Vent math

GW

And I quote, don’t know who:

“At one ounce pressure: the Gorton # 1 vents @ .330 cu.ft. of air per minute the Gorton #2 vents @ 1.100 cu. ft. of air per minute”

So if 3 minutes is good time for venting, and a 30 foot two inch main is .69 cu ft,, that means the Gorton 1 will vent the main in about two minutes at 1 ounce, yes???? Good????

Gsmith

Your math is right.

GW

Thanks I’ll do one on each 30 foot main

KC_Jones

I have a Big Mouth on 25' of 2" main and it vents in about 2.5 minutes at essentially zero pressure. Since you start at zero pressure the system will not be moving that kind of air until you can build pressure, so 3 minutes isn't going to happen. I'd honestly be shocked if you got it done in 1.5 times that time. I wouldn't do less than a #2 vent for 30' of main, and at that point, for my money I'm just using a Big Mouth. Unless you have need of a float in the vent.

GW

So we have a vendor glitch and had Gorton 1 W, some small 3/8” stuff. My awesome office girl shot is some normal #1’s. While we were waiting, I ran without main vents. I didn’t time it, but oddly it was like 20 minutes for one of the two returns to fully heat up.

Each supply is 30’ and about the same for the return.

Another oddity

GW

Boiler is cycling, fully steamed up. 3 minutes on and 85 seconds off seem good? I could fiddle with the pressuretrol if we want more run time

Fred

GW said:

Boiler is cycling, fully steamed up. 3 minutes on and 85 seconds off seem good? I could fiddle with the pressuretrol if we want more run time

Is this from a cold start? Something is wrong. I would say that is short cycling. Not Good. Was the boiler sized to the connected EDR? The Pressuretrol should remain set at .5 with a differential of "1". Either the boiler is way over sized, the main venting is inadequate or the Thermostat (if programmable) is still set at the factory default of 5 cycles per hour and needs to be programmed to 1, or a combination of the three.

GW

Fred, we simply fixed some boiler piping. Definitely better than it was before we got there this morning.

The thermostat was calling nonstop. The pressure troll was clicking in and out.

The boiler was fully steamed up,

It’s a very small house but it’s a small three section SmithBoiler. Maybe I should look at down firing?

Fred

Are they using deep setbacks? Something still isn't right. 3 minute cycles with a 1.5 minute off time before it fires back up is not good. If the thermostat was calling non stop is/was there a short in the wiring or a problem with the thermostat? I can see the short cycling if the boiler was over-sized and the boiler was running for a long time because there was a constant call for heat. But, on a normal cycle, the boiler should run, maybe 15 or 20 minutes and off maybe 20 or 30 minutes.

GW

With steam? I thought the vents had to vent which causes drops and climbs in pressure. This is the pressuretrol cycling the burner, not the thermostat

Fred

GW said:

With steam? I thought the vents had to vent which causes drops and climbs in pressure. This is the pressuretrol cycling the burner, not the thermostat

Yes, with steam. The vents have to let the initial air out of the mains and radiators. Once they get steam, they stay closed until the end of the heating cycle when they cool enough to open up for the next cycle where they are ready to let air out again.

Pressure in the system is maintained by enough connected radiation (EDR) to condense the output of the boiler. If the boiler is too large and produces more steam than the connected EDR can condense, then pressure builds and if that pressure gets above the limits set on the Pressuretrol, it will shut the burner down for a minute or so, until the steam in the system has condensed (collapsed) and the pressure drops. Then the Pressuretrol will re-fire the boiler but it only takes a minute or two, at that point to rebuild pressure and the short cycling continues until the Thermostat is satisfied. In a properly sized (or near sized) boiler the thermostat will almost always be satisfied before any short cycling begins.

GW

Thanks Fred now I can see it in my mind.

This house is small. I’ll see if we can go and drop the nozzle some, or, have her burner people deal with it.

ethicalpaul

GW just redid the piping, so I assume the boiler is oversized. Is it, @GW ?

Those times aren't that much different than mine when I had a couple radiators turned off and it was probably 30% oversized. I'd see about 2 minutes on and 1 minute off.

> It’s a very small house but it’s a small three section SmithBoiler. Maybe I should look at down firing?

I'm talking out of my posterior, but I would think this would be the order (I write this to see if I'm thinking right more than anything else):
1. Measure the EDR of the radiation
2. Clock the fire rate of the boiler to see if it's in spec (along with the combustion check/etc)
3. Compare the house EDR to the boiler's rated EDR
4. Look into ways to get them in alignment if they are mismatched

GW

Paul it's oil, and oil systems are only 'so small'. I need to manage my time with this- I didn't charge a million dollars for the re-pipe and I don't want to create an ongoing saga with the homeowner (if you can understand what i mean). I'm slowly developing communication skills on how to deal with old systems. I'm good to go on new furnace/boiler install and clearly spell out what we are doing/not doing.

I will refine my skills and better my quoting process for the steam stuff. It's hard to diagnose a system with very poor piping. I can't do a full blown diagnostic for free (maybe others can, I can not). What I can do is quote to fix something obviously wrong---that quote is generally free (geography comes into play). The EDR is clearly lower than what the boiler is meant to move (BTU). One step at a time with this one.

ethicalpaul

For sure Gary, you do what you need to do! But you could basically use this as a test case to understand if this thing is oversized, and what that means to this customer as well as future customers.

I feel what you are saying, though! I get to go downstairs in my pajamas any time I want to see how long cycles take, etc, without concern about billable hours, etc.

GW

Paul yes but we can't really down fire this thing much.

She is already a little bugged at the previous oil heating co, so maybe you can appreciate how things needs to be handled. Did you see the re-pipe video in the other thread? It's marvy!

Thanks for the comments.