Hot Water Consumption Discussion

[Fuzz]

Your con for having to run the water to get it hot...that's where the cost savings totally fall apart for me. I'm paying about $50 a month for water, and $5 for gas. So I'd be using more water to save gas. The numbers make no sense in that regard.

[kevman]

I don't get why the dishwasher or laundry machine is such a big deal. A modern energy star dishwasher only uses 4 or 5 gallons. That's between the pre-wash, wash and rinse cycle. Assuming a 2 hour cycle that's two gallons an hour.

Likewise a front load washing machine only uses 10 to 15 gallons or so. Using a warm wash/cold rinse cycle that's maybe 3 gallons of hot water when you first turn it on.

If 40 gallons isn't getting the job done you can also try increasing the temperature on your hot water heater. It won't affect how much hot water your appliances use but you'll need less hot water to shower.

[Locke]

I'd actually really like to see a detailed cost break-down on one of these things.

My parents installed one identical to what FF posted and its a head of garbage. I'd never consider one.

My dad is the crazy guy who will cuff you upside the head if you leave a room with the lights still on and will constantly complain about how much water you use or the length of your showers and blah, blah, blah.

I get it, conservation of energy and I agree to a point. But in my house we just have a conventional water tank.

Now the similarities are that we also have pretty much instant hot water, whereas at my parents' house you got to constantly run the thing to get hot water which, obviously, uses more water.

So it saves energy by not keeping water heated, but wastes more water.

That and it doesnt get water hot enough. I know about hacking the thing but I'm not hacking a water heater, it either should work that way normally or not at all.

Further, how much energy are you really using by maintaining ~60 gallons of hot water at a constant temperature?

Are you generating a net benefit by saving gas by not having a tank versus the amount of power the unit consumes and the amount of water you waste?

In my mind the difference, if any, would be miniscule and certainly not enough to justify the hassle, inconvenience or initial cost.

[afc wimbledon]

Originally Posted by Fuzz

Just curious what your savings are? If I look at my August gas bill that would only include hot water as my furnace doesn't come on, it is under $5 of actual usage(before all the fixed fees). I'd need to save a lot on hot water to make that worth it. Or is gas a lot more in BC?

I'm a foster parent so have 3 teens in the house who are hugely wasteful of heat water food etc.
I am also in a hundred year old house although the water tank was, I suspect, from the seventies or early eighties.

my August gas bill was down by half over the previous year and that was pretty much just hot water so for me well worth it. I think it worked out at about a thirty dollar saving per month

[Fuzz]

Ah, OK, I just took a look at a BC sample bill here:
https://www.fortisbc.com/NaturalGas/...s/default.aspx
and they charge more of the fees based on usage, whereas Enmax has mostly fixed fees, and only a couple tied to usage. So for us, reducing usage doesn't reduce the bill by much. For you, it has a greater effect.

[opendoor]

Originally Posted by Locke

Further, how much energy are you really using by maintaining ~60 gallons of hot water at a constant temperature?

With modern tanks, not a lot really. The energy required for an electric 60 gallon tank to maintain its temperature is about 2 kwh a day.

[Bownesian]

An often ignored consideration is that in Calgary we average ~11 degrees C difference between the heated inside temperature and the unheated outside temperature*.

This means that in all but 2-3 of months of the year, the heat loss from having a less efficient hot water vs. on-demand tank is "lost" into the house. This heat "loss" mostly displaces heating that your furnace would otherwise have to do.

On-demand water heating makes a ton of sense if you're in a hot climate where cooling is a significant concern, but it makes very little difference in Calgary. If you like how it works or the fact that you have unlimited hot water or more space in your furnace room, that's cool, but the economics made no sense at all for my household when we had the basement apart after the Bow River flood a few years back.

* ~4000 heating degree days per year / 365 days (http://calgary.weatherstats.ca/metrics/hdd.html)

[BigNumbers]

I am confused about the talk about taking 60 seconds to get hot water with a tankless? Is the recirc feature really not prevalent with the tankless units you guys have? Mine has it, and it's amazing. the CPU has a learning function so it knows what times of days, by day, I call for hot water, and it's literally instant hot. I can also program it so it always has hot water ready at the tap certain times of day, in addition to the learning function.

I guess, like most things, the devil is in the details, because I had read bad things about the instant HW tanks, but mine has been amazing.

Only concern/negative comment is that there has been some small variances in HW temp when I have 3+ units calling for hot water at the same time (ie: have to turn the shower tap up a little, if the dishwasher and washer are also on at that time).

[BigNumbers]

I think my position is this:

Do I think it saves money in a cold climate? No. Much like LEDs, during our ~200 heating days a year, you are just trading heating efficiencies. ie: the LED light bulb uses less electricity, but creates less heat.... So I am not saving on electricity when I am heating the house, I am just trading off between less electrical heat from the old incandescent bulbs and more natural gas heat from my furnace with the LED lights.

Same logic applies to the tankless heaters, in my view - any inefficiencies in the tank systems are just heat to your house - so you're burning more NG at your furnace to supplant the waste heat your tank generated.

Do I think the benefit of endless, instant hot water is worth a few hundred more than a good direct-vent tank-based system? For me and my family - yes.

[GoinAllTheWay]

/\/\/\

What? Really? I've honestly never thought about it but I can't imagine that light bulbs have any meaningful contribution to the warmth in your house.

And as far as the hotwater tank goes, do you mean the heat generated when the burner is on? I mean gas is gas, your either getting "waste heat" from your hotwater tank firing or your furnace, no? And the tankless heater must have some waste heat too, would it not?

[Fuzz]

It's heat loss while it sits in a tank. So you heat it up, no one uses it, and it has to be re-heated. Though anything in the last 10 years has pretty good insulation, so I'm not sure how much an issue it is.

[GoinAllTheWay]

It can't be much. Put your hands anywhere on a modern tank and it's basically cool to the touch. Only place I can think of that would be a weakspot is the copper stem coming out of the tank.

Not that I've been looking for it but I don't think I've ever heard mine fire up randomly. I only hear it when someone is in the shower or the dishwasher just called for water.

[Kjesse]

I can't imagine the heat slipping from a tank or conventional lights has any meaningful impact in your heating costs. If someone can point to something that says otherwise I'd love to read it.

I've heard a lot of mixed reviews about instant on. Some love it some prefer their tanks. I've never had instant on so I don't know.

But in terms of a recirculator, you can get one installed with tanks too to get instant hot to your top floor, so that's a wash in terms of comparisons.

[Ryan Coke]

Bignumbers, can you explain the recirc feature more? That's my biggest beef in our new house, takes a long time to get hot water in the upstairs bathrooms.

And also, does the recirc function only work with an instant hot water heater? Wouldn't that function work the same with a conventional tank?

[GoinAllTheWay]

Originally Posted by BigNumbers

I think my position is this:

Do I think it saves money in a cold climate? No. Much like LEDs, during our ~200 heating days a year, you are just trading heating efficiencies. ie: the LED light bulb uses less electricity, but creates less heat.... So I am not saving on electricity when I am heating the house, I am just trading off between less electrical heat from the old incandescent bulbs and more natural gas heat from my furnace with the LED lights.

I'm pondering this far too much already but isn't gas significantly cheaper than electricity? So assuming you are right and your furnace has to run longer to replace the missing radiant heat form light bulbs, your achieving the same heating result at a lower price.

[Kjesse]

Originally Posted by Ryan Coke

Bignumbers, can you explain the recirc feature more? That's my biggest beef in our new house, takes a long time to get hot water in the upstairs bathrooms.

And also, does the recirc function only work with an instant hot water heater? Wouldn't that function work the same with a conventional tank?

Yes.

http://www.homedepot.com/p/Hot-Water...0800/100426993

[Fuzz]

Interesting, my brother has a big problem with this in his house. Just found this though, and it sounds like it wastes a lot of energy:
http://www.treehugger.com/clean-tech...-me-money.html

I wonder if a point of use unit would be better for energy usage?
https://www.homedepot.ca/en/home/p.a...000841434.html

[Fuzz]

Does anyone know if the point-of-use ones can take hot water as an input, so it only runs for the first bit until hot water can come from the main hot water heater?

[FurnaceFace]

Originally Posted by GoinAllTheWay

Such as? Very interested in haring the pros and cons from someone who actually has one. I've had installers tell me not to bother which was somewhat surprising.

And should you be changing your username to tanklesswaterheaterface?

Others have basically answered for me. The positive is the water sitting in a tank needs to be heated, then cools, then reheated. With tankless this doesn't happen. In a house with many people this is less of an issue as the water is being used. In our situation there are just two of us therefore we'd be fairly inefficient constantly heating the tank.

In a larger household another positive is you don't run out of hot.

The drawback is running the water to get the hot. We don't have the recirc, never heard of it until today in fact. You just get used to having showers back to back so the water doesn't cool down. You can get the sandwich effect where you start off hot, then get a cold sandwich in the middle before the hot water comes back. That's only if you allow the water to sit in the lines for a few mins. The recirc would eliminate this.

Regarding the water temps, 120 is plenty hot I find. Edit: I just checked the system and I can increase mine to 140.

[#-3]

I think most new houses come with a 55 gal tank now. my house has a pump that pre-circulates the hot water at 6am and 8pm. I love it. ensuite is as far as possible from the tank and I don't need to warm it up at all in the morning, or for the kids bath time, but I think you have to plumb one of those pumps into the house before you drywall