Please criticise my boiler

SuperTech

I'm looking for criticism and suggestions for improving my boiler. Please refrain from suggesting that I replace it with a more efficient three pass/system 2000. I'm not ready for that yet.

I have a Peerless WBV-03-110-WPCTL with a Beckett AFG F4. I'm running a .85 80B nozzle at 145 PSI pump pressure. Oil is supplied from an indoor 275 gallon tank, gravity fed through a general 265-1A filter to a 1/2" coated copper line that goes to a Tiger Loop with a 10 micron spin on filter. Burner is equipped with a clean cut pump set up for 15 second pre purge and 30 second post purge. Primary control is a Honeywell digital R7284. The aquastat is a Honeywell L7224U equipped with the outdoor reset module. Design temp is 15 degrees. High limit is 180. Cold start boiler, separate water heater. Never had any issues with it being cold start.

Latest combustion test results are Stack temperature is 505 degrees maximum, 5.8% O2, 4 PPM CO, 11.28% CO2, 28% excess air. Draft over fire measure -.01" to -.02". Draft in the breach is -.04 to -.05. masonry chimney

Boiler piping is a monoflow split loop. All piping is completely insulated. Boiler pressure is 18-20 PSI. Circulator pump is the Taco 007 that came with the boiler, installed on the return. Emmiters are all cast iron baseboards with the exception of one cast iron radiator in the bathroom

I'll post a picture so you guys can see the boiler. Any suggestions for improving the existing configuration for maximum efficiency and performance would be much appreciated!

EBEBRATT-Ed

Sounds good as is to me. You combustion ##s are good.

I only have 1 suggestion. Do a heat loss and or check the radiation load and see if you can reduce the firing rate. Make sure the burner parts are correct for a smaller nozzle if you decide to downfire

SeymourCates

@SuperTech

Good evening,

What is interesting about your machine is that someone had the intelligence to downfire it already. It was delivered with a 1.1 GPM nozzle and it now contains a .85 GPM nozzle. My thought is that is can run with a .60 nozzle as this machine is also indicated in the catalog for the WBV. For those who have difficulty understanding this concept, the same boiler is downfired from a 1.1 GPM nozzle to a .60 nozzle with no ill effects and per the manufacturer.

Naturally, this should be setup with a combustion analyzer to ensure the airflow is sufficiently reduced to match the reduced fuel rate and it would also be advisable to use a nozzle line filter on the Beckett to prevent any issues with the tiny nozzle.

The .60 will deliver 75K which is surely more than you need on the design day. The smaller nozzle reduces the stack temperature resulting in more transfer of energy to the circulating water.

In addition, I would experiment with a reduction in the high limit from 180F. to 165F. The worst outcome is that you won't quite hold room temperature on the design day with the necessity to push it back up toward 180F. if you must. Don't run higher water temperature than you need.

clammy

If your gonna downfire that beckett check your combustion # u may need to add a low fire baffle to get your excess air # down if u downfire the nozz;e peace and good luck clammy

Big Ed_4

.85 GPH @ 100# pump pressure .... .85 GPH nozzle with 140# pump= .95 GPH input. close to max

EBEBRATT-Ed

@Big Ed that's right

SuperTech

It's funny that down firing was suggested. I actually tried that earlier this week. I tried installing a .65 nozzle. Of course I had my pump pressure kit on the burner and my Testo 320 in the breach. I had to cut the air back so much that the shutter was closed and the band at zero. Even like this my O2 and excess air were high. So I increased the pump pressure to about 155-160. I know I should have had a low fire baffle installed, but I didn't have one handy

My problem with this is that the stack temperature didn't get much higher than 420 degrees. And my CO during light off and especially shut down spiked quite a bit, even with the post purge.

I like keeping my boiler clean and really don't want concrete in the flue as a result of condensation. I was taught to keep the stack temperature between 450-550 if possible. Maybe a .75 nozzle would have been a better choice. But it seems like I found a sweet spot for this boiler with a .85

Steamhead

At 420° F you shouldn't be condensing in the flue. A 0.60 nozzle at 140 PSI gives you 0.71 GPH- well above the minimum for that boiler. You would need the low-fire baffle, part# 5880, to make it tune up properly. You also might need to change the burner head to get good combustion results- the F3 that you probably have is only rated down to 0.75 GPH. Either that or use a 0.65 nozzle which would give you 0.77 GPH at 140 PSI.

Do your heat-loss calc and if that firing rate will meet it, I'd leave it there.

HVACNUT

With stack temp, are you stating gross or net? 350 net is not uncommon on the WBV.
With an F4 head try .65 60A and adjust the pump pressure to match the boilers lowest firing rate for the AFG.
I believe the lowest firing rate for the WBV3 is only achieved with the Riello F3.

rick in Alaska

If it was a boiler I was working on, I would absolutely try to get the stack temperature down a lot lower. I shoot for 325 to 350 net and don't have any problems with crud in the flues, or condensation issues. I sure wouldn't want to be sending all that heat out the stack.
The low firing rate baffle on the beckett makes all the difference in the world on setting it up right if you are downfiring too much. There is a point where you would have to change out the combustion head depending on what nozzle you use, but i can't remember the break point.
Rick

EBEBRATT-Ed

Like I said heat loss calculation first. Then you can get the parts and make a smaller fire work. If you stay above 325-350 you will be fine. Longer run time, less starts and stops, lower stack temp=better efficiency.

Co can come from a lack of air or to much air. To much air will chill the fire and drive the Co crazy.

Leave it alone if you want to, your #s are good. If it was mine and the heat loss would support it I would downfire it

SuperTech

This is all great information. I've been worrying like crazy about flue gas condensation and thermal shock to my boiler since installing ODR. But I've had it two years now and my boiler sections and flue pipe remain clean as a new boiler.

I was taught to keep net flue temps above 450, but if others haven't had a problem with lower temps, I'm in favor of trying to be more efficient. I've obtained a low fire baffle for experimenting

SuperTech

My mistake on the flue temperature, I was taught to keep Gross flue temps at 450 by an old timer.

SuperTech

One other thing that I would like to hear the opinion of the community about

Given my cast iron boiler and single zone high mass monflow system, would the performance of my system benefit from the installation of a ECM circulator such as the Viridian or Alpha?

Given the variable Delta T performance of the Viridian, would installing this pump help with boiler protection?

hot_rod

An ECM would use less electricity, so some efficiency gain there. Not a lot of advantage on a single zone system as far as the pump modulating.

Keep in mind there is a bit of pressure drop in diverter tees, so the circa needs to be sized with that in mind.

It is always best to pump away from the expansion tank location.

Here are some other Monoflo tips.

http://unitedstates.xylemappliedwater.com/2011/04/30/monoflo-know-how-from-bg/

SuperTech

Thanks hot rod. I've been reading a lot of your previous posts regarding boilers. I appreciate you passing on your knowledge.

hot_rod

SuperTech said:

Thanks hot rod. I've been reading a lot of your previous posts regarding boilers. I appreciate you passing on your knowledge.

Thanks!
It's a group effort here at HH, The collective wisdom is mind boggling

SuperTech

I decided to try to down fire my boiler again and see what kind of stack temperatures I would get.
I was running a .85 80B nozzle on my burner with an F3 head. I tried a .75 nozzle first, then I installed the low fire baffle and installed a .65 80B. These are the results after I disabled outdoor reset and ran the burner until the stack temperature peaked.

Of course with outdoor reset enabled I don't think the stack will get to these temps except on the design temperature days.

I'd like to install a thermometer in the breach permanently so I could monitor the temperature without my Testo 320. I am still concerned about flue gas condensation

EBEBRATT-Ed

Stack temp down about 60 deg reduces heat lost up chimney. As long as it will heat the space it's fine. You will get longer run times which is good. Less cycling=less ware and tare. You don't need to worry about condensation

SuperTech

Time will tell if this works out, after reading countless past threads on the topic the other thing that bothers me is the opinion of Jim Davis, who I respect quite a bit, that lower stack temperature isn't always going to be more efficient.
But also the burner should be fired according to load on the boiler and my research leads me to believe that I'm better off with the .65 nozzle.

EBEBRATT-Ed

Manufacturers put out specific testing and efficiency #s because they have to meet certain standards including firing rates. They also have competition to meet. Rarely does a boiler exactly match the connected load.

Some read the manual and rigidly follow the manfg instructions and insist others don't deviate least you end up in hell. Whatever. I find closed minded mechanics have difficulty solving the most difficult problems.

I have a much different approach. I always start with what the Mfg wants. I set it up and install it their way. And most of the time it stays just like that. If I don't like the way it's running I have no problem tinkering.

Why? I have repped burners and other equipment. The lab is not the same as the field. Fuel temperature, air temperature. oil quality, draft etc etcetc introduce variables that need to be "adjusted out" and I have seen many, many, many jobs where the equipment ran like crap when the installer strictly followed the mfg instructions. Changes hade to be made.

You don't have that problem. Your boiler was fine the way it was (most likely with your knowledge much better than most). Nothing wrong with matching the load and increasing the efficiency.

As you said,, time will tell

SuperTech

Yup. Years ago I was that way. Every furnace and boiler had to have the nozzle specified by the manufacturer, because the engineers know more than me.

Now after seeing plenty of examples of the manufacturer specs not working in the field, I try my best to get firing rate to match the load on the system. I trust in my experience and so far it has served me well. Buy everyday I strive to learn more and become a better technician.

SeymourCates

@ SuperTech

Well done. You maintained efficiency by reducing air and fuel simultaneously resulting in a lower stack temperature and, obviously, less energy delivered up the stack.

There really cannot be any discussion regarding the greater efficiency of the smaller nozzle. It would be physically impossible to deliver less energy to the atmosphere and conclude that the efficiency falls.

SuperTech

After watching my boiler for few days I see the burner comes on and runs a little bit longer and I don't have short burner cycles like I did with the .85 nozzle that I was running.

And with the boiler running with a stack temperature around 400 degrees I don't think flue gas condensation will be an issue. This will definitely be a performance and efficiency upgrade.

I'm considering getting the variable Delta T circulator pump. I think that would be an upgrade over the 007 circulator pump I'm using.

Steamhead

Looks good. That's a 0.65 at 145 PSI, correct?

SeymourCates

@SuperTech

Do yourself a favor and check the DT for the system. If you find the DT is less than 7F, consider adding a globe valve to slow the flow from the 007 to bring the DT up to about 15F with all zones calling.

The VT2218 is an excellent product but it's generally overkill for a CI boiler that is highly tolerant of a wide DT range. You just do not want to seriously overpump it.

SuperTech

Yes it's running 145 PSI pump pressure, I didn't change the pump pressure on any of tests.
Delta T check will be performed later today. I'm wondering how the emmiters have been performing.