Boiler/EDR mismatch

WayneMech

Worst load/EDR mismatch I have ever seen. Boiler is a newer Crown 138kbh input/113kbh output. Good for about 354 sf EDR. It has 2146 sf EDR connected! The building is 2125 sq. ft., with a full basement. By the numbers, the boiler has enough capacity to heat the building. This is a two-pipe, pumped return system. When I first looked the place over, it seemed like a radiator warehouse, but I was called to get it warmed up. The system was flooded, so step 1 was to drain it to a manageable level. This took almost an hour. While waiting for the drain down, I took a look around. The 4" main was still in place, with a reducer to the 2", nipple-laden riser. Some of the nipples and fittings are galvanized! The traps have never heard the word "maintenance". Some radiators have SARCO traps, with no visible means of installation, other than threads. No unions, no spuds, anywhere close. I cannot figure out how they piped these radiators. The condensate tank had water up to the top of its vent pipe, so the condensate main had to be drained, too. The water meter on the feeder indicated 944 gallons. Ouch. Upon startup, the boiler ran out of water, so I added just a little, to keep it running. This cycle repeated itself several times, until the condensate made it back, which was about half an hour. This whole thing is in, you guessed it, a church. So which direction should I go next? I'm sure it needs trap work, and a boiler feed pump. Insulation on the mains would help, since there is none, currently. But, what about the boiler itself? Could I remove enough radiation to more closely match the boiler? Should I just tell them to bite the bullet, and get a correctly sized boiler? Hmm.

WayneMech

Pretty special, eh?

Fred

How can a 2100 sq.ft. building have 2146 sq. ft. of radiation? That 354 sq.ft Steam boiler should be able to heat a 2100 sq. ft. building. Where is it located? what is the design day temp? Did you maybe make a mistake calculating the EDR of the connected radiation? That header certainly won't work, that way. That one main, that looks like either a 2" or 2.5" main, off the top of the header certainly can't support 2100 sq. ft. of radiation either. And only one riser out of the boiler?

Jamie Hall

That header is a bit unusual...

@Fred -- I sort of assumed that it should be 214 EDR... or maybe 246... but then, I make that kind of error typing. In either case, it's oversized and it will probably cycle on pressure, once you get it running (like a new properly piped riser/header/equalizer!), but if it runs OK, it may not be worth the money to replace the boiler until something else goes wrong.

Do change to a boiler feed pump rather than a condensate return pump, and give it an ample condensate receiver. That will cover a multitude of sins...

Hopefully @Sailah will see this and have some thoughts on the traps.

WayneMech

No mistake, Fred. Checked it three times. I took pictures of all the radiators, just to make sure I hadn't had a nightmare. Located in central IL. About 0 F design. It heated the building, but required babysitting the system. Can't do that all the time. What to do?

Fred

The first thing to do is find out why someone put in that much radiation. It can't all be original. The second thing to do is figure out how much is actually needed, do a heat loss, and get rid of the extra radiation and then fix the header issues, test and correct any failed traps and then see how it runs. I doubt is will need a condensate return pump or receiver when fixed.

Fred

Personally, after you do a heat loss, if the building requires something less than 354 sq. ft. boiler, I'd leave enough attached radiation to right-size the boiler.

WayneMech

No typo, Jamie. It's 2146 sf EDR. No short cycling here.

WayneMech

Yes, Fred, it's all original. They all match. The Sanctuary, alone has eight, 32" tall, 28 section, 6 column radiators. At 5 sf per section, that's 268,800 btu/hr. Built in the mid 30's, with all the fittings matching the period. Even the paint layers confirm. It will still need the condensate pump, but only due to the low basement condensate returns. At this point, I'm leaning your way on the solution. I just have to determine which radiators to remove.

Fred

That church must have been purgatory (pun intended) back in the day. I have to assume none of the rads get hot now. Maybe a few get warm?

Jamie Hall

Good grief. Have fun!

Fred

Is it possible they shut off most of the radiators and only used the ones in the section of the church they intended to use at any given time? Some of those old churches had movable partitions so that the sanctuary could be sized depending on anticipated use. Do you see any pocket doors or similar in the sanctuary?

JUGHNE

From dealing with churches & schools it is a certainly that some well intended soul will fiddle with any valves accessible and defeat your best intentions.

Maybe consider orifices for each radiator to make them a fraction of their EDR. Traps not needed. As Jamie suggested a large tank capacity feeder pump for extra water storage/accumulator.
Is that a 4" steam main?

Steamhead

The SARCO traps probably have right/left hand thread nipples, with the left-hand thread going into the trap body and the right-hand thread going into the radiator. These could be made without using brass, which was way more expensive.

Maybe this was a vacuum system originally? This would explain the oversized rads.

WayneMech

I checked everything. the fittings are all original (mid 30's style). Condensate pump has to stay, just because of low returns in basement. I'm definitely leaning toward the radiation removal side, though.

ChrisJ

@Steamhead Would installing orifices in all of the radiators fix the problem without removing any?

Abracadabra

Super tall ceilings? Extremely leaky single pane leaded glass windows?

JohnNY

Most churches I've worked in have zone valves installed. Heating Sacristy or rectory spaces is most often very different from heating the Nave.

That's right. I said "Sacristy" and "Nave".
Catholic school for 12 years.

That sometimes explains an oddly-sized boiler. Also, some systems were designed not so much to heat the space of a church but simply to warm the radiators. You're basically providing radiant panel heating to a bunch of people in coats for an hour one day a week.

SWEI

I'm thinking orifices and a fair bit of time balancing everything.

Fred

Can you successfully Orifice down 2100 Sq. Ft. of radiation to about 15% of that to match this boiler and keep it balanced and comfortable?

JUGHNE

The orifice method would be the least amount of wrenching work. Especially if trap changing involved changing the bodies considering lack of a union, (L-R nipples). With using only 15 -20 % of the rad, steam should not hit the return and traps not needed IMO.

The operating pressure would have to be known. You can always drill larger openings if needed for lower pressures.

New England SteamWorks

One possibility for size of radiation is time to heat. When I installed heat in my basement woodshop I massively over-sized the radiation. This way when I have a whim to whittle I can bring the basement up to temp in no time at all, -no pre-planning necessary. Perhaps the church had an unpredictable schedule.

I dislike the idea of removing radiators (historical value), and agree that shutting off valves would just lead to them inadvertently being re-opened. But removing some valve knobs would seem to be a very simple solution.

WayneMech

I like the orifice solution. To remove the radiators, involves unbolting pews from the floor, and moving them. Anyone have an orifice sizing chart for 1-1/2psi steam? forgot to mention that all of the upstairs radiators have Danfoss self powered zone valves. Unfortunately,someone took all the heads, so all the valves are wide open.

JUGHNE

I got this off the Wall here from "Fizz".

Sorry about my notes scratched on it.

On my school project I should have went smaller to start with as we still overheat.
On the house project I went with 80% at ounces and come out good. No traps, cond line cool.

JUGHNE

There is also an article by Henry Gifford, I think a search here would get you that. Some good helpful ideas and hints.
His chart was based on 2 PSI. The HG notes agree with his numbers.

The orifices came from Tunstall. I just ordered them all drilled at 1/8" and upsized as needed. I did not notice that at the house job there were 3/4" risers/valves but the rad spud was 1/2". That was a little rare.

The house job runs in ounces. The end of steam mains are well vented. The orifices I think, would restrict the main venting having to push all air thru the orifice/rad.

In one case I left the headless TRV in place and just added the orifice.

WayneMech

I am still working toward a solution, but spent three weeks with pneumonia. You are right, Steamhead, the traps are, indeed, held to the radiators with "Turnbuckle Nipples". Pretty cool. I disconnected half (4) of the Sanctuary radiators, since I only had 4 caps on the truck. This helped push the steam further along, getting heat to the Cry Room and Narthex. My next step is to add a #75 Air Vent to each of the End-of-Line F&T's. I am approaching this incrementally, in the hope that I will learn as I go.

MilanD

Fascinating for me as a novice. A question: where do you install the orifice? I'm assuming it's at the trap?

WayneMech

Hello MilanD! (The following is meant to be educational, not snarky)
If we put the orifice at the trap, water will back up in the radiator. This would hold water back from returning to the boiler, bringing in more fresh water. Then, when the boiler shuts down, the radiator sends the extra water back to the boiler, which then floods. In the case of a boiler feed pump system, the excess water goes down the drain. This cycle continues, until the raw water eats a hole in the boiler. So we put the orifice on the inlet side of the radiator.