CH- Anti-Cycling on HTP

Suzook

Tryinng to cut down some of my cycling of my htp uft 80. I have adjusted my odr, to the best of my ability, i have it running almost constant, but still have some turn offs. There is an anti cycle setting. Im confused about it. Wouldnt turning it up to 30mins, means it runs 30 mins longer? Or should i turn it down closer to 1 min?

Edit, so i guess when set to 30, once fired, it will fire for 30 mins. I guess i need more adjusting of my ODR, and/or my combustion rate.

Leon82

With a 30 minute delay between firings you run the risk on not keeping up with the heat load. Depending on the amount of control options you may be able to limit the max fan speed or firing rate

Suzook

Leon82 said:

With a 30 minute delay between firings you run the risk on not keeping up with the heat load. Depending on the amount of control options you may be able to limit the max fan speed or firing rate

Ok, so I'm understanding it wrong? It means it won't fire for 30 mins, as to what I was thinking as it would fire a minimum of 30 mins? So I guess I will actually just shut the anti cycle off.

fenkel

You could turn down the  heat output btus.. see page 52 of install manual
Has a heatloss calculation  been completed?

Suzook

fenkel said:

You could turn down the  heat output btus.. see page 52 of install manual
Has a heatloss calculation  been completed?

It's down to 70%, yes heatcalc was done. It runs almost constantly in the winter, but late fall and early spring lots of cycling. So I'm thinking odr needs adjustment. How do I get lower water temp, at higher outdoor temp? I get confused.

fenkel

 
The only other question would be what is the design temp?
The other possiblity would be to.change your outdoor reset setting for fall,winter and spring..
But i think a buffer tank would make it a one time setup with no seasonal adjustments...

Suzook

Here's another idea. I have 2 zones. My upstairs is always colder than downstairs, mainly because of insufficient slant fin at lower water temps I'm using. What if I combine the 2 zones, feeding upstairs 1st, thinking I could actually get better condensing this way too.

Leon82

Yes combining them may allow it to sustain the minimum rate for longer or eliminate cycling.

fenkel

Might  need  a bigger zone pump.
Gpms might be over 4. Head pressure could be high as well.. you might lose  a 20 degree delta, because of larger
pump requirements .
Does both zones run off one thermostate?

Zman

Outdoor reset will actually make short cycling worse. Less energy is being transferred so the boiler cycles on and off. This is better than overheating the space so ODR is still a good thing.

I would experiment with the anti short cycling feature. A longer off time will equal a longer on time. The boiler will need to catch up.
You could probably set it to 5-10 minutes with no side effects.

Suzook

Zman said:

Outdoor reset will actually make short cycling worse. Less energy is being transferred so the boiler cycles on and off. This is better than overheating the space so ODR is still a good thing.

I would experiment with the anti short cycling feature. A longer off time will equal a longer on time. The boiler will need to catch up.
You could probably set it to 5-10 minutes with no side effects.

Worse? This is the 1st time I have heard this. I'm actually thinking if I lower the min supply temp, that should make the boiler run longer at higher outdoor temps.

Suzook

fenkel said:

Might  need  a bigger zone pump.
Gpms might be over 4. Head pressure could be high as well.. you might lose  a 20 degree delta, because of larger
pump requirements .
Does both zones run off one thermostate?

I have a grundfos alpha. It's plenty big. 2 different thermostats. Are you suggesting higher speed on circ pump?

hot_rod

Suzook said:

Tryinng to cut down some of my cycling of my htp uft 80. I have adjusted my odr, to the best of my ability, i have it running almost constant, but still have some turn offs. There is an anti cycle setting. Im confused about it. Wouldnt turning it up to 30mins, means it runs 30 mins longer? Or should i turn it down closer to 1 min?

Edit, so i guess when set to 30, once fired, it will fire for 30 mins. I guess i need more adjusting of my ODR, and/or my combustion rate.

You mention you have it running almost constantly??
Use all the features the control offers, but on low load mild days there will always be some cycling, until we get boilers with 99-1 turndown

A minimum 10 minute run time would be the goal and rule of thumb the industry uses.

fenkel

Does the upper floor zone run all the time?
As far as speed is concerned, you need to determine the btus for the new zone. Then you'll need to determine the length of the conbine zone..
Say your zone is 200 feet long..
And your using 3/4 in copper pipe
Copper 3/4 has a resistance of .04
The formula is length of zone x 1.5 x pipe resistance 
So..
200x1.5x.04 equals a head pressure of 12 psi.
Then take total zone btus and devide by 10000..
This will give you gpms..
Use this to see if your pump can handle it

Suzook

hot_rod said:

Suzook said:

Tryinng to cut down some of my cycling of my htp uft 80. I have adjusted my odr, to the best of my ability, i have it running almost constant, but still have some turn offs. There is an anti cycle setting. Im confused about it. Wouldnt turning it up to 30mins, means it runs 30 mins longer? Or should i turn it down closer to 1 min?

Edit, so i guess when set to 30, once fired, it will fire for 30 mins. I guess i need more adjusting of my ODR, and/or my combustion rate.

You mention you have it running almost constantly??
Use all the features the control offers, but on low load mild days there will always be some cycling, until we get boilers with 99-1 turndown

A minimum 10 minute run time would be the goal and rule of thumb the industry uses.

Ok, so I will leave well enough alone. Thanks!

Suzook

So i figured out an issue i was having with my upsatirs zone, not maintaining temp, and short cycling. I have a honeywell T-stat, and it was set for 5 cycles per hr. Meaning it would cycle it on and off 5 times per hour!. Changed it to 1, and walla. Temp is maintained, along with very little boiler cycling.

PC7060

Nice!

Suzook

You would think ALL tstats would have a proper setting for newer ModCons. They don't. My local gas company offering a free Honeywell touchscreen smart tstat. It has NO options for temp variances, or cycle per hour. Makes no sense.

BillyO

Yes, free thermostat and access to your heating system. go buy it yourself

RunMZT

Which Honeywell T-stat. I use the Honeywell Pro1000 and on my UFT 80w, short cycling and not maintaining temp. In "installer mode" I just adjusted (16:Ft "CH Anti-Cycling time from 1 to 10. Three zone system, Grundfos Alpha, live in CO mtns, 33:HA set at 5-8. Frustrating May need a great tech to help in area code 81657. Suggestions please?

PC7060

RunMZT said:

Which Honeywell T-stat. I use the Honeywell Pro1000 and on my UFT 80w, short cycling and not maintaining temp. In "installer mode" I just adjusted (16:Ft "CH Anti-Cycling time from 1 to 10. Three zone system, Grundfos Alpha, live in CO mtns, 33:HA set at 5-8. Frustrating May need a great tech to help in area code 81657. Suggestions please?

What do you mean by not maintaining temperature? Is the system not recovering after a setback? 

Are you using the ODR sensor?  Once I got the slope dialed in in ODR mode, I typically have heating cycles of several hours. 

FYSA, I set my UFT80 anti-cycle time to 20 minutes. You can also adjust/increase the return temp delta in the installer menu. Increasing will inhibit firing if the return temp delta is less than the set value.  The pump will still run, you won’t get flame. 

Do you have boost mode set on?  I found that caused my system to ramp up temp causing shorter cycles. 

RunMZT

The room temperature is 4-6 degrees F lower than the thermostat setting (Honeywell TH1100DV). Yes ODR sensor. No boost mode. Minimum supply temp (7:cL) increased to 105. Boiler ignites, temp increases to 151 degrees then shuts off. Grundfos Alpha turns on for three zones with Honeywell zone valves. Just adjusted 16:fT CH anti-cycle to 15. Is there a way to over-ride ODR sensor and change the CH set point? In this case increase it?

PC7060

Sounds like you have emitter (radiator, sun, etc.) close to the thermostat causing it to shut off prematurely.  I’d start from there and reset the min temperature back to default.  

Also, the slope of the ODR can be edited in installer mode. But I don’t think that’s your problem. 

Recommend you start a new thread and post pictures of the your system along with install dates