How to do keep burner on for combustion test in warm weather

D107

We are having our annual tuneup this week; weather will be in the 80s. Usually we do this in March. Buderus G-115/3, Riello 40 F3, Logamatic 2107. Hardest part is getting the oil co to actually do a combustion test as per contract. They still use the old Bacharach methods when they do it at all. Last time they hit the reset button ten times to keep the burner on since it was warm out. That tech will never be in our house again. Usually I keep the boiler off for a few hours before the tuneup and then run the hot water so the burner will run to satisfy the indirect. Is there an easier way to do this? I know there's a manual on switch on the Logamatic.

Jamie Hall

Say what? You can keep the boiler on as long as you need by just connecting the two thermostat control wires (usually red and white) together -- or just setting the thermostat above the outside air temperature.

D107

This is set on constant circulation. Once it reaches the outdoor reset temp burner shuts off--but of course boiler still circulates heat. But to do combustion test burner needs to be on. Main zone is on a Buderus room sensor and Zone 2 on t-stat. We want to keep burner on long enough to achieve steady state efficiency--usually 15 minutes.

GBart

If the tech hit the reset button 10 times to do the efficiency test something is seriously seriously wrong.

"Hardest part is getting the oil co to actually do a combustion test as per contract."

that is essential, any company that does not do that needs to leave and never come back

GBart

The Buderus control can be temporarily switched to another mode, you can run the hot water, etc.

If they don't know Buderus and aren't factory trained they shouldn't be touching it.

Grallert

The chimney sweep function button on is there for just this purpose. It will run the boiler up to high limit and if I recall it will call the pumps to prolong the run time. Still going to need a digital analyser most likely.

Mike_Sheppard

Now is not the time to do it, unfortunately.

I’d highly suggest doing it when it’s cold outside and have someone with modern technology do it!

D107

@Mike_Sheppard You're probably right about that but the main thing they do is vacuum the fireside and flue--also with cajoling--check/clean the electrodes and and change both oil filters, pump filter and nozzle. I may have them do that and forego the combustion test and then get a proper test done by a pro in the fall. I'm just tired of having to push for the proper test.

ratio

I run in to the same problems when I'm trying to start, say, a 3,000,000 BTUH make up air unit in the summer. 120° ΔT, with a 180° max discharge and 80-90° inlet don't add up to a good high fire adjustment. What I generally have to do is get it as close as I can, then make a pass when conditions are more suitable.

If your current guys can't meet contractual obligations without cajoling, maybe there are some others you could try who would? I know that if our service side gets too far behind on that sort of things, I get pulled over to help catch up, it's that important to us that we not be in default.

Jamie Hall

My apologies. I was thinking something simple... all the more, though, is @GBart right. If they don't know how to operate the controls, the probability that they will get the cleaning and adjustment right is pretty close to zero. Find someone else.

captainco

Is it possible you have an air conditioning system that you can cool the building down to add some load to the boiler?

D107

Ha! I think I won't go that far. With the temps supposed to be in high 80s I don't think we'll get applicable readings. My late father, a mechanical engineer once had a well-to-do client who installed on his desk controls for both heating and AC and would constantly manipulate both while he was talking to you to maintain his comfort.

HVACNUT

Is there a quick connect molex plug to the burner? If not, can you remove the primary control box from the Riello?
Raise the heat and run the tub to deplete the water heater.
Putting the 2107 in manual and hitting the chimney sweep switch will run the burner and zones for an extended time.
First thing I do at warm weather tune ups, after checking the safety is force the boiler to go cold.
I do N.F.S. and vac to give it time to cool down.

D107

@HVACNUT Yes, well usually I have the boiler turned off for hours, run the hot water, then when tech is ready to start test, raise the thermostat all the way and turn it on so it's making both heat and hw. that usually gets it done. But with really high temps, I'm afraid that any adjustments would not apply well to when the heat goes back on in October. I think I'd follow the main advice I've received so far here which is to let the oil co vacuum fireside and flue and get a really good burner tech in here with digital equipment in the fall.

EBEBRATT-Ed

@David107
You can't run the boiler without enough load. Generally with an electronic combustion tester (faster than the old dumbbells) and if the boiler is cold you can get enough run time to get a quick picture. Keep in mind that combustion test readings get better when the boiler is hot so if the reading are ok cold you are probably good.

But as noted above by others and they are correct you are supposed to run the boiler until the stack temp is steady and not climbing and then do the combustion test.

Why not put it off until September? Not that I am looking forward to winter

getting enough load to do that in the summer is difficult. You will just keep hitting high limit.

STEVEusaPA

You just have to have it done when its cold. It's even worse on a furnace that keeps bouncing off of high limit every 3 minutes.
Warm weather cleanings benefit the oil company by keeping their techs busy. In the best interest of the customer, it should be done when it can be done properly.
I wouldn't even take any tech seriously who showed up with, as Ed called them (fittingly) 'dumbbells'.

GBart

That's ridiculous, have it done when it's cold?, annual maintenance is done year round, a heating unit does not have to be run for 20 minutes to get a good reading and dial it in properly if you know what you are doing.

STEVEusaPA

A boiler/furnace has to be at steady state to properly perform a combustion test. I never said anything about 20 minutes.
And yes I do know what I'm doing.

New England SteamWorks

I just turn on all the hot water taps.

Jamie Hall

May I make one comment, sort of a variation on a theme of what @STEVEusaPA said? The only measurement which may be significantly affected by ambient air temperature is the stack temperature; it will be higher with higher ambient, though not perhaps by that much. However, the basic combustion measurements and adjustments shouldn't change much with ambient temperature (after all, the ambient might vary from say 40 to perhaps 80 -- while the flame temperature is 1000 plus and the firebox will be right up there, too!), although it is necessary to have the boiler thoroughly warmed up -- and the best way to look at that is not with your wristwatch, but with the stack temp. If it hasn't stabilized, the boiler hasn't either. If it has, it has.

GBart

Right and it doesn't take long, a few minutes at best, I would check the pump pressure, ignition and safety in one combined moment, fire unit, check settings and fire by eye, set up combustion test equipment and it's ready by that point, done.