NTI Trinity T-200 Boiler Noise

Southside

I'm a homeowner/DIY guy but this one is fairly obvious. As you've noted there is instability at lower modulation rates.

I'd suggest a cleaning and combustion analysis & re-trim. It seems that most folks recommend annual service on the mod-cons so it's time to do that anyway.

I don't know if an agressive combustion (explosion) is likely but the flame instability can draw CO into the house. A CO detector is a good thing...

boilingmad

NTI Trinity T-200

When my NTI T-200 Combi boiler fan runs at a low speed, there is a very loud noise which resonates through the exhaust flue - sounds like someone blowing a long sustained note on a tuba! This usually happens when the boiler is heating the radiant heating water but it has also happened when the domestic hot is used and the fan speed is winding down to slow. When this happens, I've noticed through the peek hole what appears to be roughly pulsating blue flames. When I turn on the domestic hot water and the boiler fan revs up to high speed, the noise stops. Since this very loud and scary noise only happens when the fan is operating at very low speed, I'm assuming that for some reason there is improper combustion occuring when there is a low demand for propane in the boiler. Am I on the right track and what should I do about it? The boiler hasn't been cleaned for about a year and a half - could this be the problem or is it possibly a problem with the Sentry computer? Is there any danger of explosion?! I've also noticed that when after turning off the domestic hot water, combustion continues in the boiler for about 30 seconds or so. Is this normal?

service guy

I have seen this happen with Ranni units. It was improper venting. In your case i would call Trinity themselves & speak 2 tech support.

Plumdog_2

Major Confusion

In your third sentence; you state that unstable combustion can draw CO into your home. I would presume, then, that the CO is outside, and the combustion fan is sucking it to the indoors? I always thought the fan sucked in fresh air and blew products of combustion to the outside. Do you live in New Jersey or somewhere like that?

Southside

It'd be nice if the boilers were sealed units. Certainly the Munchkin isn't. Sure it draws outside air but the intake is open within the boiler housing and the boiler housing is not sealed. Instability can draw combustion products into the home. If you run a few experiments you can demonstrate it for yourself. Go for a over rich condition at low blower speed.