couv:
Hello,
I will be replacing my water heater soon and I am interested in a natural gas tankless water heater. Can someone who has one or is familiar with them recommend a brand or model or even recommend against a brand or model.
I know folks in Europe have used these for quite some time so please advise.
Thank you,
couv
Renai, Takagi, Rheem, and Bosch are all commonly distributed here in the states.
Wildcard's advice to size your tankless heater properly is correct. The most important sizing factors are your incoming water temperature and the number of hot water outlets in your home.
Something to watch out for... Most European plumbing systems utilizing tankless heaters do so with a point-of-use layout. This limits the amount of water wasted while waiting for water to reach the fixture at the desired temperature. Most American plumbing systems are piped linearly from a single hot water storage tank, and such a system may not be ideal for a tankless system. In such a home, the length of piping from the water heater, coupled with the delay of temperature rise from the tankless unit, may result in a considerable wait for hot water, and quite a lot of water wasted down the drain in the process. If I were building a typical two or three bath home, I would use two or more tankless units with a point-of-use layout, with each unit supplying, for example, two bathrooms, a kitchen and laundry room, or other practical zone configurations.
While attending a manufacturer's seminar last year for Rheem tankless heaters, I related the following experience to the rep: My very "Green" customer, a Naturopathic physician, decided to replace her conventional storage tank WH with a tankless system. After the installation, she found that the wait for hot water at the fixture most distant from the tank, the kitchen sink, had increased from 15 to 20 seconds to over a minute. Water piping had been added to move the tankless unit to an outside wall for economical venting (special triple-wall venting is over $100 per foot), and this, coupled with the unit's normal delay in raising water to the desired temperature, resulted in an unacceptable amount of water wastage. The rep's proposed solution? Install a circulating hot water system, a closed loop with its own pump,
and a six to ten gallon conventional water heater, adjacent to the tankless system. He glowed with pride as he said that, clearly missing the irony that the "tankless" system needed a conventional tank, circulating pump, and additional piping to serve this home adequately.
Be aware, too, that the larger units are a sizeable BTU draw, and may require a gas supply larger than already exists in your home. The 13.5 gpm models are rated around 280,000 BTU's, and the gas piping needs to be sized accordingly. In some cases, a home will need a larger meter to adequately supply the tankless' gas demands. An undersized gas line will starve the unit, resulting in intermittent heating. Unskilled, untrained, or unscrupulous contractors commonly overlook such details. Your best protection would be to seek out a company experienced in tankless installations, ask for references, and then be sure your job is permitted and inspected by your local authority.
I'm not trying to discourage you here... I've seen a number of these systems working perfectly for happy customers. Proper sytem design and installation can overcome any pitfall, and will result in optimal function.
Steve
