newbie questions

[kgryder]

Hello everyone, I just found this forum. lots of good info. I am making plans to install a boiler and I would like to get some feedback on some thoughts I haven't seen discussed in the forum.

1. Concerning water storage tanks.I had in mind to divide the water between two tanks. My thought was that I would heat one first then the other. Seems to me that having 500 gallons of water at 180 deg and a 2nd tank at 80 degs would be more usable than 1000 gallons at 130 degs. Any thoughts?

2. Everything I have seen for an open tank system has a boiler loop that is heating the tank with some type of heat exchanger. Has anyone ever just had a completely open system where the boiler just dumps into the tank? I'm sure that additives would be needed to reduce corrosion but it would simplify the system.

3. I have found a number of nice (but expensive) SS tanks online that have the lower half jacketed. Think a tank of this type would transfer enough heat to the jacket to the be usable for DHW?

4. On a pressurized system with a large tank, instead of an expansion tank couldn't I just come up with a way of keeping adequate head space in the tank?

5. On the STSS tanks is the EPDM liner formed to the shape of the tank or is it just a sheet of material that is bunched up on the side walls?

Thanks for the response.

 

[Nofossil]

Hello everyone, I just found this forum. lots of good info. I am making plans to install a boiler and I would like to get some feedback on some thoughts I haven't seen discussed in the forum.

1. Concerning water storage tanks.I had in mind to divide the water between two tanks. My thought was that I would heat one first then the other. Seems to me that having 500 gallons of water at 180 deg and a 2nd tank at 80 degs would be more usable than 1000 gallons at 130 degs. Any thoughts?

2. Everything I have seen for an open tank system has a boiler loop that is heating the tank with some type of heat exchanger. Has anyone ever just had a completely open system where the boiler just dumps into the tank? I'm sure that additives would be needed to reduce corrosion but it would simplify the system.

3. I have found a number of nice (but expensive) SS tanks online that have the lower half jacketed. Think a tank of this type would transfer enough heat to the jacket to the be usable for DHW?

4. On a pressurized system with a large tank, instead of an expansion tank couldn't I just come up with a way of keeping adequate head space in the tank?

5. On the STSS tanks is the EPDM liner formed to the shape of the tank or is it just a sheet of material that is bunched up on the side walls?

Thanks for the response.

Welcome to the forum.

Two tanks would be desirable for exactly the reason that you mention, although it's possible to get really good stratification in a single tank if you're clever about it. I wouldn't fill them alternately - I'd plumb them in series.

I'm not convinced that the headaches and risk of increased corrosion don't outweigh any possible advantage of an open storage system.

I haven't seen any data on transferring heat for DHW through the sides of a tank.

I can't think of any serious reason other than corrosion why airspace in a pressurized tank couldn't be used for expansion.

I've never seen an STSS tank up close, but there are folks here who have.

 

[WoodNotOil]

Those of us constructing lined tanks ourselves are using single sheets of epdm and folding in at the corners, not sure about the STSS ones you buy. I agree with nofossil on the other questions.

 

[maurice]

Hello everyone, I just found this forum...

3. I have found a number of nice (but expensive) SS tanks online that have the lower half jacketed. Think a tank of this type would transfer enough heat to the jacket to the be usable for DHW?

...Thanks for the response.

When I read this, I immediately thought of a design I saw in my job of repairing commercial kitchen equipment. There is a brand of coffee urn that is about 2' x 4' x 4' tall. It has two huge coffee brew pots and a hot water spigot. Everything inside of the outer jacket is filled with 190* hot water, electric elements in the bottom, the brew pots set IN the hot water, and a loop of plumbing in the hot water to supply the hot water spigot, and the tank of hot water is used to brew the coffee. Ok, so to make a short story long... You COULD put a tank (or loop) IN the bigger tank for DHW, but be cautioned that you might get DHW that is too hot unless you use a tempering valve?

 

[pybyr]

on how the liner on the STSS is folded, I saw one of these set-up at Tarm USA; there are a large number of small folds at even spacing around the perimeter, starting narrow at the bottom of the tank and getting bigger as they go up

on pressurized vs unpressurized, though at earlier points I was leaning towards pressurized (advantage that you can skip heat exchangers) the absence of readily available and reasonably priced pressure-capable tanks that I can actually get into my cellar via bulkhead hatch has me now leaning back towards unpressurized. And I think WoodNotOil's concept of using a plate heat exchanger with 2 pumps to push in either direction is an ingenious and intriguing alternative to huge/expensive copper coil heat exchangers

 

[jebatty]

2. Everything I have seen for an open tank system has a boiler loop that is heating the tank with some type of heat exchanger. Has anyone ever just had a completely open system where the boiler just dumps into the tank? I’m sure that additives would be needed to reduce corrosion but it would simplify the system.

This would work only if the boiler is not pressurized and/or the tank is located at an elevation above the boiler to maintain the pressure needed to move the hot water to the highest elevation in the system. If this isn't the case, then the system will be pumping water upstream rather than circulating water. Not an expert here, but different plumbing considerations.

4. On a pressurized system with a large tank, instead of an expansion tank couldn’t I just come up with a way of keeping adequate head space in the tank?

Nothing wrong with if allowance is made for expansion tank air to be dissolved into the system. Will need to adjust water/air volume from time to time. As this is done also will need to monitor system pH and O2 scavenger concentrations.

 

[kgryder]

Thanks for your thoughts. I'm designing my plumbing system now. Lots of decisions to make.

 

[WoodNotOil]

And I think WoodNotOil's concept of using a plate heat exchanger with 2 pumps to push in either direction is an ingenious and intriguing alternative to huge/expensive copper coil heat exchangers

Thanks for the compliment. However, to give credit where it is due, that idea was a culmination of many discussions on this forum and input from many people. It was originally going to involve two zone valves as well, until we realized the amount of head pressure it was going to create in comparison with simply pumping through the idle pump. Then the confirmation from Taco that this was okay to do to a pump made it a golden idea. I hope it works as intended and saves me and others alot of money by not having to buy all that copper!

 

[Willman]

I hope it works as intended and saves me and others alot of money by not having to buy all that copper!

Keep us posted on the setup. Maybe a pic or two.


Will

 

[MaineMike100]

Do you have a link to a thread with a diagram of the plate heat exchanger setup instead of coils for non-pressurized storage. Getting ready to plan a system now and sounds like an option I would consider. I had always assumed I would need to use copper coils submerged in the storage tank.

 

[WoodNotOil]

The web site I list in my signature is where I keep all of the information on my storage tank project. I consolidated it there so that others could benefit from it in their own designs. Mine should be functional within a week!