Best Hot Water Solution?
user-916173
| Posted in Mechanicals on
We have a growing family of 5 located in Wisconsin. We currently get hot water from a tank system vented through our chimney. We are slowly out growing the tank’s capacity to provide hot water. I need to upgrade. In conjunction with this upgrade I would like to vacate the chimney vent (remove the chimney). I need a new solution that will serve a growing family of 5, is energy efficient and vents out the side of the house. I’ve been looking at tankless water heaters (Rinnai / Quietside, etc.) Is this the right solution for my situation?
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Replies
Look into the heat pump type water heaters... The tankless can get mis-used especially if you have teenagers as they like long showers! Most heat pump WH are easily retrofitted and priced comparably to tankless - where as the tankless usually are more involved for retrofitting...
I think the Rinnai or Quietside condensing models would be a good choice especially if you have natural gas. In Wisconsin winters you would be heating the air with your furnace and then removing the heat from that air with the heat pump to make hot water.
Jason,
I wouldn't recommend a point of demand water heater for a whole house solution. I find these to be best utilized when hot water demands are central or localized, and not across an entire home, unless all the demand locations are close to one another or you're willing to use multiple POD heaters.
Another consideration is the source of energy. Natural gas and propane are relatively efficient for a POD heater: electricity is not. Think of the amount of juice required to heat water from ground temp to bathing temp as it passes over the element.
Power vent water heaters have been available for 20 years or so and are considered reliable. They do require electricity to power vent combustion fumes. Direct vent water heaters require a "B vent" chimney that must extend above the roof.
I'd consider going to a power vent tank heater with a larger capacity that you now have. Depending on your usage patterns and locations you might consider two smaller ones.
Chris Koehn
TimberGuides
Heat pumps aren't a good choice in Wisconsin. Too cold for too long.
Chris Koehn
TimberGuides
Former Wisconsinite
Ok, so I'm on the right path here with the tankless system. Yes, we do have natural gas. I have looked into the power vented tank WH. Our water heater is located in an unconditioned basement. It seem counter intuitive/inefficient to store a tank of hot water in such a place. No?
Tankless heaters are prone to mineral deposition (which reduces heat transfer efficiency) and have minimum flow rates and can be problematic with low-flow fixtures. Users complain about the "cold water sandwich" - a slug of cold between static hot water and the time the heater turns on. The biggest ones can typically supply no more than 3 fixtures simultaneously. Also, because they require burners three or four times as big as tank heaters, they often require larger gas lines which can add considerably to installation cost.
The new tank heaters are extremely efficient - both in fuel conversion and in minimizing stand-by losses with better insulation jackets. For a family your size, I would recommend a good tank heater with a power vent - unless you have hydronic heat, in which case an indirect tank off your boiler may be the most efficient option.
I agree with Robert that for most families, tank-style heaters are often the best option (unless you already have a boiler, in which case an indirect tank makes sense).
Instantaneous heaters make the most sense for people who are often away from their homes, and are worried about standby losses. A family of 5 doesn't have the same standby-loss problem.
I've used some tankless water heaters in my new homes and based on client response and other factors I prefer tank heaters. In our area natural gas is relatively inexpensive, you just can't beat a good tank water heater. The tankless require a bit of maintenance, they are expensive, and at the just completed builders show Rinnai had one of their models opened up and it looked like a nuclear control station, it was so complicated. Lot of opportunity for something to go wrong or need maintenance. As Robert points out there are some very efficient tank style heaters available.
Allan
Jason,
I would like to reiterate Martin's comment on indirect water heaters.
Do you have a boiler? Your implying that your heating source is direct vented (by the fact you can seal up your chimney by changing the water heater) so you likely have a newer, higher efficiency model.
If it is a moderating condensing boiler your best solution is the indirect water heater.
I have put my "water heater research" on the back burner.
When I do get around to studying this in more detail....
I think that "structured plumbing" may be the most important strategy to save Energy AND WATER
Gary Klein has some good ideas about structured plumbing
http://www1.eere.energy.gov/solar/pdfs/sda_saving_water.pdf
Yes we have a forced air furnace, no boiler. Looks like an efficient vented tank water heater has the most support. Thanks for all the input.