2500 ppm CO

Dave Stroman

So I installed a boiler in my bro's house about 10 years ago. A little copper tube one. It had been eating out the part of the B vent that goes through the roof and the single wall near the boiler. He finally got me to check the thing out. Typical copper boiler, the thing short cycles like made. Did a combustion test on it. 2500 ppm CO! I took out the gas burners and blew them all out with an air compressor. Brought it down to about 10 ppm. Wow! What a simple fix. I also noticed that I was only getting about 200* stack temp. I took out a couple of the metal V shaped things that lay in between the copper fin tubes. Got it up to 300*. Much better. The thing may vent properly now. Threw on an aquastat with a larger differental to help with the short cycling. Now sure how much that will help.

Dave in Denver

Firedragon_4

Proving once again that

bad combustion is BAD combustion!

Boilerpro_3

Sounds like you have a source problem

Sounds like the boiler is too big, or the thermostat anticipator setting is wrong. Some of the copper tubes need anticipator settings around 1.6 for proper operation.


Boilerpro

Dale

V shaped metal things

I wonder if the V things are flue baffles designed to slow down the flue product to get more heat into the tubes, I would guess they were put there by the manufacturer. I wonder, since you are in CO if someone didn't derate this boiler too much, I would check the orifice sizing. How does the entire vent system look and is it sized correctly? 300 degrees is a reasonable flue temp. Good job on getting the CO down.

lchmb

one more question

Was the unit properly set up for the fuel you are using? LP or Natural gas??

Dave Stroman

It is set up for natural gas.

The problem with short cycling is just the nature of copper boilers. With only one zone calling, the thing just cycles on the high limit. I put one on with a wider delta t but it just heats up so fast with so little mass. I have gone to the modulating boilers or good old cast iron.

Dave in Denver

Boilerpro_3

A solution

How about adding a storage tank, like used with low mass condensors. This should give you a little more run time. Also, many copper tubes were available with two stage gas valves...may want to look at this. One last thing. You could set up the controls so that only the largest zone or zones call for the boiler to fire or only have the highest heating need zone call for the boiler. The other zones woudl just operate the zone pumps or valves. The boiler is piped P/S, isn't it?

Boilerpro

Dave Stroman

I suppose a buffer tank would be a solution. The house has 4 small heating zones plus a 40 gal. BoilerMate. Not practical to set up slave zones. I know Larrs used to have an additional gas valve to cut down the flame as high limit was approcahed. This one is a Lochinvar Minifin and I am not aware of a 2 stage gas valve.

Dave in Denver