Heating woes Dunkirk vlt

Mcmonster508

I had a wall mount Dunkirk vlt gas boiler installed about 4 years ago, everything worked relatively( it kept popping error codes almost every night) but still did the job most of the time well up until last year when we had it serviced for the first time
Since that service was performed it hasn’t gotten a single error code but I have multiple issues that I can’t seem to diagnose

1. It short cycles(I think that’s it) it calls for heat and starts the ignition process by ramping the fan up to 58% and gradually decreasing to 1% and then restarts the ignition process... the issue is it doesn’t happen all the time and it does it on both zones and sometimes when dhw call is made(much less often though)

2 it is sometimes very loud and makes my pipes vibrate while running, when the fan is running over 34%. This is usually also making a weird sound when it’s cycling.

3. It foghorns 90% of the time when Calling for heat

I did a little research and saw that it could be my nest thermostats that could cause these issues but noticed that it’s only ones with yellow red and white wires and I only have red and white wires so I
Not sure this applies to me.

Any help would be insightful.
Thanks in advance

Zman

Has a combustion analysis been done?

Mcmonster508

> @Zman said:
> Has a combustion analysis been done?

It has. I don’t remember the results though. It was last year.

Ironman

Short cycling could also be caused by micro zoning, but a Nest should never be used with modulating equipment.

The noisy pipes could be a result of air in the system or from steam flashing in the heat exchanger.

Fog-horning is caused by the use of CSST gas line and combustion being too lean.

The things listed above are the general cause for these issues. You mileage may vary. Please note that, as is the case 95% of the time, they are all installer or tech issues, not the boiler.

Please post some pics of the boiler and its near piping from far enough back to include everything so we can better see how your system is set up.

Mcmonster508

> @Ironman said:
> Short cycling could also be caused by micro zoning, but a Nest should never be used with modulating equipment.
>
> The noisy pipes could be a result of air in the system or from steam flashing in the heat exchanger.
>
> Fog-horning is caused by the use of CSST gas line and combustion being too lean.
>
> The things listed above are the general cause for these issues. You mileage may vary. Please note that, as is the case 95% of the time, they are all installer or tech issues, not the boiler.
>
> Please post some pics of the boiler and its near piping from far enough back to include everything so we can better see how your system is set up.

Here are some pictures of the boiler and setup

Mcmonster508

Sorry here they are

Ironman

That's a pretty good looking installation.
Regarding the piping noise: make sure the internal ball valve is open so that your system is configured for p/s, not series.

mattmia2

Did you mention the errors to whoever did the service?

Is the t-stat connection on that boiler even 24 vac, or is it designed for dry contact only?