School me: Tankless Water Heaters (whole home; Natural Gas)

[satan]

Well, I think one of these things may be an answer to getting all the "stuff" to fit into a too small laundry/utility area.

I've been watching some of the pricing and they're getting into the "can do" range.

Place has qty=1 full and qty=2 half-baths Pretty standard Laundry/kitchen type of stuff. Existing 52gallon works fine and vents up through type B flue.

I'm looking for a natural-gas fired, wall mounted, on-demand tankless, that I can work into the existing space vent etc...

Who knows what on these things>?

Thanks!

[Jeff Mason]

When I was doing research, I thought that I read that a direct-type flue was needed. Here's a little blurb I just found:

Installation issues: If you decide to look further into installing a tankless water heater, be aware that you will likely have to deal with some gas piping, fluepipe, and electrical issues. The gas units (which have the highest capacity, and thus are the most popular type) require a flue to vent combustion by-products created by the burner's firing. Because burners on tankless water heaters require a high volume of gas, they require a larger-than-normal flue to safely vent the combustion gases. So you usually can't simply replace a standard tank-type water heater with a tankless one and expect to hook up the flue to the chimney where the old water-heater flue used to go.


New models of tankless water heaters, like sealed combustion furnaces, can vent out a sidewall through a plastic PVC pipe, thus eliminating the need to upsize an existing fluepipe. However, if an old tank-type water heater shares its flue with the furnace, removing that old flue pipe in order to install a sidewall-vented tankless water heater could mean that the furnace flue will have to be downsized to safely handle the furnace-only flue gases. It gets complicated, and that's why installing a tankless water heater, while beneficial from an energy-efficiency standpoint in most cases, needs to be thought through carefully, and it is probably not an ideal do-it-yourself project.


Because of a tankless water heater's outsized burner capacity, gas piping might have to be replaced with a larger size in order to deliver the amount of gas necessary for the water heater to operate correctly. And most tankless water heaters require electricity to operate, meaning a new receptacle might have to be added if one is not already within six feet of the planned installation. Dependence on electricity, of course, means the water heater won't heat water during power outages, though some of the newest models on the market are designed to operate without outside power. The heat exchanger inside a tankless water heater requires periodic descaling in hard-water areas, using a mild acid liquid, but the service life of the unit should be 20 years or more.

[van7559]

from waht i heard the ground water temps here are colder than most other regions, and the systems do not poduce that hot of water in a lot of applications around here due to this. talk with FRANKZ he might have some firsthand experience with them, or know somebody who does

[Wild Hare]

they work awesome. i put them in every house i am building right now. noritz is the brand i am using and i have built 130 houses in the last 10 months. it takes less than a minute for hot water to be delivered to the appliance, then continuous water until you shut it off. the units have to be mounted on an exterior wall as their vent is only 1 foot vertical and 6" horizontal. they maintain 110 degrees from the factory and can be set at 120 or 130 if so desired. they produce enough btu's to run every appliance in the house at the same time.

[satan]

Thanks for the input so far! -- The big thing I'm seeing is that the flues will need to be stainless and not just old-school Type B.

There's a bit here and there on temperature rise for particular flow rates; so that'll be a key thing to look into (local Water co says to plan for 52*F source temp) so I'd like to see 78+*F at my intended flow rates -- I know that takes me past the established "baby safe" 120*F, that'll gimme enough margin for some shortcoming in other math elsewhere.

That said there are some nice ones on the market (including some that do not require external voltage sources for ignition - not a problem, but interesting) - A lot of these things look like ~200,000 BTU fires so Nat-gas lines of 3/4" or larger are players.

One of the nice part is that above a certain efficiency you can get a $300 tax break - so things get to be a bit more comfortable!

What am I missing??

[Rando]

i've put in about ten Rianni's in the last two years with no complaints.

[Wild Hare]

another thing is the gas meter would need to be recalibrated. std is 2oz. set and to run these water heaters you need to bump up to a 2lb set. its just spring in the meter to make the change.

[Clint]

Ive started to look at these as well. Our hot water heater is getting a little worse each week, and its gonna be time to replace it soon. What I want to know is where to save the most money on these things...Might end up ordering it vs the local big box stores...

[old_man]

My daughter has one of these in here new house. It works great. I have always resisted getting one since my wife gauges the length of her showers by how much hot water we have. I would hate to wake up in the morning and find a prune in the shower. ;-)