Two stage set up for vapor system (Steamhead)

gerry gill

as to wether or not low fire works well..for example a vapor system which heats very well at low fire..but was designed for it..if the boiler shuts off on pressure, there is even worse efficiency of on/off cycling..and often complaints of poor heat distribution..we use low fire very often..some customers say it saves money..some say the bills stayed the same..all say comfort has increased..

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Ross_7

Two stage set up for vapor system (Steamhead)

Hi Frank,
Can you give me any pointers for this set up? Maybe you could e-mail me the details.I have a pretty good idea, but any advice would be great. I was going to use a two-stage Uni-Line (Robertshaw) gas valve, tied into a vaporstat. Retro-fitting a Webster Type "R" system for our trades building. TIA, Frank!
Ross

Steamhead (in transit)

That's how it's done

on the Weil-McLain LGB series atmospheric boilers- just a 2-stage gas valve (installed after the redundant CSD-1 valve which I would also recommend you use) and some additional controls. Obviously this is a CSD-1 situation, right? Here's a link to the CSD-1 manual for the LGB so you can see what's involved:

http://www.weil-mclain.com/downloads/literature/lgb/lgbcsdgas.pdf

What type of boiler is it, and what ignition system does it have? Is the Robertshaw valve made for use with this type of ignition system?

Is there a minimum manifold-pressure spec you can use as a lower limit?

The Vaporstat is wired to turn the high-fire stage on and off. Whenever there is a call for heat, the burners will run on low-fire if the Vaporstat is off on pressure, or on high-fire if not. Make sure there are no light-off issues on low-fire.

Do a combustion test on both stages (but you know that). On low-fire you also want to make sure the flue temp is high enough to prevent condensing.

"Steamhead"

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don_185

please share.

Please share what advantage there is by going to a lower firnig rate on a gas appliance.

From testing in the field I find that your thermal efficency is reduce big time going into low stage.

Is it not a true statement to say lower thermal efficency = higher gas comsumption?

Ross_7

CSD-1

Hi Frank,
Yes, we will be installing it per CSD-1, per MI Boiler code.
Boiler is just a Crown Bermuda BSI-345. Intermittent pilot. Robertshaw gas valve model #700-064, which I belive is available on the BSI-376. I'll keep you posted. Thanks for the link, the help, Frank!
Ross

Steamhead (in transit)

On Steam

once the pickup factor is satisfied, the boiler becomes oversized and short-cycles. Dropping the firing rate by just the amount of the pickup factor shouldn't decrease steady-state thermal efficiency that much, and the lack of short-cycling should more than offset this.

I haven't run into a steam heating system yet that wasn't originally designed for a lowered firing rate once it was heated up.

"Steamhead"

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don_192

Thanks all

Sorry Ross, for changing the subject.

Ross_7

No problem, Don!

That's why the wall is here.. to ask qustions!
Thanks Gerry & Frank.
Ross

Ross_7