Another question on possible short cycling, and maybe a solution?

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Old 03-01-13, 05:15 PM
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Another question on possible short cycling, and maybe a solution?

Burnham boiler ESC HW with 1329 hours and 13168 cycles. That's almost 80,000 minutes for 13168 cycles or 6.05 minutes per cycle. Is that within limits?

It cycles a lot more often than I'd expect, especially in the shoulder seasons. Delta t is pretty consistent at 20F. It does a great job keeping the place comfortable.

The ODR at default setting is commonly calling for 165 +/- 5 degrees. Was contemplating reverting to the old boilers setting of 160 spring and fall and 175 dead of winter controlled manually (without the ODR) and resurrecting the HW+ Intellidyne device salvaged from the old oil boiler to control short cycles.

Would that be wise, or are we better off with things as is?
 

Last edited by thatoldguy; 03-01-13 at 05:16 PM. Reason: typo
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Old 03-01-13, 06:01 PM
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As a point of reference, if it helps any...

My new MPO installed October last:

RUN 508
CYC 4556

For an average per cycle time of 6.69 minutes.

This is the run time from the IQ control. My external ET meter reads 545 and this gives a per cycle time of 7.17 minutes.

I don't understand why there is a discrepancy between my external meter and the IQ control, but it seems to be a constant offset of about 35 hours. It's possible that the IQ doesn't start 'counting' until the boiler has run for 35 hours or so...

The ODR at default setting is commonly calling for 165 +/- 5 degrees.
What do you mean by 'default setting' ?
 
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Old 03-01-13, 06:05 PM
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I don't think a 6 minute cycle is terrible... but of course that's average so I suppose it means that the cycles during the shoulders might be considered 'short'...

How long has the boiler been installed?

Do your heating calls routinely hit the high limit before thermostat satisfies?

Are you using the 'Pump Over Run' setting?

Did you make any change to the ' df_ ' (diff) setting?
 
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Old 03-01-13, 07:25 PM
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Does the ESC have an indirect water heater attached?
Is it common to see water temps much lower in the shoulder seasons?
What is the set-up? How many zones and how are they controlled? Do you do night setback? Have you change the ODR settings at all?
 
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Old 03-04-13, 01:13 PM
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I was wrong. For two years I thought the ODR was set to default settings. What do I know?

ODR:
Boost time 20
Low outdoor temp 0
High outdoor temp 70
Low boiler temp 135
High boiler temp 185
Minimum boiler temp 120

Boiler:
High Limit 181
HDF 30
Run time 1342 hours
Cycles 13299

As I read the manual it states that for convection baseboard fin tube the high boiler temp should be set to 160-190.

We have two 80' baseboard fin zones, controlled by a common Taco 504 relay box and each zone has it's own Taco 007 pump. Pump over run time questioned in a thread was disabled by the Taco 504. Exposed pipes in the basement are well insulated. The hot water heater is a free standing old tank, not connected to the boiler.

Historically, I had the old boiler manually set to around 160/165 shoulder seasons and 180/185 dead of winter and that worked pretty well. I'd turn it up higher on really cold or windy days. As is expected with the ODR, the night setback is minimal and set to 2 degrees, it used to be 10 degrees.

I'd be happy with those settings manually set on the new boiler and adding the old Intellidyne HW+ to control cycles, if it'd be advantageous over the ODR.

It's a chilly mid 1800's house. The old wood floor radiaties cold from a chilly basement despite fiberglass within the hewn 3" x 6" joists and I don't think that was accounted for in determining the boiler size. The boiler is installed neatly and close to what the install manual recommended; only some unions are missing.

So in your expert opinion(s), is this cycling as it should and would we be better off with the ODR or the Intellidyne?

Added: If it's significant, use in December was 134 therms, January 117 and February 104 for heat with posted use adjusted to reflect other appliances. We used to use about 500 gallons of oil annually with a 1970's boiler.
 

Last edited by thatoldguy; 03-04-13 at 02:23 PM.
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Old 03-14-13, 03:12 PM
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Selfeshly bumping this as it seems to have fallen overboard.

Any thoughts on question apprecated.
 
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