Rinnai iheat vs Central Ducted Heat Pump

Forums › Home Workshop DIY › Rinnai iheat vs Central Ducted Heat Pump

bjclayto

6 posts

Wannabe Geek

#140731 18-Feb-2014 22:35

Hi-first time here
Enquiring if anyone has experience with the Rinnai iheat in terms of efficiency, running costs and installation.
These appear to be relatively new in NZL.
I am favouring the Rinnai iheat as we are also going to install and infinity system so it will kill two birds with one stone so to speak.
I am not against heat pumps-we are also considering a semi-industrial Toshiba ducted system to sit inside the ceiling space. My issue is the cost to run the system and the efficiency loss over winter etc. However it does have a six star rating.
I have seem some forums with similar issues about the G v HP debate.
Have also thought about radiators via a gas source-radiant heat versus air flow etc
Oh-I also need an urgent response and the plumber will be around in a few days!

Cheers BJCLATYO

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3885 posts

Uber Geek

#990068 18-Feb-2014 23:29

Myself - I would go with a dedicated ducted gas heater. Braemar have a 6 star efficient gas central heater. Don't know of the efficiency of the Rinnai I heat. But doubt it would be as good. Since the heat would have to go through 2 heat exchangers instead of 1. Have seen plenty of people who use Rinnai water heaters for running underfloor systems and they arent too great for efficiency.

Im a plumber and gasfitter by trade. Happy to answer any other questions.

Will you be running it off natural gas or LPG?

graemeh

2078 posts

Uber Geek

#990118 19-Feb-2014 08:56

How cold does it get in winter at your house? This has a big impact on the heat pump option.

bjclayto

6 posts

Wannabe Geek

#990124 19-Feb-2014 09:07

Thanks

We are on mains Gas-apparently they were all the rage in Europe but then were not due to efficiency issues-I was informed by a radiator expert

My main concern is that everyone has their story to tell and can see benefits of each system. The Toshiba system has the lowet outlay costs etc-but I will get paranoid about the bills over winter. With Gas not so much

We live in Palmy- can get cold-our house is a 1920's bungalow-renovated twice

bjclayto

6 posts

Wannabe Geek

#990127 19-Feb-2014 09:10

How much does the Braemar cost to install and run etc

bjclayto

6 posts

Wannabe Geek

#990130 19-Feb-2014 09:16

Check out this website-quite interesting wrt efficiencies in NZL and AUS
http://www.energyrating.gov.au/wp-content/uploads/2011/04/201102-gas-ducted-heaters.pdf

Stan

929 posts

Ultimate Geek
Inactive user

#990191 19-Feb-2014 10:08

What sort of gas are you running Natural gas or LPG?

Here is an approximate running cost chart for the Iheat naturally the 1920s bungalow will be a tad different from the costs below but it gives you an idea.

http://www.rinnai.co.nz/upload/files/productfile/iheat_running_costs_v2.pdf

Have you considered a large fireplace with a heat transfer system? This tends to be a fairly common way of heating a house of that age.

timmmay

20578 posts

Uber Geek

Trusted

Lifetime subscriber

#990259 19-Feb-2014 11:08

Ducted heat that comes in through the ceiling cuts holes in the ceiling, which I imagine reduces the insulation. The FAQ says it can go under the floor, maybe it can put air up through grates? That may not be practical though. It's cleaner and tidier to have air vents than radiators though, but radiators are very popular and effective in colder countries.

Have you considered a ducted heat pump solution? They're more expensive, probably quite a lot more expensive, but you can then cool your home in summer as well as heating in winter.

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bjclayto

6 posts

Wannabe Geek

#990582 19-Feb-2014 16:16

Yes, have considered the ducted heat pump-20 kw Toshiba light industrial model with a five star rating and approx 8000 to buy and install-not too bad I thought for the whole house

timmmay

20578 posts

Uber Geek

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Lifetime subscriber

#990588 19-Feb-2014 16:26

So you're still considering it, or you've ruled it out? I just ask because heat pumps are quite efficient.

bjclayto

6 posts

Wannabe Geek

#990596 19-Feb-2014 16:32

Yes still considering-it is 11.2 kwh and a 6 star rating. My plumber is looking into the Braemar option as well

My other issue with the Riunnai was that they were selling the unit but not the ducting. You also needed to instal the fitting kit. Also not many have been fitted into homes south of AKL I believe. If it all came as a one purchase item then things might change. Prob not worth risking 8K plus for newish (NZ) technology and not experience of installation etc

Skolink

1081 posts

Uber Geek

#990603 19-Feb-2014 16:38

A heatpump will cost about 1/3 to run compared to [LPG] gas.

Just relaised you said you are on "mains gas" which I assume is natural gas, so heatpump will only be 1/2 cost of heating with gas.

timmmay

20578 posts

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#990609 19-Feb-2014 16:47

There are plenty of other ducted heat pump solutions, you just need to talk to a company that does that sort of thing.

Stan

929 posts

Ultimate Geek
Inactive user

#990619 19-Feb-2014 16:58

Skolink: A heatpump will cost about 1/3 to run compared to [LPG] gas.

Just relaised you said you are on "mains gas" which I assume is natural gas, so heatpump will only be 1/2 cost of heating with gas.

It wouldn't be half particularly with a 6 gas star system vs a heat pump.

Skolink

1081 posts

Uber Geek

#990836 19-Feb-2014 23:31

Stan:
Skolink: A heatpump will cost about 1/3 to run compared to [LPG] gas.

Just relaised you said you are on "mains gas" which I assume is natural gas, so heatpump will only be 1/2 cost of heating with gas.

It wouldn't be half particularly with a 6 gas star system vs a heat pump.

A gas system can be no more than 100% efficient, whereas a heatpump has a CoP of between 3 and 6 (300% to 600% efficient). Have a look at the model data listed on the EECA website.
LNG is about 13c/kWh, electricity about 25c/kWh.

isis

49 posts

Geek

#991058 20-Feb-2014 12:36

i'm in the same boat as you. However with my new house being double story, installers have provided quotes for a ducted system upstairs but single high wall units to the downstairs living area. This is around the 20k figure and wasn't overly happy that the whole house can't be ducted/centrally controlled.
Come gas, half the price and they can duct the whole house..guess which i'll be going for!
Have had quick efficient feedback from Complete heat who has provided various star rating pricing including designing the system to fit the new build.

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