2min. run time

canuck_4

I have an NTI Trinity T150 mod/con boiler. The house is nice and warm and I have had no issue's to date. My only question is I noticed that the boiler only runs for 2 to 3 minutes to maintain the desired temp 69 degrees. Is this normal. Should the cycles be longer? If I drop the thermostat at night by 3 or 4 degrees and raise it back in the morning it runs steady (20-30mins.)until temp is reached. Then to maintain the desired temp it goes back to short cycles of 2-3 mins? Is this part of the efficiency of new boilers?

Brad White_2

At least

you got two or more minutes of run time.... some cycles are shorter, 30 seconds or less sometimes.

What you are seeing is "normal" in that the heat loss at the time is a fraction of even what the minimum output of the boiler is.

If the heat loss were higher (say during a warm-up period) you can see how it goes. Once at temperature the load is marginal especially if it is relatively warm outside.

If the heat loss is above the minimum modulation range of the boiler it will at least modulate. You are below that so the choice is on or off.

It is for this reason that we implore installers and homeowners not to over-size their equipment.

canuck_4

Thanks

Thanks Brad - Wow talk about response time. This site is ggggreat. I am happy to hear my situation is normal. I took a chance in 2006 installing this boiler (NTI Trinity) as the heating company was pushing this as new technology in North America. I paired it up with an indirect HW heater. $8000 later I said to myself this sucker better work well. SO far so good , nice and warm even in our cold Canadian winters.

Cheers,
Mike

zeke

Depends on the outside temperature and your thermostat;seems to indicate your boiler is way oversized and/or your thermostat is improperly set where the "swing" temperature is set too low or the cycling time is set too high. With outdoor reset ( if you have it) and a proper thermostat, it should be a lot longer, no matter what the outside temperature.

On the other hand, if the outdoor temperature is balmy, say in the high 50's 2 minutes would not be unusual. Post the outdoor temperature and the total time for a cycle, whether you have outdoor reset and the variation in indoor temperature during the test and then we can make a better assessment.

canuck_4

2min run time

Outdoor reset = yes
Outdoor temp= -5
cycle time = 2 to 3 min
indoor temp = 69

* Older home with leaky doors and windows. I am wondering what the tolerance of my thermostat is? Does it kick on when the temp is 68.9?

jp_2

that too could be

a problem, how your thermostats reacts with the boiler and ODR?

zeke

Sounds like your tstat is set too low on "swing". Once the tstat is satisfied, the burner should not go on again until the house loses about 2 degrees. In your case, I'll bet it is losing a fraction of a degree, and thus causing the high cycling rate, Readjust it or get a new one that has "swing" capability.

I assume you understand cycle time. It is the SUM of the "on" and "off" times, so your 2 minutes of "on" time with with a cycle time of 3 minutes suggests that your "off" time is 1 minute. Please comment or correct this observation.

canuck_4

I haven't measured the "off" time between cycles but I think your right with the T-Stat. It only loses a fraction of the "hold Temp" then kicks on. If the swing range was set at 2 degrees it work less often. I have a digital Honeywell T-Stat but can't see where I can set the "swing" range?