Low Water Temp in Burnham Spirit

Ron W

Just looked at a 4 yr old Burnham Spirit boiler (radiant in floor heat). The water temp will not get hotter than 100 degrees with one zone calling. With all zones valved off, it takes almost 5 minutes to heat the boiler from 100 to 180 degrees. Checked the gas pressure, pulled burners, inspected heat exchanger, checked delta T, nothing out of the ordinary.

Does anyone have any ideas?

Thanks, Ron

lchmb

how about

a bypass?

Ron W

This system does have a bypass tee'd just above the primary pump and piped back to the return - no more than 5 feet. With all zones valved off and boiler firing, primary pump pumping straight from supply to return, still takes 5 minutes to heat up to temp. Open on zone, temp falls off by 30 degrees and steadily decreases to 100. There are secondary pumps. I'll try to get a photo or sketch the system and post it.

Unknown

I would also check

the clock rate of gas to the boiler to see if you may have a gas transmission problem. While you are at it, check for obstructions in the intake and vent pipes. Without the proper intake air levels, your flame will not be as hot or as clean as desired. If you find an air/fuel imbalance to be the problem, make sure that the cast iron heat exchanger is not sooted up also. Once you find the problem, let us know. Curious minds like to know.

Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com

Ron W

Already clocked - it is consuming approx. 75K BTU (it is a 96K input). Manifold gas pressure is at 3.0" W.C. cranked it up to 4" no noticable change. Vent pipe is at 210 degrees surface temp. The heat exchanger is clean, there is a 6 inch combustion air pipe into the mechanical room. Pulled and examined the gas valve, burners, orifices - nothing out of the ordinary.

Thanks, Ron

Unknown

Ron

The Spirit boiler is certified as a Direct Vent boiler and is intended to be installed and must be operated that way. We call for a 4" air intake pipe direct to the outdoors in order to get proper air movement through the combustion chamber. This needs to be corrected. When you removed the front combustion air panel, did you notice if there is any debris on the diffuser screen up above the burners? (See below) The one below is in a Minuteman boiler but there should also be one in the Spirit. Also, if the Intake Air connection is not piped corectly, then it also may very well be that the 3" Stainless vent pipe may also be incorrect. The termination cap outside must be the straight round coupling type cap with screen inside for the boiler to perform properly.

The manifold pressure with Natural Gas should be 3.5" w.c. and not 3" or 4". The 75K clock rate idicates that you may also have a gas transmission problem to the boiler gas valve from the meter. You are only at 78% of normal input. I would like to see you getting a contant 7.0" w.c. to the inlet side of the gas valve while the other appliances are running and a constant 3.5" w.c. at the manifold. If you doubt my words, take a look at the I&O manual as it also spells this all out well.

Glenn Stanton

Manager of Training

Burnham Hydronics

www.burnham.com