Renamed: Tankless water heaters?

[Brock]

Re: Removing a sweat fitting **Mission Complete**

What John said and

First I have to say I am not familiar with that model so it might not apply, or maybe it will.

With two units in line with one another I see decreased flow overall. Without either of mine in line I get about 10 gal/min on an open 3/4 inch line, after one heater in line I can get only about 5 gal/min and a second unit slows it to about 3 gal/min. Now this doesn't really matter unless you actually use two taps at the same time, like wash machine and shower. The shower just slows WAY down. I don't mind it but my wife complains when she looses pressure. I should add our pressure starts at about 60lbs, 1 faucet no heater is about 50, 1 faucet 1 heater, about 40, 2 faucets, 2 heaters, about 15, you can see why this might be a problem.

I would also guess tap water would be about 50 to 60 F, ours is about 40 on a 700 foot well.

As far as venting you could go powered, some of the gas units have a control to turn on the power vent. I have seen this done with a 6 foot drop and a 50 foot horizontal run, they did upsize the pipe to 4 inch and upsized the blower also. I am sure it moves more air then the unit could possibly exhaust. It also had a sensor to shut off the unit if the sensor didn't sense a flow after a few seconds and the blower stayed on until the exhaust gas was under 100 or something like that.

Again I know our units, either a single or in series won't start with just the dishwasher, they do start fine with the wash machine though.

On a side note I have lost all the elements in one unit now, so I have one full working one left. I am seriously considering going to a 10-20 gal heater and putting in dual 2400w elements for quicker recovery. The other advantage would be I could run it off my genset if I had to. The electric one I have pulls 55 amps at 240v. I have found it takes at least 3 of the 5 elements to make a shower tolerable, but that's still 33 amps at 240v.

 

[Floating Spots]

Re: Removing a sweat fitting **Mission Complete**

[ QUOTE ]
John N said:

4) I have been assuming I can't use natural gas since there is no easy way to vent it -- assuming straight to the side or up. Can you vent down and over? If I went down a couple of feet I could get into the crawlspace and then out to the side of the house.


[/ QUOTE ]

My brother has one that goes sideways.
I don't know why down wouldn't be a problem.
There is a forced air exhaust fan that runs and is controlled by the water heater. So instead of the open capture design of most water gas water heaters, this one is sealed and can push the exhaust anywhere.
Might want to look for something like that.

Edit: This was for a tank type, just to clarify...

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

[ QUOTE ]
Brock said:
With two units in line with one another I see decreased flow overall.

[/ QUOTE ]

I'm betting that must be it - esp. considering they do support a parallel configuration I recall.

I'm starting to think I might just go for a single unit and just get the largest capacity I can find. Originally I wanted to support two concurrent showers (2.5gal/min each- water saving heads), but I'm starting to think I should just live with the limitation of one shower at a time.

Right now with our 50 gal tank, three consecutive showers is pushing it so it would still be better than what I have.

Brock, what is the make/model of the unit you have? What type of dishwasher do you have?

Thanks,

-john

 

[turbodog]

Re: Removing a sweat fitting **Mission Complete**

Hmmm, this thread still lives. I posted a while back and have spoken with DD directly about this stuff.

A few suggestions (after resarching/specing/ordering/installing my mom's 28.8Kw envirotech):

series heaters:
these things run the elements pretty hot and after a good wide-open run followed by a run at say 25% output, you CAN get some minor heat spikes. series heaters could make this particularly nasty.

incoming temp:
do NOT assume it will be "X". MEASURE IT yourself. In case you don't understand the importance of this, let me explain. MEASURE IT YOURSELF!!! I/she live in mid mississippi. Envirotech said "heater model xxx will be fine for the WARM mississippi temps". She had measurable incoming temps of 42F during a typical winter. Also, you CANNOT calculate for worse case @ 33F. You'll end up with e heater that will dim the lights in your subdivision when it switches on.

elec supply:
These things REALLY like the juice. Do your light flicker or "blip" when your a/c kicks on? Well, envirotech's 28.8 Kw model pulls about 3-4 times that much power. EXPECT YOUR LIGHTS TO FLICKER CONSTANTLY when this thing is used at ANY other setting OTHER THAN full on or full off. If you need more details, PM me. You WILL have to upgrade your elec supply and panel box(es). These heaters require 100% duty cycle breakers. Practically all residential breakers are 80%. If used with this thing, they will heat up and flip. This will eventuall lead to failure/fire/etc. Most electricians do not know the difference between the 2 breakers, or that there are more that 1 type. Your biggest problem with the electrician will LIKELY be convincing him that it is actually possible to use that much electricity at one time. He will try to size the wire/etc too small. It will heat up and prematurely degrade the insulation. This will lead to failure/fire/etc.

You will really have to have a twig up your butt to get these things installed and working correctly the first time.

That said... they are really nice after it is all said and done. I am building a house, and am 2 weeks from completion. Monday I will order my two units that I want. To keep from having to series them, I had my plumber split my piping into separate loops.

I decided to post again after reading some of the recent posts. I am seeing a lot of theoretical questions and assumptions. These are the exact same mistakes I made in judgement before ordering mom's unit... and I graduated from MSU in mechanical engineering. You HAVE to consider water temp and elec supply. Their recommendations (envirotech/etc) are MINIMUMS.

P.S.
An important thing we forgot was that after leaving the heater, the water goes back through pipes enbedded in the COLD concrete slab. This is a SIGNIFICANT source of heat loss that should be measured and considered. It is even more important when you learn that ALL these heaters are designed to be pretty much used as the sole source of water. This means that you will ONLY turn on the hot when bathing, washing hands, etc. Rarely will you mix any cold with the hot. See example:

mom's example:
incoming temp ~42F
temp leaving heater ~112F
temp at shower head ~109F

Bottom line I guess is this: There is WAY more to saying "this looks good enough" to getting these things to work WELL. You must measure temps and plan for elec demand. I was very impressed with envirotech's heater. It had onboard readouts for every piece of data measurable.
incoming temp
exit temp
% heater demand
left bank temp
right bank temp
flow rate
etc
NOTE: they have sold out to some "parent" company type thing. no guarantees on timeliness of info. this was 1.5 years ago.

Questions? PM me.

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

Hi Turbodog,

I currently have a 200A service and am planning to upgrade to a 400A. I shouldn't have dimming lights when I'm not that close to capacity, should I?

So you liked the Envirotech? I was looking at the SETS 220 and then found they have a brand new model 240. I think it's a 24KW unit. It looks like the Envirotech ESI 412 is a 28.8KW unit so it seems like an advantage. Is that the units you are using?

I knew there were some larger units than the SETS, but I was thinking of using them in series so wasn't looking for the absolute largest units. Now I'm changing my mind so I need to look at other units.

How long has your mom used her heater? Has she had any failures?

The split loops would be nice, but not super practical in my house since most of the plumbing is in the walls.

I'd love to hear any thoughts you may have.

Thanks,

-john

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

For what it's worth (after a lot of googleing), I used this page to find what different models are available:

http://www.controlledenergy.com/html/powerstar/compchart.html

From this list, it looks like Tankless Inc makes the largest single unit (36KW). It looks like the current model is H-36-6.

http://www.hotwaterheater.com/model-h-36-6.htm

Any thoughts on this unit?

Thanks,

-john

 

[John N]

Re: Removing a sweat fitting **Mission Complete** *DELETED*

Post deleted by John N

 

[Brock]

Re: Removing a sweat fitting **Mission Complete**

re-read what turbodog just wrote.

I have used my units by themselves, without the second gas heater, and taking a shower is touchy. The temp varies as you take a shower, I am sure this has to do with the cheaper units I have and how it really only runs at two levels. If you have standing water in the pipes that warms up to say 60F then you run the shower, then 5 gallons later the nice 42F water hits the heaters and your shower gets much colder, so then I add more heat to get the temp back up, then the heater responds with more heat and it gets warmer again. Adjusting the heat in the shower has a delayed reaction because the heater sees the change as soon as it happens and it takes a couple of seconds to get the water from the heater to your shower or faucet.

Having said that I would never recommend a cheaper unit like I have by itself, it just can't maintain temperature with two settings. It works fine for preheating the water for our main tank and the main tank is what really regulates the temp and flow most people are used to. Again with our setup we never run out of hot water, the gas heater will actually cycle after an hour of showers.

So I would recommend you get a nice unit with good controls if you are going to use it by itself. My brother had one that pulled 120amps at 240v, but the neat thing was it used SCR or some other control so the elements don't pop on and off. When you turn on his hot water the lights dim over about 1 sec or so and then fade back up when shut off, while mine you see an instant snap on and back off. Both of our houses are new and have good large electrical services. At my brothers you can see his neighbors lights dim when he turns on his hot water, I am sure this is because they are on the same transformer. He has since added a larger gas heater and it is cheaper to run.

The only thing I would say is you are much better off getting a larger unit rather then a smaller one. I know turbodog recommended smaller, but if your electrical service can handle it I would go larger.

 

[turbodog]

Re: Removing a sweat fitting **Mission Complete**

Reading above posts about incoming temp varying... her model is rock solid on output temp provided you do not exceed the capacity of the heater.

The lights flickering...
This has been a problem since the unit was installed. She has 400A service. BUT, her panel by the elec meter is only 200A. We have 2 ideas on why the lights flicker slightly.

1) the water heater (WH) turning on and off rapidly to maintain desired temp is pulling down the supply voltage. I wish I had a good enough multimeter to actually test this. I'm thinking of something like a fluke scopemeter or something.

2) the huge surge of current traveling through the WH supply wires is inducing a voltage fluctuation in the house wiring. The WH supply lines are lying over the house lighting circuits in the attic. I am thinking this is close enough in proximity for induced voltage to be an issue. Again, a REALLY good meter could verify this also.

It is important to note that the flickering STOPS when the heater is in full on mode. However, this does little to solve the problem from hypothesis 1 or 2 above. I will say that the flickering lessened when the WH supply wires were ran through a separate conduit from the meter base to inside the house. But they still lie on the house wiring in the attic. Originally the wires were ran in the main conduit heading into the attic. When the electrician (who specd the wrong size wire) re-ran the wires, he ahd to add the 2nd conduit.

She has a good "hot" elec feed there. Something like 127 volts or so.

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

[ QUOTE ]
John N said:

I've noticed I can't seem to find the flow needed for activation on most of these web sites. Looking at the SETS, Envirotech and the Tankless Inc., the only one I see the spec for is SETS.

-john

[/ QUOTE ]


Ah, I found the flow activation for the Envirotech - it was burried in their user manual. Here is what I've found so far.


Flow Needed For Activation (gal/min):

0.25 SETS 220 (now have 240, not listed on website yet)
0.40 Envirotech ESI 2000 (from install manual)
?.?? Tankless Inc.
0.80 Powerstar AE125 (from install manual)
0.75 Eemax EX200T (20kW). Can't find specs for EX280.
?.?? Seisco
0.87 Stibel-Eltron DHCE-30 (manual)

 

[Brock]

Re: Removing a sweat fitting **Mission Complete**

I don't think there is any way around lights flickering or dimming with the size loads were talking about. Even a 400amp feed and two 200amp panels didn't stop it at my brothers. I am sure it was pulling down the transformer that fed his house and his two neighbors. We went out and looked at it, if I remember correctly it was something like 14kv to 240v rated at 800amps or maybe it was 600amps? Either way that is a huge load to flip on and off.

 

[turbodog]

Re: Removing a sweat fitting **Mission Complete**

Exactly right. Huge load to handle with residential specd equipment. I have spoken at length about most all these variables with the engineers at envirotech. With the new house I am building we decided to get creative a little.

The main hot water supply is a natural gas heater in the attic. It feeds tubs/showers/washers. The sinks are on a 2 different (short) loops with 2 9.6Kw envirotech models. This allows convenient quick hot water, but still keeps the efficiency of gas for the large water uses in the house.

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

[ QUOTE ]
Anonymous said:
I can't figure out, though, why in the world they put flow restrictors in the washer, it uses a fixed amount of water..

[/ QUOTE ]

My guess is that it isn't to do with the washer itself, but to prevent it from significaintly unbalancing the temperature of other appliances (shower comes to mind!). Basically to make it "play nice" with everything else.

-john

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

So I've re-read this entire thread, and looked at a lot of web sites and I'm less sure than ever (and I have to decide ASAP).

I just measured the cold tap and get 45F. This is in the burbs of Seattle in a not particuarly cold winter. I suspect it could get a bit colder than that.

I checked and it seems like I prefer about 110F normally, but I tend to turn up the heat part way through the shower as I aclimate. My wife also likes her water warmer than I so I suspect I need to plan for 115-120F output temp.

Sounds like about a 75F rise +/- a few degrees.

Looking at the Envirotech ESI 2000 4.12 (28.8kW) as a reference point it looks like they list 2.5 gal/min with a 78.46F rise. This sounds like it should be pretty optimal.

But a couple of things bug me.

1) I'm worried about the min flow. .4 gal/min sounds like a lot to me (and .75 or higher is just nuts). I'm probably not going to be real popular around here if I spend a boat load of money (service upgrade + heater + install) only to have our new water saving appliances fail to get any hot water (Duet washer, Bosch 9 series dishwasher). The SETS models indicates it only requires .25 gal/min which sounds much better, but how much can you really trust these specs? Also the largest SETS unit is 24kW, not 28.8kW like the Envirotech.

2) I really hate the idea of the lights dimming when the heater switches on. It's bad enough for this to happen to us, but I'd feel really silly if my hot water heater causes the lights to dim in the adjacent houses. The development we are in has transformers sprinkled throughout, so I suspect that each one doesn't have a lot of over capacity.

Hmm. Where does that leave me? Well, it did bring me back to gas powered units. The main reason I had ruled this out before was that I would need to relocate the heater to an outside wall (to vent), where it is in the center of the house right now. This would mean waiting longer for hot water at various locations. The master bath would probably be most affected.

But it's a thought. Maybe I put something like a Takagi TKD20 (.75 gal/min activation) in one of the downstairs closets and put a small SETS model 114 (14kW) unit in the center of the house.

That way the SETS catches the low flow rate use, and then the gas does all of the heavy lifting.

As far as I can tell, this would be pretty optimal with the main downside of restricted waterflow (per above posts). I wonder how much?

Maybe this is all a bust and I should just leave it the way it is.

Any thoughts?

Thanks,

-john

 

[Brock]

Re: Removing a sweat fitting **Mission Complete**

I can't remember what you currently have? If your thinking of upgrading to not run out of hot water, just add an electric pre-heater in front of your existing heater, or even another unit the same as you currently have. Then you don't need to worry about flow. The heater you have will work for low flow and if a shower is on the electric one will be on for sure and that should be enough to keep you in hot water for much longer.

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

I have a 50 gal electric conventional hot water heater. I'd like to:

1) Not run out of hot water.
2) Reclaim the space taken up from the heater. Our house is small and the hot water heater blocks the entrance to a otherwise usable closet.

If possible, I'd also like to save operating costs and have a no-spill failure mode.

-john

 

[jack32088]

Re: Removing a sweat fitting **Mission Complete**

Gas to the inside of the house is going to require that you learn all there is to know about building codes. (I recently replaced a leaking gas water heater.) Here in Northern Florida you now have to have a sealed combustion chamber, to prevent house air from mixing with combustion air. That required a vent being brought in from the attic to within a few inches of the false floor of the water heater closet, but I did get to reuse the chimney going out through the roof. I am pretty sure that the local codes require that the chimney not go "downhill."

 

[John N]

Re: Removing a sweat fitting **Mission Complete**

Due to a big goof up with our remodel, I'm going to end up spending a fair amount more for windows than planned. Since I don't really need to do the on demand heater and it was going to be fairly expensive, I'm going to put the on-demand heater on hold and reallocate that part of our budget to fixing our window goof. Maybe I'll try to do this later - hopefully with gas if we can swing it.

Thanks for all the help and info!

-john

 

[turbodog]

Re: Removing a sweat fitting **Mission Complete**

Ok, here is the advisor asking for advice.

As I have said earlier, I am building a house and am putting in some on-demand heaters. Deadline to moving in is drawing near, and I am having problem getting an envirotech heater in the right time frame (by like tuesday or so).

I need suggestions here. They will be 2 240v 40a units. Need to turn on at .5g/min or less flow. Digital temp reg desired. Need available ASAP. Will self install or have plumber do it.

Thanks.

 

[Brock]

Re: Removing a sweat fitting **Mission Complete**

Well after this last round I went and checked my unit and found I had lost 3 of the 5 elements in it, so it is out of line now. I went out and bought a 10gal 2000w heater. I put it in the same place the instant unit was (just in front of the 40gal gas heater). I am toying with the idea of swapping out the 120v 2kw element for a 240v 4.8kw element, but I am afraid it might boil the water? It can heat the water 100F in 40 min, and it raises the shower flow about 10F. I still think I might run out of water on those days where 6 people take showers one right after another and some at the same time, but the 4.8kw element might get me past that? Hummmmm...