Setting Vaporstat

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12 unit Apartment building has been running 3lb plus forever, I recently had a Weil McLain LGB 6-23 put in, it was expensive and installer (50 year pro) put in 0-30 gauge a Pressuretrol that didn't go below 3.2 lb. (why did he do that?) my NG bills are always higher than what other buildings are. After reading here and Dans book, Lost Art of steam I've been on the quest of low pressure for efficiency and heat balance. I just installed a honywell Vaporstat and 0-3lb gauge, I'm running at 12 oz, cut out, 6 oz cut in just fine. Yes I can go lower I've tried it to 6oz cut out, but balance is an issue different radiator venting may not cure. I still get like 2-3f swing so maybe thermostat needs to be set to cycle narrower. My question is, I have not seen charts, or numbers relating to how much lowering each OZ saves in energy $, its time consuming lowering pressure and rebalancing the system. Is there a "maximum efficiency range" that is only a % or two different? Can lowering pressure be given a % saved per lb. lowered? Presently the Vaporstat cycles 3-4 times per boiler run at 25f outside. In Chicago thanks all.

Jamie Hall

It's an art

not a science.  Sorry about that.  Some systems -- old vapour systems, with very large pipes (relatively speaking) can get by on lower pressures than others.  You do need enough pressure to overcome the friction losses in the pipes, and there is definitely a pressure which is too low for a system.  You may well have found it.



On the other hand, you might be able to get by with less if you had more main venting; the fact that the system does cycle on pressure (I presume at the end of longer runs?) suggests more, however, that the boiler is slightly oversize for the radiation.  Not enough to worry about, I'd say -- and better slightly over than under.



The relatively wide temperature swing, coupled with the longer runs, does suggest, though, that you might be able to set up your thermostat(s?) to manage the system more smoothly -- which would both reduce the swing and tend to give shorter, though perhaps more frequent, runs.  How you would do that depends on what sort of thermostat you have -- some have anticipators, some have cycles per hour, some have swing.



I doubt that it would make much difference in fuel use, though it could make a significant difference in comfort.

leaking

Setting Vaporstat

The building is about 100 ft long and boiler is at one end, the 3 returns are vented at the boiler with one and two gorton main vents each for a total of 4, I wonder if I should do more as at some end radiators a lot of air comes out, also at the far end I put on vents where I found caps, I guess it's a main feed? Can I over vent returns? Are 4 gorton main vents on a 600000 btu boiler enough, yes I think the boiler is a bit oversized. Good news, I just got a gas bill today of 1000, we had a cold month and I remember paying near 1800 a few years ago and it wasn't as cold, so everything is helping. Thanks

Jamie Hall

From your comment that

at some end radiators a lot of air comes out makes me think that this is one pipe steam?  If so,  there would be no harm at all to putting a couple of Gorton #2s at the ends of the steam mains.  It can't hurt anything, and it might make the heating a little more even, particularly at lower pressures.



Your gas bill sounds like my oil bill...

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Setting Vaporstat

Can you over vent a return or end of main, yes one pipe steam it is.

Jamie Hall

No...

Conceptually, the ideal main would be constructed and sized and vented so that the steam would arrive at all the radiators at exactly the same time.



Right...



But if one can manage to get it even as close as 5 minutes or so, you're doing fine.



The trade off is between the idea' and the cash...

Dave in QCA

Even Better.....

Activate the 2-stage function of your boiler. If you look at your wiring schematic, you will a notation for firing rate control. You can use your vapor stat for that, or purchase another and use one vapor stat for an operating control and the second vaporstat for HI-LOW control. When the pressure opens the contact on the vaporstat, the HI-LO valve will go to LOW FIRE. If the pressure drop, it will go back to HI FIRE. This will be a more effective control that ON/OFF, and from what I am told, the LO FIRE function on the LGB boiler is about as efficient as the HI FIRE.

leaking

Setting Vaporstat

Wow , I didn't know it was 2 stage! So why didn't my installer set it up this way and with a Vaporstat and 0-3 gauge, these guys have been doing this for like 40-50 years and only do boilers . I really don't feel like I got my 25000.00 worth of service for a Lbg 6-23, I even used my old thermostat ! That 2 stage will definatly make a difference

Dave in QCA

Most Don't even know

I've never come across one set up as 2 stage. Most don't know it is even on there.

nicholas bonham-carter

How many main vents for a big system

I have 55 radiators, 1,050,000 BTU, and 6 dry returns with 5 Gorton 2's on each. You may be better served by using steam traps for more throughput of air.

When the boiler starts to steam, and push the air out, you can see on your gauge the ounces of back-pressure which indicates the resistance to escaping air.--NBC

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Setting Vaporstat

Do all Lbg 6-23 come with 2 stage valve? I'm sure balance , comfort and efficiency will increase with a 2 stage properly operating. Thanks for all the help everyone.

Dave in QCA

standard equipment

it is standard on the lgb-6 and above. But, their would be the ability to order other control options, so its impossible to say "ALL". check your wiring diagram. Check the second gas valve. If it has 3 wires coming out of it instead of 2, like the first gas valve, you know you got the two stage valve.

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Setting vaporstat

Ok thanks, my manual didn't mention it, it will be a few days before I see the unit. What benefits are there running two stage that you see, I wonder if it's worth putting in a 2 stage set up if it didn't come with it, the low fire option sounds advantageous to balance and efficiency , I had it on a furnace and liked it. Thanks everyone!