Coal Boiler Water Temp Problem

Hi, new to the boards and new to coal burning this season. Lots of good info on here, thanks to all contributors.

I have a done a fair amount of searching but have been unable to find anything that pertains to a problem I am having. I am not sure if I can get an answer here or if it might be more involved than just a forum post. However, here goes...

I have an older Burnham No. 26 coal boiler with radiant water heat. To start the season I had a few issues keeping a good burn going while away at work all day. That was just inexperience and after a couple weeks everything was going great with house temperatures in the mid 70s. Since I was away over Christmas and the coal furnace died out (I have an oil furnace backup that took over) I have been unable to get the water temperature in the boiler much over 100 degrees. I was keeping the water temperature pre Christmas around 120. Since then I can't seem to get the water temperature above 100 degrees. The aquastat that controls the pump will not activate that pump until it is slightly above 100 degrees. Therein lies my problem. I have good draft and a seemingly good fire burning (equal to pre Christmas burning) but the water temperature just will not go up.

I know more information is probably needed to make any suggestions. If there is any additional needed info please let me know. It has been driving me insane and keeping the house mid 60s with oil is cold and expensive. Thanks in advance.

It's a little confusing since you use the term furnace interchangeably with boiler. A furnace has no water. Is the backup oil also a boiler? If it is and they are piped together perhaps the coal boiler is heating the oil boiler.

The temperature you are referring to, is it inside the boiler water temp. or the temp. of water in the radiant (is it infloor ? ) system ? Infloor radiant typically uses lower water temp with a mixing valve. A boiler will condence if the temp. is 100 or 120, way too low, unless it's designed to be a condencing boiler, it will rust.

Sorry, new to all this. Yes the backup 'furnace' is an oil boiler. I'm not sure why things would have changed suddenly after Christmas though as far as the coal boiler heating the oil boiler.

The temperature I am referring to is what is shown on the thermometer/pressure gauge that is sticking out of the top of the boiler. The radiant heating I have are just radiators in each room.

When you started the fire after Christmas, did you completely clean out the firebox and grates?? Are you sure your fire is as hot as before?? No changes in the chimney?? Have you cleaned out the chimney to make sure you don't have a build up of flyash in the flue pipes [horizontal sections] ??
If you are sure that the fire is as hot as before, then lets look at the plumbing.

How is the coal boiler hooked together with the oil boiler?? Does the coal=heated water pass through the oil boiler,keeping it hot too? on the way to the distribution manifold for your heat??
Or , do you have a primary, secondary loop system??

Were ANY water valves moved, changed etc to allow the oil system to take over when the coal got cold?

and this was asked above, but bears reasking.. is your radiant hot water finned baseboard, cast iron radiators, or underfloor radiant heating??

We can help you a lot better with a few photos of the plumbing, and a bit more info on the system and house..

Greg L

Before I restarted my fire I did completely clean everything. I did not clean the chimney.

I don't have recorded temps of the actual fire but it seems to be burning the same.

There were no changes to allow the oil boiler to take over. It is set up to take over at whatever temperature I have the thermostat set up.

I am thinking this might be something that I may need to take up with a local professional...heh.

It seems like a pretty confusing set up to me but I really don't have much knowledge in this arena.

The hot water runs through cast iron radiators throughout the house.

I'll try to snap a few photos when I get some time hopefully tonight or tomorrow.

Thanks.

here is a link posted earlier in another thread

http://www.oldhouseweb.com/how-to-advice/gravity- ... nued.shtml

its possible your pumping too fast here but read this -= see if it applies -- post a pic as suggested

it depends

Let me get back to you!

Ok, so this might be hard to explain how it works by typing it out but maybe you can tell what is going on by looking at the pictures.

Basically the aquastat on the right side is what is controlling the pump for zone 1. The aquastat on the left controls the damper motor to open/close the damper.

In the photo showing the pumps he pump on the left controls the water going to radiators in zone 1. The pump on the right controls water going to zone 2.

The thermostats in the house confuse me but I will try to explain how I think they work. The zone 1 pump is controlled by the aquastat as mentioned above. The thermostat in zone 1 seems only to control the oil boiler. The thermostat in zone 2 seems to directly control the pump. When the thermostat in zone 2 calls for heat the pump runs regardless of water temp.

picture 2 of the pumps -- I cannot see if they are pumping away or to the boilers

It looks like they are on the return pumping to the boiler.

I would say they are pumping up (away from the boiler) because at the bottom the pipes coming out of each pump combine together before going into the oil boiler.

Since they are piped to the low tapings == YES you would think they are pumping at the boiler

BUT???? I cannot see for sure - or even if they are on the return side