Topic: Ventilation system and Heat Pump or Fully Ducted system.

Ventilation system and Heat Pump or Fully Ducted system. 

Hello all,

Sorry the question might seem very strange and stupid but I am trying to learn. We are planning to build a house using the turnkey option. We are looking at a Ventilation system and Heat Pump or Fully Ducted system but can’t seem to make up our mind. It’s for a 200 sqm house and 2 level.

I understand from reading online that a heat exchanger ventilation system would cost around 4K to 5K (Heat exchange option since I not comfortable with the pulling air from the roof option). Also installation of 2 heat pumps (3.5KW) would be another 6K to 7K. We are planning to get the house insulated with R3.2 in the roof and walls with around R2.2. With this and brand new baby when the house will be ready, I THINK 2 heat pumps should be enough to keep the house warm or cool. So at a total cost of 11K to 12K, why shouldn’t I swap these 2 for a fully ducted system?

• Please advice if this seems like a good idea or should I stick to the plan of 2 systems.

• Does a fully ducted system act as a standalone ventilation system when neither heating nor cooling is not needed thereby saving electricity?

• Would a fully ducted system be close to 12K for a 200sqm 2 level home.

Thanks a lot for the replies and the advise.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

In NZ climate you should not require cooling unless your insulation and windows are poor, the design is poor (not enough eaves) or to many dark surfaces ouside. Also external shutters do magic keeping the heat out. Also in a cold night the windows oerform even better with the external shutters closed.

The other thing is whether you like warm air blowing around.
Radiant heating (whatever source) is the better option in all aspects especially in a new built.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

As far as I understand fully ducted heat pump doesn't mean it includes ventilation.

A Mitsubishi Lossnay heat recovery system and an 8kw ducted heat pump would be within the price you specified.

Wellington University used such a system (much lower kw heatpump to reflect smaller floor area) in building their award winning eco home (Lighthouse).

Re: Ventilation system and Heat Pump or Fully Ducted system. 

As far as I comprehend completely ducted electric doesn't mean it contains air flow.
http://www.peerlesswindows.co.uk/

Re: Ventilation system and Heat Pump or Fully Ducted system. 

I would agree with the use of a heat recovery ventilation unit, but look for a better unit than the current NZ Lossnay unit.

It only achieves between 48 and 58% heat recovery efficiency:
http://www.bdt.co.nz/aircon/data/manuals/lossnay/OM_SKU-50RJ-E.pdf

Mitsubishi commercial units in NZ achieve more like 70-80% efficiency:
http://www.bdt.co.nz/citymulti/data/brochure/2009_Lossnay_LGH_RX5.pdf

At the same time, UK spec residential units achieve up to 90% efficiency:
http://www.mitsubishi-aircon.co.uk/default.asp?url=http%3A//www.mitsubishi-aircon.co.uk/mitsubishi_electric.asp%3Fid%3D120065

I'd love to see the UK units here...feels like the NZ-specific product is poor, a theme unfortunately aired many times on Ecobob (please don't kick off at this again, unless you can refute the Lossnay figures above).

In the meantime, there are NZ manufactured heat recovery ventilation systems that achieve up to 95% efficiency, but probably at greater cost according to other forums here. I guess you get what you pay for, as ever. It would just be nice not to be insulted by importers...

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Sorry, poor weblink. Uk model is the lgh-50rsdc-e, google it if necessary.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Forgot to add: the NZ Lossnay unit uses 89w to push 67l/s through, versus 14w to push 100l/s for the UK model.

I'm not looking to knock particular manufacturers; like most people looking on here I'm just looking for a solution I can trust for my house. if someone from Mitsubishi wants to set the record straight (no fluffing facts/figures/test conditions then I'd be happy to hear it.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

That's interesting. I had seen product announcements for Lossnay on NZ and British sites. All I could find on the NZ site was the power supply rated at 200 watts which I thought was quite high as you can usually assume a fair proportion of the rated power supply will be used in operation. That suggests it is not even using an ECM motor which is becoming the norm on such units.

Sadly, it is often the case that manufacturers will specify different hardware for different markets depending on what they can get away with.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Hello Newbynz,
Reidential Ducted Air con creates a great controlled temperature throughout the house but is really only suited to single levels.
With a two storey home both ventilation systems and Ducted Air conditioning (heat pumps)are incredibly dificult to design and then install because of the lack of access due to the 2nd storey and overcoming the flopping and boyancy of hot or cold air so I would flag this in favour of using split system heatpumps or perhaps a multiroom system with a single outdoor unit(dearer cost but higher COP).
For both the ducted system and the ventilation system the ductwork design is as critical as the specification of the product used, if you go down this line of some form of ducted system ask for examples of their work either photos or better still ask if there are any systems due to be installed and can you come and see it go in. I say this as I am in the industry and the duct work installation of some companies is shocking.For any heat pump or ventilation system do ask how long the company has been around and what assurances they can give you.

Lossnay is a good product,it might not be the ultimate condensation remover but its job is to bring in fresh air and remove stale with minimal effect on house temperature and for a low price point it succeeds and is exceptionaly quiet ,the difference in heat recovery % will not be as much a determining factor in the running cost of the house than other components such as the insulation and chosen heating method so I wouldnt worry too much about which ventilation system as long as you use a true HRV/ERV modelnot a dvs or roof space ventilator(these brands are often accompanied by swear words around our company)

Do you really NEED a ventilation system-when choosing your home fittings get a more powerful kitchen and bathroom extraction system with a timer and that will make a major improvement in water load inside the house and keep bedroom doors open if possible as this often leads to bedrooms being closed off to the major heat source areas,keep the house well insulated and warm and you would need a major load of absolute humidity to cause condensation- then ventilate the house on a good fine day by openiing windows.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Hey Newbie.

You need to ask yourself "what am I wanting to achieve".
A new home is a good starting point as it is dryer than lived in homes but that will quickly change with inhabitants. You need to ventilate the home, 24/7 from day one to control moisture build up, IAQ and VOC's' from all the new buiolding products.
There is nothing wrong with taking roof space air so long as the system has a good filter and where does roof space air come from? outside. There are more pollutants outside than in the roof space so even if you went for a HRV which draws air from outside, it will need a good filter which most dont.

To Mr " I am in the idustry" keep up the self promo work for your lossnays and to refer to ventilation as open your windows puts you back in the category of the dumb.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Outside air is preferable over roof space air.
Yes it is outside air but not the same quality.
And there are more toxic particles in the roof space than outside air. And air which has been in the dark has a low ionisation which is important for well being.
We have a wall mounted venti machine with heat exchanger in our horrible box and I would never want the roof space stuff which is never the right temperature when you really need it.
For a new build I would (or will) probably go for a Paul system (with heat exchanger) from Germany.
Or another passive house suitable system from Europe.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Roof space air is transiting from outside, it is not sitting arpound in the space long enough to be contaminated or to be rendered unhealthy. It is in essence outside air. To say it is lower quality is not correct. Roof space air that is filtered is better quality than outside air persay.
Many sufferers of allergies, asthma and respiratory problems have experienced dramatic relief with the install of a roof space ppv. If the air quality was inferior to outside air there would be no relief.
If you choose a heat exchanger then its your choice. It does not mean it is superior. They cost more, cost more to run and require a primary heat source running alongside to maintain the temperature that is lost in exchange.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

The air exchange between the roof space and outside can be very slow (especially in modern houses) and therefore the quality of air is questionable.
The use of roofspace air is a grey zone in the building code.
What if the filter gets damaged by rodents and remains undetected for some time???? It can be quite bad, especially with glass wool used as insulation in the ceiling. If the filter of an outside air unit gets damaged it is like openinmg the window and the risk of contaminating the house is simply not there.
With regards to additional heating. Roof space PPV systems don't work without additional heating as the roofspace cools down rapidly after sunset.
The roof is a very unreliable heat source.
Also the PPV's rely of leaky windows and thermally ineffient construction and so on, therefore any heat gain during the day will be gone in a flash.
Even the power consumption of a good balanced system with heat exchanger is no more than PPV.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

And the relief of athma sufferers comes from the removal of moisture but not the "superior" air from the PPV. PPV might give some relief of moisture in old unrenovated houses but in new modern homes it is out of place like single glazing or open fire places....

Re: Ventilation system and Heat Pump or Fully Ducted system. 

What if ... the sky fell in

Re: Ventilation system and Heat Pump or Fully Ducted system. 

The relief of asthma comes from the removal of moisture AND flushing out VOC's, pollutants, dust, pollens etc etc and helping to prevent these pollutants from commming in to the house 24/7. It is not a 100% fix and it has faults but... it has major benefits and is cost effective. If you want to nit pick, you can nit pick any product.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Roof space air can be totally replaced in the average home in as little as 15 minutes. This is dependant on the system. The specific system I am refering to will do this.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

"The use of roofspace air is a grey zone in the building code.
What if the filter gets damaged by rodents and remains undetected for some time????"

What if these same rodents chew through your heat exchangers ducting and filters as well.......

Re: Ventilation system and Heat Pump or Fully Ducted system. 

"Even the power consumption of a good balanced system with heat exchanger is no more than PPV."

Name '1' heat exchange system that has a maximum output of 85 watts and runs 80% of the time at 15 watts which has a full at the fan output of 860 cmph when required.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

"The roof is a very unreliable heat source".

Hello, were talking ventilation, not heating. Dont drag that age old argument up, it was never claimed or mentioned (but I disagree with you).

Re: Ventilation system and Heat Pump or Fully Ducted system. 

OK I accept your are a sales rep. for PPV's therefore discussion pointless, ....time wasted.
I am not commercially involved in venti systems therefore my opinion is based on my over 20 years work here and in Europe....totally unbiassed

Re: Ventilation system and Heat Pump or Fully Ducted system. 

No I am not a sales rep for ppv.

Why discussion pointless - what I have said to date is correct, if you disagree then thats o.k. I can back up what I say with experience as well.

All and any ventilation for homes whether they be caves or these airtight viral cesspits they are building these days are good. It comes down to what your wanting to acheive, your purchasing budget and running budget.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Time has definately not been wasted.

Look at all the relevant information readers will now have to which they can make their own deductions from, definately not wasted.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

NZ's Ventilation code for residential homes is NZS4303 which specifies that not less that an area of not less than 5% of the floor space must be in openable windows OR a mechanical device that provides 0.35ACH.
The problem for homeowners is that in NZ almost all homes (except passive design) pass NZS4303 building inspection requirements because of the 5% rule - therfore any aftermarket ventilation systems installed by the homeowner does not have to meet any standard apart from electrical safety requirements.
NZ's ventilation problem is that in winter temperatures who wants to open their windows. So the ventilation rate is not being satisfied.
Companies should be trying to install mechanical
ventilators that then give the home back its NZS4303 requirement.But do they?
HRV / DVS and other positive pressure ventilators do not comply with this ventilation code only units that give 24hr a day ventilation with outdoor source air are going to comply,Heat recovery is not a component of NZS4303 but why wouldnt you use heat from expelled air.
I have seen houses that had bad condensation on windows removed by positive pressure systems so they are not all bad but one is much the same as the other,what does need to be said though is that these systems will cool the house done a degree or so as well and can introduce a musty smell to the home.The roof space is also a dusty environment especially in the cold damp older homes the PPV companies target.yes a G7 Filter captures 99.9% of particles BY MASS, yet 99% of particles are actually microscopic and still pass through the filter, hence the musty smell from a HRV.
HRV brand marketing told how there is loads of warm air in the roof to HEAT your home, now the Otago university study has dismissed this the HRV brand marketing has shifted away from the free heat claim.

Re: Ventilation system and Heat Pump or Fully Ducted system. 

Funny that the air stays long enough in the roof to get heated, but not long enough to get contaminated ...