short cycle

Rich_2

I hear the term 'short cycling' used , can I get a explaination of what that means

Mike T., Swampeast MO

Can't define it in terms of time but...

...three major causes are an oversized heating plant, small zones calling singularly and an improperly adjusted thermostat anticipator.

Some problems it cause are excess wear on the equipment (gas valve, igniter, etc.), and efficiency loss.

A well-insulated buffer tank is an effective (if somewhat stop-gap) solution to a terribly oversized boiler--you can think of "micro-zoned" systems as having such as well.

The mass of the system as a whole and the speed with which the emission device(s) liberate their heat play a huge part in determining the "normal" cycle time for any given system.

Joe_30

Mike, would outdoor reset help? I also get some 5 minute runs and some 30 second runs.[ Five zones in a not so big house...2,400 square feet plus basement].

We used a 130K input [110K net] Buderus boiler to meet a design 95K load here in Minesota where we have some COLD weather and some long milder swing seasons..

Does reset work well with zones?

If it does not hurt the boiler, the heart of it all, does it really matter.

Rich_2

short cycle

Which "part" is "short" the run time or the off time? A friend of mine had a new utica installed with a storage tank I don't remember the btu but the firing rate was 1.25 it seems like he's burning alot of oil.We first thought he had an oil tank leak (in ground)then we thought about down firing maybe 1.00 ,but he tells me it runs alot, he has three zones nothing big. We haven't done anything yet

hot_rod

It's important

that the boiler HX and entire flue warm up beyond the condensing temperature. Continous operation in the "cold" mode will lead to vent corrosion and potential HX failures.

I have heard folks say the Buderus can handle return temperatures in the 100 F range. I'm not convinced this is possible on a continous basis. And still you need to warm the vent up beyond the temperature where it condenses, prefferbly on every cycle.

I'm not sure there is an exact time figure for what constitues a short cycle. I like to see a minimum of 10 minute burner on cycles for cast or copper boilers. The longer the cycle the less wear on the components involved. Ideally on a design day, a properly sized boiler would run continously. This article polled some experts to get an idea on cycle times. As you can see opinions varied.

http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,7658,00.html

Reset can help your system if properly installed and set up.


This is another good article that explains modern day boilers and the issues, further.


www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,90176,00.html

hot rod