smart 30 as buffer tank

keyote

I found a new unused smart 50 on craigs list for a couple hundred and from another post a TT110 with a smart 30 I decided to use the smart 50 for DHW but the heating is only 52 kbtu and i have 16 loops each with actuator so i started thinking maybe a buffer tank would be a good idea and since i have ths smart 30 basically free doing nothing also eventually I would like to add some solar which i think a buffer would help simplify. So this tank would would not be for potable at all but i guess the question is would it flow equally well through inner and out tanks and which would be best way to utilize its ports, if its not an ideal buffer tank how far off from ideal is it? thanks

keyote

Now im thinking the ports on the 30 are too small huh 3/4 on the top and 1 for indirect
BTW one reason i decided against using this tank was it had crud visible when i removed old fittings made me think maybe it and boiler could use a cleaning is there a way to do that.

Paul S_3

i guess it could work....its definitely not ideal....i wouldnt do it....you also wouldnt get good stratification in the tank because of the top and botton connections would mix the tank water too much....if you really want to get the most from a buffer use the 2 pipe method like in the pic below minus the pellet boiler....also the ports are very small

keyote

the smart is an inner SS potable and outer steel spiral shaped tank as i understand it no inner coil. Your suggesting dont bother with the smaller ports on the domestic tank at all , your diagram shows a third inport smart doesnt have but i would ignore that just use the two boiler inputs i suppose there would be a check valve to keep unintended flow through boiler. I see the tempering valves because the radiant is 124 degrees max. could you elaborate a bit on why you dont like the idea i assume its a flow issue

keyote

https://blog.heatspring.com/2-pipe-versus-4-pipe-buffer-tank-configurations/

reading siggys article on two pipe vs 4 pipe buffers Im not sure it would apply to a tank built like the smart since it would not actually be pulling directly from the tank as much as the out tank [coil]
I did have a crazy idea im too stupid to really critique but i thought what if one say piped from boiler into smart as usual but out to zone from the boiler return port then return from zones to inner tank then return to boiler from inner tank this way the fluid makes the entire trip eventually but im not sure if you stioll get separation and the different flow requirements of the boiler and zones would require some sort of valve ill call a pressure differential /temperature valve .
I think this boiler buddy is ideal but expensive would plastic work its only 19 psi

hot_rod

Or connect the inner and outer in series, use the entire volume of the tank(s) The both will run at low, system pressure.

The 3/4 port will just cost a little pressure drop, like an 80% ball valve, not a big deal if you increase with a bell reducer at that connection.

Probably the least expensive way to get buffer is an electric water heater. Use the 1" element holes.

But you already have a tank.

hot_rod

Or this? The drawing above uses the fossil boiler to just heat the very upper tank, you want your boiler to see all the tank volume.

Gordy

The whole idea of buffering is to create a load that the boiler can feed for a sustained period of time with out cycling.

Then the buffer can feed the micro loads for zones that are sub low end modulation. I would pipe in series as hot rod suggests. Use the full capacity of the inner, and outer tanks may as well use it all. I'm not a fan of using zones sub low end modulation any way. However since the TT boiler is temporary as I understand it, and the buffer is a mute cost then use them.

However I would seriously look at some mod/cons that have 10:1 turndown with a low low end modulation that fits your micro zones. Like the uft by htp, and the Lochinvar KHN. When it comes time to actually size a boiler to your load.

Your issue I see with your dwelling may be your DHW load will be more than your CH load. So size accordingly.

keyote

Thanks guys
Hattersguy I wasn't going to use only the outer tank i simply meant i wasnt going to use it for hot domestic water.

So hot rod I think you are suggesting an improvement on my crazy idea of running through the inner and outer tanks but youre doing it in a balanced way into both simultaneously then out of booth simultaneously which would eliminate the flow and temp dif problems i mentioned. and spread the smaller port issue to both supply and return and it even eliminates the question of is the heat transferring well between tanks Brilliant.
So Hot Rod are you the same Hot Rod that does the Caleffi videos?

Gordy yes I picked this boiler up cheap i had intended to go with a new version but found this then found my heat loss to be less than i expected so i haven't forgotten your suggestion about these 10-1 mods alsi i see TT came out with smaller models. it might just be fortuitous that Ill get to actually see real operation.life before investing the big bucks.

As you know this idea of running so many pumps when only one loop or a couple loops have a heat call has bugged me and ive been looking for a way around it. all of a sudden i got it and realized all low mass mod cons should have buffer tanks this might sound a bit much and i realize not everyone has a lot of zones but i still think im right everyone could do with less pumps pipes and longer cycles everyone has spring and fall. i dont know just realizing how well its do so many things i might just buy this boiler buddy and do it right. i could just run that inner TT pump through it and come out other side with a secondary pump on generously sized headers with zone valves if i can do all my zones with an alpha pump which is still confusing
one of the reasons i want one secondary pump and zone valves is ai can imagine one loop on each riser/manifold/floor calling for heat like say the outside big end rooms with all the glazing will always want heat and if they get it the inner rooms wont really cool down but that would mean four pumps running but only 4 of 16 loops calling for heat.

keyote

so I piped the smart 50 indirect took me forever i realized i needed to run it real hot and then need a tempering valve then i start reading about heat trap loops and keeping the temp valve away from the boiler top, then someone suggests untempered water for dishwashers and washing machines and of course i had the pressure tank and a make up water feed, the vent and pressure relief oh and the TTsmart boilers have no drain out on the base, so you have to provide a drain valve on top on the cold and a shrader valve on the hot side if you ever need to drain it.
three days later must be a dozen valves but it looks prettyy good for a tin knocker I hope those heat traps were necessary since i am in cellar its up out of tank down trap then back up to house. looks a bit much and i kept trying to convince myself the checks in the honeywell temp valve would be heat traps. I did have some 3/4" p traps we used for traps on condensate pans on a job i did so the heat trap loops are one piece rounded s shapes.

hot_rod

So hot rod I think you are suggesting an improvement on my crazy idea of running through the inner and outer tanks but youre doing it in a balanced way into both simultaneously then out of booth simultaneously which would eliminate the flow and temp dif problems i mentioned. and spread the smaller port issue to both supply and return and it even eliminates the question of is the heat transferring well between tanks Brilliant.
So Hot Rod are you the same Hot Rod that does the Caleffi videos?

Exactly on all points.

You have 8 gallons in the outer space. For the cost of the fittings, may as well use it. Keeping that space filled with water is probably better than empty with hot humid air, that could accelerate corrosion in the plain steel outer vessel, just my thoughts.

hot_rod

No question you would want to add a valve or two and balance the flows if you parallel pipe them. It is just a quick sketch to show another option to series. It's not an engineered drawing by any means

With both circuits being tanks, really the only pressure drop difference might be the port size.

The multi energy tank that triangle offers is designed along the concept of multiple function buffering.

I suppose even if the fluid never flowed in and out of the 8 gallon space, it still would store thermal energy from the conduction transfer, if it were filled with a fluid, or heat transfer, phase change latent gel.

keyote

Hatter Im pretty sure at least in my situation [16 zone radiant, highly insulated, erratic occupancy of large multifamily, low mass TT110 ] a buffer is going to turn out so ideal a solution to several problems including adding solar one day; that i will bite the bullet and buy a good buffer tanks, i liked the boiler buddy but notice its not stainless but still quite expensive seems like such a simple thing ought to be cheaper maybe i can have one fabricated in stainless and just spray foam it

Gordy

I think I would experiment with different configurations with low temp emitters. By design the indirect is made to have the water in the outer tank heated by the boiler. Which then heats the inner tank. I don't see anything wrong with using it like that honestly. Drawing the zone off the inner tank.

Piping in series, or parallel just adds 8 gal of capacity. That 8 gal is really already there piped in a normal indirect configuration. k.I.S.S.

keyote

I also wonder if i could just weld four 1 1/4 stainless nipples to the inner tank and just fill the outer with thinset or foam but i see its the inner thats corrugated and Im guess they took advantage of shape and used really light gauge. But youre probably right that 3/4 inch is sufficient

keyote

Theres an htp stainless indirect which im trying to find a price on, locknvar is SS and not much more than cost as boiler buddy which is back iron.

Gordy

3/4" can deliver 42k. Above the minimum modulation of the TT 110. Your calculated load is 52k. That's if all zones are calling at one time. At design odt. Your discriptive of occupancy, and usage indicates you should be okay.

Gordy

I would not trash a good indirect in that manner. Let alone the inner tank would collapse.

keyote said:

Theres an htp stainless indirect which im trying to find a price on, locknvar is SS and not much more than cost as boiler buddy which is back iron.

i

hot_rod

Gosh, even 50 gallon electric HW tanks are pushing $400 at the box stores. They make millions of those a year. It is a challenge to build a well insulated, pressure rated tank with multiple ports for a few hundred bucks.

Galvanized well tanks are about the least expensive pressurized vessels you can buy, off the shelf around $250 for a 42G, but you need to insulate them.

I think the Buddy is a 75 psi, plain steel tank, maybe expansion tank gauge metal.

Our buffer tanks are a glass lined, thick steel, injection foam, 300 psi test, 150 rated with a heavy gauge powder coated outer jacket, a more expensive tank to manufacturer..

I'm not convinced you need stainless for a closed loop- buffer?

9 gpm in 3/4 copper gives you about a 6.5 fps velocity. A tad high but you should not see a condition often where 100% flow is in or out of the tank, that is the beauty of the 2 pipe method. When zones are calling, that gpm flows from the boiler to the loads, the balance goes into the tank. Only when all heat calls stop would the entire boiler flow go into the tank.

Recovering that 54 gallons with 90K boiler input would not take long, depending on the delta T you run across the tank.

hot_rod

Hatterasguy said:

hot rod said:

Our buffer tanks are a glass lined, thick steel, injection foam, 300 psi test, 150 rated with a heavy gauge powder coated outer jacket, a more expensive tank to manufacturer..

Now why would anyone buy a 300 psi test tank for use as a buffer tank on a system that will never see 30 psi?

The epitome of nonsense.

Build a proper glass lined buffer tank with 60 psi test and watch the price drop to one-half of the current number.

Give me a quote on that glass-lined 60 psi insulated tank, insulated and jacketed of course.
50, 80 and 119 gallon. If you can build it, I can sell it. We will call it the Trumpf Tank, it will be unbelievable!

BobC

Call it the Drumpf tank, accuracy is important.

Bob