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cbradley View Drop Down
Direct Link To This Post Topic: Rinnai water heaters
    Posted: 13-Apr-2005 at 1:55am
I am a plumber in Texas and tankless water heaters are just now becoming popular. Do you recommend these and is water flow rate a big problem?
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Selgas View Drop Down

Joined: 29-Aug-2002
Location: Wanganui, New Zealan
Points: 769
Direct Link To This Post Posted: 13-Apr-2005 at 8:01pm
Hi there

Speaking from ways down south Rinnai instantaneous gas water heaters have been in use here for many years along with approximately 5 other brands of the same type and function. As a service agent for many of the different brands I guess I can throw a little more light than perhaps an installer can so if you have a question that I can answer for you then I would be more than happy to assist.
The principal behind these units is to provide a continuous supply of hot water for as long as the hot water outlet is turned on so there is vertually an unlimited supply of hot water. Because the hot water is not stored in any way these units are more economical to opperate than a conventional cylinder - down here a saving of some 16% over a stored gas hot water cylinder system.
The operation of these units is quite complex but efficient and effective but one should be aware of the following - each of the models and sizes available can provide XXX litres of water heated by a 25 degrees C rise per minute and as a result of this the water flow is slowed whilst it passed through the heat exchanger to be heated by the gas burners - as the temperature selected climbs then the flow slows to allow the heat transfer to take place - in short yes there is a reduction of water pressure and flow. Depending on the inlet water pressure and flow is drops approximately 20% to achieve the desired outlet temperature. If a shower is running and then a hot water tap is turned on the flow will drop away from the shower unless the shower has been piped out to give it priority - a trap for the unwise.
If you are in a " Hard water" supply area these units will calcify and lime up unless a water softener is installed on the supply feeding the water heater. Hope all of this helps and if I can be of any further assistance drop me a note.

Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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