Hot Water Heaters

[Dragline]

So ours is at the end of its natural life. As in, if it doesn't stop leaking and shutting down, DW is going to have me leaking and shutting down.

I am trying to decide whether to replace it with another standard issue job or go with one of these new-fangled tankless contraptions, which supposedly save a lot of energy, but I'm not really sure if they do. And they seem to require extra maintenance.

Does anyone have any recent experience with these?

For reference, it will be powered by natural gas. Exciting solar things are not an option where we live.

[Riggerjack]

There's a few reasons to go tankless. Capacity, do you run out of hot water now? Space, do you have something else to put there? Heat loss, heat lost from the tank is where the efficiency claim comes from. That heat goes into your house. Your preference and climate determine if that works for, or against you. I live in a predominantly heating area, so the heat added wouldn't bother me. If I lived in Florida, it would. I'd be more inclined to put my money into a more efficient natural gas tank, myself.

[Spartan_Warrior]

Some things to consider:

Your ground water temperature (if you live too far north where the water is too cold, even the best tankless heater may not be able to heat the water)

Your usage, particularly maximum flow rate (gpm). The more fixtures you plan on using at a time, the higher your gpm requirement (e.g. running a sink at full blast is generally about .5 gpm, a shower is about 2.0 gpm, two showers simultaneously is about 4.0 gpm, etc).

I think most tankless heaters top out at a max around 6 gpm. So, if you have three people running showers at the same time, you may have problems getting hot water around and maintaining water pressure. (Most heaters will shut off if it doesn't have enough pressure.)

On the other hand, if you have things like one large tub that you want to fill with hot water (and the durn tank always runs out before you can fill it), or you want to take longer showers but one at a time, tankless would be better for those uses.

The standard tank heater is less efficient because the element has to run continuously to keep the water in the tank heated. Tankless heaters only run when being used--but for those brief periods, they draw A LOT of power. This means it might not ultimately save you any money if, for instance, you used to take short showers and now you take long ones because your tank never runs out. They're only more efficient if your habits don't change.

I don't know anything about the gas tankless, but as far as electrical tankless are concerned, the final consideration would be whether the power supply in your house can support it. Most tankless heaters will require two (or even three) double-pole 40 amp breakers and a total draw of around 200 amps. When they run at full blast, they'll be drawing up to 28,000 watts. Your home electrical service may need upgraded if it's less than 200 amps, or there's not enough space in your panel. Again, I don't think this applies for gas.

Personally, I will probably upgrade my conventional electric tank to an electric tankless when my current one dies. It fits my needs and I'm sure it will save me energy based on my usage habits.

[lilacorchid]

To add to Spartan's excellent post, you may not be able to upgrade to a big enough electrical panel if you live in an old neighbourhood. Though, it may be fun to cause brown outs for your neighbours.

[Dragline]

Thanks, everyone. This is helpful. I probably will go conventional with this one based on what you told me and where we live.

I was hoping to do this with the old one (watch the slo-mo at 1:25): http://www.youtube.com/watch?v=61uDmQF5I2E

But somehow I don't think I'll be allowed that indulgence.

[jacob]

Same issue here. Tank or tankless?

We're definitely going to run with gas regardless. However, because our chimney is old and decrepit (needs a $1500 liner to keep using it), we'd like to vent through the wall with a PVC pipe (condensing direct vent) just like we did with our our furnace. (Our basement is unfinished, so our intake is directly from the basement.)

Our water and gas bills are pretty low, so wall venting is the primary concern. Capacity doesn't matter very much.

I saw some random reviews that complained of fan noise for tankless heaters. Is that a general issue?

[Ego]

Capacity doesn't matter very much.

ERE options.

1) The Wim Hoff
2) The MacGyver

[Dragline]

When we lived in a house that was closer to your size and our water heater broke, we just got the most basic AO Smith model that fit the space/configuration that was already there. I think it cost in the $5-700 range at the time. There are other brands that are just as adequate, though.

You should be able to direct vent it. Avoiding modifications is probably a key factor, because they could easily cost more than the unit itself.

[jacob]

@Ego - I should add that I'd rather avoid any "And then we also have to pay to upgrade the water heater..."-arguments from potential buyers when that time comes.

@Dragline - Some piping has to be modified. Currently, it's exhausting into the chimney, but that's not a sustainable solution.

[Dragline]

I should add that I'd rather avoid any "And then we also have to pay to upgrade the water heater..."-arguments from potential buyers when that time comes.

Exactly. You want kind of the minimal "standard issue" for the house. That was our thought in our other house, because we knew we would be selling in a few years. Considerations would be different if you are going to be there "for the life of the unit".

[tommytebco]

I didn't see it mentioned, but the amount of "hardness" in the water matters. I have read that scale can build up and ruin one in short order if the water is very hard,
No first hand experience with one though, just a heads up.

[llorona]

We had a Norton tankless water heater put in about two years ago, mostly for space reasons. It's in the attic. If I listen carefully, I can hear the fan noise when the hot water turns on. DH noticed it the first week or so but hasn't mentioned it since then. Neither has anyone who has come to visit.

[cmonkey]

If venting is an issue, maybe switching to electric is a potential solution? Putting in a 240v 30 amp line (or 20 amp if you get a smaller water heater) isn't hard. We switched from gas to electric 1.5 years ago and didn't notice any uptick in our electric bill. Many of the new ones are very efficient. The one we got supposedly learns when 'peak usage' is and will optimize around that.

Adding in that you have a 'smart water heater' is a plus to future buyers.

[JasonR]

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