This 1973 boiler controls schematic.

Teemok

Found posted on the back of the boiler room door. That boiler is long gone.

Custom designed?

The current boiler is likely 2x or more too big.

Steamhead

I think so. See:

https://6sense.com/company/ray-burner-company/605db34b10fce904a7963a4d

EBEBRATT-Ed

Back in the day when things were done right. Looks to me like a wiring diagram made by the burner MFG with probably some modifications to it by the installing contractor.

hot_rod

Did Miners do the load calc and design, or just a control schematic?

Teemok

Who knows? What looks like it was once a clever zone control system has been dumbed down to all zones on at once for two heating periods a day by timer. Huge blowers push from living room sized rooms through walls to coil rooms with walls of heating coils that cover zone ducts. It's a poured concrete 3 story structure. 6' diameter blowers. The 2 million BTU KN20 modulates down and cycles. Whoever installed it 10 yrs ago used the original compression style tank that soon lost it's charge and the relief purges at the top of every cycle. I think the existing boiler is oversized but it could be that the distribution system is just very compromised. It would be an interesting manual J. I'm guessing the first boiler was not as efficient as the KN20 but the contractor up-sized it cause… more power will make it work better. There's no one who knows anything who works for the building. It took some 6 months of desperate pleading reminder calls to get them to understand they needed an expansion tank. It had to wait for a board meeting. Just did a new set of 12 B fan belts and shot grease in all the bearings. When I explained that the un-neutralized condensate will cut groves in the floor drains cast iron piping they lit up and said that must be why it leaks. My visit was sub contracting for another shop. I do what I can.

hot_rod

I suspect not many plumbers or even radiant guys could decipher and troubleshoot that control system. Especially if it has been hacked and modified.

A stubborn building owner adds to your troubleshooting pains🙄

mattmia2

it probably was never installed the way it was drawn so it never worked right so you got the 2 zones kludged together out of whatever was installed.

Teemok

That drawing is the original boiler only wiring. The zoning is mostly the wall of coils. Each coil or group of coils has an older Belimo 3 way diverter valve. The by-passes are all plugged. 20-25 of them but I think the building was originally pneumatic. Now the 3way valves are always open coils are hot when the boiler is on and the 3 huge blowers and the boiler shut down together.

Funny thing is they aren't complaining. Yes they called when the system was down but after a fix and a ton of warnings and recommendations it works just as it has for years. I think previous people in my position dumbed it down for reliability or as a path of least resistance. It seems all the zoning was not that necessary. The building is very high mass and is about 2 miles from the ocean. It never gets very cold but it rarely warms. The timed pulse heating method keeps the thermal fly wheel going.

Teemok

I've been thinking about what I would propose to do to improve efficiency, longevity and comfort. I know it's a dangerous game altering what apparently currently works well enough.

1# the system must have a working flow switch

2# boiler maintenance , new igniters, condensate neutralizer media and combustion analysis

2# big buffer tank installed to elongate boiler short cycling. Limit max. firing rate.

3# ODR the SWT from 180F it is now and shoot for more of a constant circ. approach

4# Clean all the coils and blower wheels

5# Run cleaner in the hydronic system a couple times with good flushes in between.