Problems With KAA-2 Temps.

kstills
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Post Sat. Jan. 25, 2014 7:32 am

KLook wrote:If I was to return to Maine and run my VF3000 again, the first thing(s) I would do is reduce the draft carefully to experiment with slowing the exhaust down, and install at least a 40 gal, Extrol tank to increase my standing hot water capacity. I have 50 gal. in the VF3000, I would think in these conditons, 24 gal. in the K-aa2 would be no where near enough to supply 100 ft. of slant fin.

Kevin
If he's running 3/4 inch copper, 100 feet of pipe equals 4.1 gallons of water required. Give another 100 feet for the spaghetti in the basement, and your using 24 gallons of hot water to feed 8 gallons worth of piping.

That doesn't seem like a lot.

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Rob R.
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Post Sat. Jan. 25, 2014 7:47 am

The amount of water stored in the boiler has little effect on steady state operation. Thermal storage takes out the temperature swings when large loads come and go, like a large flywheel...but you still need enough power to get the flywheel back up to speed. Imagine trying to heat your house with a 120 gallon electric water heater.

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blrman07
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Post Sat. Jan. 25, 2014 7:51 am

Long and short is your boiler is too small for the temps we are seeing this year. Doing all the calculations in the world and playing with system balance isn't going to do it for you with your setup. Rewire your system so the thermostats control the circ pumps. Your probably wired where if the water temp falls below the lower aquastat setting your circ pumps shut off. If the t stat controls the circ pumps then you have a better chance of using the hot water in the boiler for the radiators.

When the temps moderate or go back to a normal winter, you will see your house temps return and everything settle out again. At moderate or normal winter temps the small boiler can keep up.

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Ashland, Pa.

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Rob R.
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Post Sat. Jan. 25, 2014 7:52 am

Could just turn the low limit all the way down. Tankless coil won't work, but at least the circulator would run continuously.

kstills
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Post Sat. Jan. 25, 2014 8:12 am

Rob R. wrote:The amount of water stored in the boiler has little effect on steady state operation. Thermal storage takes out the temperature swings when large loads come and go, like a large flywheel...but you still need enough power to get the flywheel back up to speed. Imagine trying to heat your house with a 120 gallon electric water heater.
Well, there are maddening gaps in the narrative, if you know what I mean. :lol:

Water is definitely circulating. I can hear and feel it running through the pipes. The return water is less hot than the water coming from the circulator.


He says the supply is almost too hot to touch, so what is the return? 120? 130? He says the water is circulating, but won't say if it's continuous or whether the boiler is being limit high shutoff.

My guess, fwiw, is that he's running continuously, and that the radiation/btuh can't keep up with the heat loss of the dwelling. I'm insulated and I'm running about 47kbtuh loss at these temps, if he's uninsulated even with a smaller dwelling he could be easily seeing 70-80k per hour.

In fact, running the heat loss calc for a leaky house yeilds ~71kbtuh at 0deg f. It would be nice to know if in fact the circulators are running constantly, what the outside temp is, whether the boiler is hitting the high limit.....

Cause if the boiler is hitting the high limit, the suggestion to turn up the boiler temp is the only one that will increase heat to his dwelling. Unless he makes a run to Home Depot and picks up a few rolls of fiberglass insulation for the attic. ;)

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titleist1
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Post Sat. Jan. 25, 2014 8:23 am

This is where a skype session would be very very useful!

Hey Farrel2k....can you skype, preferably with something mobile you could take to the boiler?

waldo lemieux
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Post Sat. Jan. 25, 2014 8:36 am

My money is on air in the zone. What is the pressure in the system,do we know that? He mentions that there is 100 ft of bb ,is that all in one loop/zone?Too, fin tube with no insulation is scary; with cast iron maybe but....

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titleist1
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Post Sat. Jan. 25, 2014 8:50 am

fins on the baseboard cleaned out real good for maximum heat transfer?? A small contributor but in this real cold weather every little bit helps.

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KLook
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Post Sat. Jan. 25, 2014 9:30 am

If he's running 3/4 inch copper, 100 feet of pipe equals 4.1 gallons of water required. Give another 100 feet for the spaghetti in the basement, and your using 24 gallons of hot water to feed 8 gallons worth of piping.
If you are correct in the math, that is 1/3 the capacity of his boiler. You don't think pushing cold water into the vessel at a rate of ? GMP will overrun the unit before the stoker can even get started? My VF3000 would cool all the say down from 200 to 150 before the stoker would start to run! Then it would settle in at about 140 and just run n run n run. 8 gal. of water in a 50 gal system would not be to bad. And I remember being chastised by the fabulous Sting for having the return water start my stoker! But it still works that way with cube relays because when the 2 cast iron radiators in the basement call for heat, you better get that coal pushing right now! The sensor to start the unit up is on the top and it is to late when it realizes ITS COLD. Plus I slowed the flow down on those zones to give the stoker more time to get ramped up.
I can only report what has worked for me with an undersized boiler.
It seems the speed/gmp of his circulator wood be important and maybe throttle it down a little to help the stoker catch up.

Kevin

waldo lemieux
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Post Sat. Jan. 25, 2014 9:43 am

Or put in/ open a bypass loop . or maybe keep the aquastat from turning off the circulators on low limit...

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Carbon12
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Post Sat. Jan. 25, 2014 11:00 am

Yeah try hi limit 200 low limit 150 with diff of 20. Couldn't hurt to try that. Maybe if you can get the house up to temp once, it will be able to maintain the temp better. If that doesn't work, get some electric heaters to help the house out during the coldest weather. Hopefully you won't need them often.

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KLook
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Post Sat. Jan. 25, 2014 12:49 pm

I would do this.....shut down the circulator, shut down the valves that supply the circulator. If there is one on the return side fine, some here holler about not shutting down the suction side and they know more then I do. set the high limit to 200, watch the pressure as the boiler gains temp to make sure the expansion tank will handle it. It should no problem, but you never know. Once the boiler is near 200 but still running, turn on the circ and only just crack the water flow for it. You would be amazed how much water will go through a valve at 1/4 open. Monitor the return temps, with 200 degree water, you should not be able to hold your hand on it with a normal temp drop. With the boiler still running flat out, it may have a chance to recover with the lower flow rate. It is worth a try.

Kevin

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oliver power
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Post Sat. Jan. 25, 2014 8:44 pm

I'll give you my settings. First off, I'm heating 1700 square feet using 76 feet of 3/4" finned baseboard radiation. I'm heating my place to 73*. So, unless you have a big heat loss, the little Kaa-2 is not too small to heat your 900 square foot house. I'm burning buck size coal. Stoker feed: turn the feed screw all the way clockwise. Then back it off about 3 - 3-1/2 turns. Triple Aquastat: is set 160* Low - 180* high, w/10 differential. Timer: with these temps, I need 3 groups of 5 pins. Being only 900 square feet, 5 pins per group may trigger your high limit aquastat. Then you'll try 3 groups of 4 pins. Maybe add / subtract one or two pins. You get the picture? With the Kaa-2 boiler, you need to maintain a higher, more responsive fire on the carpet. And you do this with timer pins, depending on weather conditions. The Kaa-2 is not engineered to run on the timer, but that's how it has to be run. That's what throws the non-Kaa-2 owners off. On other boilers, the timer is for keeping min fire. As for the Kaa-2, the bigger the fire, the less lag time, which gives the stoker time to ramp up, and take over in these bitter cold temps. If the carpet fire is too big, you'll trip the high limit aquastat. Take out pins to fine tune. Too much lag time, and the boiler drops below the low limit on the triple aquastat, shutting down the circulator, which if I'm reading into this correctly, is your problem. Yes, if you hear water going through the pipes, I too am guessing the noise is air. I'm guessing your problems are; 1.) not enough pins in the timer. 2.) Air in the system. 3.) Too much heat loss. 4.) As Sting said, slowing down the flow gives time for heat to be absorbed by the finned baseboard radiation. Let us know how you make out. Oliver

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Carbon12
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Post Sat. Jan. 25, 2014 9:26 pm

Wish we had an update!

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KLook
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Post Sat. Jan. 25, 2014 11:00 pm

Wish we had an update!
X2

Kevin

Good advice from Oliver, I had not thought about keeping the carpet more lite up, because it is not always this cold. It fluctuates alot in coastal Maine. I still like my idea to get it running when the zone calls because it probably is going to take all it has to heat up properly.

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