I’m building a new small house and plan to put in heavy amperage wiring to support a Tankless water heater. If anyone has any pros or cons about those types of water heaters please pass them on. I know the gas models are probably better but I’m trying to stay away from gas if I can. Thanks.
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I just talked to my plumber about a electric tankless hot water heater and he said it doesn't exist for a whole house system. You would have to have one at each fixture in order for it to keep up. Much like an instant hot. From my understanding, gas is the only fuel that can produce the high temp. to accomodate a whole house tankless heater. You'd be better off getting a traditional tank electric hot water heater. They are so well insulated that you only really pay for the initial heat up...not maintaining the temp. gas tank hot water heaters loose a lot of heat through the exhaust...that is why they are inefficient. Keep in mind I'm no expert...just forwarding my plumbers advicde.
Edited 1/23/2007 1:27 pm ET by aztimber
Depends a lot on where u live if it will work well - u aztimber probably live way up North (judging by the name) but bayouguy probably lives in Miss or La (also judging by the name) where the ground water is much warmer all year round.
You are correct...I'm in Michigan. For some reason I didn't even consider that. But now I do remember my plumber mentioning our areas ground water temp.
I've had my plumber install a dozen last year. Norritz is the best brand in my opinion. 10 year warranty, and saves about 2/3rds on your gas bill and outlasts tanks by double.
Yes, they are for the whole house. Each faucet can have remote sensor which can set the hot water temperature remotely for that faucet, which is pretty frigging cool.
Regards,
Scooter
"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
I know they are available. But, I can't find my link I saved for them.
It takes, IIRC, three 40 amp 240v circuits to power an electric whole house heater.
Bryan
"Objects in mirror appear closer than they are."
Klakamp Construction, Findlay, Ohio
I'm working on a house where the owner had a Seisco electric tankless put it. It uses (4) 30-amp breakers and is about the size of a small suitcase. He is very happy with it, and it fits in the small space he has available. I have a Takagi gas unit in our house and we like it fine.
My strong opinion is that tankless units do not save much energy although they do save a little, and that it is hard to recoup the cost. The main reason to install one is to save space. They work great for showers, tubs, and laundry, and are slightly less appropriate for the kitchen sink.
just curious. why do you say they are less appropriate for a kitchen sink?
They have a rather high flow before the heater kicks in. Can't run a slow hot rinse water when you're washing dishes.
It becomes a slow cold water flow.
Most of the units have a short delay between when water starts flowing and they start heating. You get a shot of cold water thru the heater every time you turn the water off and then on, such as when rinsing dishes. In our case, this does NOT result in actual cold water coming out of the faucet, because the piping and heat exchanger both store heat and actually warm that cold water as it travels towards the faucet. So, you rinse dishes with somewhat warm water, but not hot. If you leave the hot on a short while it reheats the piping and the water gets hotter. Myself I am perfectly used to this and it's not a problem, my wife is not as happy.
Our unit will produce hot water at a trickle. The low flow cutoff is 5/8 GPM, which is not much water.
I have a client who is not happy with their relatively new on demand heater. It's been in about one year. A bosch aquastar that is designed to be able to supply two showers simultaneously. They complain about not getting hot water at the kitchen sink, only warm water. I have been thinking that it is because the flow volume is not enough to properly trigger the heater. Your theory explains why this could happen.And, in the upstairs bathroom, which is farthest away from the on demand heater, once the water gets hot, they claim that it will get cold spurts during a shower. All of these fixtures are new, low flow water conserving fixtures. And, the shower valve is a pressure/temperature balancing valve.My theory here is that if the temperature balancing function shuts off the hot flow, even for a moment, this decreased flow will shut off the on demand heater and you will get the burst of cold water that you are talking about. Then the valve allows the hot to flow again and the heater kicks back on and after a minute, you get hot water again. Sound plausible?I have already checked gas supply to the unit to make sure it has proper volume and pressure. So those variables are taken out of the equation.
Are they on a well?
Is there a remote control available for the Bosch?
no, they are on city water with good pressure - 55psi. no remote control with the bosch.
whoops, i re-read your question. yes, there is a remote available for the bosch, but they don't have it.
David - u have to take the saving on context of the anticipated use.
A family of 5 with 3 teens probably wouldn't save anything because they use hot water all the time for one thing or another. But I, as a single person use it sparingly 12 shower on the morning, 2 washer loads a week, dishwasher every other day. For me it's big bucks.
Consider a recirculating loop if possible as well.
It can help reduce water waste, and provide you with near instant hot water. THey can be set up on demand, or a timer.
Just my .02
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WWPD
Why put a recir pump in a tankless system. 1/2" pipe only holds less than one gallon per 100', the average run in a home is probably 40' so you would be running just over a quart of water each time you turned on the faucet. IMHO it would defeat the purpose of reducing the energy used by a tankless.
I would look at the bigger picture.
Living in an environment where we have water restrictions pretty much year round, why would any waste be acceptable? And for that matter, why would any waste be acceptable at any time?
And my second point was for convenience. Wouldn't it be nice to crank the water on, and not have to wait/waste water? Just take care of you business right away.
The pump would cost pennies to run
more of my .02
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WWPD
The trade off of running the pump is that you're turning the whole loop into a radiant heater for your crawlspace or wherever. Save water, waste energy. I don't think there's an answer that saves both water and energy that doesn't involve a good chunk of up-front investment.
I agree, and it is not the cost of the pump but rather the cost of the tankless heater running. Note, the tankless heater has no insulation, the demand for the heater to come on, I would think, would be almost constant.
I guess it's just a matter of making the initial (perhaps 1K depending)
According to research the low watt, 2 pole pumps are equivalent to a 25 watt lightbulb, while "significant water (and sewer) disposal savings, retaining the 12000-38000 gallons of water a typical U.S. home wastes annually waiting for hot water."
I'm just offering the original poster options. Is there a right way? I guess it's to each his own kind of thing
I must say however, I may be somewhat myopic in my views. There are more factors to consider than just running the recirc. pump, and the addition minute or so of the water heater to give one Hot water at the finger tips and minimal waste.
My locale is never cold. the water coming from the city requires little energy to heat, and to keep warm in the pipes. Overall costs for my location are beneficial as well as environmentally sound. It may not be such in all areas. Costs from the city/county electric companies etc
I will try harder to remember that there is more than just South FL. ;-)
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WWPD
Edited 1/26/2007 12:05 pm ET by Sailfish
Wait, South FL is still actually part of the Union? I thought it was annexed by Cuba sometime back in the '80s.
I think it really is about a bunch of different competing priorities and deciding which ones rule in a given situation. There are a lot of folks who say the expense of tankless will never work out. For us, we justified it based on being able to put it outside and having it close to point of use.
We have a tankless, and it still takes 10-15 sec or so for the shower that's 3 feet, as the crow flies away, to get hot. It would've been 3 min using our tank heater on the other side of the house. Lav faucets take a little longer. But, I just figured it out, we still on average use only 75 gal/day for 2 plus a munchkin.
I have 2 apartments in the house we have and I have installed electric on demand tankless in both of them with great success. I have also installed one in my sons house and now that we are adding on a second story we will be putting in a second larger unit. I installed a multi point propane in my mother in-laws and she loves it.
I'm planning to install two Rinnai tankless units (their largest residential ones) to serve two kitchens, four bathrooms and two washer-dryers, using natural gas. The house is two floors on a 1,200-square-foot footprint. I've heard there's a new commercial model that would serve my entire house but it's not yet available in Canada.
My plumber says I should put the two units side by side in a fairly central location, but I'm wondering if it might be preferable to split them, so each unit is close to where the hot water is required. I don't like waiting for hot water to arrive because (a) I'm impatient and (b) it seems a waste of energy.
We had a SETS electric tankless unit installed because my wife cannot tolerate any gas in the house plus we had a small space for the unit in the kitchen of our small house. We live in the northeast so I knew we had to deal with 45? winter water temps to feed the unit.
I did research on the net and the SETS unit looked good.
NEVER AGAIN!
We had to install a 100 amp breaker and when the electric unit went on, the house lights flickered. Found out it draws 22 KW! We had to go round with the power company until they installed a 25KW transformer on the pole to our house!
The temperature never stayed constant. First it warmed then got cold. I tried to talk to their tech guy about the 2 gallon per minute rate it was supposed to work at. He said you can't measure that rate accuately and kept telling me to follow their trouble shooting guide, which was no help. I made numberous calls to the tech help and it was no help at all. I finally adjusted the cold water valve that fed the unit so the water could not go through it too fast. I worked fine for three minutes then the temperature would drop, then come up later. I had to constantly shower with one hand on the shower valve to keep adjusting for warm water. This truely sucked when taking a shower. All this with no other water use at the same time.
Thank god we sold that house. So much for the claims of manufacturers!
We have a 40 gallon electric water heater on a use timer. Now I can shower without fear.
I know I will be sorry I asked??? But I have to. Wife can not tolerate gas? What does that have to do with a gas HW? Gas heat yes or maybe?
If properly installed I can not see how that could effect anyone?
Ditto. Inquiring minds want to know, even if it may shorten one's life - what did he mean about his wife's not "tolerating" gas? I mean, there's a myriad of one-liners waiting in the wings, but I don't want to hijack this thread as I'm finding it very informative.
As far as the tankless water heaters are concerned there are about as many opinions out there are contributors to this fine forum. I feel that re-circ pumps are best used in commercial/hotel uses where the demand is much higher than in a single family home. I have also read about the drawbacks of using the PEX-type of plumbing vs. copper and the internal "wear" that can be associated with a continuous flow of hot water. Of course, hydronic heating systems use a loop of flowing water, but the flow rate or volume may be less.
A local plumber finds the cost of venting the "instant-on" heaters to be more than the actual heater, in some cases. They are classified a Type-3 appliance and require stainless steel venting, for example.
The ambient temperature of the ground water is indeed another thing to factor in to properly size and calculate a unit's size.
Is the payback really there? Once again, a local HVAC pro has calculated that in our area (British Columbia) with the new air make-up codes and attendant costs it's now becoming more affordable to simply install an electric water heater. Yikes! However, there is no flue required, no combustion air needed, etc. The cost to heat water is around $ 10/mth. Go figure.
I've got a neighbor who's installing a ground-source heat pump, but at $ 20,000 the payback is l-o-n-g. Even if it cost him nothing to operate (and it doesn't, of course) that's $ 2,000/year factoring in a 10-year period before service will be required. You can heat a lot of bath water and heat a home for that much dough.
I wish there was simple, low-maintenance, reliable solution but there just isn't' a free lunch anywhere. Water hardness and a constant light-up whenever you call for a shot of hot water must surely affect the life span of these units?
I try and convince myself that the heat that radiates off the water tank and the B-vent (albeit very little) somehow contributes to heating the basement area, so all is not lost. Anyway, I will continue to be educated. Cheers,
Ken"They don't build 'em like they used to" And as my Dad always added... "Thank God!"
Well I'm sure I'm going to to get nay sayers on this but you know who has the last word.
If you don't you're not married.My wife is chemically injured and reacts negatively to very small amounts of lots of stuff.Gas and gas exhaust, Any gas appliance has pilot lights air intakes exhaust ports. Unless the air comes from outside and goes out the chimney it will make her ill.Since I've been in an environment away from gas appliances I notice gas odors in other peoples houses as soon as I enter.
I installed a Tagagi tankless in my house and the best I can say for it is that when the Mrs. and I get into the dual shower for some 'relaxation' we never run out of hot water like before with the holding tank type. need I say more?
Orbs