Is HRV required even if I have a central heating system

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Rmani

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#265355 17-Jan-2020 15:07

Hi,

As per subject, I am in the process of installing a central heating system. Should I consider installing heat recovery system as well? There were few GZ threads that I went through, but couldn't find a definite answer.

If yes, should I have both from the same company or can I have from two different companies, like central heating from EES and the other one with Smartvent?

Cheers

Rmani

sparkz25

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#2400798 17-Jan-2020 15:15

I would just get a fresh-air supply added to the installation of the ducted system (your installer should be able to sort this for you) if not it might pay to talk to a few other installers and tell them what you want.

HRV is just a well-marketed fan in a box system that just blows air. There is nothing special about it at all!

timmmay

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#2400826 17-Jan-2020 15:41

Central heating typically recirculates the same air, which can get stale. Bringing in fresh, properly filtered air is good, but cools the place down in winter. A heat recovery ventilation system (I'm referring to the technology not the company) uses the outgoing warm air to prewarm the incoming air, reducing losses. It works in reverse in summer. When I say filter, I meant F7 / HEPA rather than a sock filter, which only really filters out huge things like mice, and shoes, and large pieces of dust, not the really damaging small particles.

So, yes, ventilation is good.

evilengineer

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#2400873 17-Jan-2020 17:05

timmmay:

Central heating typically recirculates the same air, which can get stale. Bringing in fresh, properly filtered air is good, but cools the place down in winter. A heat recovery ventilation system (I'm referring to the technology not the company) uses the outgoing warm air to prewarm the incoming air, reducing losses. It works in reverse in summer. When I say filter, I meant F7 / HEPA rather than a sock filter, which only really filters out huge things like mice, and shoes, and large pieces of dust, not the really damaging small particles.

So, yes, ventilation is good.

Depends what type of central heating you're referring to.

I'm originally from the UK so automatically assumed he meant hot water radiators.

Either way, ventilation/air changes are definitely required to get stale. moist air out of the building. Whether that's by a mechanical system or just opening the windows is up to you.

Compared to your typical HRV arrangement a balanced system with a heat-exchanger at least gets some of that warmth you've already paid for back into the incoming fresh air rather than just forcing it out through the gaps in the building fabric.

Hammerer

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#2400879 17-Jan-2020 17:18

There will be confusion over the term HRV because it has two main cases in relation to your question?

1. HRV is the generic term e.g. see http://www.level.org.nz/energy/active-ventilation/air-supply-ventilation-systems/heat-and-energy-recovery-ventilation-systems/

2. HRV as the NZ company with a name designed to monopolise discussion of and options for the generic term. This company did not have an HRV system with a heat exchanger that works to maintain the internal temperature of the house instead of losing it. Maybe they have now?

Rmani

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#2400922 17-Jan-2020 18:03

@Hammerer I see where you're coming from
I understand the 2 HRVs(Heat Recovery & the Company). The company EES(HRV) now does both central heating and heat recovery. Hence I wanted to know if it makes sense to do both from them.

Rmani

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#2400924 17-Jan-2020 18:04

evilengineer:
Depends what type of central heating you're referring to.

I'm originally from the UK so automatically assumed he meant hot water radiators.

Either way, ventilation/air changes are definitely required to get stale. moist air out of the building. Whether that's by a mechanical system or just opening the windows is up to you.

Compared to your typical HRV arrangement a balanced system with a heat-exchanger at least gets some of that warmth you've already paid for back into the incoming fresh air rather than just forcing it out through the gaps in the building fabric.

I am planning to go with ducted heatpump.

Rmani

mrdrifter

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#2400963 17-Jan-2020 20:42

I'm also right now comparing quotes for a ducted heatpump and am trying to decide if I have the ventilation components added into the system. My understanding is that it sits between the return air inlet and the main unit with some backflow protection and that enables the introduction of fresh air. I was given the impression by one company representative, that it should only be in the region of $500 to add.

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Rmani

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#2400984 17-Jan-2020 22:03

Yes, just received quote from another company, the ventilation component is $700

Rmani

Jase2985

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#2401036 18-Jan-2020 07:38

Rmani:

Yes, just received quote from another company, the ventilation component is $700

likely not a true HRV for that price

Rmani

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#2401289 18-Jan-2020 13:40

Received the below. Looks like it'll be integrated with the central heating.

ARIZONA 6 DIFFUSERS GEN3 1 $4199.00 $4199.00
Pana S100PE1R5B R32 Ducted R/Fit-HRV 1 $10449.00 $10449.00
HP HRV Integration Arizona to S100 - S125 1 $699.00 $699.00

Rmani

Jase2985

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#2401438 18-Jan-2020 17:25

they are giving you one of these:

https://www.hrv.co.nz/ventilation

still doesnt look like a true HRV just looks like it a big ass fan/filter unit

a true HRV has 4 inlet/outlets which allow the warm outgoing air to transfer its heat through the core into the cooler incoming air, which warms it up a bit to help with heating. it also filters and can dehumidify it a bit depending on its design.

Scott3

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#2401468 18-Jan-2020 19:45

I try not to use the term "HRV" because of the NZ company trading under that name. They now offer lots of products, but their main offering historically was a positive pressure ventilation system. Essentially this system sucks warm air from the roof space into the house, via a filter, fan (with controller) and some duct work.

The claim for the name "heat recovery ventilation" was that the system recovers hot air from the roof-space and blows it into the house. Unfortunately a university study has proven that there is rarely hot air in the roof space at times when heating is desired.

Also it is widely accepted that air quality in the roof space is often poor quality. Claims are made that filtering this air makes it OK, but I don't really buy into that. The filters typically used are "F7" grade, which is described as a "Medium" filter, and still allows the passage of some harmful particulates.

Personally can't really see the point of the above systems unless for some reason windows can't be opened (perhaps for example due to noise or security concerns)

The other type of system is a Balanced Pressure system with an air to air heat exchanger. These systems transfer the heat from outgoing stale air to incoming fresh air (drawn from outside then filtered). Along with a well sealed house, great insulation etc, they are one of the main things that makes passive houses so efficient.

Both balanced pressure and positive pressure ventilation systems can be integrated with ducted heat pump systems. In commercial settings the latter is offer called fresh air injection, and typicall uses outside air rather than roofspace air.

Which route to go depends on how much money you want to spend. Balanced pressure systems are a lot more expensive.

mrdrifter

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#2401469 18-Jan-2020 19:55

What is the separate line item for - ARIZONA 6 DIFFUSERS GEN3

Is this an additional item of some sort?

mrdrifter

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#2401471 18-Jan-2020 19:58

Oh nevermind, I figured it out, they are charging you for a complete Ventilation system at $4200 and then charging you the $700 for integrating the two.

That would seem steep to me as you don't need the extra diffusers and everything else that comes with the ventilation system.

timmmay

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#2401507 18-Jan-2020 20:59

I had an old ventilation system with a sock filter, taking air from the ceiling cavity. The sock went black in a few weeks when I put a new one on. Best thing I did was re-route it to get air from outside, and put a filter inline. Right now it's only a G4 filter, but I will upgrade it to HEPA potentially with active charcoal when I get to it - we live near a motorway.