Hello,
My husband and I are going to be having a house built. I was thinking that if we'd ever want a tankless system, now would be the best time to do it (much easier to install now than to try to retrofit later). Anyway, other than the cost difference between the actual units (generally 300-500 bucks, from what I've found comparing 12-yr 50 gal tank to 9.4 gpm tankless), what additional installation costs would you expect there to be over the cost of a storage (tank) system? I know that there are different venting requirements and possibly a need for a larger gas line, but don't know how much these really would add to the cost given we are starting from scratch rather than modifying.

Any other general notes regarding the pros and cons of tankless, in your experience?

Thanks!

In new installation, you will find almost no difference in cost. (beyond cost of the unit)

In new installation you will have to take in consideration size of gas line. Therefore, bigger gas lines throughout the house will be required. Here, I recommend that you place new tankless heater as close to the gas meter as possible. If Seismic Valve is required than cost of the seismic valve will probably double as well. Tankless heater require special and dedicated venting system. So depending on position of heater, you may spend few hundreds of dollars extra, too. If mounted on the exterior, you will eliminate vent issue. Figure about $1,200 cost for an average tankless water heater and water installation kit. For comparison, figure about $500 for 50 gallon conventional hot water heater.

If you have larger house and plan on installing hot water circulation pump than there is NAVIEN tankless hot water heater that has pump and buffer tank built in. All is enclosed within the water heater case. These heaters run around $2K.

As far as hot and cold piping goes I agree with Fr.Chuck. Cost should be just about the same.

Tankless water heaters have higher start up costs but technically speaking, they are very good units, last longer and are economical to run. They also require lot less space, are quiet and visually not disturbing. Since you are building new house, I would highly recommend you use one.

Hope that helps

Milo

I can't say my experience is typical, but we recently stayed at a time share resort that used tankless heaters. The time it took to heat water, especially for showers was very long. Sometimes more than 15 minutes. I wondered if the wasted water negated some of the other savings.

Like I said it could have been just a bad experience and the system was not adjusted properly. But, if I were you, I would like to see demos of tankless systems before making a decision.

I just ran across this and thought it may be helpful.

Good Luck with your new home.

Some local building codes require the more expensive condensing models (higher efficiency) and if non condensing, an expensive exhaust with fan, which runs around $350 extra.
No tankless heater should take 15 minutes to get hot water to a bathroom.
There are 2 rates to look at: minimum flow rate (to start the flame), which if high, means running the faucet wide open just to get the heat started, and the gallons per minute of delivery of water. That number should be high, or you will have trouble with tubs and whatever else takes a lot of hot water.

ScottGem, sorry you've had a bad experience with tankless water heater in the resort where you stayed.

Usually, multi-unit hotels / motels / resorts have hot water circulating pump to make sure hot water is delivered to each shower quickly. In your case, it looks like the pump was either not present or not working. This problem is not tankless heater problem as you will have exactly the same problem with conventional hot water heater.

Joypulv: Very good point. Starting Jan. 2014, in my area of operation, they now sell only condensing units. As with every condensing unit, you will need to run a condensation tube to the nearest drain.

Thank you for sharing all of you !

Milo

Milo, good to hear. Like I said, it was my one experience. But I saw this and just thought it might be of interest to the OP.