Water heater advice

[Melayl]

Our current water heater is a gas model, 40 gallon tank. It's about 12 years old (with a 6 year warranty), and just not keeping up anymore. We need a new one, very soon, so I have come to seek the collective wisdom of the Playground for advice on a new model.

I'm looking to see if anyone has any experiences with tankless gas heaters vs. tank gas models. I particularly would like to know about reliability, peak flow, problems, etc.

I have done some Google searches for reviews, but, frankly, I trust the Playground more than anonymous reviewers.

---edit---

We are a 5-person home with a dishwasher, washing machine and 1 (soon to be 2) full baths. And a wife and daughter that like to take looong showers.

[Manga Shoggoth]

We recently had our kitchen rebuilt, and as part of this had a new boiler fitted. For several reasons we went for an "Instant Heat" one (which has a very small internal tank and then kicks in to provide freshly heated water) so we could remove the hot water tank in my daughter's bedroom.

It works quite well for us, but the breakdown is:

PROs:


Not quite instant heat, but very close to it.
Use of hot water not limited to the size of the tank.


CONs:


Gas usage is higher - it kicks in each time you turn a hot tap on, so you are burning gas a lot more. (It took quite a while for my daughter to grasp this...)
If the water flow rate isn't high enough, the heater can cut out. This can lead to nasty surprises in the shower.

[TuggyNE]

Gas usage is higher - it kicks in each time you turn a hot tap on, so you are burning gas a lot more. (It took quite a while for my daughter to grasp this...)

As I understand it, while it does burn whenever you're using water, gas usage overall should actually be lower, since it only uses enough energy to heat the water once, rather than having to maintain the heat continuously over time.

The only advantage of a regular tank water heater is that you can use much smaller burners.

[smellie_hippie]

We recently purchased and installed a Rennai tankless water-heater. It's nice because these things are supposed to last for 20 years, as oppsoed to tank-models which have a life of about 7-10.

It takes a little while for the water to heat... so don't be misled by the claims of "instant hot water". I have yet to run out of hot water on my shower... but I don't take loooooong teenage girl showers. It has also done well with showering while dishwasher runs simultaneously.

I haven't done the full tilt boogie comparison (Dishes, washing machine, shower and flushing toilet). I would say that I am pleased overall.

[Melayl]

We recently purchased and installed a Rennai tankless water-heater. It's nice because these things are supposed to last for 20 years, as oppsoed to tank-models which have a life of about 7-10.


That's the brand our plumber sells and is recommending. Which style/model did you get?

[Manga Shoggoth]

As I understand it, while it does burn whenever you're using water, gas usage overall should actually be lower, since it only uses enough energy to heat the water once, rather than having to maintain the heat continuously over time.

The only advantage of a regular tank water heater is that you can use much smaller burners.

I noted that the bills were significantly higher. I'm not really in a position to check the actual usage figures at the moment - it could equally be due to a hard winter last year or the supplier hiking their prices. And to muddy the waters the cooking methods, control systems and thermostat systems were completely changed in the refit.

So yes, I could be unfairly blaming the boiler here. But you do still need to watch the flow rates in the shower...

[smellie_hippie]

That's the brand our plumber sells and is recommending. Which style/model did you get?

Can't remember off the top of my head... I will check and get back to you. Send me a PM if I don't reply promptly...

[smellie_hippie]

Sorry for the delay.
Rinnai RL 94 i

Small amount of loss in water pressure and slow to build heat... but I am pleased!

[Melayl]

Thanks, Hippie! I'm still not sure about installing one here. We get COLD in the winter, and the water temp coming out of the cold tap is only a degree or two (F) above freezing. The spec sheets on tankless heaters say they don't have a great flow rate with that high of a temp rise. Plus, it'd cost about $2400, installed...

[smellie_hippie]

$2400 was pretty close to what the plumber quoted us for installation as well.

Expensive but a nice long-term investment. Plus eco-deduction on taxes...

[JDMSJR]

Generally, tankless water heaters are most efficient the fewer the number of people who are using the hot water. It costs more to heat the water than a regular hot water heater, but you make the savings on all the time that you are not using the hot water. In your situation, it does not sound like a lot of the hot water in the water heater is not being used and would probably save you more money in the long run to go with a regular hot water heater, maybe upgrading from to 40 gallon size to a larger size.
Hope that helps you with your decision.

[Melayl]

It does help, yes. I think, financially speaking, that a larger traditional water heater will be best for us at this point in time. Mostly because $2400 is a huge chunk of savings right now. Assuming my wife agrees, that is. :smallsmile:

[GybeMark]

Generally, tankless water heaters are most efficient the fewer the number of people who are using the hot water. It costs more to heat the water than a regular hot water heater, but you make the savings on all the time that you are not using the hot water. In your situation, it does not sound like a lot of the hot water in the water heater is not being used and would probably save you more money in the long run to go with a regular hot water heater, maybe upgrading from to 40 gallon size to a larger size.
Hope that helps you with your decision.

I'll second that with one amendment. On-off-on-off cycles also hugely contribute to tankless inefficiencies. This pattern is doubly true for large households :smallbiggrin:. But, for example, washing dishes by hand (with lots of on/off) will lower efficiency compared to a dishwasher.

[JeenLeen]

Does anyone know how much this would change if it were an electric water heater as opposed to gas?

I ask mainly for myself as I'm also considering something like this in the near future, but it could help the poster as well if his house has both electric and gas lines easy enough to set up where the heater is.

[tomandtish]

My Aunt and Uncle were actually selected (along with 49 other families) about two years ago to test a new electric (don't remember the model) tankless system in the Houston, TX area. Test ran about a year then the system was removed. What they learned:

Pros: As long as water flow was adequate, they didn't run out of hot water. Electric bill was lower assuming equivalent usage. Took up a lot less space.

Cons: They had to be a lot more careful about using multiple things that required hot water at same time (no showering while doing dishes or a hot load of laundry). Hot water cuts off completely if flow rate is too low. Also, they noticed they were more likely to take longer showers, so water usage went up. Even when they avoided that, they did use a little more water.

General consensus among the test group: They work best in small homes with few (1-2) people who aren't going to use a lot of water. For larger homes or larger families, traditional heaters are probably still better.