Large hot water system efficiency

Sorry about the confusion. I finally got the reading at the door to read .02 and at the collar reading .04 (with the burner running).

I set
high limit at 190 low limit diff. 10
low limit at 170 high limit diff. 10

feed at 6
air at 5.5

Anyone see anything i need to change?

Did you have to change it much?

Scott raises a good point - was the draft way off?

How does the fire look? 1-2" of ash around it?

Draft was really good. no i didn't have to change it much. i think my problem was that i wasn't giving it enough coal. and that was causing it to run very often. I also switched out the timer on it. I have that set up to run 2 min every 30.

Any other changes i should make right now?

Oh i forgot to mention that the fire is going strong and there is 1-2' ash ring around the outside.

How are your controls wired? How is the EFM tied into the old oil boiler system?

Does the EFM get a signal that there is a heat call from the house? Or does it just maintain the low limit setting...

I added a picture to help explain what's going on.

What i called the boiler bypass comes from the top of boiler and then loops back to the return side of the boiler. Then i have 3 zones off the header. Each zone is run off it's on thermostat.

The aquastat that you see is for my "dump zone"

one thing i've realized is that when my zone's call for heat the stoker seems to run regardless of what the water temp is.

I currently have the following setup
feed 6
air 5.5
high limit 190
low limit 170
high limit and low limit differentials 10


any help is appreciated.

What is served by "zone 3"? Is that the air handler? It looks like it is piped in 1/2"...depending on how your controls are setup, I can see the boiler spending a lot of time at the high limit because it can't transfer enough btu's to that air handler...so that zone keeps calling for heat.

A boiler that is often at 180-190 degrees and is uninsulated is going to lose a lot of heat...no wonder your garage is so warm.

Forgot to mention this is an old picture. I have since insulated and jacketed the boiler... the garage holds at 66-68 degrees with an insulated and jacketed boiler.

Zone 1 heats a very large hot water system (this also serves as my dump zone) it is all hot water radiators.

Zone 2 heats a small heat exchanger that is no more than 10 feet from the boiler. That is a very small run.

Zone 3 is done in 1/2 work at the header. It heats cast iron baseboard whhich is all done in 3/4 in.

Could I possibly have a wire that would causing stoker to run when pump is running?

If the zone controls have an end switch hooked up to the triple-aquastat on the EFM, the stoker will run whenever there is a heat call...until it reaches the high limit setpoint.

I don't think i've ever seen the boiler reach it's high limit point.

It always seems to shut down at 170.

Every morning i wake i take a full bucket of ashes outside. Then every night prior to turning in i take another full bucket of ashes out. So i burn about 2 full bucket of ashes in a 24 hr. period.

Am i wrong in thinking that something has to be setup incorrect?

2 full ash tubs in 24 hours...either your coal produces a LOT of ash, or the stoker runs almost all the time.

Here is a crazy question - does your boiler have a cast iron baffle hanging at the top of the fierbox and two steel plates hanging on the heat exchanger?

I will have to double check tonight but i'm almost certain that everything is in there properly.

I just don't understand why the stoker would run everytime that the pumps are triggered to run.

THE ONLY TIME THE STOKER IS NOT RUNNING is when it has hit the low limit and nothing is calling for heat.

If anything is called to run then stoker runs.

There should be two of these hanging on the hooks:



And one of these hanging at the top of the firebox:

CoalBurner5 wrote:I just don't understand why the stoker would run everytime that the pumps are triggered to run.

That is how the aquastat is designed, when there is a heat call (contract across the TT terminals or 120v to ZR terminal) the stoker will run until the boiler reaches the high limit. If your boiler never reaches 190, then the stoker will start whenever there is a heat call.

I am wondering if your coal is not so great. If you were running 4 teeth of feed before, the stoker would have to run 24 hours per day to generate two full tubs of ash...and even then the ash content would have to be greater than average.

At this point, I am out of ideas. Get a real EFM pro to stop by and look at the boiler, stoker, piping, and control strategy.