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Author Topic: Wetback and Gas Combined  (Read 4566 times)

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Offline Offgrid

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Wetback and Gas Combined
« on: April 26, 2018, 09:54:31 AM »
Hi guys,
I've got a wee house just moved into the middle of nowhere in central North Island where it gets coooold in winter. No mains electricty. It's about to be rennovated. Water is to be tank supply from roof.  We intend to have gas hot water (something like the Rinnai Infinity).

The gas heater raises water temp so many degrees at its rated output. I figure if the starting temperature is wamer, then it will be able to hit its rated output better.
That lead me on to thinking about how to get the water temperature warmer. I have a fire that I want to have installed and utilise with its wetback.

The Rinnai installation manual I found online shows a nice digram of a solar system feeding a cylinder, then that heated water goes to a diversion valve where it goes either the taps if hot enough, or via the gas heater then to the taps (with tempering valve).

My question is: Is it possible to pre-heat the cylinder with a wetback, instead of the solar? Then off to the gas califont and/or taps. I can't imagine why not, but I can't find an example of anyone doing it online.

We will of course be getting a plumber in to do all the work, but I'd like to have an opinion as to the feasibility of the system before I go too far.
Thanks


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Offline Plumber

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Re: Wetback and Gas Combined
« Reply #1 on: April 26, 2018, 12:18:41 PM »
Quote
My question is: Is it possible to pre-heat the cylinder with a wetback, instead of the solar? Then off to the gas califont and/or taps. I can't imagine why not, but I can't find an example of anyone doing it online.

Yes you can. Infact you can preheat it with Solar and wetback if you want. Any plumber that specialises in heating or solar should be able to help you setup such a system.

You could have Solar as your fultime preheat, Wetback as your secondary (when you feel like firing it up) and Rinnai as your first backup and the HWC element as your second backup if you run out of gas. Great system when you are in the middle of nowhere.
Please note that the advice I am giving is only my opinion and not necessarily a fact.  Please refer to our terms and conditions.

Offline Offgrid

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Re: Wetback and Gas Combined
« Reply #2 on: April 26, 2018, 02:59:29 PM »
Thanks for the input, it makes sense that I can. Makes sense to consider solar as a preheat as well. I'll now confidently talk to the local plumbers about what I want to happen! Looks like I can find registered plumbers in the area using this website too- what a great tool.

Have a  great day everybody.

PS Any plumbers in Central North island (Ohakune area) want to give themselves a plug (haha unintended plumbing pun) here & I can contact you to discuss the work?

Offline Enn

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Re: Wetback and Gas Combined
« Reply #3 on: April 29, 2018, 07:57:52 PM »
I have a wet back\electric heating a hot water cyl, and a gas water heater  i run gas in the warmer months when the fire is not needed and when the winter arrives i use the fire to heat the cylinder and run of that via a 3 port valve to change from one to the other.
The only down side is the gas runs mains pressure and the hwc is low pressure altho i have restricted the shower so the difference is not too great. could not afford to put in a mains with a coil....
Never thought of using one to pre heat however is does not get that cold here to notice the temp rise much and it is a rinnai 24l gas unit.
''Never have so many been fooled by so few''
Plumbing is not a career it is a disease....


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