Electric whole house tankless water heaters

[John Wright]

I have been looking into a few options whenever my current water heater goes out...

I'm curious if a 4 gallon per minute tankless water heat will keep up. Anyone have any real world experience with these?

I don't want to take an unexpected cold shower.

I expect the natural gas or propane heaters would do a better job, but I was looking at the electric tankless heaters to replace my current electric 50 gallon model, rather than to get a propane storage tank and all that jazz involved with switching everything over.

[Happyfunballs]

I think they'll keep up, the part you need to be careful of is the wiring. I believe a unit like that may take a 100amp breaker.

[John Wright]

I think they'll keep up, the part you need to be careful of is the wiring. I believe a unit like that may take a 100amp breaker.
Thanks for the heads up... I just checked and it takes 120a worth of service for that rascal. Current breaker is a 60a, so I will have to look into my breaker box to see if I have any room and run a heavier ga service over to the water heater location. It's not located very far away from the breaker box, so that shouldn't be too bad to rewire.

http://www.lowes.com/pd_200420-1136-AE-125_4294856715_4294937087?productId=1057489&Ns=p_p roduct_rating|0

[H2Ogbodies]

Other things to consider is to get the model that has multiple heating zones. This way, you can program your sinks, showers, ect. to have different heat ranges-something to think about if you have kids...cause you will have damn near instant hot water when u turn it on. Also, if you are paying to have it all nstalled, watch out for the cost of the ductwork required to vent the heater unti outside. They charge by the foot and that's where they try to mark up the install. My advice is to mount your tankless heater on your wall as close to say, your dryer duct as possible, so my tank vents out rigth next to the dryer duct outside-that's how I did it.

[gordonquixote]

John, a new water heater is on the market that utilizes a heat pump in lieu of electrical resistance heating. They claim $320 in annual savings for a standard single-family dwelling. (http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12840)

Most also will have a federal tax credit/rebate as well as subsidies on you local level....not to mention the fact that it will pay itself off in no time.

Just throwing it out there.

[John Wright]

Other things to consider is to get the model that has multiple heating zones. This way, you can program your sinks, showers, ect. to have different heat ranges-something to think about if you have kids...cause you will have damn near instant hot water when u turn it on. Also, if you are paying to have it all nstalled, watch out for the cost of the ductwork required to vent the heater unti outside. They charge by the foot and that's where they try to mark up the install. My advice is to mount your tankless heater on your wall as close to say, your dryer duct as possible, so my tank vents out rigth next to the dryer duct outside-that's how I did it.
Vent? I'm guessing that you are speaking of the gas(propane or natural gas) models? I'm looking at the all electric on demand heater. I plan to install my own.

I'm thinking that I might have to call the power company to upgrade my meterbase. I have 200a service, but with a heat pump and wanting to add a future shop on....I'm not going to have enough service through the current meter.

[sniper]

When I looked into this, everyone I talked to said stay away from the electric models. As already stated the amperage and current needed is pretty high. The cost of the wire needed to run one might be pretty steep as well depending on where it's located.

Other than that, no real world experience.

[gordonquixote]

I just called one of our "A-team" plumbing subcontractors. To quote him he said "Tankless electric whole-house heaters are pieces of s**t".

He said to go with a gas 200,000 btu heater (Rinnai) hands down.

[John Wright]

John, a new water heater is on the market that utilizes a heat pump in lieu of electrical resistance heating. They claim $320 in annual savings for a standard single-family dwelling. (http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12840)

Most also will have a federal tax credit/rebate as well as subsidies on you local level....not to mention the fact that it will pay itself off in no time.

Just throwing it out there.Thanks Gordo...I'll have read up on that.

[vintageracer]

If you have a shower that has multiple sprayers, pulses and does all that fancy stuff the tankless heaters will not heat enough water quick enough to keep up with use.

Tankless GAS water heaters work well IF you operate within the rated flow capability.

[Happyfunballs]

The Rinnai is good stuff but expensive. $2500 I believe. Then, based on your local codes, you need to purchase a double walled vent and run it out your roof line. The venting is costly as well. I couldn't justify the additional cost.

[joejaze]

I've done tons of research on this subject and decided to go with the Takagi Mobius M1 for my 2 family home. I went with gas as electric prices are not even close to being in line with actual dollar savings. The M1 claimed 3 showers could be on at the same time and they werent kidding. As soon as I installed the unit I turned on all (3 showers and 6 faucets) of my fixtures and while the flow was paired down a bit the unit had no issues keeping up with demand. Now, I dont expect that we will ever have all of those on at the same time however it was an interesting experiment.

Here is the link to the unit I have:

http://www.tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/takagitm1main.asp

[John Wright]

Wonder if it might be better to put in several single source heaters for each item requiring hot water..ie...bathroom, kitchen, washing machine..rather than installing one to handle it all?

Gas seems like a hassle that I don't want to fool with...installing vents, finding a place to put the gas storage tank and plumbing the house for gas, having it refilled every month or whatever, extra hassles that I don't deal with currently.

[joejaze]

Wonder if it might be better to put in several single source heaters for each item requiring hot water..ie...bathroom, kitchen, washing machine..rather than installing one to handle it all?

Gas seems like a hassle that I don't want to fool with...installing vents, finding a place to put the gas storage tank and plumbing the house for gas, having it refilled every month or whatever, extra hassles that I don't deal with currently.

Ahh, Propane? I was talking Natural Gas. My house was already using Ng so installation was easy. I could see how adding gas would be a problem.

If you do decide to to go with gas I have some extra vent pipe sections. The pipe is definitely not cheap...

[wmhjr]

I just put in a new gas furnace and AC unit this past spring, and looked into tankless "on demand" water heaters myself. Up this far north, they appear to be a non-starter except for some niche uses, such as a separate tankless heater for a specific bathroom, etc. Beyond that, the extra cost made it so in order to pay for it, you'd have to save energy for about 35 years - by which time you'd already have replaced it.

Depending on where you're at, it may be different. However I could not find a single contractor who would recommend one in the Pgh area. And everyone I talked to that had 2 or more people in their house that had one has complained about it not having the ability to keep up.

[joemac]

Myself personally I would shy away from gas too. It does provide great heat and will keep up with nearly any load. All the associated venting, piping and tanks are a pain to install though. Ask me how I know. I would venture to guess the plumber that called the electric stuff junk makes better money off the gas stuff and obviously you can't expect any electric appliance to rival gas. I would say that the tankless electric would be inline with the electric tank heater though. They also have electric boilers which is what you may be referring to. I have also seen the heat pump electric water heaters which have a tiny heat pump on top and pull heat from the surrounding area to heat the water. There is some savings there and probably slightly better recovery.

[vintageracer]

Cold showers save water and energy.

If you are REALLY concerned about the environment you will not have any type of water heater at all in your house.

Just burn wood to boil water. That'll piss em off!!!

[joemac]

Cold showers save water and energy.

If you are REALLY concerned about the environment you will not have any type of water heater at all in your house.

Just burn wood to boil water. That'll piss em off!!!

It would take some large gonads to take cold showers.:smoke:

[John Wright]

Cold showers save water and energy.

If you are REALLY concerned about the environment you will not have any type of water heater at all in your house.

Just burn wood to boil water. That'll piss em off!!!Brrr....just the thought made me shiver. The last shower I took without any heat gave me a headache that lasted two days.

I thought about the wood heaters too...several friends have water circulators with a water jacket on their wood stove. Wood fire is good,.... if.... someone is at home all day to keep that stove chunked full of wood. I would burn more wood for heat if my wife or I both didn't work all day, we have no one at home during the day to keep up the stove. I hate letting a stove smolder along all day with the drafts closed up...that is a chimney fire just waiting to happen.

[joemac]

When I build a house I'm going to supplement with solar hot water. It seems to be low hanging fruit in the solar world.

[wmhjr]

Here in Pgh I'm starting to think solar power would actually chill the water and not heat it :)

[John Wright]

Here in Pgh I'm starting to think solar power would actually chill the water and not heat it :)
LOL..yeah, I don't want to have to sweep the snow off the panels either.....BTW, it's snowing like crazy right now...AGAIN! They were calling for rain here today with snow mixed in...it's 100% snow right now and you can't even see across the road.

[wmhjr]

Heck, I'm not even talking about the snow. I'm talking about how the sun is something rarely seen anymore regardless of snow - though we're getting hit again as we speak.

[joemac]

I'm fairly certain the angle of the panels would cause the snow to slide off. They are also very slick and are held off the roof a little.

As far as heat, the radiant heat of the sun heats the fluid, not the ambient temp.

[John Wright]

There was a company here in town that made those solar water heaters. They started back in the late 70's but have since gone out of business. They used a window box with a coil of copper tubing routed through and it was all painted with some sort of heat absorbing flat black colored paint. I think it was some kind of special formulated paint for that application to take advantage of the radiant heat like Joe talked about. I know they worked good in the Summer, but have no idea how they did in the colder months or what kind of antifreeze they used.

[joemac]

The newer designs of solar collectors have a bunch or rows of VERY thin plates that water runs through to pick up heat. More like an automotive radiator than coils of tubing. The plates are fractions of an inch which allows the water to be heated by a small amount of heat. It can be below freezing outside and as long as the sun is shining it can heat the water above your tank temp (120-160).

The technology has come a long way, it just can't provide hot water during overcast conditions, hence the supplemental description in my original post.

[wmhjr]

I'm fairly certain the angle of the panels would cause the snow to slide off. They are also very slick and are held off the roof a little.

As far as heat, the radiant heat of the sun heats the fluid, not the ambient temp.

Yeah but when you can't even see that a sun exists.....

And my skylights are covered. The entire roof is under about 20" of snow.

[gordonquixote]

And my skylights are covered. The entire roof is under about 20" of snow.

So you're sayin' you have snowlights? :lurk:

[joemac]

Yeah but when you can't even see that a sun exists.....

And my skylights are covered. The entire roof is under about 20" of snow.

Your roof must not be very steep. We have had probably half a dozen roof collapses in my area from all this snow. It is common to see people up on flat roofs shoveling.

We are finally going to get some rain it looks like. I actually prefer snow myself.

[wmhjr]

So you're sayin' you have snowlights? :lurk:

Yeah, it's real romantic.

[Jim Nilsen]

The main thing to have a tankless unit that most don't consider is that you really need a water softener or you will clog that baby up with residue and lime if you have really hard water. Read the warranties on them and if you don't have a water softener it will be void.

I have considered it myself and have gas, but when I was told how much to purchase the water softener and a GOOD tankless unit I was going to be paying for ten yrs to offset the cost and that was installing it myself. Electric will knock the idea even further.

The idea of adding a solar alternative to help is cost effective if you do it all yourself and have the discipline to maintain it.

[wmhjr]

Your roof must not be very steep. We have had probably half a dozen roof collapses in my area from all this snow. It is common to see people up on flat roofs shoveling.

We are finally going to get some rain it looks like. I actually prefer snow myself.

My roof is a pretty standard pitch It's not at all flat. It's just this damned snow. Never had a problem before. Original house built in '65 and added on in '80. I bought the family homestead, so nobody ever lived here besides one of us.

This snow was amazingly heavy considering the rapid fall, and the temps have never yet gone above freezing. combined with good insulation, it results in the snow staying on the damned roof. gutters are a frozen mess. It's starting to be a real problem - and we've just gotten another 1" of the 4-7" we're supposed to get by tomorrow PM.