Instant v stoarge Howt water service

[Mcblurter]

Hi eceryone
I have looked through the archive and found a little bit on this subject but not much. If it has been done can someone direct me to the appropriate post please.
Doing a reno and will be shifting an old HWS (2 star rating!!!!!). Tossing up between storage and instant. Instant looks good due to size and star rating. We are very water conscious and would like to be more efficient gas wise. Some say it takes time for taps to heat to desired temp, so wastes water but that's okay, we often collect this water anyhow. We also tend to have baths more than showers and very rarely would two hot water taps be on simultaneously.
The thing that is worrying me though is people saying there may be a need for new gas pipes and water pipes? We have just got a Brivis ducted gas heating installed and no need for new pipes.
Can anyone tell me in what situation I would need need water or gas pipes? I live in Melbourne and as I said have gas ducted heating and water pressure is great. Any thoughts you think would be helpful would be appreciated.
Cheers
McBlurter.

A woman walks into a bar and asks for a double entendre, so the barman gave her one!

[Sturdee]

Can anyone tell me in what situation I would need need water or gas pipes? I live in Melbourne and as I said have gas ducted heating and water pressure is great.

The instanteneous gas HWS uses a large quantity of gas to quickly heat the water when required whereas a storage heater doesn't as it will heat slower over a longer period of time.

When I looked into it I was told that the existing gas line, which ran past the proposed HWS, of I" diam would not be sufficient and that it would have to be replaced with a 1 3/4" pipe.

This would have virtually doubled the cost of the unit, so I went to an electric storage HWS at a quarter of the cost of the proposed gas one.


Peter.

[OBBob]

I love mine. Yes had to add a new gas pipe but I needed that anyway, they do take a large pipe but if you've got gas ducted you may be OK?

Not sure about the 1 3/4 above ... that's huge! I have a 1 inch main gas line in melbourne that splits into two 3/4 inch pipes feeding the Hotwater an ducted heating.

[Sturdee]

Not sure about the 1 3/4 above ... that's huge! I have a 1 inch main gas line in melbourne that splits into two 3/4 inch pipes feeding the Hotwater an ducted heating.

The existing gas pipe that we wanted to tap into runs to the ducted heating which was a 1".

The plumber enquired from the gas shop and the manufacturer of the HWS and the existing ducted heating as to the pipe needed and that was their advice.

Something to do with if both started up at the same time I suppose, but it is definitely something to factor into the equation and should be enquired about when pricing the two options.


Peter.

[OBBob]

The pressure requirements are important ... maybe the pressure is a little lower in your area?

McBlurter - The pressure requirements are in the manual that you can download for the Integrity ... I assume they'd all be similar.

As for different water pipes ... don't see why that would be the case ... my are normal. My gas bill certainly dropped when the old inefficient storage unit was replaced. But you may get the same drop by using a newer more efficient storage unit.

My other main consideration was the size. Being close to the city ... space is a premium ... probably not as high on the importence list for Sturdey in Donvale.

[Mcblurter]

thanks OBob and Sturdee.
Will check out the specifications and see what they say.
Cheers
Mcblurter

[Mcblurter]

Hi
Just checked the Rinnai specs and found this
** All Rinnai INFINITY models will operate at lower pressures, however the specified flow rates may not be achieved. Gas pipe sizing should be performed using an approved sizing chart, as specified in AS 5601 / AG 601. Water pipe sizing should be in accordance with AS 3500.

Can anyone shed some light on these?
Does anyone have both Ducted heating and instant HW on a 1" pipe (is 1" standard?) and have any problems?
Cheers
Mcblurter

[Sturdee]

My other main consideration was the size. Being close to the city ... space is a premium ... probably not as high on the importance list for Sturdee in Donvale.

As the house, without the garage, is only approx 40 squares in the old measurements and I'm on a quarter acre block, space is not a major issue. In fact our BBQ area is bigger than most units backyard.

But I never have enough space in the workshop.


Peter.

[Mcblurter]

Gathering more info.
We have a 1/2" pipe and seems like instant HWS would need at least a 3/4 to 1" pipe.
So next question is what size pipe do I put in. do I need a 1 1/4" pipe to cover the 1/2' and 3/4"? or Would a 1" pipe be adequate, I'm not a plumber so unsure of how the pipe size thing works?
Is it a costly job, any ball park figures? Probably about 6mtrs from mains to HWS.
Cheers
McBlurter

[SilentButDeadly]

So.....solar is not an option?

[Grunt]

Hot water consumes about 1/3 of all energy needs of a house.

Do your bit for then environment and seriously think about solar or a heat pump type system. Quantum Energy

Chris

[peter_sm]

The most energy efficient hot water is off peak electric. With solar added it can only save more. The pressure is not good though. In country area's with plenty of sunshine you would be mad to do it any other way. In Melb mains gas area, storage is more efficient. In my own personal opinion, instant gas is for people who are obviously not on the poverty line and struggling just to meet house repayments, and can afford extra gas costs.

[Designsync]

McBlurter,
As OBBob says, pipe size will depend on gas pressure and pipe distance. You mentioned 6mtrs. Whats the pipe distance to your Brivis unit? Check the supply pressure from your meter/regulator. As an example only...if the pressure is between 2.75-5kPa, 25mm (1") copper pipe will supply 600MJ/h upto 12 metres.
Mate, my best advice would be to get your local gas fitter out to have a look. If you tell him the gas consumption in MJ/h of your new Hot water unit and your Brivis unit, he'll size the pipe within seconds.

[bricks]

With instantaneous you have greater efficiency ( not by much) but a reduced flowrate to your taps- good if your water wise, bad if you like blasting showers.

Storage has full flow rate but heats water when you dont need it to.

With Instantaneous heaters you sometimes have trouble fitting water saver devices- eg shower head- because of the reduced flow rate. But your already using less water so you dont really need the devices anyway.

In sa plumbers/ house holders can ask for the gas pressure to be increased from 1.4 kpa to 2.75 kpa- this will let us install big heaters with no pipe size change. Maybe you can too?

If you have a plumber / gasfitter come around they will be able to tell you on the spot if you need bigger pipes so you can make a decision then.

[Mcblurter]

Thanks again everyone
A few issues raised.
I've looked at quite a number of units before solar, electric and heat pump. If I can remember rightly the heat pump needs a certain outside temp to work efficently so would have to have a backup, also has electricity needs. Solar is a bit too costly to set up initially and storage again heats water when don't need it, plus always forget to turn it off during holidays etc. Will be looking at installing some solar panels, but holding off until after next election. Seems to be a lot of research and develoment in this area and hopefully some larger rebates on the way!!!
We are very enviro friendly and wanted to stay away from electricity as much as possible (not only greenhouse gases but also uses lots of water to produce it) As I have said, we don't use a lot of water (229 lt per day for two adults and two children) so think would be using a lot less gas than we do now. Have installed ducted gas but again see the use of this as minimal (we don't need to live in T-Shirts in winter!!!)
I will speak to a professional. I really like this forum as it helps me get to know what I need to know so I can ask the right questions!!! I can then do a bit more research so when I do speak to th eprofessional I don't waste his time andmine with stupid questions about stuff that isn't important, or using jargon that isn't correct.
So thanks again. Please feel free to make any more comments about any of these issues, especially the environmental impact.
Cheers
McBlurter