hot water on demand.

[Cynthia]

My husband and I are in the process of renovating our bathroom. We are interested in getting rid of our water heater in the basement and replacing everything with "hot water on demand" boxes (I don't know what else to call them). They were in our hotel room while in London. Have you heard of them, or do you use them at all?

[tigerlily78]

I think for the most part these are referred to as "tankless water heaters". I don't happen to have one personally.

[edbegleyjr]

Since you already have a water heater in the basement, you should consider a high efficiency tank model like the AO Smith Vertex 100. It can go right where your existing heater is, use the same 1/2" gas line, and produce 96% thermal efficiency, blowing away most tankless models and providing you with endless hot water. You can even use it to heat your home. I know - I do!

Ed

[Cynthia]

We were thinking we could use less gas heating a tank of water. I seems like a waste.

[tallgirl]

Cynthia,

I'm also not Ed, but better combustion efficiency and tank insulation can greatly reduce the amount of heat lost and excess fuel required.

The problem with many tankless heaters is that they have incredible energy demands in order to heat water from the cold supply temperature up to the thermostat temperature. This can require new gas lines (for tankless gas heaters) or a new electrical service (for tankless electric heaters).

Green choices should include all factors, and tankless water heaters compare poorly to tanks like the one Ed mentioned.

[mlaiuppa]

Putting either a big tankless where your water heater used to be or several smaller ones right next to their point of use needs some consideration.

First, unless they're electric, you'll need a 3/4 inch gas line feeding them. Also, you'll need to vent using stainless steel ducting. Very pricey. If you can vent quickly to out of doors, that saves you money. Having to replace or lay extra gas line at 3/4 would be an expense to be considered.

That said, I replaced my conventional tank with a tankless. I had the gas line already and was able to vent out the existing opening, even though I did have to spend more for the stainless steel. And I reclaimed lost space where the old water heater was.

Do a little searching.

[Reno]

I am thinking of replacing the existing hot water tank with hot water on demand. I have a two story house and I am debating if I shoud go with two hot water on demand, one for downstair and one for upstairs, I know it will be more expensive but will I get hot water faster to the upstair's washroom? I have a 400 Amps service.


Reno

[Cobalt]

Another technology to consider is solar thermal panels. I'm not sure what the payback period is, but the panels last over 25 years. They can heat your water and use excess heat to heat your home. Why pay for natural gas/electricity when Sol will heat your water and home for free? Evacuated tubes can produce hot water in extremely cold conditions but they're more expensive.

Anyway, good luck with whatever you pick.

[Guest]

+I too was thinking of going tankless with propane out here in the desert. The water is hard,27 grain and eats through the tanks in 5 years. I used to have a solarhart 20 years ago somewhere else and it was a nice unit but very expensive then and now. We need programs for the semi handi man to learn how to make passive solar stuff. Like Ed's show of him installing a red rain catch barrel that cost a few hundred . Not. I went to a reclaim yard and got blue 50 gallon drums for 10 bucks. I now have a line of them on my back wall trying to collect the less than 5 inches of rain a year. We aren't all rich enough to be buying redi made stuff yet we want to save OUR resources.
Most of the year I can lay pipe on the ground and heat enough hot water with no help. Heck the cold in summer comes in hot. But then I don't want to blow up the plumbing and loose precious water.

[SwineInsanity]

I thought about a tankless but decided against it.... The water heater holds water if we loose our power.... emergency water.... As long as we don't flush or pour down the drain we are fine... electric septic pump....

[Bill4112]

My wife and I have done a number of things to reduce our carbon footprint while saving money. As part of this effort, I've considered both tankless water heaters and solar water heaters. I've discovered that tankless water heaters tend to be significantly more expensive than an equivalent standard water heater. They also require either an upgraded gas line or an upgraded electrical service, which can be very expensive to install in an existing home. It is much more efficient (and much less expensive) to install a tankless water heater when a new home is built. Unless you use a LOT of hot water, it is probably not cost effective to upgrade to a tankless water heater. Doing so is probably more cost effective for a hotel or a resort.
As for solar water heaters, they are also more expensive than standard water heaters, but they generally do not require upgrades to either the gas or electrical systems (one of which would be used as a backup to the solar heating). Also, solar water heaters are more like standard water heaters in that they have a storage tank, which can provide hot water even during a power failure. Of course, solar water heaters work best in places that receive a lot of sunlight. You wouldn't want to install one in northern Alaska, for example, because you wouldn't have hot water for much of the year!
For those who have very hard water (as we have in Phoenix), it is advisable to install a water softener in the water line before the water reaches the water heater. This will maximum the life of the tank, no matter what kind of water heater you have.
As my current (standard) water heater approaches the end of its useful life, I intend to replace it with a solar water heater. I anticipate doing so by 2016, when the current federal tax credits expire.

[SwineInsanity]

As for solar water heaters, they are also more expensive than standard water heaters, but they generally do not require upgrades to either the gas or electrical systems (one of which would be used as a backup to the solar heating). Also, solar water heaters are more like standard water heaters in that they have a storage tank, which can provide hot water even during a power failure. Of course, solar water heaters work best in places that receive a lot of sunlight. You wouldn't want to install one in northern Alaska, for example, because you wouldn't have hot water for much of the year!
For those who have very hard water (as we have in Phoenix), it is advisable to install a water softener in the water line before the water reaches the water heater. This will maximum the life of the tank, no matter what kind of water heater you have.
As my current (standard) water heater approaches the end of its useful life, I intend to replace it with a solar water heater. I anticipate doing so by 2016, when the current federal tax credits expire.

Here is you have a solar water heater... You have to have yearly plumbing inspections to make sure the water does not backwash into the system.... same goes with sprinklers..... If you don't they say they can shut your water off....

[ejfirestorm]

We recently opted to replace our electric hot water tank with an electric tank-less system. It was the best decision we could have made.

We considered a solar-heated option but in our location in S. Maryland, our contractor said he was having to put RADIATORS on them because they were generating more hot water than the tank could store!

We do not know the incremental savings on our electric bill becasue we also upgraded our HVAC system. Our net savings on our electric bill has been 30-50% per month since making the change and I would wager that more than half of that is becasue we are no longer heating the water in the tank only to have it cool sitting there and be reheated.

[GregGreen]

Hola!

For people considering to improving their energy efficiency, the best time to make the change is when the original source needs replacement or the value of the savings needs to include the residual value of the first item.

My idea that I implemented for FREE solar hot water is basically a batch breadbox solar heater. It heats up during the day and cools off during the night, since it is totally passive and does not contain a tank to store the heat. I used about 100ft of Pex tubing in the roof that delivers 5 gal/20 L hot water when the sun is out and gets the water above the temperature above the water coming in from the street that is much cooler. It could be drained and bypassed during the winter. Add the Pex tubing before it goes into the regular heater. Simply getting the water above its ground water temperature will benefit the user whether a tank or instantaneous heater is used.

My idea does not have much initial cost. It needs Pex tubing, 3 shut off valves to bypass the system, and I use 2 Sharkbite connections http://www.sharkbite.com/ that fits Pex tubing to Copper, CPVC, or PVC pipe in about 10 seconds, but PVC should not be used with hot water. You can add a drain too if you have average temperatures below ground temperature during the Winter.