Richardson - Largest Radiators heat poorly

Robert O'Connor_3

I have a Richardson 2 pipe steam system. The two largest radiators (9 sections of 3 column) are at opposite ends of living room. One happens to be the first radiator off the main and the other is the last. During a typical heating cycle (30 - 40 minutes) both rads get hot all the way across the top and then very slloowwllyy they heat up further down. At the end of 40 minutes or so they are barely warm to the touch at the return elbow. By contrast the 8 other rads in the system are hot hot hot all the way across and from top to bottom.

The radiators are exactly as described in Lost Art and We Got Steam. The previous owner replaced the original column radiator in the dining room with a 5 tube radiator and the original is sitting in the basement. I was able to disconnect the return tailpiece on this one to reveal the vent orifice and see how to clean it. I disconnected the return elbow and cleaned the orifices on the two living room rads but that hasn't made any difference. It seems that something is preventing steam from freely entering these rads.

The previous owner converted from oil to gas and installed a Peerless boiler about 12 years ago. The system has a pressuretrol (I lowered it to cut-in at .5 and cut-out differential 1) and from what I've read and seen posted here it should use a vaporstat. That seems to make sense since the system never seems to go off on pressure.

Could it be that the extra ounces of pressure are preventing these rads from heating or is it common for radiators to become clogged?

Overall the system produces plenty of heat but since the two worst performing rads are in the living room and closest to the thermostat I would think that the system would be more efficient if they put out more heat.

DanHolohan

It needs

that vaporstat. How's the main vent working?

Robert O'Connor_3

Main vent

seems to work OK. It chatters just a bit and occasionally lets out a soft low pitched whistle.

The system holds a lot of vacuum. I had made the mistake of trying to drain off some excess water when the boiler wasn't firing and when I opened the blow down valve it sucked air in instead of expelling water.

DanHolohan

It could be

the vacuum that's causing what you're seeing. Do you have the original T-shaped main vents?

Robert O'Connor_3

Original vent

is in place at the end of the main (patented July 30, 1918) exactly as pictured in Lost Art. It is the only vent.

When I disconnected the first radiator to clean the orifice I discovered the the check ball in the return elbow was missing. I thought that was the problem but when I opened up the second rad that wasn't heating I found it's check ball was in place. I would think that the missing check ball can't be helping the situation but the other radiators work OK.

DanHolohan

Try this.

Lift the check on the main vent. Just prop it up and leave it like that. Let me know if it makes a difference.

Doug S

Tried what you said

Didn't seem to make a difference. After 30 minutes of boiler run time, the two 9 section column radiators are just barely warm to the touch at the return elbow. Meanwhile the rest of the radiators are very hot all over. The surface area of the smaller rads are hot all over so they are giving off as much heat as the larger ones.

DanHolohan

Are you seeing

vacuum on the gauge with the vent's check valve open?

Doug S

I don't see vacuum

on the gauge, but I've never seen vacuum on the guage and it is probably faulty. The gauge is usually registering positive PSI even when there is vacuum in the system. It did register fewer PSI with the vent open though. The last guy that was here for service (before I bought your books and got addicted to 'The Wall') just shrugged and said that the gauge usually goes bad after a year or two and not to worry about it.

DanHolohan

Doug,

are you able to get the supply valves open to see whether they're intact?

Doug S

Sorry

for the delay in getting back to you. I was thinking of that but figure I will wait until this cold snap passes and the boiler isn't firing as often. I think the supply valves are OK though. They move freely from opened to closed and if I do move them to the closed position I can hear the flow of steam to the radiator stop. Are the orifices in these supply valves prone to clogging so that they don't let enough steam pass?

One of the original radiators had its supply valve replaced with a standard supply valve. This rad heats real nice but according to Lost Art this can lead to equalizing the pressure between the supply and return so I have cranked this valve way down to where it is barely open and the radiator heats up at the same rate as the others.

Fizz

Supply valves

Just say post from 04, don't know if you still are hooked up.  Do you still have Richardson?  If so, did you ever work on valves?  If so, what and how?