New system, new heat storage tank

[dmac]

Hi folks,
This is the first time I have ever participated in an online forum so please bear with me if I screw something up.
I am building a new home and garage in Northern Ontario Canada on the northern side of Lake Huron.
I am planning to buy an EKO 40 or 60 and a backup oil boiler from Cozy Heat along with all the equipment necessary to heat the slab floors and DHW.
I have purchased a 1200 gallon fiberglass tank for my hot water storage system.
I plan to spray foam it (2 to 3 inches) and then bury it behind the garage (the boiler is in the garage as well).
I then plan to transfer excess heat from the boiler to the tank through a heat exchanger.
The tank will be a closed loop system.
When I need the heat from the tank I will reverse the flow and run the tank temperature down to a set point and then go to the boiler for heat.
Has anyone done something like this and would you help me with the layout and design of the control system?
thanks
Dean

 

[Nofossil]

Hi folks,
This is the first time I have ever participated in an online forum so please bear with me if I screw something up.
I am building a new home and garage in Northern Ontario Canada on the northern side of Lake Huron.
I am planning to buy an EKO 40 or 60 and a backup oil boiler from Cozy Heat along with all the equipment necessary to heat the slab floors and DHW.
I have purchased a 1200 gallon fiberglass tank for my hot water storage system.
I plan to spray foam it (2 to 3 inches) and then bury it behind the garage (the boiler is in the garage as well).
I then plan to transfer excess heat from the boiler to the tank through a heat exchanger.
The tank will be a closed loop system.
When I need the heat from the tank I will reverse the flow and run the tank temperature down to a set point and then go to the boiler for heat.
Has anyone done something like this and would you help me with the layout and design of the control system?
thanks
Dean

Welcome to the forum and to the boiler room, Dean. You'll find lots of discussions and schematics - start with the stickies at the top of the page.

I'd consider a LOT more than 3" of insulation unless you really like heating the ground.

 

[dmac]

Thanks nofossil ... I just found them and yours in particular is very helpful. What insulation type and thickness would you suggest?

 

[Willman]

I have purchased a 1200 gallon fiberglass tank for my hot water storage system.

Is this tank pressure and temperature rated up to your design temp ?
If you don't know I would make it a point to find out.
Will

 

[jebatty]

Assuming that you researched first, but only certain types of fiberglass construction can take the high heat of storage, and I found those to be expensive. Ordinary fiberglass will soften and fail at hot water storage temps. If my recollection is correct, you want an FRP (fiberglass reinforced plastic) type of tank.

 

[Justburnit]

I have a large inground storage tank with 6" under it and 7 to 12" of insulation all around and above. I would not want any less than that. My insulation is primarily blue foam planks.

 

[kabbott]

My tank has 4" polyiso foam on bottom and top, 1" foam + 9" fiberglass on all sides.
Heat loss is ~5-6 degrees a day when idle(some of this is due to a thermosiphoning problem that I have yet to tackle)
My tank is in the basement so this is not a big deal as the basement needs heat and is not overly warm.
If it was outside this would be tens of thousands of btu's lost(~ 13000 lbs water) so I would second the "At LEAST 6" of foam", and I think 8" would be a
reasonable minimum.

 

[Nofossil]

Most folks would consider 6" of insulation to be a reasonable minimum for a house wall that sees an 80 degree difference between inside and outside. Your storage tanks will see a 180 degree difference, so I'd think that 12" on the sides and 24" on the top would not be excessive.

 

[trehugr]

My 500 gallon pressure tank is boxed in and surrounded by very densely packed cellulose (blown in) about 12" on top, 8" on sides and ends. There is also 2" foam over the entire top and 1" foam on sides and ends. It holds heat better than I expected. You can't have too much insulation, wait let me say that again, there is no such thing as too much insulation !