Programmable thermostat

realolman

I have a honeywell CT3451 programmable thermostat.
there is a section in the manual that describes setting a number in the "Heat Cycle Rate"

1.. for steam, gravity

3.. hydronic heat, condensing gas furnaces

6.. gas or oil forced air (default)

9 .. electric heat

4,5,12.. Special applications


what does this mean?.... there is no explanation of it in the manual

Weezbo

it is written ....in Squint eese...

you cannot possibly read that ...well,...maybe,.. you bad , have a large spectroscopic combo electron microscope small cray and digital analyzer...YOU BAD ...

however it basically means ,..that certain types of emitters require a little more attention than others.

the t stat can be given a bit more authority in the matter when it has work done to it...
the t stat by being warmed up a bit "thinks "as it were that the temp in a room needs to be checked a little more often than not.

realolman

would this setting

have anything to do with why my oil boiler runs 33 times a day in 40 degree weather?

Timco

Hot water or steam? The anticipator would not control that. Just overshooting the set temp...

[edit] unless you are losing heat real quick!

Tim

Steamhead (in transit)

It might

what type of system do you have?

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Kevin_in_Denver_2

Heat cycle rate is cycles per hour

If you have a steam system the thermostat will enforce a limit of only one cycle per hour, 6 cycles for forced air, etc.

This replaces the old "heat anticipator" of analog thermostats, and theoretically does a much better job.

realolman

I have

a burnham v74 12 yr old, hot water, 140 psi pump, 1.0 GPH nozzle. , cleaned every year, 2 circulators, mostly baseboard, 2 radiators. The house is in good shape ... insulated, andersen windows, 12" in attic... I do have a lot of windows and doors, though.

I have been trying to figure out why I am using so much oil, and have hooked up some sensors to my boiler. I had no idea it ran so much. In the attachments, the red vertical bars are when the burner runs. with a list of them in the text boxes. The blue line is the outdoor temp.

In the graph the red line is the boiler temp , purple is the stack, green is one pump return and blue the other pump return. The high limit is set at 150 with a 10 deg differential. The graph was made this morning when the house is recovering from being set back over night.

Last night I set the cycles per hour on the thermostat to 1, just to see what it would do. In 12 hrs, the burner ran 29 times.
There are two thermostats that run the burner. If the thermostat calls, and the boiler temp is not above high limit, it runs. It could be that the other thermostat called, but it is set pretty low and doesn't run much ( I don't think ). I still want to hook up both thermostats so I can tell which one is doing what, when.

I appreciate any and all your input.... thanks.

Weezbo

that is some pretty fancy graph or two

i didnt study the graph as long as i should however i noticed a (what i consider high) stack temp...and the run times were like 6 mins or so... the boiler temp seems like a good number.. the return temps to me seem like the comfort level must be reasonable.. have you considered changing the piping near the boiler? is it a new burner?

sorry i went sideways to your question ...the t statswhen you have slightly different heat emmitters makes it something of a bugger as to what to dial them at...you might have to go with the idea that the type of emmitter that you have the most in a room is the logic to use...until you maybe throw in a few t's and a couple sections of pipe and a pump or two....

you been at this a while,...Glenn Stanton is the Burnham guru here. he is sorta big on boiler bypasses as am i. i likestation and system by passes alot also:) the v 7 probably has a burner on it that likes high stack temps to me longer run times of the circulation of water at lower temps and boiler protection with the stack temps lower would be something that would be a good thing for you...and seeing as you are into the maint..of your boiler i might have two nozzel sizes around for winter and the shoulder seasons...

psd_3

Your data is focusing on the "raw" input side of the equation. To understand what's happening, you need to focus on heat loss and efficiency also.

Have you done a heat loss analysis for a day that averages about 40 degrees? What is the design day temperature for your system? From the plots you show, it looks like you would have trouble handling a really cold day without sacrificing inside temperature.

Have you measured the efficiency of your system? Your stack temperature looks very high during the majority of the on cycle (700 degrees!). My stack temperature peaks at 345F and averages <250F. Perhaps your heat exchanger is fouled and your BTUs are going up the stack instead of into your distribution system?

The tight spacing of heating cycles when the outside temperature is at 50F suggests that you are using a daytime set back, or have high domestic hot water demand in the late afternoon or early evening. You may need to account for domestic hot water usage also ... especially if you have multiple family members that like to camp in the shower.

My house is 2400 sq ft with similar windows and doors. I keep the inside temp at 68-69F during the day and ~64F at night. I use a programmable Honeywell Chronotherm IV. On a day that averages ~40F outside I use <2 gal of #2 fuel oil. My heating system operates at an efficiency of about 87% with minimal standby losses. I use an outdoor reset control to regulate boiler (source) temperature.

realolman

Thank you very much

for looking at this so carefully.


The things you mention are why I put the sensors on in the first place. I wanted to see how much of the heat that should be in the oil was getting into the water.

The heat exchanger is definitely clean on the fire side. I think I'll have to try to do something on the water side.

Wayco Wayne_2

Heat loss

would give valuble information. If boiler was oversized it would short cycle. The short cycling would cut down on efficiency. An apt comparison is what stop and go traffic do to your cars mileage, as compared to city driving. I don't know how you are piped around the boiler. Maybe a buffer tank would help. WW

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Wayco Wayne_2

I forgot to add

that with hydronic systems it is ususally helpful to add an outdoor reset control on the boiler. A design that uses constant circulation through the heat emmitters would also add to comfort and efficiency. Most designs aim to get 20 degrees temperature across the heat emmitters. Maybe the circulator is not sized properaly. Your differences seem to be larger than 20. WW

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Techman

Your system

With two stats ,each set at 1 cycle per hour,you could get upto 48 cycles per day.With the 2nd stat set low( how low?)you are bring back cold water(how cold?),and having the hi limit at 150* w/ a 10* diff ,I think that would cause short cycling of the burner.Also,on the 2nd stat zone ,is it possible you have "ghost flows" thru that zone?Just curious!

realolman

thanks

thanks thanks.

The stack temp is too high though isn't it?
You could really get a 300-400 stack temp with a burnham v-74???


The nozzle is already downsized from 1.1 to 1.0.

The flues are clean. I am beginning to really think it needs flushing / boiling it out with something on the water side.

Bernie Riddle_2

Cycle times look fairly reasonable -

The green return does look odd ... a 40 degree drop with about 8 degrees of variation. The large drop and small variation could be due to poor circulation, but then you'd be retaining heat in your boiler (hopefully ) which would slow down the cycling. Perhaps this loop isn't carrying its weight and your other zone is trying to compensate. This could happen more readily if the T-Stats were partially influenced by the temperature of the adjacent zone (located in a drafty common area, or on a dense wall heated by the adjacent zone). This would be easily detected because one zone would overheat and the other would never satisfy.

If this behavior started with the installation of new T-Stats. then make sure the T-Stats did not get cross-wired somehow ... T-Stat1 controlling Zone2 and T-Stat2 controlling Zone1. Perhaps the small temperature variation seen in the green zone is due to gravity turnover and not active heating, while the blue zone is attempting to carry the load but can't communicate the heat effectively to the other T-Stat.

If this is not the case, then you're dumping lots of heat in this green loop somewhere.

Still don't like the high stack temperature ... means low efficiency. Check the heat exchanger and for excessive draft.

It's time to study where the BTU's are going with a complete heat loss analysis.