DVS - HRV - MoistureMaster

[Wayne]

Do you think a stud finder can help me to find ceiling beams??? So i can cut the hole without hurt the beams.

given that the ceiling sits on 40mm ceiling battens attached to the trusses (ceiling beams) the stud finder won't bridge the 40mm gap. I have done it on my own - note what the rooms look like (shape wise) and try to work out where you are when in the ceiling. Walls will generally have 150mm wide top plate so you can work it out from there. If you are unsure drill a small (2mm) hole from above and then find that hole from below. Makes for a lot of climbing around

[Giggles]

ventilation

sounds like an advert? SmartVent make a system now that does the same

Ha ha - perhaps I should enquire about a job? Yes looked at the Smartvent "Synergy" system (NOTE - smartvents normal system is only fan forced). Talk about high tech I was keen to look closer as it calculated all sorts of things moisture removed power saved etc... but two issues here were that I could not understand how these calculations could be accurate, as there looked to be no accurate measure on volumes of air moved just fan speeds etc (among other things) - or that’s what I was told...

I could have overlooked these un-pure calculations - as their display was very high quality and interactive (I like to play with technology) however the price we got back was significantly more than the other quotes received.

my 2c worth anyway...

I am supportive of all companies bringing to market true heat exchange technology rather than just the al-cheapos attic fan variety...

[Wayne]

the al-cheapos attic fan variety...

El Cheapo - I wish. I think they are expensive for what they are. I installed a Smart Vent for the simple reason I could buy it trade and install it myself. Saved over $1000 for less than a days work.

[Giggles]

El Cheapo - I wish. I think they are expensive for what they are. I installed a Smart Vent for the simple reason I could buy it trade and install it myself. Saved over $1000 for less than a days work.

Thats what I mean the component cost itself is cheap for these brands the rest of the ticket price is to hold up their marketing budget. Our quotes Lossnay & Intelivent were within 7% of the HRV & DVS quotes - but the differnce is you get a heat exchanger and advanced controller... with the first two - and the result is arguably better ventilation and lower heating costs!? What was your trade price for the smartvent system?

[Wayne]

less than $1300 for a 5 outlet system. To buy an extension is around $130, that's for an outlet, 3m duct and a 'Y' - purchased same (actually 6m duct) for $35 for the bits.

[MarkS]

Putting in vents. General thoughts on HRV's.

Hi ytao003

I helped a plumber friend put in a roof space gas heating system and he used a simple system of drilling a tiny hole (1mm) in the ceiling, from below, then poking a piece of brazing wire up through the hole. With me in the roof space checking to see where the wire came out and shouting to go 100/50/(or whatever)mm to the back/right side/left side of the house to avoid any battens or joists. He drilled very few dud holes and they were either removed with the vent hole material or quickly filled with a dab of filler which made them near invisible. Very quick method. If you have more time it's more accurate to drill the hole from the ceiling space but you must have a very good idea of room position.

Hi everyone else

We are in the process of researching a ventilation system and have found the comments on this thread very helpful.

One thing that occured to me is do these systems actually remove moisture or do they just stop layers of cold air forming against the windows and releasing the moisture from the air thereby causing condensation? If they are just moving air then any ducted fan system will work (like the Bunnings ones) The only way I know of to remove moisture from air is using a dehumidifier or heat pump or a dessicant like silica gel.

It seems like the ideal system in heating mode would use heat from the roof space when available or redistribute warm air from the rooms when the roof space was too cool. As for cooling, I'm not sure if any ventilation system is capable of this other than just keeping the air moving and not allowing condensation to form. I have yet to see any humidity comparision figures for any HRV system.

Keep up the discussion.


Cheers

Mark

[Wayne]

I helped a plumber friend put in a roof space gas heating system and he used a simple system of drilling a tiny hole (1mm) in the ceiling, from below, then poking a piece of brazing wire up through the hole. With me in the roof space checking to see where the wire came out and shouting to go 100/50/(or whatever)mm to the back/right side/left side of the house to avoid any battens or joists. He drilled very few dud holes and they were either removed with the vent hole material or quickly filled with a dab of filler which made them near invisible. Very quick method. If you have more time it's more accurate to drill the hole from the ceiling space but you must have a very good idea of room position.

A less invasive method is a person above and below with a reasonably stong magnet to find where they are.

[RobBurling]

One thing that occured to me is do these systems actually remove moisture or do they just stop layers of cold air forming against the windows and releasing the moisture from the air thereby causing condensation? If they are just moving air then any ducted fan system will work (like the Bunnings ones) The only way I know of to remove moisture from air is using a dehumidifier or heat pump or a dessicant like silica gel.

Hi Mark,
Moisture is effectively removed by changing the air in the house ... warm air from the roof space is forced into the house, and the (moist) air in the house is pushed out under doors, through open windows or vents in aluminum joinery, etc.

[Wayne]

Hi Mark,
Moisture is effectively removed by changing the air in the house ... warm air from the roof space is forced into the house, and the (moist) air in the house is pushed out under doors, through open windows or vents in aluminum joinery, etc.

Warm air should probably read drier air as warm implies that it provides heating to many people.

The drier air in the house means that there is less moisture (obvious really) therefore the house is easier and cheaper to heat. The modern house is quite air tight so sometimes it pays to leave windows open a crack.

[MarkS]

Yeah but...

We live in Hamilton and I can tell you that we get bad humidity in summer and fog in winter. We have a house about 10 years old so it's well insulated and situated for the sun. We don't really have heating problems. Our main issue is humidity and cooling.
If the roof space air is coming from outside on a humid day and being heated in the roof space it won't lose moisture, in fact hot air will retain more moisture so apart from the air moving through the house and having a slight cooling feel to the occupants from evaporation I can't see how the air can become drier. That's my point I guess, any positive pressure system will cause air movement inside the house but may not actually dry the air out although will reduce condensation forming. So if condensation is an issue then spend $1000 at Bunnings rather than $3500 for one of these systems especially with some of the previous comments on the mediocre heating effect.

Mark

[Wayne]

Yeah but...

We live in Hamilton and I can tell you that we get bad humidity in summer and fog in winter. We have a house about 10 years old so it's well insulated and situated for the sun. We don't really have heating problems. Our main issue is humidity and cooling.
If the roof space air is coming from outside on a humid day and being heated in the roof space it won't lose moisture, in fact hot air will retain more moisture so apart from the air moving through the house and having a slight cooling feel to the occupants from evaporation I can't see how the air can become drier. That's my point I guess, any positive pressure system will cause air movement inside the house but may not actually dry the air out although will reduce condensation forming. So if condensation is an issue then spend $1000 at Bunnings rather than $3500 for one of these systems especially with some of the previous comments on the mediocre heating effect.

Mark

None of these systems will really heat. If you want cooling then get a heat pump - could go for ducted, mine just installed only cost $12k. Condensation isn't an issue in the summer but in the winter you produce and keep a lot of moist air in the house - showers, cooking, breathing. The ventilation systems will force some of that moist air (I would think more moist than the air outside) out of the house. The idea of the more expensive heat exchanger units is to recover some of the warmth from the house to reduce the heating need - it is debatable how much they recover and therefore how long they would take to pay back.

[RobBurling]

Hmmm....

Not really sure how you could deal with high humidity ... I think you might be surprised by how much moisture in the house is generated from people just breathing ... not to mention showering and cooking. I did see the figures in one of the sales blurbs, and was surprised by the number of litres, but I can't recall any numbers.

I suspect that even in high humidity areas you might get some benefit from moving the air through the house, but I'd just be guessing

I do know that both the HRV and DVS we have installed in seperate properties work really well in Christchurch (where humidity tends to be fairly low).

I have noticed that the heating effect works really well down here, because we tend to have high sunshine hours on our cool winter days, and the roof space heats quite well. On our really hot summer days, when we have hot nor'westers, the roof space doesn't really cool down until the early hours of the morning, so we don't get much cooling ... I have often thought that something to bring air from outside (rather than the hot roof space) would provide better cooling. I think the 'smart' systems that Bunnings sell have an option for that.

[Wayne]

... I have often thought that something to bring air from outside (rather than the hot roof space) would provide better cooling. I think the 'smart' systems that Bunnings sell have an option for that.

The smart vent does have that option. It needs a 'cool' side of the house if there really is one on a hot nor'west day

[Clark Kent]

HRV / Heatpump

We installed an HRV in Feb this year and found it complemented our heatpump extremely well. Great for providing fresh air in the house in sticky summer evenings when you are trying to get some sleep.

Good on warm winter days for providing extra heat in the house up until 5.30pm so no need to put the heatpump on. Using an HRV makes your heating more efficent as it takes the moisture out of the air, an increase in moisture by 1% reduces your heating effiecency by 10%.

[starlyte]

We installed an HRV in Feb this year and found it complemented our heatpump extremely well. Great for providing fresh air in the house in sticky summer evenings when you are trying to get some sleep.

Good on warm winter days for providing extra heat in the house up until 5.30pm so no need to put the heatpump on. Using an HRV makes your heating more efficent as it takes the moisture out of the air, an increase in moisture by 1% reduces your heating effiecency by 10%.

What about warmth in the areas that the heatpump is not heating
does it move the heat?