2 Pressuretrol Cut-Ins and 1 Cut Out?

EBEBRATT-Ed

@holograham your boiler is firing for 35 min and off for 37 min that is probably as good a you will get. fussing with the pressure controls to lower the pressure will decrease your run time and cause shorter cycles. It may or may not make a slight difference in the amount of fuel burned as it does take more fuel to run a higher pressure.

It's a compromise to work through and see which is better for your building. what works on paper sometimes does not translate to real world use.

ScottSecor

We were the Powerflame/Weil McLain start up reps for northern NJ. We never converted a fixed air shutter JR style burner to a unit that could change/vary the inlet air shutter. Not saying it couldn't be done, but it would be tricky to perform on your particular burner.

As others have suggested, your run times don't sound too bad.

holograham

EBEBRATT-Ed said:

@holograham your boiler is firing for 35 min and off for 37 min that is probably as good a you will get. fussing with the pressure controls to lower the pressure will decrease your run time and cause shorter cycles. It may or may not make a slight difference in the amount of fuel burned as it does take more fuel to run a higher pressure.

It's a compromise to work through and see which is better for your building. what works on paper sometimes does not translate to real world use.

The clarify - the timeline is 35min runtime till first shutoff. Then 2 mins off and back on at 37 as the call for heat isnt satisfied yet. Then cycles from there. I'll have to time another cycle to see the next cutoff and cutin.

Timeline from a cold start:

7 mins - steam generation
10 mins - steam throughout basement mains (these are well vented)
20 min - Third floor furthest radiator - fully hot
35 mins - pressure cut-off at ~5 PSI (reading on gauge)
37 mins - boiler cycles back on at just below 2 PSI (reading on large gauge)

109A_5

Hello @holograham,

If you are just interested in stretching that 2 minute pressure cut off, a timer can stretch the off time so you are not doing the rapid on-off-on-off-on-off-on-off until the thermostat is satisfied thing.

You can set the delay (maybe 5 to 10 minutes) to give the radiation time to warm the room(s), condense the steam they have, and thus greatly reducing the amount of needed boiler cycles for one thermostat cycle. The more the steam in the radiation is condensed the longer the next boiler cycle will be (if needed).

Inexpensive, and easy to try.
One timer example;

https://www.supplyhouse.com/ICM-Controls-ICM203FB-ICM203F-Delay-on-Break-Timer-6-Wire-Leads-03-10-Minute-Knob-Adjust-Delay

neilc

109A_5 said:

https://www.supplyhouse.com/ICM-Controls-ICM203FB-ICM203F-Delay-on-Break-Timer-6-Wire-Leads-03-10-Minute-Knob-Adjust-Delay

@109A_5
Delay on Break?
or,
Delay on Make?

109A_5

Hello @neilc,
As pictured, Delay on Break, when the Pressuretrol / Vaporstat opens (turning off the burner) the delay begins. In @holograham case the pressure decreases in two minutes to the Cut-In pressure, then the burner fires up again. However after two minutes the radiators are probably still hot, so do you need the burner running just to build pressure again ?

Delay on Break would keep the circuit open (off) until the delay expires.

From the web page.
Description
Delay on Break Timers ("anti-short cycle", "ON delay on break") helps to protect air conditioning, refrigeration and heat pump equipment from damage which may be caused by the rapid short cycling of compressors.

neilc

I feel like you're overriding the safety/control of the Trol,
would it ever shut off ?

I seem to remember others here using delay on make to space the cycles, boiler shuts off, and then stays off for 5(adj), allowing rads to shed heat, and maybe satisfy the stat, before restarting a new, short cycle,

IDK, carry on

109A_5

Hello @neilc,

neilc said:

I feel like you're overriding the safety/control of the Trol,
would it ever shut off ?

I seem to remember others here using delay on make to space the cycles, boiler shuts off, and then stays off for 5(adj), allowing rads to shed heat, and maybe satisfy the stat, before restarting a new, short cycle,

IDK, carry on

I think you would find that either would insert the needed delay. It would be wired in series with the Pressuretrol / Vaporstat so it does not override the function of the Pressuretrol / Vaporstat, but enhances it. I like the Delay on Break since it just extends the off time, like if the Cut-In could be set to near zero pressure and then wait a bit.



The Delay on Make will delay the thermostat call for heat, not what I would want.

EBEBRATT-Ed

@109A-5

Had to look that relay up as I couldn't picture it working. But is works as you said. TD relays can be confusing!! In series with the Ptrol when the ptrol opens the burner shuts down and the time delay starts timing. If the ptrol re makes it will not start the burner until the timing setting is reached.

That will do it. The only issue I see is that it is good for only 1.5 amps. Probably have to use a n additional relay to make it work on the OPs boiler as the commercial burners generally have a 5 am control fuse and with the pilot gas valve , ignition transformer and 2 main gas valve & burner motor contactor on energized at light off it will be way over 1.5 amps.

holograham

Who would I even consult to do this work. Ironically I am an electrical and computer engineer so I know what you both are talking about technically - just dont trust myself to wire it in and would want an experienced pro.

109A_5

Hello @EBEBRATT-Ed

EBEBRATT-Ed said:

The only issue I see is that it is good for only 1.5 amps. Probably have to use a n additional relay to make it work on the OPs boiler as the commercial burners generally have a 5 am control fuse and with the pilot gas valve , ignition transformer and 2 main gas valve & burner motor contactor on energized at light off it will be way over 1.5 amps.

Yes, if the Pressuretrol is not a part of a low current control circuit the ICM Controls ICM203FB may be very awkward to implement in this situation. Since it is a 2 wire device buffering it with a simple relay may be awkward also. I think the PA404 is rated up to 8 Amps at 120 VAC.

@holograham, So far I can't find a good wiring diagram for your burner / limit / control setup.

Looking closer at your wiring situation pictures, I would leave the present 120 VAC safety limit circuits as they are. With another Pressuretrol / Vaporstat / Dwyer Photohelic pressure type pressure switch (maybe up near the pressure gauge) I would interrupt the 24 VAC control circuit and add the ICM-Controls ICM203. This pressure switch would have to change state at a lower pressure than all the rest. All easy to disable with one SPST switch if desired.



30" Water Column = 17.34 Oz