Post by: JAlexander on January 10, 2007, 10:51:04 AM
James
Post by: mtnbkr on January 10, 2007, 11:02:53 AM
That said, I think it would be nice to have one on the top floor of my house. It can take 1-2min for hot water to reach the upstairs showers. The sink faucets take even longer.
Chris
Post by: K Frame on January 10, 2007, 11:13:06 AM
The electric ones SUCK the juice.
You'd need an electrician to look over the home, the current electrical demands, and the new water heater.
Post by: K Frame on January 10, 2007, 11:13:52 AM
You should consider a bypass circulator pump.
Easy to install.
Post by: Brad Johnson on January 10, 2007, 11:15:03 AM
Brad
Post by: Mabs2 on January 10, 2007, 11:20:04 AM
Were it my house, I'd got with a large solar hot water heater with a smaller electric backup...but that's me.
Post by: Brad Johnson on January 10, 2007, 11:24:35 AM
My understanding is they're way more ineffecient than normal gas hot water heaters (which are around 80%) or so, so look to pay a lot more for your hot water.
Were it my house, I'd got with a large solar hot water heater with a smaller electric backup...but that's me.
Were it my house, I'd got with a large solar hot water heater with a smaller electric backup...but that's me.
More ineffient at spot heating, yes. However, you're not trying to keep 40 gallons of water hot all the time, either. For most households there is a net decrease in energy use with instant heaters. If you have a household that uses a lot of water on a constant basis then a tank-style heater and a circulation system might be more efficient (presuming that the heater and all the supply pipes are well insulated against heat loss).
Brad
Post by: mtnbkr on January 10, 2007, 11:26:16 AM
Chris,
You should consider a bypass circulator pump.
Easy to install.
Next time you're over, remind me. You should consider a bypass circulator pump.
Easy to install.
BTW, the tankless heaters I've known people to use have all been gas. Never known anyone to use an electric one, if that matters...
Chris
Post by: wingnutx on January 10, 2007, 11:32:02 AM
Post by: wingnutx on January 10, 2007, 11:35:35 AM
Post by: ilbob on January 10, 2007, 11:39:12 AM
An electric one would have the issue of needing a lot of juice while the heater is running. Most showers are 3-5 gpm. You would need about a 40kW heater for such an application. Thats about 180 amps for a typical 220V residential system. Most homes just are not going to have that much current available from their service.
If you want instant hot water, maybe a better answer is a small electric hot water heater near the point of use. Feed the existing hot water line to the POU heater so there is always hot water at the POU. It does not need to be real big.
Post by: K Frame on January 10, 2007, 11:48:19 AM
[Professor Farnesworth voice]Wha... huh? Good news, everybody, I don't know what the hell you're talking about![/Professor Farnesworth voice]
Post by: Sylvilagus Aquaticus on January 10, 2007, 06:39:41 PM
Given my druthers, I'd prefer to have a solar hot water heater and a full compliment of solar panels, bateries, and a windmill. With 3 full baths and a half, I can't justify retrofitting to the tankless models.
Regards,
Rabbit.
Post by: cassandra and sara's daddy on January 10, 2007, 07:24:53 PM
Post by: K Frame on January 11, 2007, 05:30:15 AM
Why not just drop a nuke plant in the back yard?
Post by: ilbob on January 11, 2007, 05:34:00 AM
if your gonna remodel and can upgrade to 400 amp electric service you can go electric otherwise its as and i plan on replacing my heater with one of the instant ones.. i've installed em and they apparently save money. at least thats what my clients tell me.
Do you have any idea what an "upgrade" from a typical service to a 400A service is going to cost you?
We are talking in the neighbourhood of $5000.
All that so you can barely do better than break even on your energy costs.
Post by: danny on January 11, 2007, 05:41:55 AM
It heats the water as we use it and so, as mentioned, we're not paying to keep a tank hot around the clock. It's also impossible to run out of hot water. It takes some getting used to. The water gets hot enough that one must add cold water in the shower but it never gets scalding hot like a tank-type heater can. As a result we must use a dishwasher which has the capability to heat the water a bit more.
While showering, you must have the dishwasher and/or clothes washer off or it'll exceed the flow-rate for full temperature.
The only maintenance in all these years has been to replace a $3 rubber diaphragm every few years.
Post by: mgdavis on January 11, 2007, 11:16:51 AM
Post by: ilbob on January 11, 2007, 11:20:35 AM
We've had a Thermar natural gas tankless water heater for well over 20 years. Our gas bill dropped substantially when we put it in. I don't think they make that brand any more.
I don't see how a tankless heater would change your gas bill a whole lot over a modern standard gas water heater. The tankless units are less efficient at heating water than a standard tank type unit. The main difference is that you do not lose as much heat while it is not in use. But, for modern water heaters, that kind of heat loss is relatively low anyway.
I would not be surprised to see a substantial drop in gas usage if the old water heater was worn out, poorly insulated, and used a standing pilot.
You will get the advantage of an endless shower if you so desire. But that will NOT reduce your gas usage.
Post by: danny on January 11, 2007, 01:19:54 PM
Indeed our tankless is less efficient. How many minutes a day do you actually draw water? For these, relatively few, minutes it's running at not much more than 50% efficiency. A tank-type heater, while more efficient, is experiencing a steady heat loss 24 hours a day. Even well-insulated, this loss adds up.
Our winter gas bill didn't change much as the furnace draws so much more than the water heating that savings weren't very obvious but it became VERY significant in the summer.
They've been using these for a long time in Europe where energy costs are much higher than here.
More recently we replaced our furnace with a 95% model. that's when the savings REALLY started.
Post by: Mabs2 on January 11, 2007, 03:48:38 PM
...whereas a gas heater with its heat exchange running through the tank in contact with the hot water, the water will heat the air in the heat exchange causing it to rise and be replaced with cold air...which'll heat up and rise. So it kicks on occasionally for nothing.
Which is why solar is so great.
Get a solar hot water heater with a pump to circulate the water on a photovotaic(sp?) panel and you've got almost free hot water.
Post by: cassandra and sara's daddy on January 14, 2007, 01:38:15 PM
box will cost you 250 bucks on ebay buried service can be more but check wih power company last conversion i did the house already had right cable all i had to do waas pull panel box and swap in new one was 2300 bucks done deal and with 400 amps you can run all the power toys your heart desires
Post by: K Frame on January 14, 2007, 05:06:51 PM
Not if the thermostat is properly located, it shouldn't. The thermostat reads the temperature of the water in tank, not the air in the heat exchange tubes
Post by: Mabs2 on January 14, 2007, 05:46:28 PM
Post by: Desertdog on January 14, 2007, 07:37:58 PM
Tankless WH have certain flow rates per minute with temperature rise. Too much flow and the temp drops.
Research tankless and tank waterheaters on the internet. Do not pay much attention to the tank ads, but pay attention to the specifacations and cost of equipment.
Tankless are more expensive to buy and to install than tank type. The biggest selling point I have seen in researching them is there is no standby heat loss. My summer gas bill, two people in 3 BR house, is under $20 for the water heating, cooking and gas clothes dryer.
Everything else I have read on tankless WH has not convinced me that they are that good of a deal.
Natural gas is the cheapest type of fuel if available. Propane is the next cheapest, and normally it can be put into any home at a reasonable price.
Electric is the most expensive to use.
Post by: K Frame on January 15, 2007, 02:45:07 AM
The air rising will constantly cool the water...I didn't say it ready the tempurature of the air.
Ah, gotcha.
That's why some new gas water heaters have dampers in the exhaust. To keep that from happening.
Post by: Brad Johnson on January 15, 2007, 10:18:53 AM
Brad
Post by: K Frame on January 15, 2007, 10:37:09 AM
They also have little flapper valves in the water fittings to keep heat from migrating out of the tank via the water. Such clever chaps, these engineers...
Brad
Brad
Di-electric heat trap nipples.
They actually aren't little flappers, they're two little balls.
Post by: Brad Johnson on January 15, 2007, 12:12:59 PM
Brad
Post by: K Frame on January 15, 2007, 12:19:53 PM
Post by: grampster on January 15, 2007, 12:27:30 PM
Post by: Brad Johnson on January 15, 2007, 12:32:24 PM
What doesn't make sense to me is they are installing all this paraphernalia in a copper pipe. Looks like the copper, being a darn efficient heat conductor, would carry away far more heat than the water. Why don't they put some kind of heat-resistant joint on the heater so that you don't have direct contact with the copper piping? Hmmm... something to ponder.
I can just see one of those little flappers either getting scaled up from our hard water or coming lose and getting stuck in something (which is why the little flappers ended up in the trashcan).
Brad
Post by: mtnbkr on January 15, 2007, 12:35:00 PM
Damn. That's a new design.
They existed back when we did my water heater. I recall seeing them.Chris
Post by: K Frame on January 15, 2007, 12:50:23 PM
Damn. That's a new design.
They existed back when we did my water heater. I recall seeing them.Chris
I don't recall seeing them when we were getting the stuff we needed. I sought out the di-electric heat trap nipples because your old one had a serious case of electro-rot around that one pipe set.
Maybe it's the di-electric part that has something to do with it?
These are very similar to the ones I put on your water heater...
Post by: mtnbkr on January 15, 2007, 01:24:36 PM
Chris
Post by: 280plus on January 15, 2007, 03:23:13 PM
Quote
Natural gas is the cheapest type of fuel if available.
Last time I figured it oil was more efficient/cheaper than nat gas. I haven't done the numbers lately but when comparing high efficiency gas boilers to high efficiency oil boilers the last time it became necessary the oil won out. You need to compare the price in your area between a "therm" of gas which is 100 Cu Ft x 1000 BTU per cu ft or 100,000 BTU and a gallon of oil which is 140,000 BTU. The best (conventional) gas efficiency available right now is 93% the best oil efficiency is 86% so if you take 100,000 BTU and multiply it by .93 you get 93,000 BTU of usable heat to your house from gas, if you take 140,000 and multiply it by .86 you get 120,400 BTU of usable heat to your house. And that's what it's all about. Propane is even less efficient than nat gas as it has less BTU per cubic ft than nat gas.
Post by: gunsmith on January 15, 2007, 05:57:16 PM