System 2000 Water Storage Tank

rockwall

Can you anyone explain why System 2000 offers both a 40 and 80 gallon storage tank? Their marketing material says "Endless hot water" with reviews from people saying they take multiple showers while running the washing machine, etc - perhaps these claims are with the 80 gallon tank and not 40? But either way, help me understand when and why you would *need* an 80 gallon tank with the plate heat exchanger. The more technical info, the better! Thanks!

HVACNUT

First, a lot of homes need an 80 gallon tank. I was at a home yesterday commissioning 2 Bosch 399K boilers with three 119 gallon indirects.
If your asking about the EK Frontier, oil or gas, it's more typical for an 80 gallon tank to match the EK2, which is a larger boiler with a larger flat plate exchanger. The 80 gallon tank with the larger HX can be ordered with the EK1. It all depends on DHW use for that particular home.
The Energy Manager can make the water heater priority with a dip switch and it takes very little time to satisfy a cold tank.
EK makes a great heating system.
Have you looked at the Resolute?
90+% non condensing.

GBart

Water heaters are rated in first hour use and constant in GPH, a tech has to survey the home and find your usage in GPM and figure GPH and match the proper tank so you don't run out, bear in mind that for a given GPH the tank has to be supplied a certain BTU/HR from the boiler it's in the product data sheets.

A 40 might be 95GPH and a 80 might be 200GPH for example.

rockwall

Thanks for the replies, @HVACNUT and @GBart!

1) It's an EK1 (I only have oil) - we have 4 bathrooms, but only 3 people live in the house. Our worst case scenario (which has never happened, but I want to be prepared) would be 3 showers at once (worst case, let's say 15 minute showers at 2GPM flow) with a dishwasher and washing machine going. This calculates to approx. 100 gallons in 15 minutes.

Although I guess we also need to also consider demand for hot water for my heating system, but I'm not sure how to calculate the demand for that?

2) I'm confused about the GPH production rating on the System 2000 brochure. I hope you can clarify this for me...

The brochure says an EK1 with a 40 gallon storage tank can provide 202 first hour gallons. Since I need 100 gallons of hot water (and again, probably more with heat) in 15 minutes, would a 40 gallon tank be OK for me? My installer is recommending an 80 gallon tank, but I can't wrap my head around *why*. It seems like a lot of extra hot water "sitting there for nothing". But so far he's been very helpful and I trust him, but I want to VERIFY.

Since it's called "first hour rating", can I truly get 202 whenever I want? Or does it need to be spread out over 60 minutes? Meaning in 15 minutes, it would only deliver 50.5 gallons (which obviously isn't enough)?

Last question - to me, a "maximum gallons per minute" rating would be better to calculate my situation, but is this something I can get by simply dividing the GPH by 60?

Thanks in advance!

HVACNUT

If you had a jacuzzi tub I'd recommend the 80 gallon tank.
I've never had a call for insufficient hot water with a family of 3 and the 40 gallon tank unless it was a mechanical problem.

rockwall

@HVACNUT Thanks. Can you educate/clarify how the demand works with GPH and such? If it's as simple as 40 is OK for situation, then I won't waste the $$ on the 80. Thanks.

HVACNUT

I think @Roger can give you all the clarification you need. He's the owner and designer of the EK boilers and is frequently on this site. Maybe shoot him a PM.

Jim Hankinson

The 80 gallon tank would be recommended if there is a large Jacuzzi. The draw to fill it would be more than the 2.5 GPM capacity of the plate exchanger. With an EK-1, the 80 will supply up to a 120 gallon tub. If the boiler is primarily used for heat then size it to the heat loss.

Increasing to a larger plate exchanger will not increase the output rating to any extent so it's not worth the extra bucks.

First hour draw is based on the recovery rate at maximum firing rate, plus the tank capacity.

rockwall

I don't have a Jacuzzi tub - only 4 bathrooms but one of the showers (our master does have multiple heads, however I never use all of them at once. Usually just 2 heads (regular and rain shower).

I just want to make sure I have enough hot water for heat and up to 3 15 minute simultaneous showers.

In summary, I want a EK-1 with plate heat exchanger and either 40 or 80 gallon storage tank. It's to be used to heat and hot water, 4 bathrooms, with max 3 showers being used at once.

I'd love to hear from @Roger and get an education on all of this. I have been thoroughly impressed by the support and response of Energy Kinetics representatives so far and I am definitely sold on an EK-1, but I just can't seem to get my head around the water storage and demands. The advice I got was "get the 80 to be safe". but I feel like this is oversized and just hedging bets to make sure I don't run out of hot water. I want an actual, true, mathematical answer. :Thanks, all!

GBart

The thing with large usage is also will your pipes handle it? You can only get so much water through pipes so if you are in the shower and someone does laundry and the dishwasher you may have a drop in pressure.

Average shower is 2.5gpm, so figure how long like 10 min is 25 gal, if you have 4 showers and everyone is getting ready in the am you need to add them all up, then you know gph, EK has sizing charts for their equipment too.

STEVEusaPA

P

rockwall said:

...I'd love to hear from @Roger...

@Jim Hankinson is an EK guy too

szwedj

EK1 with a 40 gal tank is rated at 228 gals first hour draw. 228 gal – 40 gal storage = 188 gal/hr. recovery which is equal to a little over 3gpm.

Think of it like this, with your 3 showers at 2gpm each, equals 6gpm for 15 minutes, which equals 90 gals of hot water used during the 15 minute showers. With a 40gal tank you have 40gals of stored hot water available. So at that combined 6gpm shower use, that tank only lasted a little longer than the first 6-1/2 minutes. The boiler needs to supply the additional 50 gals needed (90gal total – 40 storage). At the 3gpm recovery, it will take almost 17 minutes to produce the 50 gals needed.

Remember this is just for the 3 showers, not the possible load of dishes of clothes washed. Now with the 80 gal storage tank the boiler only needs to recover 10 gallons of the 90 gallons used for the showers which it can do in a little over 3 minutes leaving plenty of recovery capacity for the load of dishes and clothing.

And remember, it really doesn't cost you more in fuel for that 80gal tank because the boiler will only run to recover what has been used. A tank of unused hot water will sit for days be before cooling down enough to call for heat.

Realistically, the 40 gal tank would most likely be fine under normal use, but if you want to be covered for what you have defined as your worst scenario, the 80gal tank is the better choice.

Joe

rockwall

@szwedj Thank you very much for your explanation. It was quite helpful and it makes sense to me. The main thing for me is that I didn't want to waste oil/energy storing an additional 40 gallons that we will hardly use.

You've clarified this for me and explained how it's not much more oil used. The 40 gallon is probably fine for 90% of my usage. Since the price difference in the tank isn't too much and knowing that oil consumption will barely increase, it seems like relatively cheap insurance to get the 80 (and truly never run out of hot water.) Thanks again!

Roger

Thank you @rockwall for your questions, and everyone for your prompt and helpful replies!

I'm glad your questions were all answered to your satisfaction. One other thing you may wish to test is your multiple shower head flow. You can time filling a 5 gallon pail and calculate your flow rate per minute to make sure the system design is adequate.

Another rare consideration is that if your city water or well pump can flow over 5 or 6 GPM through the tank (multiple fixtures running simultaneously), the cold make-up water may "jet" into the bottom 3/4" tank fitting and tumble the water, potentially producing uneven hot water supply temperature. It is very rare to see this happen, but a commercial tank with larger tappings could be used to reduce this possibility; these tanks are usually 119 gallons and substantially more expensive, though.

For reference, @Jim Hankinson and @jszwed both work with me at Energy Kinetics.

Best,
Roger

GBart

Yeah the 5 gallon bucket test is great, you just measure the height and cut that measurement in half and mark the bucket at that height and that's 2.5 gallons.

I remember some city water jobs that were flowing so much water they still ran out, some are way over 100psi, all should have pressure regulators and dirt/rust filters IMHO.

Another issue with city water is temperature fluctuation, in the summer it's as warm as the air temp and same for winter so you can lose recovery rate. I've measured 15-20F water coming into peoples homes in the winter.

GBart

So you can put a 5 gal bucket under a shower etc with the halfway marked and run it for 1 minute and you know your GPM from that device, X 60 = GPH.

rockwall

@Roger - Thank you for your response. I've been lurking on the forums and I'm always so impressed when I see you replying to customers. It let me know I made the right choice and I'm very happy to support your company! Thanks for the bucket tip. I will try this and see how it works out. I'm leaning towards the 80 since it seems like the added annual oil costs are incredibly low and the only real cost concern is the cost difference between the 40 and 80 gallon tank. And thanks for the heads up about the (rare) situation of jetting. I love learning little tidbits like this, especially from experienced people like you! Thanks again!

@GBart - Thanks for your continued replies as well, I appreciate your help!

Roger

Thank you for such kind comments and for your support, @rockwall - it's my pleasure to help out where I can. I'm sure you'll be very happy with your Energy Kinetics heating system!
Best,
Roger

rockwall

A quick update: I did the bucket test and with 2 heads running in my master shower alone, it took about 1 minute 15 seconds to fill the 5 gallon bucket. Figuring half for hot water, that's 2 minutes and 30 seconds for 5 gallons of hot water, or 2.5 gallons every 1 minute 15 seconds.

If I were to add another shower plus a dishwasher and washing machine, it seems like I should go with the 80 gallon to be sure. Thanks for all of the input, everyone - I learned a lot and I appreciate the education!

GBart

You're welcome.