Dual infinity system or single

Forums › Home Workshop DIY › Dual infinity system or single

t0ny

414 posts

Ultimate Geek
+1 received by user: 84

Lifetime subscriber

#323833 22-Jan-2026 19:09

Hi, I have a new build and the gas plumber recommended that I install two infinity system, one on each end of the house as he figured that a single A26 unit is not sufficient for 4-5 bathroom house with washing machine, taps etc. Houses similar size in the area seem to have only one A26 unit so not sure if plumber is just upselling or actually true. I could consider upgrading to a single bigger unit but he insists that putting two will heat water faster and actually save on the water bill which would offset the initial cost (~3400 extra)

Thoughts?

1 | 2

8810 posts

Uber Geek
+1 received by user: 5287

#3455137 22-Jan-2026 19:15

What are the lengths of the pipe runs to each bathroom is you have one, and what would the calculation be if there were two... also do all the Bathrooms have showers/baths.

As an aside giving its a new build have you looked at using a Heat Pump hot water system, Gas is only going to get more expensive in the future, and if you go all electric you get to knock daytime usage on the head by sticking some panels on the roof in the future.....

t0ny

414 posts

Ultimate Geek
+1 received by user: 84

Lifetime subscriber

#3455138 22-Jan-2026 19:43

Pipe length is around 10-15 meters to majority of the bathrooms and all of them have showers. Cost for two infinities installed would end up costing around 7200. I did want to consider heat pump based system (as i have solar being installed as well) but have issues with finding space for a large tank and a reclaim 315L would be around 10-11K. The other half still prefers a gas cooktop and since we have NG, prefers not to use tanks.

rscole86

4999 posts

Uber Geek
+1 received by user: 462

Moderator

Trusted

Lifetime subscriber

#3455139 22-Jan-2026 19:43

Most washing machines and dishwasher heat their own water, ie cold feed only.

As above, consider hot water heat pump and/or solar powered cylinder.

johno1234

3350 posts

Uber Geek
+1 received by user: 2843

#3455144 22-Jan-2026 20:21

Gas fixed charges are annoyingly high these days. I would never willingly have it in a new build.
it’s nice to cook on but induction is very good and it is so much easier to clean the hob.

tweake

2641 posts

Uber Geek
+1 received by user: 1137

#3455145 22-Jan-2026 20:56

t0ny:

Hi, I have a new build and the gas plumber recommended that I install two infinity system, one on each end of the house as he figured that a single A26 unit is not sufficient for 4-5 bathroom house with washing machine, taps etc. Houses similar size in the area seem to have only one A26 unit so not sure if plumber is just upselling or actually true. I could consider upgrading to a single bigger unit but he insists that putting two will heat water faster and actually save on the water bill which would offset the initial cost (~3400 extra)

Thoughts?

mate has this. dual califonts. one feeds the kitchen and laundry and the other does the bathrooms which are at the other end of the house. interesting downside is the size and expense of the gas line to the far away unit. as his runs off bottles (by the kitchen) the pipe is huge. that might not be an issue with natural gas but worth checking.

the problem with single is the amount of cold water you have to run off before you get the hot water. normally with a tank you run a loop and install a small circulator pum,. so you have hot water within a meter of the tap. you could do that with a single califont if you used a small tank (to give the burner some run time).

mattwnz

20515 posts

Uber Geek
+1 received by user: 4795

#3455190 22-Jan-2026 21:08

Depends how much of a delay to get hot water you want.

Geekzone

Want to support Geekzone and browse the site without the ads? Subscribe to Geekzone now (monthly, annual and lifetime options).

antoniosk

2382 posts

Uber Geek
+1 received by user: 742

ID Verified

Trusted

Lifetime subscriber

#3455192 22-Jan-2026 21:53

I guess the question is what are you expecting to happen for usage. Ie will all the showers come into use from 6-7am then go silent, with washing machine/dishwasher from 9am-230 and dishwasher/showers again from 8-10pm.

this is down to your family setup, how you think they hw will be used and so on.

________

Antoniosk

t0ny

414 posts

Ultimate Geek
+1 received by user: 84

Lifetime subscriber

#3455194 22-Jan-2026 22:10

Thinking about this bit more.....I currently have the A26 and bathroom is on the other side..takes anywhere between 7-10 seconds before water warms up. Will a bigger unit close that gap? Thinking that if i stick with just one unit, it may be easier in the future to swap the unit and decomission gas vs having to deal with two infinity units

Bung

6733 posts

Uber Geek
+1 received by user: 2926

Subscriber

#3455195 22-Jan-2026 22:29

Available flow rate is possibly more significant than time for hot to arrive.

insane

3324 posts

Uber Geek
+1 received by user: 1006

ID Verified

Trusted

2degrees

Subscriber

#3455202 23-Jan-2026 05:53

I see the logic in his recommendation. You're building a high end house with many opportunities to draw hot water simultaneously. I have a E24 with long pipe runs, inc two large 20mm sections acting as a central manifolds, and it takes an age to get hot water to most of my outlets and wastes a lot of water.

Could you do a hybrid setup and keep a small under bench hw cylinder in the kitchen to take advantage of solar generation and faster access to hot water?

Goosey

3014 posts

Uber Geek
+1 received by user: 867

Subscriber

#3455204 23-Jan-2026 06:38

With that many bathrooms, you probally have the people….so it’s highly likely two bathrooms would be in full use at the same time plus kitchen plus washing.

whats the water pressure like?

I thought gas was becoming less populaR for various reasons and solar is the flavour of the moment?

Geekzone support

Support Geekzone with one-off or recurring donations Donate via PressPatron.

CYaBro

4708 posts

Uber Geek
+1 received by user: 1182

ID Verified

Trusted

#3455206 23-Jan-2026 06:57

Since you’re getting solar it’s seems a no brainer to get a heat pump hot water system.
With the price of gas only going up and the ability to heat from the solar for free basically during the day, and add to that the health risks of a gas hob inside I know what I’d be installing.

We currently have a gas hob oven but since we had solar installed recently we’re looking at replacing that with an induction cook top
oven and also replacing our califont with a heat pump hot water cylinder.
The oven has also developed a fault so that has helped the decision and will be the first to be replaced.

Opinions are my own and not the views of my employer.

WWHB

55 posts

Master Geek
+1 received by user: 47

#3455207 23-Jan-2026 07:11

Your plumber/gasfitter is correct

If I were you though I would 100% pay the extra and install the Reclaim with the cylinder. The power saving will more than cover the install costs. I had a Sanden at my old house and it took a $100 a week of my power bill, we moved to gas at our new place. Big mistake not taking the Sanden with us, especially since I am a plumber/gasfitter myself.
Gas hot water system install used to be one of my most popular upgrades, I now try and steer people away from gas to hot water heat pumps.

Saor Alba

timmmay

20858 posts

Uber Geek
+1 received by user: 5350

Trusted

Lifetime subscriber

#3455208 23-Jan-2026 07:15

Putting gas into a new house seems unusual, given it's getting expensive so quickly. In your place I would do electric for everything, induction stoves are great, and probably heat pump hot water with solar. I'd also consider a solar thermal system where the sun heats a fluid that heats the water, as it's something like 80% efficient whereas solar electric is about 25% efficient + hot water pump is 400% efficient. Either way with so many bathrooms you will probably want more supply than one unit of whatever you get can provide unless it's somehow rigged for super high flow, and you'll waste a lot of water getting it all around your mansion ;)

t0ny

414 posts

Ultimate Geek
+1 received by user: 84

Lifetime subscriber

#3455396 23-Jan-2026 11:28

Did a site measure and heat pump based heating with a large cylinder will be a tough one to squeeze in. Other potential issue the electrician mentioned is that I have single phase power and we would struggle to keep up if everything is turned on hence i should minimize anything else that will draw lots of power. Three phase is not an option as I intend to use my existing single phase washing machine and appliances have been already bought.

For now, I am just going to stick to two infinity system as it will give a reliable solution though at slightly higher cost.

1 | 2