Gas califont clearance requirements from air vents

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Paul1977

4983 posts

Uber Geek

#270222 29-Apr-2020 11:41

We are having a Mitsubishi Lossnay installed in our new build and just trying to determine the best positions for the external vents.

The way it's currently drawn up has the Lossnay intake under a soffit very near the external gas califont for water heating. From my experience a gas califont throws out a fair bit of heated exhaust fumes.

Is there a minimum recommended or required distance for a soffit mounted air intake to be from an external gas califont? What about for the Lossnay outlet, or other extractor vents - is the a minimum distance for those too?

Thanks

Paul1977

4983 posts

Uber Geek

#2473347 29-Apr-2020 13:41

Second part of the question:

Is it ok to have a regular extractor fan exhaust gill (in soffit) above an outdoor heatpump unit?

Thanks

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Froglotion

208 posts

Master Geek

#2473722 29-Apr-2020 23:15

Yeah there are minimum distances. Will come down to the input rating of the water heater, what model are you getting? The minimum distance applies to all openings into a building, whether they are inlet or outlet, or a nearby window to the side etc

I'd personally not have any air intakes near the water heater.

As for the heatpump question, I don't know of any restrictions for that one. Could get noise transfer via the duct though. Put all heatpumps as far away as you can from bedrooms. Certainly at least from master bedroom.

snnet

1410 posts

Uber Geek

#2473726 29-Apr-2020 23:18

Paul1977:

Second part of the question:

Is it ok to have a regular extractor fan exhaust gill (in soffit) above an outdoor heatpump unit?

Thanks

Yes. No issue with that (assuming it's not a gas heater, I'm assuming you mean an electric heat pump external unit). What you don't want, for obvious reasons (gas smell), is vents around califonts and other gas appliances outside that could bring the vapour back in

Paul1977

4983 posts

Uber Geek

#2473826 30-Apr-2020 09:38

Thanks guys

Tracer

343 posts

Ultimate Geek

#2474242 30-Apr-2020 19:14

If it's anything like Rinnai the installation manual will have good guidance on clearance from vents and openings. You don't want to draw CO from the flue into your home, and even less so unburnt gas if something goes wrong.

Kickinbac

414 posts

Ultimate Geek

#2474321 30-Apr-2020 22:06

NZ Building Code acceptable solution G4 ventilation says:
2.4.1 The location of a flue terminal on a dwelling shall have:
c) Flues which terminate on the wall of a building located clear of inlets for outside air in accordance with the minimum clearances specified in AS/NZS 5601.1, section 6.9

You can search and download G4 if you want to read it.

So found this...

https://www.pgdb.co.nz/media/1552/tl20001-final-flue-clearances-pc-1.pdf

Which looks to be 1000 - 1500mm clearance from the flue to the intake grille. Personally I would allow a lot more clearance so that the gaseous exhaust is not being drawn into your house on a still night. But I also wouldn't install gas at all but that is a topic for another day ;-)

Best thing to do is discuss with the gasfitter. They have to sign off the installation and ensure it meets the relevant standards.

(edit: to add link)

Froglotion

208 posts

Master Geek

#2474339 1-May-2020 00:21

That measurement doesn't usually apply when installing a califont as it will be close to the soffit than 1m, so any openings always have to go to the side. Minimum distance to the side is determined by the appliance input rating.

Kickinbac

414 posts

Ultimate Geek

#2474490 1-May-2020 11:16

Froglotion:

That measurement doesn't usually apply when installing a califont as it will be close to the soffit than 1m, so any openings always have to go to the side. Minimum distance to the side is determined by the appliance input rating.

In the table, the largest 'minimum clearance' distance is 1500mm for any of the options. Those dimensions are the NZ Standard and are minimum clearances.

I would put any air intake as far from the gas califont, gas meters etc as practically possible so as not to draw in pollutants. Definitely wouldn't locate an intake above a gas califont. If possible I would put any outdoor air intakes on a different face of the building to a carbon monoxide emitting appliance.

A side note, I had a lossnay in my last house, my problem was that in winter on a still night it would draw smoky air in from outside and our house would stink from the neighbourhood smoke.