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[Sluggo]

The buffer tank theory has been discussed quite a bit on here but I'm having problems finding a clear answer.  I came across a free 80 gallon water heater.  When it's extremely cold I can get some pretty drastic delta t.  What's the benefits and downsides of a buffer tank?  Where is the best location to put it?  Lines come from my stove into my garage and at that point everything splits to do it separate task.  I have easy access to everything at that point.

[caper]

I soo wish some good knowledgeable guys would discuss this, my bro says I need one as I only have an electric furnace which has no storage maybe 5 gallons tops,so when I have temp drop he blames it on no storage, he has oil furnace prob 30 gallons storage...

[dukethebeagle]

imo,it depends what u want to do.!!
1-do u want a heat store
2-do u just want buffer
I use buffer which i have in my basement.300 gallon which really isn`t much in
comparison to european setups
they can really help with on-off cycling.stops the shock of cold water on inflow on ur stove.
BUT recovery times can be long so u have to be vigilent on firing  and keeping a regular schedule
don`t think ur gonna gain alot of heat by adding capacity of 100-300 gallons
to do that u would need to add thousands and make sure to keep heat losses to a minimum
some are for and some against but what i can tell u is this

    1-heating a larger buffer tank allows for a super clean and efficient burn
    2-stopping short cycles will save u wood
    3-reduced creosote deposites
    4-less smoke (burn open wide open)
   
  there could be more but i can`t think of any right now
some commercially sold buffer are small like say 40 to 80 gallons
i tried that route for a while and was not impressed
just not enough capacity to make much of a difference(for me)anyway

 cons 1-to much heat loss at tank and ur gonna have to fire that much extra to try to get it up there
         2-extra space needed for tank
         3-some setups require extra pumps etc
         
   i can say i much more enjoy firing wide open and after temps are good i just maintain till it needs a hard fire again
with the smaller tank u fire like u normally fire ur boiler but in real cold temps the extra is not
 really enough to make it worth while and its just a headache to  keep that extra hot
   imo either go bigger or just leave it alone cause it can hinder as much as it can help

      if anyone else response i will go into detail about piping etc
   i`m curios what info is out there as i am always tring to improve my system also
         
   twiw, i am no expert,just a guy who likes to tinker and try things so i`m learning to

[slimjim]

In my opinion, a buffering tank will definitely help with the surge of cold water returning from the cast iron rads, just be sure the tank has at least a 1 inch coil so you don't restrict the flow on the main loop.

[caper]

thanks guys, its def something to think about, if so, it will be a summer project,along with a horse barn and too many other things to list....thanks again guys...

[LittleJohn]

Remember, your OWB can only put out so many BTUs, it does not matter weather your radiant application is taking those BTUs or it is your buffer tank (you can only get so many BTUs out of your boiler).
Buffer tanks do help with the extreme spikes and dips that can occur.  Another way to help reduce this is to run the pump between the OWB and radiant application all the time.

Also agree with DUKEtheBEAGLE; by adding the volume of a buffer tank to the system it can reduce the reaction time of coming up to temperature, because of the extra load it is putting on the OWB

[dukethebeagle]

ljohn is right ,you only get so many btu's in a firebox.

[LittleJohn]

There are really only two ways that I know of other than a buffer tank to reduce the shock to your OWB

• Increase pump speed, may not help if the BTU load of radiant is greater than boiler
• Install a mixing device, to maintain the return temperature to OWB at 140+

[dukethebeagle]

yup sounds about right.
also people think by installing buffers,they will get more heat output.
naaaaah!!    eases the load on stove but don't give extra heat

[slimjim]

You guys are exactly right about the not producing more heat but yes the buffering tank will decrease the shock, I'm not a fan of the mixing valves as they do reduce flow.

[caper]

Slim, you state that you dont like mixn valves, what other options are there, honestly, i just put in mixn valves this fall, and you know what, my system hasnt been right since, my garage is always calling for heat now, basement infloor acts up now and then, and the mixn valves make alittle noise in the furnace room, house still really warm , but you always know when something just isnt right...

[Bondo]

Ayuh,....    I believe I'd be takin' that 80 gallon tank, 'n usin' it as a hydraulic separator, 'n doin' the boiler as the primary loop, 'n the radiation on the 2ndary side,....

Easy, simple, ya might need 1 more pump,....

Fewer starts, 'n slow-downs for the owb,....

[slimjim]

Mixing valves have their place, in my opinion that place is not on the primary loop, the primary needs to have as little restriction as possible in order to satisfy the heat loads in the secondary system. For those guys with cast Iron rads and in concrete radiant, mixing valves are almost imperative, concrete should be mixed down on the supply side and rads should be mixed up before returning to the main loop.

[stratton]

Slim, not to get off topic, but how do you like your new job.? Are you at liberty to discuss your new adventure.?

[stratton]

Sluggo, The buffer tank for me has really helped quite a bit for my app.. I have an old 2inch pipe-gravity system with huge cast rads.. A benefit for me is when i have pump on between boiler(45 gal) and tank (80) i get a lot of thermo-syphoning into the system.