One pipe steam. Over sized boiler problem. Last owner gutted part of system.

randallkc

I own a one pipe steam system that's 100 years old with a 10 year old boiler
My building is two / three story 1890's downtown brick
Total ft/2 is about 10k. However only 5k is hooked up to steam.

The last owner under bad advice started tearing out the radiators in in the retail main section (5000 ft2) and was in the process of removing radiators in the lofts. I had him quit pulling them when I was purchasing the building. What I'm left with is a 750k BTU boiler running 5000 ft/2. It's way over sized. It was very neglected. All the vents were bad and leaking including the main vents. Most of the radiator valves and vents were leaking and 70% of the pipes were not insulated.

I have finally got the unit property descaled and cleaned. Got vents replaced and installed ATP valves on radiators. I was thinking of ways to turn down boiler. Adjusting gas flow? Removing burners? Or should I just hook up missing radiators? I really don't want to spend 3k hooking up old rads. It's sad they were torn out. They are no longer with the building. I would have to find replacements.

Advice?

Abracadabra

What model boiler? A possibility would be installing a 2-stage gas valve, but modifying the gas train needs to be done by a trained professional and most boiler manufacturers won't offer support and/or recommend it as you are modifying the gas control system.

vaporvac

What is the installed edr compared to the sq ft steam rating on the boiler plate? How long are the mains and what sort of venting does it have? Were the mains ever reinsulated?
Perhaps a two-stage gas valve with plans to reinstall missing rads as funds become available.

randallkc

There are two runs. The boiler is in the front 1/3rd of the building basement. One run to front then thru basement wall into other building. Hoffman 46 vent

Other run is to back. That vent is small. Not sure what it is.

They had to replace the boiler in 03 due to a flood.

It's a Weil McLain LGB.
It's a big unit with a control panel with bunches of switches and cool lights on right side.

The exhost flue is probably bigger round than a basket ball by quite a bit.

There are two water level sensors. One to fill one to kill. They are on left and both have pipes that go back into system and drain lines. The glass sight is in between them.

Return is on left front with steam out on right back. The out is big. 8-12" pipe. That elbows up and tapers down to 6-8"?

The pipes near the boiler were not insulated and didn't appear to ever be since the reinstall. The runs are some of the "A" word insulation is missing or broken.

I insulated the whole thing. About to insulate the returns.

randallkc

I used fiberglass roll insulation that was backed. It wasn't as nice as the fiberglass pieces made for pipe but it didn't cost me $3.30 / ft either. I think I spent maybe $50 for two R-19 rolls that did over 100ft of pipe. I probably have another 80ft to do. Most return line. The return from the long run was 3/4" copper. I purchased the black foam pieces and used that. The other side is 3" pipe

Dave0176

randallkc said:

I used fiberglass roll insulation that was backed. It wasn't as nice as the fiberglass pieces made for pipe but it didn't cost me $3.30 / ft either. I think I spent maybe $50 for two R-19 rolls that did over 100ft of pipe. I probably have another 80ft to do. Most return line. The return from the long run was 3/4" copper. I purchased the black foam pieces and used that. The other side is 3" pipe

Unfortunately insulating will make your oversize issues worse. I would uninsulate the entire system at this point.

Abracadabra

An LGB boiler already has a 2-stage valve on it. All the installer needs to do is wire in a vaporstat to switch between hi and lo. Another possibility would be to carefully select and remove a couple of burner tubes.

Abracadabra

randallkc said:

The return from the long run was 3/4" copper.

3/4" return line? What kind of EDR is that return line handling?

You mentioned a 750K boiler. Not sure if that's input or output, since there isn't an LGB that matches exactly 750K either in or out. I'm guessing that's somewhere in the vicinity of a LGB-7,8,or 9.

Got pics?

randallkc

Boiler information

LGB -7
Series 2
Natural
Input BTU/hr 780000
Minimum input 390000
A.G.A. Gross output 651800
Water MBH 549
Steam ft/2 1975
Steam Mbb 474

Installed 12/1/94

randallkc

I don't know why the north side return is 3/4" copper. Was there before me.

KC_Jones

randallkc said:

I don't know why the north side return is 3/4" copper. Was there before me.

Depends on the EDR it is trying to support. Hard to imagine it's big enough. I only have a 125k boiler and my returns are 1".

randallkc

Just one side is 3/4 copper. Other side is 3"

Abracadabra

randallkc said:

Just one side is 3/4 copper. Other side is 3"

What EDR is supported by that 3/4" return?

randallkc

Yea... I don't know what a EDR is..

Dave0176

randallkc said:

Yea... I don't know what a EDR is..

Equivalence of direct radiation, meaning the sq ft of your radiation.

randallkc

Well this boiler has two modes. On or off. How do I enable the two stage burners?

Abracadabra

@randallkc Take a picture of the gas train and closeups of the gas valves showing model numbers. Every LGB I've installed in the past 15ish years has a honeywell v4944. Current LGBs 6 and over include a 2 stage diaphragm gas valve in the gas train.

randallkc

I will get the pictures I promise. My phone camera is broken.

What pressure should this system run at?
At present it is set to cut off at 7 psi. That seems high to me. I want to use TRV's and recommended max is 2psi. The Danfoss documentation said if pressure is above 2psi the radiator air can compress and steam enter the radiator anyway.

Abracadabra

max 1 psi to start. adjust as needed. a small system should not need more than 10-12 oz/in^2. use a vaporstat

randallkc

My system has two pressure units. A big one with what looks like a Mercury switch. And a smaller one. Is the big one the backup and the smaller one the main trip?

There is also a dial pressure gague. It shows the system getting up to 7 lbs before cut off. That's probably why I have vents leaking?

ratio

One of the switches should have a little red button on the face of it - this is a manual reset button & that is the safety device. If it trips that's an indication that you need professional service. The other one is the operating control & nearly certainly is set to high. Post some pics!

randallkc

Ok. The first one is another boiler project
Sorry for all the duplicates. My iPad isn't quite compatible with this forum

My big concerns with this system

1. Operating pressure
2. Two stage?

And now the state wants me to put in a reset switch and a check valve. I don't know what a check valve will do besides the back flow prevent or

Abracadabra

1 - pretty sure that's a honeywell v4944. it can be setup for 2 stage operation. Provide a pic of the label showing the model number.
2 - the big pressuretrol with the clear front is your backup with manual reset.
3 - the smaller pressuretrol that's all gray is the operating control. It looks like the cut-in is set all the way down. Take the cover off and provide a picture of the diff setting (white dial).

Take a closeup of the pressure gauge.

randallkc

I looked at the gas regulator. Says two stage on it.

The pressure sensor "white wheel" was turned completely to the right. To the limit.

randallkc

<img src="https://us.v-cdn.net/5021738/uploads/FileUpload/65/311b150f62a48417d64da351d2d9b4.jpg" />

ChrisJ

That R-19 looks pretty compressed around the piping. Isn't R-19 6 1/2" thick!?

Compressed insulation = garbage.

Buyinsulationproducts.com has good insulation for usually around $4-6 for 3 foot sections.

randallkc

I thought that too when installing it. But I will say it has made a huge difference and I insulated over 100ft of pipe for less than $60. I was also able to wrap over "the A word" and not disturbe it.

The boiler room doesn't get hot anymore.

Abracadabra

The gas valve is defintely a 2stage. Add a vaporstat to control the gas valve.

randallkc

would that help improve efficiency?

My inspector required I add the following items to my system.

1. Low water cut off manual reset
2. an additional check valve

I guess on the low water cut off manual reset I would have to open a port in the boiler and add it? If possible I would like to add a manual reset to my already existing low water cut off sensor. My system has two low water sensors. One for fill and the second for? I would think the second low water sensor would cut the system off and require some sort of manual reset. I am going to look into this closer.

The check valve I don't understand at all. The system already has a three stage back flow preventer. They are now asking me to add a additional check valve. gasp

vaporvac

Is the gas valve set for high or low fire?

randallkc

Im not sure. I will check