Question for the Boiler Guys Out There

just installed a keystoker kaa-2 boiler in series with my oil burner seems to be running pretty good only has been in for a week. I am trying to dial her in but could use some advice. I have the stoker abustment 5 turns out from full feed. my draft is set at .02 per keystoker. my stack temp is 275-300 under full fire about 100-125 on the maintance fire. seem to be buring 40# ina 24 hour time frame and temps are in the 10-20"s.time runs for 45 seconds every ten minutes . my house is 2000 sqase foot ranch built in 1969 with 2x4 walls with r13 and r39 isulation in the attic. just a bit of info when I was buring oil I was using about 575-625 gallons a year .the only probelm I am seeing is the lag time to bring up to temp. she idles along at about 175-180 but when circulators turn on temp goes to about 140-150 and then climbs back up takes about 30-45 minutes. I don't have my circulators wired to my l8124 aquastat on the coal boiler becuse iam using all the electronics off the oil burner plus I have four zones here. does this sound unreasonable could I be dialed in better. help is very appricaited. I did post some pics under another thread check them out

chris

The pics don't show the plumbing and that may be the problem. Need to see the two boilers, pumps, checks and zones and directional flow of plumbing. Leaving the honeywell Aquastat out of the loop here isn't good either. I assume there is a draft blower?

Crudely comparing your oil and coal usage by btu's: I calculated an average usage of 38 pound per day over a seven month heating season with oil at 140k btus/gal and coal at 22.5 million btus per ton. Average temps for the entire oct to april heating season are probably higher than the 10-20's. Assuming an efficiency for your oil and coal boilers are the same, which is likely with a new stoker and a middle aged- boiler, I'd say you are about right in consumption.

yes I do have a draft blower. I have it plumbed in series with the feed of the coal boiler going into the retun on the oil burner and then out to the house. I am currently running four circulators three are for heat and the other is for the hot water tank. I currently have hooked up the thermostat to the aqua stat on the coal boiler from my erie boler controls on the oil burner. seems to have cut some of the lag time. now when circulators come on the themp drops to about 155.on the coal boiler and seems to recover within 20-30 minutes up to 180 to keep up with demand. if you need some pics I will have to get some I can also give you a hand drawing of the plumming to detrmine where things are. thanks for the imput. one other quick question what did you think of my readings are they in line stack temp/draft/coal cunsumption/temp differential

let me know

1975gt750 wrote:yes I do have a draft blower. I have it plumbed in series with the feed of the coal boiler going into the retun on the oil burner and then out to the house. I am currently running four circulators three are for heat and the other is for the hot water tank. I currently have hooked up the thermostat to the aqua stat on the coal boiler from my erie boler controls on the oil burner. seems to have cut some of the lag time. now when circulators come on the themp drops to about 155.on the coal boiler and seems to recover within 20-30 minutes up to 180 to keep up with demand. if you need some pics I will have to get some I can also give you a hand drawing of the plumming to detrmine where things are. thanks for the imput. one other quick question what did you think of my readings are they in line stack temp/draft/coal cunsumption/temp differential

let me know

Your objective is to make uour oil boiler is an automatic back up to your coal boiler? i.e. no intervention by you? Is that correct? That is something I cannot help you with. I am not familiar with what it takes to do that.

If it were me I would shut down the oil boiler and have a single pole double throw switch to prevent simultaneous electrical operation and install by-pass valving. All trim and controls would be shared by the two boilers. Then the boiler is available for use while away for long periods and to run your hot water in the summer. Otherwise your keystoker is reliable enough for the winter.

As for your readings, I don't think they are out of line but I don't know the unit. a 180 to 155 drop to satisfy a load is nearly ideal. Why it takes 20 minutes to recover is a matter of stoking.

The lag in temp is because your coal unit's aquastat has no idea what you are doing with the heat its producing. When there is a call for heat (circ pump) the blower should come on to keep up with the load. Because yours is not in the loop, it doesn't fire the fan until it reaches the low limit on the aquastat. It should fire anytime there is a call for heat and lower than max by a set point, usually 10-15*.

There are a couple of ways to set it up to go auto to the oil in the event that the coal dies, but need the plumbing stuff to see what is going on. Do you have one or two circs or are they individual for each zone? Is there a domestic hot water coil in the oil boiler? Are you against replumbing?

I just went back and actually read the posts. Duh. Your temps are good, both water and stack. Looks like everything is right except we need to let Mr. L1824 know that your stealing his hot water. When he finds out he will tell Mr. Draft to get to work. With the beast you have there, you will see almost no drop in temp unless there are several zones calling for heat.

The immediate fix is to connect the thermostat directly to Mr. L1824 and the circulators too.

This is how my system is hooked up. When my wood/coal boiler reaches 120, it starts circulating to my oil boiler. When the oil boiler gets up to about 140, it starts putting uncontrolled heat to the zones; dump zones. It's all done through some aquastats, relays and two circulators. It's really the easy way to avoid overheating my oil boiler, which also has a bypass loop to prevent the zones from pulling the oil boiler water down more than 10 degrees or so.

When ever I get the chance to install my KAA-2 boiler , I'm plumbing it in as a two pipe system just for that reason. I'm not a HAVAC man. But , I kind of figured if the water was circulating continuously in one pipe , it wouldn't be as much "all at once" demand on the KAA-2 , with it's smaller reserve capacity. Your coal consumption and stack temps are exactly as I was thinking , about half of what my HITZER coal stove is doing now. With the HITZER in the basement , I'm heating the basement and the house. (1700 square foot house w/same size basement) The KAA-2 boiler is only going to heat the house.