Keysoker by Pass Loop

Thank you Rob, I still don't understand how Keystokers works. My vf3000 stratified and I simply installed a small taco to circulate 24/7 and equalize the boiler vessel. It worked like a charm. I needed full temp water to heat my house so I did not "mix" my outflow. I set up an injection system to mix it for my slab. I want that 50 gallon boiler sitting there with full temps from top to bottom when the house calls. I need it in fact as the boiler is undersized for my sq. footage in Maine. I even considered another tank to increase the volume available. The equalizing loop also tempers the return water somewhat.
I guess my question is....how does the passive loop prevent stratification and why would you pull the cold water down through the boiler? It goes against the natural tendency of hot water to rise.
It seems like when the circulator kicks on, it will pull across the boiler through the 1 inch bypass pipe first, then pull through the boiler second to satisfy the flow it desires. It would be a crapshoot if this was enough heat to work. I know I needed 180 degree water to hit my radiators to be effective. Actually 190 to 200 was even better!

Kevin

Found this on keystoker page

1. In smaller size boilers, maintaining a small fire will produce less than 10,000 BTUs, but Keystoker's efficient boilers trap and store maximum BTUs. Even a small maintenance fire will cause boiler temperature to rise above desired water temperature setting in the upper part of boiler. The loop will allow hotter water, stored in the top of boiler to flow naturally to lower part of the boiler. This will maintain a more even boiler temperature and reduce chance of overheating water.
2. Installing a loop will prevent boiler shock. When circulator runs cooler water from return, the line will not all dump into boiler. Some of the cooler return water will flow through loop and mix with heated water in supply line. This will allow circulator to run for a longer period which is especially important in large heating loads or for homes with radiators.
3. If timer is running too long, or if coal feed adjustment is set too high, water will be overheated. If water temperature reaches temperature setting of 4006B (recommended setting is 220), circulator will turn on to reduce boiler temperature. Cooler water from return line will be forced through loop to cool water quickly (approximately 10 to 15 seconds). This will lessen the likelihood of overheating the entire heating system.

I can hear Sting on this. Circulate for longer periods of time with lower temps to even out the highs and lows and the shock to the system. I get that. Maybe that works fine for PA. but in many areas, you can circulate 150* water all day long and not get your house up to temp. I would have to have a way to see the output temp from that hookup. (I do have that in my system in Maine) and return etc. That is not a result of an improperly sized boiler, 150* just won't cut it. Improper radiation maybe, but you only get so much heat out of the water and then send it back really cold which gets back into boiler output, capacity and recovery time. Seems radiation should match output for the 20* drop desired. This gets really difficult as the factors of insulation, location, mixing radiation types, and wind chills are put into play. The further north you go, more is better. I know, I know, do an energy audit and figure all those things out. THEN buy a system. In another lifetime maybe.

Kevin

Just because you install an equalizer loop on the boiler doesn't mean it will temper the supply going to the radiation. The main objective is just to reduce stratification in the boiler. Depending on what you want to accomplish, there are small changes in piping that will make the system behave differently.

When I first got my stoker boiler up and running, before I got an aquastat I was using the idle feed rate control to adjust boiler temps. I was very surprised to wake up one morning in the low 40's outside to a warm house ... and the boiler water was only 118°!! If that can keep THIS place warm, it'll keep anyplace warm. I prefer to have the water north of 150° though for quick DHW recovery.

I'm glad I read this thread! From what has been described here, it seems my tie-in with the oil boiler inadvertently created a loop - just a larger than normal loop.

I believe that the first pipe down from the circulator and the easiest one to pull through will get the pull from the circulator. As the cold water returns from the house this will be recirculated and supplemented with a little hot water from the bottom of the boiler. A restriction should be necessary to prevent this but this would also prevent gravity feeding to equalize the boiler. I know I am wrong by the results people have. I seek to understand why.

Kevin

Yeah, I know. By a book! Hoolihans maybe.

Yes, this is the confusion...there are different types of bypasses as Rob has pointed out.

As I recall from my learning...system bypass and boiler bypass.

http://hvac-talk.com/vbb/showthread.php?488222-Bo ... tem-bypass

And the Equalization Bypass, if that's the proper name...it is more so of a solid fuels thing... it keeps the boiler's water volume from stratifying into different temperature layers within the boiler when setting idle between firings by allowing a gentle natural thermosphion from bottom to top through a externally piped bypass...this is, I think, really a System Bypass that is piped to be friendly towards the thermosphion action.

KLook wrote:My question would be how does the bypass loop work in your system wiz as there is no circulator making it flow? Gravity? Or are you taking the hot water off the bottom? Even looking at the schematic put up I don't understand what makes the water flow. I installed a small circulator from the top back to the bottom of my VF3000 and it worked great.

Kevin

Pressure differential when circulator is on; probably I know my primary loop acts like a bypass loop. It naturally circulates. When firing up my Kaa-2 boiler at the start of the heating season, I leave my thermostats turned down till the boiler is up to temp. Otherwise, the secondary circulators run continually. Meanwhile, as the boiler heats up, so doesn't the primary loop.

KLook wrote:I can hear Sting on this. Circulate for longer periods of time with lower temps to even out the highs and lows and the shock to the system. I get that. Maybe that works fine for PA. but in many areas, you can circulate 150* water all day long and not get your house up to temp. I would have to have a way to see the output temp from that hookup. (I do have that in my system in Maine) and return etc. That is not a result of an improperly sized boiler, 150* just won't cut it. Improper radiation maybe, but you only get so much heat out of the water and then send it back really cold which gets back into boiler output, capacity and recovery time. Seems radiation should match output for the 20* drop desired. This gets really difficult as the factors of insulation, location, mixing radiation types, and wind chills are put into play. The further north you go, more is better. I know, I know, do an energy audit and figure all those things out. THEN buy a system. In another lifetime maybe.

Kevin

Most homes are way over radiated, so 150 would be fine, however on the flip side, many homes have lousy radiation, requiring much higher temps.
I'm in a pretty cold area up north.
Piping and control strategies are huge too.