1000 gal. water tank

Larry Weingarten

...taking combustion efficiency into account? That might have an effect :~)

Yours, Larry

Greg_25

1000 gal. Water tank

Here's the application.Customer has a 1000 gallon hot water storage tank thats used to mix fertilizer.It is currently being heated by an oil fired boiler(very old one) that has a large domestic coil in it(2" tappings).Want i want to do is use an oil fired water heater to recover the tank instead of a boiler.They would like to recover the tank in 2 hrs but 3hrs would be acceptable.Keep in mind they fill the 1000 gallon tank with 50 degree water,then heat it to 140 degrees,then drain the tank to mix fertilizer, then refill the tank with water.So there is no incoming water to temper the 140 degree when they are drawing.Sizing is my question.I can't use the man. literature on recovery because thats based on continuous draw , not recirculating water between the two tanks.So I am thinking 1000gal x 8.3lbs per gallon x 90 degree rise = 747,000 btu/hr or 373,500 for 2 hr recovery or 249,000 for 3 hr recovery. Is this correct?

Greg_25

I did'nt get that far yet, but yes i'll have to consider that. I'm just wondering if i'm on the right track or not ,and if i'm on the borderline between commercial & residential water heaters maybe i can talk them into a 4hr recovery time and go residential.Thanks for the heads up though!

Constantin

here are an additional $0.0002 of thoughts

The temperatures you're mentioning are pretty much ideal for a condensing boiler. Given where oil and gas prices are these days... perhaps a low-cost, modulating boiler like the Trinity 400 could serve to heat that tanks and some other zones, with the tanks getting priority. I wouldn't be surprised if the operational savings pay for the installation cost difference in a couple of years. On the downside, you need natural gas, not oil as intended.

Joe Brix

Continuous Running

Just filling the tank must take just over 2 hrs @ 8GPM flow. The Munchkin 399VWH has a listed 510 gal/hr at a 90° temp rise. But that's gas. Same with the Laars Reos. I've seen some comercial oil fired HW tanks that need almost 600K/BTU to generate 10gpm @ 100° rise.
For oil, I think you'd be better off with a boiler tied to a reverse indirect like a ErgoMax, TFI Everhot or Turbomax. They're designed to generate tons of hot water.

Ron Schroeder

Hi Greg,

Can the tank be filled from a heated hot water source or does it have to be filled and then heated?

How accurate does the temperature have to be?

Ron

Greg_25

Yes

.... the tank could be filled from a heated hot water source,it would just require some piping.Actually, right now,the water they fill the 1000 gallon tank with comes from another tank outside.So most of the time the water is probably warmer than 50 degrees coming in.( They just use this in the spring/summer months).But i want to size it for worst case.And as of yet, i don't do any gas work, just oil & A/C and I'm too busy to even think about doing gas, so I'm pretty much limited to oil equipment.I could heat the water before it goes into the tank(say overnite so i would'nt need alot of flow), but i would still need something to maintain the temp in the tank, being as it's a plain , uninsulated steel tank.And i think that some days they need 2 tank fulls in one day so i would'nt have all night to heat the 2nd batch.