This weeks case, Replacing a steam boiler at my kids school What would you do?

RayWohlfarth · January 31

This isn't the name of the case but the title would give away my solution.
@DanHolohan suggests never doing work for your church and I tried not to. Let me tell you what happened. The school attached to my church was in desperate need of a boiler replacement. The single LP steam boiler was leaking and unreliable.The school building had two wings. The original wing was steam. The newer wing was hydronic. They used a steam to water heat exchanger to heat the hydronic loop. The heat exchanger required 7 psi steam pressure so the boilers operated at that pressure.

I didnt want to bid on the project because I was on Parish Council and felt it would be a conflict of interest. The Buildings and Grounds committee asked me to review the bids and I agreed. When the bids came back, the contractors all proposed to replace the single boiler with another boiler. There was no backup in case of a malfunction. When I suggested at least two boilers, the contractors scoffed. One said the old system worked for 40 years, why change. The committee asked what I would do and I told them. They asked me for a proposal and accepted my solution. I have enclosed a sketch of the original system.

My question is what would you have proposed for this project. I will tell you my solution on Friday at 6am EST

Mad Dog_2 · January 31

Two Boilers in any case..

Ideal option

1) Steam Boiler at Lowest operating pressure possible to match the EDR of the main building AND a Dedicated Hydronic boiler to match Heat loss of wing. Best control of comfort levels better efficiency.

Stand your ground. Tell them you're looking out for long term savings, comfort and redundancy for the parish. If one boilers down, not totally without heat. Better combustion efficiency on Hydronic boiler.

I've been in your exact situation many times, including now, with several churches. What I do...

1) Set or suggest the specs.

2) Walk contractors through job.

3) Inspect job during, on start up and after.

If the "experts" in the Parish Council don't heed, your sage advice, that's on them. Stand your ground...with a smile. Of course, your doing this Pro Bono, have no vested interest, and you need to lay that down. Ray, they don't know How Lucky they are to have YOU advocating for them. As grandpa Norb used to say..."sometimes...a prophet is without honor 🎖 in his OWN Country." This is how I handle My Churches. Mad Dog 🐕

JUGHNE · January 31

Two boilers for sure.

For our school I replaced a 65 year old double sized steamer with 2 zones by installing 3 smaller boilers.

I wrote all the specs down to the last detail.

And then submitted a number and a cash donation towards my number. Donation was about 25% of my bid. Talk about buying job!

Even without the discount, my actual number was still less than 2 other bids.

For me it is/was the only new steam boiler install I will most likely do.
Just a project/hobby I wanted to accomplishment.

Not the situation for everyone.

clammy · January 31

2 boilers not a second though to it . It’s amazing the original contractor would not have jumped at it I know I would have ,simpler in all aspects and I would guess less maintenance And less short cycling just to satisfy the heat exchanger . Plus I would image there’s a lot more in terms of cycling indoor temp reset for unoccupied periods of time and out door rest that more then likely would not have been in the works as easy as a 2 seperate boilers. Sounds like a win win except for the unwilling contractor .
Peace and good luck clammy

EdTheHeaterMan · January 31

Would you consider a 3 boiler job using less expensive (largest residential) boilers to make steam that could handle the entire load as needed. Steamer #1 and #2 would make steam for the steam wing of the building. boiler #3 would be a steamer also with a HX that would do the hydronic side but use internal tankless coils for that purpose. Boiler #3 would not fire for steam unless #1 or #2 were down for some reason.

Tankless coils could be added to boiler #1 and#2. as back up for the lower temperature boiler in case of failure. No fancy controls for staging. Just have the custodian manually switch on boilers and open/close valves as needed based on the load, keeping the control system basic and simple.

No body wants to be responsible for manual operation these days though. How easy is it to get a coal fired system and pay someone to tend to the boilers? Could they pay off their student loan with a job like that?

Mad Dog_2 · January 31

Either way, Ray, don't get more involved than Free Consultant. Dan's right....Never "do work" for your church ⛪. Mad Dog 🐕

ethicalpaul · January 31

The argument that one boiler served them well is quite strong. I think it would be for them to decide 1 vs 2: they would consider the worst case scenario and other scenarios and how likely they are to occur. 40 years is a long test period, I would tend to agree that one has proven to be enough.

But I don't like the steam to water heat exchanger. 7 psi is not optimal, and it seems to me that heating the hydronic wing requires overheating the steam wing, at least sometimes.

I would change it to a hydronic loop on the steam boiler in the more traditional way, then with a simple aquastat the boiler doesn't have to steam to heat the hydronic side.

EBEBRATT-Ed · January 31

Depends on the loads.

But not knowing that I would put in 2 steam boiler each sized for 80% of the total load (HW & Steam). 1 Boiler will carry the entire load most all the time. If one boiler fails your still covered in any case as 80% will keep the place from freezing and in most of the winter carry the entire load with one boiler.

ethicalpaul · January 31

Or with typical current pickup factor, even on design day 80% will fully heat it and still cause it to cycle on pressure

JUGHNE · January 31

Age and replacement cost of the heat exchanger would be one of my considerations.

retiredguy · January 31

What I would recommend is 2 steam boilers sized to about 80% of capacity for each. Tie the two boilers in parallel as normal and add a lead/lag control system. Leave the steam pressure set at the 7 psig or even slightly higher to accommodate the lead/lag control. Add zone valves for each wing and a steam pressure regulator to control the steam pressure to the steam section. You could lower the steam pressure on the steam wing and still provide the higher pressure for the heat X. Take the heat X to a rad shop that can clean and pressure test the coil. (There used to be one in Homewood). Kind of old school but 2 boilers instead of the one original since most steam boilers are not as dependable as the old one was.

Option 2; convert the steam wing to hot water if feasible and still utilize 2 boilers as above. With you on the "board" they should allow you to put in the best system as per your recommendation since this is the work that you do.

Steamhead · January 31

@RayWohlfarth , is the steam wing piped so it can easily be split into 2 or more zones?

jumper · January 31

You didn't say how big the old boiler is.
Why 7 psig? 232° versus 212°? How hot does HHW have to be?
Can pumps be eliminated with multiple small steam boilers?
Steam to hot water is definitely better than hot water to hot water.

I once recommended replacing a school's big boiler with multiple baby boilers.
While that recommendation was taken under consideration the board paid rent on a temporary boiler in a trailer.

Pumpguy · January 31

I like @retiredguy's option 1.

For condensate return, I would recommend the returns be split so the high temp. return from the HX are handled separately from the low temp. returns from steam radiation.

This is especially important if the direct radiation returns have a vacuum pump.

I frequently recommend this arrangement.

mattmia2 · January 31

I would tell them who is competent to do the job and have them re-bid it with those contractors.

Barring that I would go with the simple 2 boiler solution with one for the steam wing and one for the hot water wing.

jumper · January 31

Pumpguy said:
I like @retiredguy's option 1.

For condensate return, I would recommend the returns be split so the high temp. return from the HX are handled separately from the low temp. returns from steam radiation.

This is especially important if the direct radiation returns have a vacuum pump.

I frequently recommend this arrangement.

If the LP system uses vacuum you can consider using the 7 PSIG steam to generate that. You can even consider thermocompression. In my day venturi vendors would check my calculations. They probably have computer apps to do it now.

Long Beach Ed · January 31

Ray, you've been around long enough to know that any job you do for your church or a relative won't work no matter what you do.

That's just the way it is.

ethicalpaul · January 31

jumper said:

Why 7 psig? 232° versus 212°? How hot does HHW have to be?

I think he said the steam->hot water heat exchanger required 7 psi. Another reason to get rid of it or have a separate hot water boiler like @mattmia2 said

RayWohlfarth · February 2

Thank you all sirs! Here is the link to the new video

https://www.youtube.com/watch?v=Ty6UfzToebc
Lots of great ideas and some wise points. Here was my solution. Since the school was worried about backup, I used two smaller steam boilers for the steam side and two smaller hydronic boilers for the hydronic side. We left the heat exchanger in place because they weren't sure we would need it. We never did. The school dropped their fuel costs dramatically because we were able to operate the new steam boilers at 2 psi and reset the hydronic loop. I did learn a valuable lesson on this project. Once you touch it, you own it. Every heating issue in the school from then on was blamed on my boilers. It could be a defective pneumatic thermostat or a defective blower on a unit ventilator, I was blamed. I can't even count the times I heard, "We never had this problem before you changed the boilers."
I wish I had listened to @DanHolohan

DanHolohan · February 2

😂

Intplm. · February 2

@RayWohlfarth

I really like your style.

I too have been there. Its so true, "No good deed goes unpunished."

CLamb · February 2

@RayWohlfarth I love the graphics.

RayWohlfarth · February 2

@Intplm. Thanks I appreciate it
@CLamb Thanks I think it helps explain the points

jumper · February 2

How did you size the boilers?
What sort of boilers did you use?
How did you pipe the boilers into mains?
What procedure to isolate unfired steam boiler?

ethicalpaul · February 3

I love it Ray! What a trick question! "1 boilers or 2?"

Answer: FOUR!!!

RayWohlfarth · February 4

@jumper I sized the hydronic boilers by doing a heat loss on the hydronic wing and double checked my calcs by comparing the steam to water heat exchanger size and the pump gpm. I sized the steam load by adding all the univents together and added 15% for the piping. I used Triad vertical fire tube boilers. I piped the steam boiler output into the existing horizontal header. I used swing check valves on the steam boiler piping to isolate the boilers.
@ethicalpaul LOL thanks. The committee was really concerned with backup. The old solo boiler had failed numerous times causing school to be cancelled.

SgtMaj · February 4

“We never had this problem before”. That response always makes me laugh, and it’s usually given by a person with very little mechanical knowledge. Nice set up.

EdTheHeaterMan · February 5

I think I got pretty close with three boilers. I was only 1 off. LOL

RayWohlfarth · February 7

Thanks @SgtMaj I always hated that saying
@EdTheHeaterMan Yes you were sir. Thanks

jumper · February 7

How times change? In the seventies the fashion was to replace big steel with small CI or finned tube. Atmospheric burners. Good luck meeting modern air quality rules with those.

ann1more · February 8

Clearly you went with the redundancy of several boilers in a critical situation. The difference of commercial/industrial/institutional compared to residential are two separate trades! Nicely done sir!

RayWohlfarth · February 9

@jumper I agree with that. We are quoting a boiler that requires 9 ppm not and the price double over a traditional boiler
@ann1more Thank you very much I appreciate it

PC7060 · February 9

SgtMaj said:

“We never had this problem before”. That response always makes me laugh, and it’s usually given by a person with very little mechanical knowledge. Nice set up.

Yes, the infamous “IDKB” (I don’t know but…) always ready to express an unfounded opinion.

This weeks case, Replacing a steam boiler at my kids school What would you do?

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