Modcon Heating Cycles Per Hour

Danscrew

I hear what you are saying

I have plenty on the top end. When I purchased it I listened to the sales man size my load not knowing much about Mod/Cons as I do now. I would like to find a 027 orifice Like the one they use in the 70.  Honeywell makes the Venturi and the gas valve is it possible to buy the venturi housing or orifice? Weil Mclain wants to sell you gas valve and the venturi for $160 I just need the Orifice. as far as warranty i would take the gamble   thanks Dan

ced48

Is It All About

equipment lifespan? Because isn't it true, that as long as we are satisfying the building's heat loss, as well as maintaining a comfort level, who cares wether the boiler is on once an hour, or once a day? In fact, logic tells me it may use more energy, factoring in electric usage, as well as perhaps less efficient use of colder water in a baseboard situation. I was also wondering how often are you guys replacing gas valves and blowers on on demand dwh systems? Those things run 30-50 times every time some one washes dishes by hand, not?

Gordy

Equipment cycling

Does shorten the life of the product.



Fans , gas valves, circs etc.



ECM circs need to be implemented with the design.



The average person does not care true. Comfort is the goal. So is load matching.

Gordy

Think of it like this

The human body is in a constant battle to maintain a setpoint in which it is comfortable, and functions. The heart, and blood flow does not ever stop when set point is maintained, other controls regulate temperature. Of course it has it's limits, and the body is supplemented by clothing, shelter etc.

ced48

After a -2 Degree Night-

and a lot of fretting over ORC, I think you guys are a bit out there, thinking you can fine tune these systems so the boiler is running efficiently, and non stop, almost of the time. When I was down at design temperature, let's call it 0-, I was running 140 degree water, and heating just fine, with some off time, but much more running than off. I reset the water to 135 degrees, and could maybe maintain temp, but felt like it was slipping. So, I went back to 140, and to sleep. Yes, I could have tried 137, 8, but really, is this practical? This system is in my own home, so I could fool with it forever. But how could I ever do this foe a client? I can't move in.



There also seems to be way to many variables, things like solar gain. Also, it seems unlikely that this settings are all linear. Getting the bottom right, doesn't mean the top, or more likely, the middle will work. And what if the home owner changes the thermostat setting 1 degree, it won't work.



I would like to hear from others who are living with a Modcon and fin tube baseboard. Maybe we can come to some reasonable expectations of how best these systems can run in reality, not theory. I am have no doubt, that some of you guys have been able to fine tune to the degree you say, but what about the rest of us hacks?

Danscrew

Well said Ced48

My wife calls me the Boiler Guy LOL. She keeps asking me if there is something wrong with it? I keep going down the basement to fine tune it.     I just installed it in October I have a hard time understanding the efficiency of a running boiler compared to a boiler that is off there is no better Efficiency then one that is not running compared to one that is running at it's minimum ?  What are the best Practical Parameters of run times and off times for these type Boilers?

Gordy

Was-2

A design day for you? If so was it -2 for 24 hours?

Gordy

Math

14000*24 =336000



110000*3=330000



Your boiler will burn more efficiently for a long period than banging on and off for short periods. Cycling kills components.



Like Kurt says dump the zoning.

ced48

Dan, We Are Both

in the same boat-My boiler is in our den, five feet away from me. It is driving me crazy, and Mrs. Ced even crazier. I sleep with ear plugs, so not to count the minutes between on-off cycles. My system is really running pretty darn well, but perfection is the beast that haunts-The thing is a marvel to watch run, but sometimes I wish for the oil guzzler back. Life is to short to be obsessed with BTU's, and blower fan lifespans. We should start a therapy group for guys we our problem-



Gordy- More or less, call it zero-No temperature was not -2 for 24 hours, did feel like it-My point has more to do with the fact that unless a computer is doing the fine tuning, not going to happen-One other variable I am noticing, baseboard BTU charts are not accurate. They are fare less lineal than they report. They loose more in BTU's as water temp is decreased, than published. Also, higher water temperatures allow the baseboards to continue to heat longer after shutdown, something I did not factor in.

Gordy

Ced

When I refer to a boiler running flat out 100% modulation at design conditions that would be for a 24 hour period design condition which rarely happens. IF you are lucky enough that a boilers modulation matches your heat loss at 100% as it ramps down through lower modulation points it can if controlled right match lower loads non stop until you get to shoulder season in fall and spring.



Of course it's theoretical you have to start some where, and always start with perfect. From there you do the best you can with what controls, and strategy you implement.



It was not the intent to drive anyone crazy in achieving the theoretically superior system, but this is a good thread to take note that a lot of times we end up with an oversized boiler even though a proper heat load was done. Padded calcs through input, and program.



We always tend to favor extra output even though it's probably not necessary. From an installers point no one wants to chance an install that could put them in a position of a system that chances under performing for a customer.

SWEI

Fin-tube baseboard and outdoor reset

Will take some experimentation to set the ORC properly.  Its actual response is a curve, so fitting the typical onboard boiler ORC (a straight line) to it is a matter of trial and error.  There's definitely a "bottom" where performance falls out for every emitter type, and that happens at a higher temp with baseboard than with most other types.

sandeen

Jean-David Beyer said:

I sure wish I could hook up my computer to the U-control on my boiler so I could read out everything that shows on the front panel.

Maybe you can, check out my hack at http://sandeen.net/wordpress/energy/residential-boiler-monitoring-via-modbus/

Abracadabra

sandeen said:

Jean-David Beyer said:

I sure wish I could hook up my computer to the U-control on my boiler so I could read out everything that shows on the front panel.

Maybe you can, check out my hack at http://sandeen.net/wordpress/energy/residential-boiler-monitoring-via-modbus/

wow... sweet project! Now all you need to do is add a cheap 7" display to the rpi and display the graph in real-time!

sandeen

The image above is a screenshot from a webserver, so I actually can see it in realtime, from my laptop.

extremetemps

Hi Jean-David -

Does your boiler controller have a modbus interface? I have a NTI boiler that does, and I am able to read out all of these parameters with a Raspberry Pi. I'm still in the process of trying to optimize everything but it certainly is nice to be able to access the data. If you do have a modbus interface, I would be glad to try to help you with the hardware/software setup.

Regards,
Jason

sandeen

Jason, have you read over my link to the blog post above? I'd love to add an NTI collectd/modbus config file to the mix, if you wanted to give it a shot. Sounds like you already have most of it set up.
-Eric