Enclosing a gas water heater - air requirements?

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SomeoneSomewhere

1787 posts

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#3354827 18-Mar-2025 16:41

Gas fired cylinders exist, but they're not very common here. They often have a much faster recovery rate than typical electric cylinders; 10-20kW. Much harder to run out.

You can get gas & electric continuous flow, and gas and electric cylinders. But not all combinations are equally common.

OP has a gas continuous flow system; no cylinder.

elpenguino

3392 posts

Uber Geek

#3354828 18-Mar-2025 16:47

SomeoneSomewhere:

OP has a gas continuous flow system; no cylinder.

Thats right.

I call it an infinity water heater because when you're in our downstairs bathroom, it takes forever for the water to warm up 🤣

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

tweake

2349 posts

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#3354975 18-Mar-2025 18:51

elpenguino:

Looks like this general model has a few variations. I found the model label inside (WR-325-1 KV1 B23) and eventually found the exact manual here.

https://bosch-au-en-techdoc.boschtt-documents.com/download/file/file/6720605088.pdf

The manual has a decode of the model information as:

W Multipoint gas water heater
R Automatic power adaption
250 Code number 17,5 kW (250 kcal/min)
325 Code number 22,75 kW (325 kcal/min)
400 Code number 28 kW (400 kcal/min)
-1 Version code number
K Chimney flue
V Connector
1 Temperature selector
B Battery ignition
23 Gas code number, natural gas H

However, when you search for 'flue', the manual says 'Use approved single or twin skin flue in accordance with AG601'.

I would have thought a single skinned flue would make it impossible to draw air in at the same time as expelling exhaust ( but what do I know?) .

having a quick look, its open air intake. pretty common afaik. its the later ones that went to intake around the flue (typically high efficiency burners where the gases are cooler). the bosh has a dual wall flue but its more for heat protection, much like a normal fireplace where it goes through the ceiling.

a mistake i've made before is assuming that the opening in the door should be at least the same as the vent. its actually not, you need a massive amount more. can't remember the number, but its like 10x the size.

WWHB

30 posts

Geek

#3355312 19-Mar-2025 18:26

I wouldn’t cover it in if I were you. A lot of older gas water heaters rely on natural draft for combustion. Not enough air can lead to incomplete combustion and be dangerous to the occupants of the dwelling.

I am a Gasfitter and would advise to get a local Gasfitter in for professional advice

elpenguino

3392 posts

Uber Geek

#3355544 20-Mar-2025 10:19

WWHB:

I wouldn’t cover it in if I were you. A lot of older gas water heaters rely on natural draft for combustion. Not enough air can lead to incomplete combustion and be dangerous to the occupants of the dwelling.

I am a Gasfitter and would advise to get a local Gasfitter in for professional advice

Thanks @WWHB. I agree ventilation to this cupboard needs to be maintained.

Do you know if there's any regulations / rules / standards I can point to when I am talking door styles and venting options with the joinery company and the boss ?

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

WWHB

30 posts

Geek

#3355696 20-Mar-2025 16:58

AS/NZS 5601.1 2013 pages 100 and 101 cover ventilation for appliances

there is a 2022 version as well but that’s not cited in NZ yet

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