Replacing Hot Water Storage Tank with Hot Water Heater - System 2000

beyondvoid

I have an EK1 System 2000 (oil) which includes a 40 gallon storage tank, the water is heated through a heat exchanger. The tank leaked out yesterday and I am looking to replace it. I am considering purchasing a standard 50 gallon electric or gas hot water heater and using it as a replacement storage tank (i.e, unpowered and not hooked up to electric or gas).

The current storage tank (model # 0823145) has two thermostat wires that come through the top and connect to the boiler for temperature control.

My question is, is there any reason I shouldn't be able to just tap off of the thermostat input in a new hot water heater and run this to the boiler? A search on the internet implies that people have used hot water heaters as storage tanks, but I want to make sure this sounds doable before doing the work!

And yes, I will also be looking into a direct replacement for the tank, but I suspect it will be triple the price so I want to weigh my options.

Any help is greatly appreciated!

psb75

To be clear: what was the original purpose of the tank that went bad? And then what purpose would you like the new tank to perform? You are calling the old tank a "storage" tank. Do you mean that it was a buffer tank--storing heat for the house? Or was it a domestic hot water indirect tank? If you are looking for a "buffer" tank you could do what you are planning.

beyondvoid

Thanks for the reply. I'm not exactly sure how to answer that, but I think a buffer tank is correct. The boiler heats the water in the tank indirectly through a heat exchanger. Water comes into and out of the the tank via a tee at the drain pipe & inlet at the top, circulated heated through an external heat exchanger and returned to the tank. Here's the overview of the system:

https://energykinetics.com/system2000-quietest-most-efficient-boiler/

My biggest concern is that the thermostat wires are accessible on a hot water heater unit (I've never had a traditional hot water heater) but from what I've looked at online, it should be.

SuperTech

@psb75, the original poster was using the correct terminology.  The Energy Kinetics system 2000 uses a brazed plate heat exchanger and a bronze circulator to make and store domestic hot water.  The tanks EK uses are just repurposed electric hot water heater tanks without the elements.  Chances are that the tank failed due to lack of maintenance such as anode rod replacement, or perhaps just age and wear. 

@beyondvoid, I'm pretty sure that EK offers a replacement tank that comes with a ten year warranty.  Thats much better than what you would get from buying an electric water heater,  modifying it and then using it for something other than the manufacturers intended purpose. I think the manufacturers tend to void warranties when products are not used as intended.  

Roger

Thank you for your question @beyondvoid and for everyone’s posts. 

Energy Kinetics’ tanks are specially engineered and optimized to take advantage of thermal purge with the plate heat exchanger. That arrangement can save up to 10% off an annual fuel bill vs a conventional indirect water tank with coil as the boiler can thermal purge and recover the heat left in the boiler; coil type tanks can’t because coil is hot in the middle of the tank. 

Energy Kinetics’ tanks include a special dip tube plus a thermostat that is higher up in the tank than the lower thermostat location on typical electric tanks. We do offer electric tank conversion kits with instructions.

For reference, we will not void your boiler warranty if you are not using and Energy Kinetics tank. Also, tank manufactures have indicated that tanks will last a much longer time or even indefinitely if the anode rods are replaced and there are no site specific problems. 

Best,
Roger 

archibald tuttle

@Roger it looks like you are saying that OP's tank had a sacrificial anode that could have been replaced (i'm assming it was your tank although i'm not schooled on your model #s).

And on the system theory, there is a circulator for the domestic tank that pulls cold water from the bottom if the thank and returns heated water to the top of the tank to help purge heat from the boiler after cycle?

One question I have is, if using hot water doesn't the tank thermostat force the boiler to run until the temp is satisfied, or maybe if the thermostat is located in the top of the tank there remains some cool water in the bottom to accept purge heat even thought the thermostat is satisfied?

Roger

Thank you, @archibald tuttle.  

The tanks do have a sacrificial anode rod, although like all tanks with replaceable anode rods they are tightly installed and not easy to remove and replace.

The circulator arrangement heats the tank “from the top down”.  The location of the aquastat in the tank creates a reservoir of cold water at the bottom, which is nearly perfectly balanced with the amount of heat left in the boiler.  This results in a very effective thermal purge, without any complex controls.  The entire tank finishes hot and the boiler finishes cold. This virtually eliminates both off cycle losses and oversizing losses.

Drawing the cold water off the bottom of the tank and heating it through the heat exchanger and pumping it into the special dip tube at the top of the tank allows for a very fast recovery.  The heated water is right where it’s drawn from to feed the fixtures for very good and responsive hot water temperature quality as well.

Tanks with coils become less productive as the tank heats because the temperature difference continually decreases. The heat exchanger arrangement allows the full output of the boiler to heat the tank through nearly the entire cycle.

Roger

 

archibald tuttle

@Roger thanks for your reply. you can be my heating valentine for being the CEO that responds on sunday. my wife is already no doubt upset that i spend this sunday thinking about abstract problems in the warming of civilization. back to the homefront momentarily but more questions.

I would think that the cold reservoir and purge has got to relate a little to duty cycle and cycle length which i'm sure are contemplated in the control algorithms although i would imagine that at cold times with limited DHW use maybe the purge recovery is not as complete, which is no criticism of the approach. I like the approach. I built a purge recovery to my warm floor flywheel heat exchanger tank (my warm floors are all polybutyl so i separate the hydronic circuits.)

but i do hope to remedy my lack of awareness of your boiler product. i admit, i'm intrigued. it looks like you obtain low stack temperatures by the long spiral dwell of the combustion stream. I can't really tell from the pictures if the spiral is constructed from water tube heat exchangers although it sounds like it would be a medium without the thin gaps of something like the munchkin style water tube where the exhaust goes through the small gap between water tubes.

it seems the combustion chamber is removable. what about the combustion spiral. the thing that bugs me about the munchkin is you have to dismember the gas and unpipe it in order to get the spiral out of the boiler so most often it is cleaned in place with the 'credit card' method which is effective but drops any scale into the 'sump' where it is almost impossible to clean out well with the drain located in the middle bottom of the unit. i have installed them up on blocks with some access to remove the condensate drain so they can be rinse out or the small drain hole cleared, but I would much prefer a design where the heat exchanger has unions and can be easily removed. Especially where this looks to be a tri-fuel approach, I would be hoping for detachable cleaning so I could take the combustion spiral outside and spray it off with a pressure washer (and easily replace if it fail, which again is intended as a reflection on your product comparatively but just an understanding of the generally lower mass heat exchangers in modern boilers.

I wish I had just been able to go the AHR show and see one for myself if there were such a thing as the AHR show. Do you have a dealer network that has stationary or mobil version I can take a look at in southern new england.

thanks,

brian (archibald tuttle to his 'friends', see the robert deniro character in Brazil)

Roger

Thank you, @archibald tuttle - I enjoy answering questions and helping out where I can. 

Our spiral boilers have wide open flue passes and wide-open water passes and they are very easy to clean, there are no micro flue passes or micro water passes found on most condensing boilers.  Our EK1 size cross section looks like a rectangular pipe; it’s the equivalent of a 2 1/2 inch pipe on some models and a 4 inch pipe on other models. So there’s very little restriction on hydronic side.

The flue side is also wide open, with the smallest cross-section around 1” x 11” - you could literally throw marbles in it and pick them out as they roll to the bottom. Ceramic chambers are not to be removed for cleaning (there’s no need), however the stainless steel chamber can be removed on the models that have them. 

Today’s oilheat and bio fuels have ultra low sulfur, so they burn as cleanly as gas and ash buildup and cleaning have been virtually eliminated.

We follow a similar strategy on our condensing boiler, the Accel CS - we eliminated issues we found on nearly all other contending boilers. That is a fire tube design, with three-quarter inch fire tubes and “super turbulators” for easy access and cleaning if ever necessary. The waterside has wide-open passes as well, with the smallest restriction being the equivalent of a 1 inch pipe cross section.

We have videos on our website where you can see some of these details, although we also have a fleet of live fire demo vans and trailers so you can see the equipment in the field in New England and mid Atlantic states. Contact us or PM me and we can get you in touch with our local territory manager. 

Best,
Roger 

vincem14

jumping on this old post as I am faced with the same scenario. I would like to instal an electric water heater leaving the elements in and then using the electric during the summer months and shut the boiler down for the summer vs running it all off season.

pecmsg

vincem14 said:

jumping on this old post as I have am faced with the same scenario. I would like to instal an electric water heater leaving the elements in and then using the electric during the summer months and shut the boiler down for the summer vs running it all off season.

Look for Heat Pump Water Heaters!

vincem14

That’s an option too, just a pricey one! Either way I want to setup a system so I’m not burning oil year round at $5/gallon!! 

Larry Weingarten

Hi @vincem14 , About the price, have a look at https://www.dsireusa.org/ and see if there are some rebates that might help bring the cost down.

Yours, Larry

HVACNUT

Do you also have an EK?

vincem14

Yes I have the same EK system as original post describes. I was quoted $ to swap the water tank out. Seems crazy for a $ 40 gallon water heater.

Roger

Sorry I’m a bit late on this one, @vincem14 and all. 

Electricity prices per unit of energy should be considered; The Energy Information Administration shows $.27 per kilowatt hour for residential electricity in New England in September 2022. This is equivalent of over $11 per gallon of oil, so converting to an electric tank would cost over twice as much as $5 per gallon oil. That also means that most heat pump water heaters would be more expensive to operate than oil during the summer with those costs. 
Best,
Roger

archibald tuttle

@Roger you are right about electricity costs vs. oil costs although you have to apply some efficiency factor to the oil and I think your calculation is straight btu to kwh conversion. it seems that in making domestic hot water you might have it worked out to get up into the 90s of efficiency but unless you got a trick for heating, most baseboard operations aren't going to condense so maybe 85% is right?

Still makes $4 oil look like the way to go if that is what you have access to. is the plate heat exchanger for domestic in the flu path or in the boiler water side?

So you gonna be in atlanta? i'd like to get a look at this thing . . .

brian

Roger

Thank you, @archibald tuttle . Tank type electric water heaters have a UEF of around .93 (they're not 100% efficient), so taking high efficiency hot water system efficiency in comparison still yields close to electricity costing about twice as much with the figures noted.
The plate heat exchanger is in the boiler water side, and we have ones optimized for condensing boiler operation, and for chimney vented boiler operation.
Sorry, we won't have a booth in Atlanta next year.
Best,
Roger

dbloemker

Similar to Vincem14 I want to go electric for my dhw as I have solar panels that will easily power the water heater and other power needs (on grid energy credits for the winter months). Planning on installing an energy kinetics system this year and am wondering the best route to go. We don't use a ton of hot water, base board hydronic, 1300 sq' of living space plus an attached garage of 600 sq'. Oil is the fuel of choice here in interior Alaska. Will be replacing a 2005 burnham V74 boiler with an indirect tank.

Roger

Thank you for your question, @dbloemker .
Here are a couple of thoughts to make a more informed decision on “excess solar PV for hot water”.
For an active household, Energy Kinetics systems with thermal purge typically use about 10 gallons of oil per month for domestic hot water in the non-heating season. Since the tanks are super insulated, that figure is nearly proportionately lower for lower usage, and extremely low in standby with no hot water use.
If the photovoltaic system has reasonable net metering rules, it is likely more cost effective to sell the power back to the utility. As mentioned above, $0.27/kWh is over $11/gallon for oil. “Reasonable” means that you are not credited back at a much lower wholesale rate, and that the utility does not charge you for overloading the grid with excess PV power. This means that net costs will likely be lower using oil and selling the power back to the utility.
If using “excess photovoltaic power” is still desired, you have to make sure it will only heat the tank when excess power is available – not when power is needed for other household needs, and not at night or when the sun is not shining as you do not want to use electricity supplied at residential grid prices. There are inverters with dump zone capabilities to ensure power is used where needed first and the tank is only heated when excess power is available, but these are not necessarily standard features on grid-tied systems and could require specialized equipment and potentially significant additional setup and costs. This feature may only be available on “off grid” type inverters/chargers, and it wouldn’t work out of the box.
If, knowing all of these considerations, it is still desirable, we might recommend a 120 gallon tank with the boiler heating water based on a thermostat at the top element location (in case electricity can’t keep up; this may heat the equivalent of a 40 gallon tank vs the whole 120 gallons). Then have the dump zone electric heat based on the bottom thermostat/element (which will gravity heat to the top to prevent the boiler thermostat from calling).
I'm sure there are additional considerations as well, but this should help you figure out what you want to do.
Best,
Roger

hot_rod

This is a clever control that watches for excess PV, uses it to heat a tank of water instead of giving it back to the utility at low $$
So a preheat tank upstream of your DHW tank or DHW source.
Or to supplement a hydronic load. 

Not available in the US unfortunately, developed by a German company when their Utilities started rolling back the FITs


we worked with Resol to build the Caleffi I Solar controls, a small family owned company.

https://www.resol.de/en/produktdetail/210

archibald tuttle

@Roger well, that begs the question of whether there is such a thing as 'reasonable' net metering in which the grid serves as the battery/backup for the homeowner at no charge.

the subsidies in these markets whether for condensing boilers, heat pumps, solar are incredibly dislocating.

But, you raise the very reason that there is no American version of the control @hot_rod mentions. Because if the grid gives you the power back whenever you need it at a more or less even trade, you have zero incentive for storage schemes.

That said, it is an interesting question if this would be notably more cost effective than a battery. To the extent that it takes advantage of existing infrastructure, e.g. DHW storage tank or existing heating flywheel tank, I would think the answer is probably yes.

@hot_rod Will resol folks be with you in atlanta?

Roger

Everything is notably more cost effective than today's battery technology.
A Tesla Powerwall is currently listed for $11,500 and stores 13.5kW (90% useful), which is the equivalent of 41,500 BTUs. That stores the equivalent of 30% of a gallon of oil, and at $5/gallon, that would be $1.50 worth of energy.
Of interest, cold climate heat pumps serving a home with 7 kW peak load during winter weather (23,884 BTU/hr x heat pump COP) would require as much as 500kW capacity to cover a 3 day period without power. If utility-scale battery storage were to cost $200 per kWh (Tesla is $946/useful kWh above), the cost of storage would be approximately $100,000 for that home.

hot_rod

archibald tuttle said:

@Roger well, that begs the question of whether there is such a thing as 'reasonable' net metering in which the grid serves as the battery/backup for the homeowner at no charge.

the subsidies in these markets whether for condensing boilers, heat pumps, solar are incredibly dislocating.

But, you raise the very reason that there is no American version of the control @hot_rod mentions. Because if the grid gives you the power back whenever you need it at a more or less even trade, you have zero incentive for storage schemes.

That said, it is an interesting question if this would be notably more cost effective than a battery. To the extent that it takes advantage of existing infrastructure, e.g. DHW storage tank or existing heating flywheel tank, I would think the answer is probably yes.

@hot_rod Will resol folks be with you in atlanta?

I doubt they will be at AHR. Probably at ISH in March, if you are headed to 🇩🇪