Pressuretrol pigtail changed, burner now cycling

Wcurtis

doing maintenance on my boiler and changed pressuretrol pigtail, now burner seems to cycle on/off to frequently. 

This doesnt seem normal but how can it be corrected?

Jamie Hall

It may be quite normal. What is the pressuretrol or vapourstat set at? What pressure does the boiler actually run at? And, perhaps, more important, how big is the boiler vs. how big is the system which it is powering?

ethicalpaul

Tell us the times of cycling, start with the beginning of the call for heat, and note any event such as "main vents close" and "steam reaches radiator valve" and then note the cutoff and cut-in times and how long the overall call for heat took.

- Do you have operating main vent(s)?
- What are your cut-out and cut-in pressures?

What you are seeing likely is the correct operation of the boiler. With the (assumed) clogged pigtail, the pressuretrol couldn't see that the pressure was rising so you were running the boiler at high pressure, probably a lot. This is harmful to the vents and the good operation of the boiler (affecting water level, etc). It is preferable that a boiler cycle like this rather than running at high pressure.

Wcurtis

pressuretrol cutin .5, cutout 1.5, replaced gage also and it bounces just off 0 everytime I noticed it.

172k btu output from boiler

Wcurtis

Pigtail was definitely clogged, main air vent was replaced recently and all radiators work as well, this is milder temperature day than recent past, could this have something to do with it?

Jamie Hall

172 K BTUh net output? that's about 540 EDR. What is the EDR of your system?

Wcurtis

172,800 is gross output, I do know the EDR rating for the home

Jamie Hall

Wcurtis said:

172,800 is gross output, I do know the EDR rating for the home

Let's make it simple then. What is the EDR rating of the boiler (it will be on the data plate) and what is the EDR of the home, since you know it.

Waher

Are you sure when you disconnected your pressuretrol to replace the pigtail that you reconnected the wires correctly and didn't accidently loosen them at the control panel side of thing?

Wcurtis

nameplate shows 540 sq ft

Wcurtis

I had a typo, I do not know the edr rating of the home

Wcurtis

I will check the connections however the wires were not disconnected because a toggle switch inside the pressuretrol has 2 terminals soldered 1 from LWCO and one to the gas 

Wcurtis

Chris_L

You need to compare that 540 square feet on the boiler tag with the EDR total for all of your radiators. See:https://smithfieldsupply.com/company_info/forms/radiatorest.pdf for example, for an explanation of calculating EDR for various types of radiators.

Wcurtis

totaled all radiator edr's from chart
360

boiler 540
Seems to be too much boiler but is this the reason for the pressuretrol cycling now

Jamie Hall

Wcurtis said:

totaled all radiator edr's from chart
360

boiler 540
Seems to be too much boiler but is this the reason for the pressuretrol cycling now

Oh yes indeed. That much oversize and it's going to cycle on pressure -- and there isn't much you can do about it other than grin and bear it.

Wcurtis

I never could tell before, now need to focus on slowing down vents since pressure gage hardly jumps off 0, trying to warm a cooler room and those two vents open 100%