HRV/DVS/MM

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#1084224 8-Jul-2014 16:33

More research on your part is definitely needed. That's super expensive given they're selling you plastic pipes, fitting, and a fan. For that price I hope it has a heating option (which you shouldn't get/use/pay for) and a heat recovery unit. The heat recovery unit is pretty important, it means instead of just pushing cold air in at night it sucks stale warm air out, takes cold fresh air from outside, warms the outside air, so you have warm(ish) fresh air in your house.

Removing sources of moisture is more important. I don't like shower domes, but extraction is critical - kitchen, bathroom, and laundry. Ventilation by opening windows is mildly effective.

Condensation is caused by warm moist air hitting a cold surface - the window. The reason a ventilation system helps reduce (not eliminate) condensation is because it blows cold, dry air into the house, so there's less moisture and the air's colder. A more effective way to almost eliminate condensation is double glazing. The cheap way is to get a firm to fit 3mm thick solid plastic inside your existing window frames, if they can be mounted. It's basically cheap double glazing, perhaps $5K for the whole house, whereas replacing every window with a PVC double glazed unit will cost you more like $30K. It works almost as well as "proper" double glazing, but is a little uglier.

Plastic ground mat made a big difference to the damp smell in my house, combined with under floor insulation.

I do have a cheap ventilation system, only because it was in the house when I bought it. I don't like taking air from the ceiling cavity as it's a bit smelly in my old house, so I'm going to bypass it and draw in fresh air soon. That will still dry the place out, but won't warm it from the roof cavity air. I value air quality over warmth, I'll just schedule it to come on say 11-3pm, when it's warmer outside anyway. Because we have double glazing in most of the house we don't need it on all the time, it makes the place cold, blowing cold air in constantly.

Check out Cleanaire for a good value heat recover ventilation system. That's who I'll use when I eventually fit one.

This and much more on the older threads. Google will find them for you.

mattwnz

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#1084225 8-Jul-2014 16:33

Dynamic:
mattwnz:
CuriiuosGeorge: Hi guys, thanks heaps for the quick reply. I've read a lot of the other forums but the prices seem to be from a few years ago so I'm not sure how accurate the prices are. It's a 3 bedroom house and essentially we just want it to reduce the condensation and to dry out the house in general. It's a pretty standard house and they said it should be relatively easy to set up. They said the prices are non-negotiable and they'll give us a ring tomorrow night so I just wanted to do some further research with regards to the pricing. Thanks again guys for your help and input! :)

You need to treat the cause of the problem, which may eliminate the need for one in the first place. If you are on piles, you may benefit in installing polythene over the dirt under the floor and sealing it at the edges and joins, and installs insulation under the floor. Then installing more insulation in the ceiling where most heat is lost.

I wouldn't think that the condensation is from moisture under the house, but agree that it should be checked to confirm under the house is not a 'significantly damp' area. Most of the moisture on the windows IMHO would be from the heavy-breathers overnight.

I actually recall seeing a story about a ventilation system that was sucking up damp air from under the house, up through the wall cavities, and then pumping this damp damp roof air into the house, so it actually made the condensation worse. Ling the subfloor with poly apparently ended up fixing this.

Certainly some condensation is for people, but not sure how many litres one person produces overnight, I wouldn't have thought it would be that high. But opening the door in the bedroom overnight may help with that

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#1084226 8-Jul-2014 16:35

NonprayingMantis: If you have gas available, you could get gas central heating installed with 5 vents for about that price, and it circulates the air AND provides heating at the same time.

I have gas (bottles) and got a quote for one of these gas central heating systems. Very high rating (18kW from memory) but the cost was closer to $10K (Rinnai Infinity based and that is based on me already having a continuous gas hot water system), and that's for a 3 bed bungalow less than 100m2. Plus the installers said it needs a space about 300x400 for a 'return vent' that has to be centrally located, which didn't work out with the house layout.

If you know where I can get it for $4K I would be very interested.

(EDIT - bad typing)

scuwp

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#1084227 8-Jul-2014 16:38

+1 for SmartVent. HRV salesperson just too pushy and then hounded us for weeks after - big turn off. Also SmartVent don't lock you into costly maintenance, you can actually do things yourself like change the filters, and they will willingly supply parts. Ultimately they all do a similar job of moving air around. The rest is just sales-pitch and hype.

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CuriiuosGeorge

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#1084228 8-Jul-2014 16:44

Hi guys, thanks a lot for your input! Sorry, I should've probably provided more details. We have a heat-pump in the lounge to heat up the house, rangehood for the kitchen and an extractor fan for the bathroom although there are often still plenty of moisture after we shower. So is the general consensus that it is too expensive? i.e. has someone installed one recently for a cheaper price? (either HRV or other similar products) Thanks again everyone! :)

scuwp

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#1084253 8-Jul-2014 17:07

i.e. has someone installed one recently for a cheaper price? (either HRV or other similar products) Thanks again everyone! :)

SmartVent have now done a number of workmates houses...word of mouth got around. Last one I am aware of was a 5 outlet system in an older home, don't quote me but my recollection was it was <$3,500. I think that included a summer vent (or similar) as well. No heater.

Disclaimer...I don't work for or have any association whatsoever with any vent company, just word of mouth from a number of users.

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#1084262 8-Jul-2014 17:21

CuriiuosGeorge: Hi guys, thanks a lot for your input! Sorry, I should've probably provided more details. We have a heat-pump in the lounge to heat up the house, rangehood for the kitchen and an extractor fan for the bathroom although there are often still plenty of moisture after we shower. So is the general consensus that it is too expensive? i.e. has someone installed one recently for a cheaper price? (either HRV or other similar products) Thanks again everyone! :)

Make sure that both aren't venting into the ceiling cavity. Old range hoods used to go straight up into it, with no external vents. ALso check for any leaks under you house in the subfloor space. Many houses do have minor leaks which they are not aware of.

cep32

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#1084448 8-Jul-2014 21:59

From memory the you can expect around 40-50 litres of water per day to have to evaporate out of the soil under an average 3 bedroom home if the soil feels dry and crumbly. Of course it will feel dry and crumbly because the water is evaporating out of it. If you have really good ventilation under your house then it shouldn't be a problem but most 1960's houses for example have pretty poor ventilation so the other option is to stop it getting out of the soil and into the house. We spent $100 on a roll of 250 micron polyethene (4m x 25m) and it took me 4 hours or so to lay ot under the house and tape the joins and around the piles. It has been down for only 4 weeks and already the floor boards are starting to shrink as they dry out. The condensation we get in the house has also reduced to a very fine mist rather than running.

I don't really understand the whole HRV thing. I would have thought that unless you insulate directly under the roof then the air in the roof space will be the first to cool down. If you have a corrugated iron roof it will get a lot of condensation on the underside of it so when it starts to warm up in the morning the moisture content in the air will increase just as the system starts to pump air into the house from the roof space.

Check out Seven Sharp this Thursday for Nelson City Councils energy efficiency specialist talking about all of the low cost things you can do to your house to make it drier and warmer.

richms

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#1084449 8-Jul-2014 22:00

Put a timer on the bathroom fan so it keeps going for 20-30 mins after a shower and run a dehumidifier in winter. They produce useful heat and will remove moisture. A heatpump just makes the existing moist air hotter. Running costs are stuff all being that they are usually 200-300 watts and you get all that and more in heat from them.

Check that the basement is ventelated ok, lots of people block the vents to reduce drafts thru the floor and that just lets the ground moisture build up. Poly on the ground will help a lot too.

HRV's etc are a croc, they bring in chilled roofspace air that you have to then pay to heat, which is then pushed out of the house via cracks etc where the now moist warm inside air will hit the cold building paper etc and condense out in the structure of the place if it can get in there. Get a balanced heat recovery system or dont bother, for those insane prices for a fan, a filter and some vents you are well on the way to the cost of the better systems.

Richard rich.ms

timmmay

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#1084533 9-Jul-2014 07:55

Get a better extractor for the bathroom - Bunnings don't sell them, I got mine through the bathroom firm that redid the bathroom. We have high pressure hot water and even on low no steam collects.

CuriiuosGeorge: Hi guys, thanks a lot for your input! Sorry, I should've probably provided more details. We have a heat-pump in the lounge to heat up the house, rangehood for the kitchen and an extractor fan for the bathroom although there are often still plenty of moisture after we shower. So is the general consensus that it is too expensive? i.e. has someone installed one recently for a cheaper price? (either HRV or other similar products) Thanks again everyone! :)

No, the general consensus is you need to take a step back and consider the problem you're trying to solve, as well as fully reading this thread and the others linked to. A ventilation system will increase your heating bill significantly if not set up properly. I also recommended another firm to consider, who are both better and cheaper than DVS.

shk292

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#1084545 9-Jul-2014 08:33

I remember looking into these systems a few years ago when I bought a house. The most interesting I found out is that the systems sold by "HRV" are not a true heat recover ventilation system - the company's name itself is inaccurate description of their product. A true HRV system uses a heat exchanger to move heat from the warm air sucked from kitchen, bathroom etc to the cold air it draws from outside and pushes into your house. Compared with the overpriced systems that HRV sells, which simply suck air from your roofspace and blow it into your house.

If you could get a true HRV (non-trademark) system for $4k that's probably worthwhile. But with HRV(tm) you're probably paying $500 for some fans and ducting and $3.5k for marketing and those flash V6 commodores the reps drive around in.

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#1084547 9-Jul-2014 08:49

Just in case anyone with a Weiss heat transfer system installed is reading this thread, read the following. I wasn't aware of it until this morning despite a recall being in place already.

http://tvnz.co.nz/national-news/fires-feared-despite-heat-transfer-system-recall-6022449

Speedtest

blackjack17

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#1084548 9-Jul-2014 08:59

I would start fixing the cheap stuff first.

Polythene under the house $100

[Url=] https://touch.trademe.co.nz/listing/view/751745099 [url]

Crack a window at night free

Shower dome $150

Thermal lined curtains ~$200 a room

3 double glazing for non opening windows. $15 a window

And if all doesn't work then consider a air transfer system

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andrewNZ

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#1084557 9-Jul-2014 09:22

DON'T DO IT!

PPV (positive pressure ventilation) is a scam!
If you're going to get a ventilation system get a real one that recovers heat.

I have an HRV system which was there when we bought the house. It does do some good things, but mostly these systems are terrible and overpriced. Over all I hate it, and it's coming out as soon as I can afford to replace it with something better

Pros:

It does remove moisture from the house.

It's true, it does make the house drier. However There are other ways to achieve this.

On some sunny spring and autumn days, it provides some heat from the roof.

This is nice, and on these days I'm happy to have it.

On some summer nights it brings in cool air.

This is good, but usually doesn't happen till very late at night, until then it's pushing in hotter air than is outside.

Cons:

The system can't be turned off permanently unless you unplug it. If you turn it off, it turns itself back on after a few hours.

This is the default and I understand this can be changed by the installer but that doesn't make it any less crap. Basically, in the summer it's ALWAYS pushing in hot air, and in the winter it's always pushing in cold air. Some may argue that it's not that big a deal, I disagree, it makes a huge negative difference.

They want more than $500 to replace filters and "service the system". I forget if it's 1 or 2 yearly.

I did the filters myself, it cost $140 for better filters and about 30 minutes of my time. The system doesn't have anything to service except filters, and they're held in with tape.

It steals bucketloads of heat in the winter, and overheats the house in summer.

As I've suggested already this type of system has a massive negative effect in summer and winter, and this is by far my biggest gripe.

In winter, there is a constant flow of cold air which forces warm air out. We always have trouble getting heat to the bedrooms because of the constant flow of air these systems produce. On an exceptionally cold day recently (about 3-5 degrees all day), I had trouble warming the house up even with the fire roaring, so I turned the system off and the house, including bedrooms, was warm in no time.
They have a "solution" to the cold air problem, and that's to put a tempering heater in it. IMO this isn't a solution, it's a bandaid, and an expensive one at that. If it didn't replace warm air with cold there wouldn't be an issue.

In summer, there as always hot air being pushed in. Most days when we get home, the house is too hot to be in and takes hours too cool down.

The system is cheap and nasty.

It's seriously crap. It consists of vents, flexible ducting, and two sheet metal boxes with a fan and a filter in it and the two halves of each box are just taped together. The price they charge for this crap is criminal. I'm honestly surprised they're

There are far better solutions to the problems these systems claim to solve. Avoid PPV like the plague!

CuriiuosGeorge

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#1084559 9-Jul-2014 09:30

scuwp:
i.e. has someone installed one recently for a cheaper price? (either HRV or other similar products) Thanks again everyone! :)

SmartVent have now done a number of workmates houses...word of mouth got around. Last one I am aware of was a 5 outlet system in an older home, don't quote me but my recollection was it was <$3,500. I think that included a summer vent (or similar) as well. No heater.

Disclaimer...I don't work for or have any association whatsoever with any vent company, just word of mouth from a number of users.

Hey mate, just wondering how your workmates are finding SmartVent. I've had them come round for a quote, they said it'll cost $3450 and they'll chuck in a free filter. Is this deal similar to what your workmates got? Thanks mate!
'

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