OT: Water heater question

As always, a thoughtful and helpful discussion. The comments from Karl and Robert were particularly helpful. I've decided to stay with the tank, but will downsize to 50 gals as it's just the two of us plus the dogs (and they don't use hot water).

Larry

I have long advocated small "point of use" electric water heaters to provide "instant hot water" for convenience. They can be on a timer to make sure you have hot water on demand when you want it and still save power by not maintaining hot water when you don't need it - or to only run the heater in "off peak" if you are on time of use billing like we are in Ontario. The payback in not putting 10 gallons of water down the drain waiting for it to get hot can actually be pretty quick, depending on the cost of municipal water and sewage services.

By "point of use" I mean a standard small tank heater -something like 5 gallons close to the point of use. In a bathroom at the far end of the house from the water heater, for instance - or an upper floor bathroom. Have it come on 2 hours before you get up so you have hot water to shave and shower- and let it shut off when you go to work - then come on an hour before you come home to make sure you have available hot water to "freshen up". A well insulated tank will maintain the water temperature fairly well with the power off if no water is drawn, so you are never reheating an entire tank from cold.

Really?

OK... so let us say that you get "point of use" 5-6 gallon water heater to run in addition to your regular unit to save money and use the timer scheme . I'll bite.

BTW Larry, a 40 gallon with do for two people regardless of those pesky dog s taking so many showers!) as he is looking at now. Check the posted energ y ratings and projected cost of use on the tanks and you MIGHT see a bit mo re savings over the life of the heater. Probably not too much, but it depe nds on local energy costs.

So, Larry is in for $1000 for his straight replacement, give or take a coup le of hundred depending on his site conditions, code requirements, permitti ng fees, old tank disposal fees, etc.

Check the prices of a 5-6 gallon water heater and you will see they are abo ut the same cost as a 40 gallon, about $275 to $300. Add fittings, about $

You are now about a $1000, $1100 bucks. But, you now need to have your ele ctrician run a 30 amp circuit to this new unit (you weren't thinking of pip ing in gas with your remark of the unit turning off and on by itself). Do you have room in your circuit box? How hard will it be to run a new circui t across the house or upstairs through the walls to get it there? My elect rician could probably do something like that for about $1500 or so. Don't scream bullshit! Remember, copper wire all the way, a new 30 amp breaker, a new 220v plug/box/cover and a pigtail as well as a 30 amp servic e rated timer have to be purchased and someone will be fishing wire and cra wling through attic insulation to get it where you need it. Fishing 10ga d own a wall is no picnic.

Will you be repairing the demolition you did yourself to allow access to yo ur piping yourself? Maybe if you have the time, the inclination and the sk ills. (I can do anything on site with wood but I really suck at tape/float , myself.) You might need to add a little to your estimate for sheetrock re pair, wood work and paint on top of the plumbing and electrical. $500?

With you doing the demo, cleanup and replacement yourself, you are going to be in at about $2600 or so for the "point of use" system.

How long would it take you to accrue the kind of savings you anticipate to get to $2600 for its recovery? Remember too, there is NO consideration for the extra annual power usage for the POU unit, and even if it is just on 6 hours a day that is still a helluva hit for an electrically powered water heater.

If you would, please take a minute and explain how long in real numbers it would take to pay off this machine, and don't forget a probably $ 20 a mont h ($240 a year) for its operation (that is a very minute .66 a day, only .3

My HUD classes told me that in a retrofit for energy saving updates, they s hould all pay out in 3 to 5 years or they aren't worth doing for a number o f reasons. A water heater is an appliance, and it falls in the 5 year cate gory. So if we take your project at $2600 (remember, you do he demo/rebuil d/job cleaning) and add in $1200 for energy use in the same period (the cos t would never go up, right?) we now have a $3800 bill for a five year payba ck number.

That's $760 a year. Really? That is almost $65 a month in hard cost expen se for five years. That means your investment wouldn't pay off unless it w as actually saving you that much every single month for FIVE years before y ou realize one dollar of gain to recover your investment.

How is that supposed to work? You have seen all my numbers and how I arriv ed at them. Seriously, I would like to see how you arrived at the point of thinking this is a good idea and how you justify your dollars spent vs. th e savings gained. I would love to the "point of use" scheme justified for an existing home.

Robert

Something I did to get hot water to the faucet more quickly through galvanized pipes was turn the heat up at the heater. One of the reasons, especially with those heavy pipes, that it took longer to get hot water to the faucet was because the heavy pipes absorbed the heat from the water. Hotter water cooled less getting to the faucet and heated the pipes more quickly. Yes we had to be more careful with the hotter water. Did I notice an increase in electricity usage? Not that I recall. You use less hotter water than not so hot water.

Heated or not hard water plugs pipes and valves equally. Think about the shut off valve to your toilet. We had no water softener at our house for the first 20 years that we lived in the house, new when we bought. I turned the water off at the main valve because the shut off valves at the toilets were crusty and difficult to close when replacing toilet valve parts. Two years after installing a water softener the shut off valves worked like new. As a bonus I did not have to replace the toilet valves as often after installing the softener. And the faucets and drains no longer had to be cleaned to remove the white mineral deposits.

In many ways, use less soap too.

Not that big of a deal. If I did not water my yard with softened water I probably would have to put in 3-4 bags a year. As it is I do that twice a year. Our first softener was a Culligan softener that regenerated twice a week. That was way way way too often. In our new house I bought a different brand softener that measures water flow and regenerates after somewhere around 3,000 gal. IIRC. So instead of 8 times a month it is now only 1-2 times a month when I am not watering the yard.

And that's being generous. I could be way off but the numbers I've run a few times in the past for various clients and situations indicated a realistic payback expectation of 15 to 20 years.

Still, discussing that fact with clients doesn't seem to have an impact, so my conclusion can only be that going tankless to some folks is culturally equivalent to driving a Pious... er, Prius.

It can certainly be a selling point, depending upon the socioeconomic of the neighborhood.

" snipped-for-privacy@aol.com" wrote in news: snipped-for-privacy@googlegroups.com:

For those who want instant hot water as a retrofit, they might consider the recirculation method:

A friend just went through the details of tank-less versus tank type and the deciding factor in going with a tank was that the heater only raised the temperature of the water a fixed amount and his well water was too cold to get really hot water. 95F - 100F was about all he could expect.

Jim

Lots of 15 amp 115 volt nominally 5 gallon water heaters available. Home despot has Ariston Model # GL4.0 4 gallon 1500 watt for $250. It will fit under the vanity sink. In my house it would require pulling the vanity, opening the wall and 1 sq ft of flooring, and less than 6 feet of copper pipe to service both the sink and shower ( the shower would still have about 12 feet of half inch copper full of room temperature water to purge - a lot less than 45 feet currently required) - and mine is a SMALL house. Adding another 15 amp circuit in would be relatively simple as the washroom is at the end of the house with the electrical service. It's a job my Dad would have done in a couple hours as an experienced electrician - and my old panel (soon to be replaced with a breaker panel) still has room for at least 2 more circuits. Less than 50 feet of 14/2 or 12/2 would do the job - not prohibitively expensive. I've seriously considered doing it but we'll likely be moving in the next 5 years if we can find a bungalow we like - and in a Bungalow it's a whole lot easier yet to accomplish.

I replaced the 40 gallon hot water heater last year, looked at doing a gas replacement for the electric. Routing the piping (pvc) was not possible without demoing the 1/3 of the basement ceiling and moving HVAC. Tankless electric big enough to handle the load required a 100 AMP circuit. So went with a 6 year warranty 40 gallon, cost was around $350, plus about $15 for diaelectric connectors.

Mark

I'm seriously thinking about doing the same, though it's even easier in my case. There is ~70' of pipe between the water heater (in the garage) and the master bath. Both are on the first floor and the basement is unfinished. There are loads of blank breaker slots in the entrance panels (slowly using them up for the shop, though ;-). It would be a simple matter to strap a point-of-use water heater to the joists (though they are manufactured I-beams), next to a wall, somewhere.

Sounds like the one he was considering was simply not big enough for the demand he expected to place on it. I would be very surprised if the unit was purposely designed to raise the water a fixed amount above the actual temperature of the water. While well water is cold, that is not a unique situation. The water coming from a normal/regular water supply can be close to freezing during the winter months. Regardless of where his water was coming from I suspect there were other unique variables that were going to limit the ultimate temperature of the water at the faucet, too small of a unit being my first guess.

That is actually how tankless units are rated. :)

While well water is cold, that is not a unique

Flow Rate.

Tankless units are rated on their temperature rise/flow rate, (gallons per minute). "Temperature rise" being the difference in temperature of the water between input and output. The lower the flow rate, the more the water can be heated.

There is a limit to what the temperature can be raised. That is one of the complaints I've heard with people that have very cold incoming water. Electrics have less capacity. I've seen them at 36kw or 122,000 btu. From what I saw, you can get 65 degree temperature rise at 3.8 gpm flow rate.

That is how I understand it. Since the precious statement that I was responding to did not indicate flow rate being a factor the broad brush statement of only raising the temp X amount of degrees seemed pretty problematic. I can absolutely understand raising the temp only x degrees at full throttle at the faucet but at a lower flow rate I would find it hard to believe that the temp would not rise.

One of the problems is that these things sense flow rate internally, so a low flow rate can cause them to either shut down and/or lower the temperature rise.

Counter intuitive as it sounds, one of the cures for that problem that is practiced widely is to turn on a second hot water faucet to keep the sensor from lowering the temperature.

So much for being "green" and "conservation" minded... like many "progressive" concepts which focus on feel good issues, the opposite effect is often the ultimate consequence.

A common problem with tankless units though, because a "big enogh" tankless unit would require more electrical power than the total service available, and a big enough natural gas one would require a larger meter/regulator, and often even a bigger supply line than the gas co has installed for most residential services. I'd need to put in a new underground electrical supply to install the recommended electric tankless because I only have a 100 amp service, and I cannot install more than 125 amps on the existing infrastructure. My current gas meter would support the water heater with the furnace not running, but would be borderline (at best) for sure if I also had a gas drier or range running

------------------------------------------------------- That's going to be marginal.

Water coming out of the ground will be around 50F-54F year around based on a lot of heat exchanger design and development work I did many years ago.

A delta of 65F will give a discharge of 115F at 3.8 gpm.

Lew