Tankless water heater?

[Phishfan]

Has anyone gone gone this route or know someone who has? I may need to replace my water heater so I'm starting to look at options and was wondering if anyone has experience.

[fyo]

Yeah, those water heaters just don't know how good they have it ;p

The main two issues with tank-less heaters are a higher upfront cost and a somewhat limited flow rate. The upside is that it takes less energy and less space. If you're replacing an existing heater the space might not matter much, but we really wanted to go tank-less when we built our house (but were not ultimately allowed to for "reasons").

As for the flow rate, you need to consider what you are using hot water for in your home. There's a federal max limit on shower head flow rate of 2.5 gallons per minute, although most use a bit less, but if you have a shower with decent water pressure and turn it all the way up, figure something like 2 gallons per minute. If two people need to be able to shower at the same time, that's 4 gpm. Add in any appliances that are connected to the hot water, like some dishwashers and older washing machines. You might also want some overhead for anyone washing their hands or whatever.

The flow rate of your tank-less heater will depend on the needed temperature rise (output water temperature - input water temperature), but the detailed specs should list a bunch of different values. Just find out how hot your cold water is and how hot you need the hot water to get and you can look up the number.

Back when we were looking a few years ago, the recommendation was to go with tank-less heater capable of providing around 6.5 gallons per minute at a 60F temperature rise.

[MyGodWearsAHoodie]

As for the downside of not being able to take simultaneous hot showers, our tanked hot water heater can't do that either.

[Phishfan]

Damn auto correct  .

I stopped in Home Depot simply looking at prices and the 6.5 gpm was a couple hundred less than the average 400 gallon tank. I didn't look at specs any more than that so far. I live in the Orlando area and my pipes are overhead so a good portion of the year my cold water is pretty warm.

[MyGodWearsAHoodie]

Damn auto correct  .

I stopped in Home Depot simply looking at prices and the 6.5 gpm was a couple hundred less than the average 400 gallon tank. I didn't look at specs any more than that so far. I live in the Orlando area and my pipes are overhead so a good portion of the year my cold water is pretty warm.

I suspect that your water heater has a much easier job than mine. 

[Spider-Dan]

I had to replace my water heater last May and was looking at a tankless.  The problem was that I would have needed to upgrade my natural gas line (from 1/2" to 3/4", as I recall) from where it enters the house all the way to the existing heater.  And in my eyes, it didn't make sense to be installing a natural gas line upgrade; as natural gas prices increase, I'm probably going to be moving further away from gas usage.  So I just ended up installing a new tank water heater.

I did also consider switching to an electric heat pump water heater, but the price difference was something like $8000 vs. the $2000 (installed) I paid for the tank heater I went with.

[MyGodWearsAHoodie]

Another option if you have southern roof space is a solar hot water heater

[masterfins]

I don't use that much hot water so I have found it easier, and cheaper, to just stick with a regular tank. BTW it is extremely easy to change one out yourself and save a thousand dollars. Just watch a YouTube video, only takes about two hours, less if you're doing a second one.

[Spider-Dan]

BTW it is extremely easy to change one out yourself and save a thousand dollars. Just watch a YouTube video, only takes about two hours, less if you're doing a second one.

The two areas of my home that I will not work on are plumbing and electrical (outside of changing out a faucet or a fixture).  It seems to me that the insurance companies are just waiting for homeowners to do unlicensed plumbing or electrical work so they can deny your claims in the case of water or fire damage.

[CF DolFan]

I was told by an engineer that unless the tankless is gas you will end up spending more money on electricity. Not sure but my sink in the kitchen is on the other end of the house and it takes a while to get hot. My pipes have been repiped through the attic. It is warm but doesn't get hot for a while. I have debated getting a small tankless for that sink alone. I have gas for our back up generator but would still need to run it inside the house. I do a lot of the electrical and plumbing myself but would pay someone to run the gas line if I did it.

[Brian Fein]

are gas-powered tankless heaters common?  I thought they were all-electric?  This is news to me.  I don't even have natural gas in my house.

[Spider-Dan]

The vast majority of tankless are gas, as electric are not going to be able to heat up as much water as quickly.

[pondwater]

I just spent $2500 putting in a tank and asked the guy about a tankless. He told me that I would have to get an electrician to run more breakers or something. Also told me that if something goes wrong with a tankless, most of the time you don't repair it, you just replace the whole unit. Whereas on a regular tank, as long as the tank is good you can replace parts.

I also have a solar water heater on the roof, but at some point before my dad died he turned it off because it was leaking off the side of the roof. I don't think the actual tank is leaking, my guess is that a fitting or pipe seal went out or something. So I probably need to get it pressure tested and find out if I need to use it or just get it taken off the roof. But then again I don't guess having it on the roof and not using it makes any difference.

[Pappy13]

It's a matter of opinion. I've seen professionals debate the pros and cons and honestly they kinda balance out. There's no one "right" answer in my opinion, just whatever makes the most sense to you.

[MyGodWearsAHoodie]

What is "best" for new construction may not be best for replacement.  A tankless system typically uses less energy over the course of a 24 hour day, but uses considerably more power at the time of heating it.  (It saves energy by being off when the water isn't running).  So swapping might require upgrading powerlines etc.