Should I upgrade to the tankless water heater or use a power vented storage type?

by Water Heaters on June 25, 2010

I purchased a on demand Rennai 190k BTU on demand water heater this week. I was talking with a plumber friend of mine, and he said not to install it, but to go to a storage type power vented unit instead. He insisted that these on demand units are riddled with problems and issues, and that I should stay with the power vented setup. I have the appropriate 3/4 gas line coming in, along with a large 1′ coming in from the water meter. What should I do? Do I sell the on demand unit, and go to the power vented….. or stick with the on demand?


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{ 4 comments… read them below or add one }

UNCOLA June 25, 2010 at 12:41 am

I have been researching the tankless water heaters and decided against it. One of the issues that really bothered me is you end up wasting alot of water, because they take a few minutes to kick on and get hot. I have heard of other problems especially at low volume flow where they just don’t kick on.

Dave June 25, 2010 at 12:41 am

USA My experience is this: My brother has a hot water boiler, and had a boiler mate for domestic hot water. In the summer, when the heat was not needed, he paid $100 per month for gas to heat the domestic water. We put in a tankless heater. His gas bill dropped to $26 per month. Yes, you have to wait a minute – maybe even two if a long distance – but that is the only drawback so far. He has had it 3 years and loves it. Temperature control is extremely easy, and can be changed with a remote control. How cool is that???

With a conventional water heater, you pay to keep the water in the tank hot 24 hours per day all year, use it or not. Tankless heats as it is used. I think waiting an extra 30 to 60 seconds is worth the fuel savings. And the fuel prices are going to keep rising.

I currently have a 40 gallon gas fired water heater. When it no longer works, it is gone. No more tanks. Tankless here I come !!!!!

Jim D June 25, 2010 at 12:41 am

I think tankless water heaters are great. The biggest drawback is the cost of the unit, but you already have it so it is not an issue. Sure they can have problems, but so can anything else mechanical. Power vent water heaters are good, but they really are not too much more efficient than a standard natural draft water heater. What a power vent water heater is good for is using it in a house that doesn’t have a chimney. It can be vented out the side wall with pvc. Yes it is true that it takes a few seconds for the unit to fire and begin heating the water but it isn’t too bad and you will get used to it. The biggest advantage to owning a tankless water heater is that you only heat the water you use. Also, they are designed to last 2-3 times longer than a tank heater. There are several things that need to be taken into consideration before installation. You already covered the 3/4" gas line. And the water line size is adequate. The unit must be vented with stainless steel or pvc pipe, depending on which model you have. It should never be vented in an existing galvanized flue pipe, and it cannot be common vented with any other appliance.

rocky June 25, 2010 at 12:41 am

I am master plumber and do not recommend tankless water heaters. If your tankless water heater breaks where do get parts or a tech to fix it. The cost factor will take years to recoup. Plus people complain they don’t receive enough hot water.

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