then duct another 6m to a bedroom, the air you a putting in the bedroom is roughly 19 deg.

It's not a heating solution. the idea is to remove dirty warm damp air through the exchanger to outside, and bring in cool clean air which will warm up by the exhaust fins and also remove moisture. They do that very well. However, the clean, dryer air is cheaper to heat

Yes, as I said, the fault was with my expectation. 'Heat recovery' can be interpreted to mean different things, hence me offering a real world example to show why its not a heating solution.

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mdf

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#2084327 5-Sep-2018 13:46

networkn:

Hi.

Interesting. I called SV to talk to them more about positive vs balanced. After some faffing around with someone who was not much better than the guy who came out, they put me through to a guy who apparently is the design engineer, who compiles the stats for the councils and a bunch of other stuff that led me to believe he knew what he was talking about. He understood my concerns but was adamant the positive system would be the worthwhile solution for us. His reasoning (not word for word):

1) New houses are ones built on the 2012 spec for insultation and other revised standards. There have been subsequent updates in 2014 and 2016 which are even more stringent. Those houses are airtight.

2) 2006 is a newish home, but still very leaky, unless they are designed well well overspec.

3) 2006 home will leak air and make a full HRV system not as effective as they are designed to be.

4) In an balanced system in our house config, the ducting runs are very long. There is a lot of pressure lost.

5) I am unsure if I got this exactly right, but air changes more frequently in the positive pressure system.

Neither will cool my daughters room or wifes office which are side by side, very much, but the summer kit in the positive pressure system is going to reduce temps slightly, he estimates 2-5 degrees, but it isn't possible to know easily in advance of installation.

He thought 8K for the balanced system was likely due to huge insultated ducting requirement and thought it was likely to cost slightly less with SV but not much less.

Thoughts?

Disclaiming any kind of qualification about this in advance, but that sounds pretty reasonable. Certainly puts some perspective on what amounts to a "new" vs "old" home though!

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networkn

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#2084330 5-Sep-2018 13:48

mdf:

Disclaiming any kind of qualification about this in advance, but that sounds pretty reasonable. Certainly puts some perspective on what amounts to a "new" vs "old" home though!

Agreed! I was pretty blown away by that as well. Slightly horrified.

Next house we build or buy, we will be putting in a system at the start.

networkn

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#2086735 10-Sep-2018 10:44

Well I am HELL confused.

Everyone except CleanAire who don't sell positive pressure, have said to us, even though they might sell both, positive pressure is the way to go.

I am struggling to understand the downsides of positive pressure. Some discussions I've held have indicated that positive pressure moves the moisture from the windows, into the walls, that it's not getting "out" of the house, or actually reducing the moisture, but "moving" it to less obvious places.

The summer bypass at least seems to move the air from outside, but you wouldn't want this in winter.

At the home show we looked at companies who retrofit double glazing, and they have double latches which allow you to have your windows open a crack but still secure. Would a combination of this plus a positive pressure system be ideal? 25K for double glazing so we won't do this.

One thing worthy of note, is that our rooms retain their heat really well. Even rooms with gaps under the door (kitchen leading to hallway both tiled for example) keep the vast majority of their head, even for quite a few hours after the source of the heat is off.

We had a look at SkyVent as well.

hadenkose

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#2086743 10-Sep-2018 11:01

Double glazing won't fix your problem. It can help to mask it, but unless you go for thermally broken joinery with argon filled low E glass, then you're still gonna get condensation (on the window frames at least).

As I said earlier, I have a SV Evolve PP with summer feature (and double glazing with double latches) in a house built in 2014. Before my SV install i had condensation on the windows. After the SV install, 99.9% of the condensation in our home is gone.

Not sure what your hang-up is on PP systems?

networkn

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#2086756 10-Sep-2018 11:08

hadenkose:

Double glazing won't fix your problem. It can help to mask it, but unless you go for thermally broken joinery with argon filled low E glass, then you're still gonna get condensation (on the window frames at least).

As I said earlier, I have a SV Evolve PP with summer feature (and double glazing with double latches) in a house built in 2014. Before my SV install i had condensation on the windows. After the SV install, 99.9% of the condensation in our home is gone.

Not sure what your hang-up is on PP systems?

Well, according to some people, the moisture has simply moved from the Windows, to elsewhere in your home, therefore you aren't getting rid of moisture, you are simply moving it to other areas of the house (which may be less easy to get rid of with a squeegee etc).

A drop in condensation, is not necessarily a drop in overall moisture though. Did you make any other changes, like provide additional OUT ventilation, or everything else is the same?

networkn

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#2086763 10-Sep-2018 11:15

We had a Auckland person for Moisture Master in on Friday. He was very knowledgeable and thorough. He was the first to acknowledge that the previous rights holder hadn't handled after sales service and installations well, but assured us things have changed. I don't mind the system in and of itself. Waiting for a quote. They also do SV on request too if we wanted them to.

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hadenkose

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#2086764 10-Sep-2018 11:15

networkn:

hadenkose:

Double glazing won't fix your problem. It can help to mask it, but unless you go for thermally broken joinery with argon filled low E glass, then you're still gonna get condensation (on the window frames at least).

As I said earlier, I have a SV Evolve PP with summer feature (and double glazing with double latches) in a house built in 2014. Before my SV install i had condensation on the windows. After the SV install, 99.9% of the condensation in our home is gone.

Not sure what your hang-up is on PP systems?

Well, according to some people, the moisture has simply moved from the Windows, to elsewhere in your home, therefore you aren't getting rid of moisture, you are simply moving it to other areas of the house (which may be less easy to get rid of with a squeegee etc).

A drop in condensation, is not necessarily a drop in overall moisture though. Did you make any other changes, like provide additional OUT ventilation, or everything else is the same?

The PP system moves the old moisture laden air through the path of least resistance. In my case that is through the windows that I have cracked open in every room of my house. (not through my walls or ceilings). I know it is working because the humidity sensors on the SV system throughout my house show me that it is working. (Another bonus of the SV Evolve system, as opposed to other PP systems which are just working off a temperature setting and running constantly at a set speed).

networkn

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#2086767 10-Sep-2018 11:19

hadenkose:

The PP system moves the old moisture laden air through the path of least resistance. In my case that is through the windows that I have cracked open in every room of my house. (not through my walls or ceilings). I know it is working because the humidity sensors on the SV system throughout my house show me that it is working. (Another bonus of the SV Evolve system, as opposed to other PP systems which are just working off a temperature setting and running constantly at a set speed).

Well if you have cracked the windows open, that is the the part that is "missing".

If we open our windows in Winter, our house will be cold and require additional heating. If I understand this correctly, the Balanced systems don't require this step.

I'd be interested to see if you left the windows open and the SV system "off" what the effect would be.

hadenkose

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#2086783 10-Sep-2018 11:34

networkn:

hadenkose:

The PP system moves the old moisture laden air through the path of least resistance. In my case that is through the windows that I have cracked open in every room of my house. (not through my walls or ceilings). I know it is working because the humidity sensors on the SV system throughout my house show me that it is working. (Another bonus of the SV Evolve system, as opposed to other PP systems which are just working off a temperature setting and running constantly at a set speed).

Well if you have cracked the windows open, that is the the part that is "missing".

If we open our windows in Winter, our house will be cold and require additional heating. If I understand this correctly, the Balanced systems don't require this step.

I'd be interested to see if you left the windows open and the SV system "off" what the effect would be.

My double window latches have been installed from the get go - Had condensation, hence why I installed the SV. A couple of times during the previous winters I have got up in the morning and noticed "wet windows". I've gone to check the SV system and it was not on.

As for the additional heating...I haven't noticed any extra costs. We were using the heaters before the SV was installed and also after. With the added humidity sensors in the SV, it can tell when condensation is about to form and then react to that. I believe SV have inline heaters that can rapidly heat the incoming air as well, if you're worried about the temperature. They are supposed to be super efficient. It all adds up though unfortunately.

The end of the day it's your call. I'm just relaying my experience, which has been positive with SV (bad joke I know)

networkn

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#2086786 10-Sep-2018 11:36

Hi.

Thanks for your information. I am not disputing your account or experience, simply trying to understand the situation fully. I wasn't aware you had windows open until today, that explains where the moisture goes. It's the missing "piece" per se.

How many windows do you have open per room, do you know?

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