Replacing oversized 1955 boiler with Multiple Steamers....FINALLY WITH MORE PICTURES! AND STILL MORE

MY only comment is that the sizing of a steam boiler is by counting the installed radiation and piping heat loss with little regard for the building's heat loss. Are you going the resize the radiation? I bet that that Kewanee is a beauty.

@JUGHNE

To me which boiler is lead or lag doesn't matter. I would keep the sizes you picked that way if one failed you will still have about 1/2 capacity.

The trick with two boilers is to control the water lines which is difficult in my opinion with out a boiler feed tank and 2 overflow traps.

The idle boiler with it's steam supply valve open will fill with condensate. Two boilers if there returns are connected below the water line require check valves per ASME Code (a leak in one boiler will drain the other boiler)

Do you have or are you planning on a feed tank or is this gravity return?

I have a drawing for a manual lead lag system with manual switches so you can run both boiler lead, both boilers lag or either 1 lead and either one lag if you want it

You can also do it with an alternating relay so it will alternate the lead boiler if you want

Does that lever contraption on the gas valve allow it to modulate or is it just some sort of slow opening mechanism?

Would you consider using one large header, into which both boilers feed with drops?
Also, maybe Gifford loops would prevent the condensate from entering the lag boiler, by virtue of their higher point of connection.
What will control the boilers-interior sensor, and multistage VisionPro?
For sizing the boilers, “A” boiler sized to average heat loss, and “B” boiler sized to the difference between “A” and total EDR? In the morning, both boilers would fire until pressure, or thermostat cuts off the lag boiler.
When the polar vortex hits, the thermostat cuts “B” back into operation. —NBC

This is very similar to the heating plant for my church I installed last spring. Originally 2.100,000 btu.hr input LGB, 3 zones, 2 direct steam and 1 steam to HW convertor. We put in a small hw boiler to handle warmer weather heating for the hw system a few years ago so the main boiler would be kept off about 1/2 the heating season with the main zones in setback. Instead of installing 2- PB64-07 we installed 2- WM380. Since the 380 is only 350,000 input and the tapping are 4 inch, there is very low velocity in the riser, so little backpressure and little carryover. We used a single tapping on each boiler to a common 4 inch header. The PB would have required separate headers..... a whole lot more piping. We also orificed the system at the same time and balanced the steam flow to the steam/hw heat exchanger. The boilers are staged via relays and 2 stage thermostats. The HW boiler is brought on only when the thermostats go to second stage... this reduces the load on the steam boilers by closing the steam zone valve to the HW heat exchanger when the steam zones need more heat.

Found a picture!

I think the thing to do is to think about what gives you options to change the controls and change how it behaves if you don't like how you configured it the first try.

I love your sizing process and reduction of the pickup factor. Wow, 15 capped supplies!! I get the idea one of your primary concerns is you don't want the system to be oversized and I agree completely. I like the backup boiler...is the thinking that in normal operation just one boiler will be operating?

May I ask about your double drop headers? Does the manufacturer suggest that piping? If not, do you suspect that the manufacturer is cutting it too close with their supply pipe sizing vs steam generation? I would be disappointed with a manufacturer if their recommended piping causes carryover, and in my visible boiler (admittedly tiny tiny compared to yours), I never see one drop of carryover. But maybe in larger boilers carryover occurs (I don't know hence all my questions)

@JUGHNE

I know that Shipco can build you a tank that is not a stock tank. 9" off the floor is tough, if you raise the water line and come up into the tank you would make a trap and have to vent the return of air.

The other option is a tank that is flush with the top of the floor.

Or a condensate pump in a pit and have it feed the feed tank.MOre $$$$ I know From Shipco web site:

Type DUMC
Durable Underground Make-up Stainless Steel Boiler Feed Unit
Boiler Feed Pumps & Surge Tanks


A Durable Underground Make-up boiler feed unit with stainless steel receiver uses a patented design to pump water in applications where the return piping is at or below floor level. The underground basin is made of stainless steel in various sizes. Pumps are located above the basin cover plate allowing for easy maintenance with disturbing the cover plate. The propeller shaft and it high temperature patented (U.S. Patent #4,932,846) bearing design is more durable and simpler than most other designs.

An electrical solenoid make-up water valve with float switch control is standard. Units available in either simplex or duplex configurations; motors are 3500 RPM, single or three phase. Unit equipped with bronze-fitted Model U pumps fitted with industry standard motors and with mechanical seals rated for temperatures up to 250°F. Higher temperature seals and special faces available upon request.

Other accessories include gauge glass assembly, thermometer, inlet strainer, butterfly isolation valve, low-water cut-off and electrical control panels.

OR THIS MAY BE BETTER

Type DMS-MU & DMSS-MU
Durable Steel/Stainless Steel Boiler Feed Pump, Low Inlet
Boiler Feed Pumps & Surge Tanks

Type DMS-MU and DMSS-MU use a patented design pump which handles up to 210°F condensate with a 2 ft. NPSH pump. Type DMS-MU is made with a rectangular steel receiver while Type DMSS-MU has a rectangular 300 series stainless steel receiver. Each has an inlet height of 6-1/2" from floor to centerline available to help with extremely low inlet issues. The top-mounted, close-coupled pump is bronze-fitted with an industry standard motor and utilizes a propeller shaft with its high temperature patented (U.S. patent #4,932,846) bearing design. Type DMS-MU and Type DMSS-MU are available in either simplex or duplex configurations with a variety of options. These units also eliminate the need for pump isolation valves since the pump is mounted on top of the receiver. As an added advantage these units can fit into a smaller floor space area than conventional Type DMS or Type PMS units. The standard mechanical seals are for 250°F. Higher temperature seals and special faces available upon request.

Just for your information only. that old general gas valve in the picture of the old boiler did come as a an on/off gas valve as shown or as a "modulating gas valve" for that same type burner. Boy were they efficient.

sizing the solonoid valves is important.
Using this formula will tell you gpm flow rate of the solonoid valve.
10X diam squared x square root of thee inlet pressure.
it seems that a 1/2" valve will serve you best at 8 gpm (you may need to have a lockable balance valve on the discharge side of the solonoid valve.


Jake

Instead of the bypass valve back to the tank from the condensate pump, you could just orfice the pump's discharge. If you do not like orfices they also make valves that do the same thing. You could check with the pump mfg and see if they could cut down the impeller to change the flow.

You could come off the top of the boiler header. The velocity there would probably be less that a boiler riser. But that may not be the best spot

Typically you don't want to come off a pipe with flow in it so it doesn't affect the 150.

The other place would be a cross under the boiler relief valve. Even if the relief valve tapping is only 3/4" you could blow it up to 1" for the 150. There is normally no flow in that pipe.......it's just a pressure balancing line.

The 150 won't know the difference. I think the only reason they use 1" is to resist clogging. But the top pipe on the 150 only sees steam anyhow

I don't know about a solenoid valve. I have visions of water hammer. Maybe id it feeds slow enough it will be fine