Trying to save a customer $$

RJMCTAFO

Have customer with a large building heated with two newer oil fired steam boilers. In the course of the tune up he asked if I had any ideas on saving some fuel. I told him I would suggest changing the pressuretrol to a vaporstat on both boilers.

Then I got to thinking about using the vaporstat to "stage" the boiler. My thinking is to set one at 3oz and the other at 5oz. They would both fire to satisfy the pickup and initial load and then one would drop out. Anyone think this is an idea worth trying. My thought is worst case scenario he still gets the benefit of running lower pressures.

Already have addressed proper venting and insulation.

Thanks.

nicholas bonham-carter

Is this one-pipe, or two-pipe?
Leave the pressuretrol on one boiler, which will be the lead boiler, and put the pressuretrol on the lag boiler.
When the call for heat comes, both boilers will fire, but when the pressure hits the sweet spot of a few ounces, the lag boiler will be cut out, leaving the lead boiler to carry the load for a while. Unless the boiler is grossly oversized, it will never build any pressure, but will keep steam in the pipes.
You will need excellent main venting so as not to short cycle.--NBC

nicholas bonham-carter

I meant vaporstat in place of pressuretrol on the lead boiler!!--NBC

nicholas bonham-carter

More thoughts on this:
How are these boilers piped? If there is a common header, which there should be, then that would be the best place for both pressure controls.
Watch the waterline carefully of the lead boiler as it cuts out. A Gifford loop may be necessary to prevent the lag boiler from absorbing water from the lead when only the lead is running.
At these desirably low pressures, the venting needs to be very generous, and not just there with some guesstimated number of vents.--NBC

Abracadabra

Might want to think about rotating which one is lead.

nicholas bonham-carter

Good idea!--NBC

RJMCTAFO

The current system is two pipe using fan coils. When we installed this we put in a few extra tappings in the common header for things that may come down the road. I periodically check in on these boilers during the heating season because if I did not then nobody would!!!! Would most likely switch the lead boiler monthly on my visits. Was gonna try this and if I noticed any water level issues then I would just run them at a lower pressure to still save some fuel for the customer.

Thanks for the input fellas!!!

nicholas bonham-carter

I think 2-pipe will work best for this application.--NBC

Steamhead

We have a similar situation in a church with three zones and two identical boilers. I hope to find a control that will stage the boilers according to how many zones call. Going to call Slant/Fin first, since they use some sort of staging control on their Caravan systems. I'll post about it if I find something that works.

icesailor

They do it with hydronics/water. I had an account with three equal HW boilers. It had a Techmar controller that would rotate the lead boiler weekly and stage the burners to run on load. On a warm day, only one boiler ran, but on a cold day, all burners might run but one might drop out.

Maybe it can't be done with Steam. I don't know. Where I worked, Steam was exotic.

Abracadabra

weil-mclain also has a sequencing control.

http://www.weil-mclain.com/en/weil-mclain/pd-boiler-sequencing-control-bsc/

SWEI

That looks a lot like a re-branded Heat-Timer.