Poor Steam Pressure
I have a three family building with steam radiators and a Burnham boiler. Last winter, we really had no heating issues to speak of. Prior to this season’s heating, we had our local plumber do a tune up of the boiler and also replace most of the radiator valves, pitch the radiators and generally “balance…
I have a three family building with steam radiators and a Burnham boiler. Last winter, we really had no heating issues to speak of. Prior to this season’s heating, we had our local plumber do a tune up of the boiler and also replace most of the radiator valves, pitch the radiators and generally “balance the system”. I thought we’d preempt any trouble but since that was done, the house takes quite a bit longer to heat up. Unless we set the thermostat very high, the boiler usually kicks off before heat can even get to the last two risers at all. There is also one radiator that never gets hot. The plumbers tinkered and looked and looked and finally concluded that the boiler is undersized. It is a Burnham model 406b rated for 447 steam sq ft. The plumbers say I need something in the 600s. The building is four stories and 20 by 40. This diagnosis would make sense except that the building is the same as it was last year! The only difference I can think of is that they had noticed that two risers that run in the middle of the house that don’t have radiators attached to them had old valves attached. I think that last year one of them wasn’t getting hot at all. This year, with the new valves, that riser gets hot too. I wonder if the steam going to that extra riser could tip the scale and make the difference? Or could they have adjusted the boiler pressure in a bad way. On the boiler pressure gauage, it literally reads zero now, even when it is on. I’m not sure if it is broken or not. I don’t really trust the old plumbers who did the work so maybe I will get someone else in but any advice from anyone else that has seen their heating pressure (as I would describe it) drop would be great.
so the room that has the thermostat is nice and 70F right?
This means your boiler is supplying that radiator with enough heat (and your neighbors are helping too as you said) that there are indeed some radiators (that stay cool) that have vents that are too slow. Change them to a faster vent (it is pretty easy, both to do and figure out. Just go from slow to fast when going up a riser.
You also might want to close the vent on top of the interior riser that stay cool last year when system was working fine.
Correct me if wrong, but 447 sqft=69,000 btu which seems quite low for a 4 story house. Mine, about the same size, has a 150k input which is 120k output (and which is smaller than the one recommended by KeySpan but I did a radiation computation.)
And why was the tuneup done if you ‘had no problems’ (asking not to be snarky but curious)…steam systems are notoriously touchy and best left alone if they work.
That said, it’s probably out of balance now, probably as a result of wrong vents. The two risers, if not connected to rads, cannot change the balance that much (and may contribute to more even heat?)
Steam systems run on very low pressure, sometimes 1/2-1psi and if the gauge is 0-20 or more, won’t register, it’s normal.
OP,
Sorry to hear you and the family are having a rough time in this cold weather.
Let’s give you some ideas, so you can get started warming up your family. First some questions.
When was your boiler replaced? You alluded to it being undersized so that means it could have been replaced before last year….
Did your plumber replace the end of main vents? These vents help to get the air out of the main at the risers furthest from the boiler. It sounded like you weren’t getting any steam at these risers.
What kind of vents did your plumber install and where? As another poster stated, the size of the vent and its location matter quite a bit.
You got a new digital thermostat, check the wiring schematic very carefully, there may be a jumper installed in the t-stat that needs to be removed. Those stats are made for multiple types of heating systems and therefore are generically set-up. Also, check the voltage required for your stat, chances are you have a 24 volt stat and a 24 volt feed from the transformer at your boiler, but hey, you never know.
Regarding the risers with no rads. Yes this does make a difference. Here’s the deal, having replaced the vents, you are now allowing steam to go where it wasn’t going before. The boiler may have been sized with the lack of these risers in mind. By now engaging these risers, you have just undersized your boiler. The likelihood of a boiler being sized so closely is not too good but again, anything is possible.
Oh, last thing regarding the digital thermostats, check your programming, could be mis-programmed. Good luck, sorry I can’t fix it but I hope my points help.
-Steam Man
I’ll check the valves tonight in all of the apartments – good idea, thanks.
They are supposed to be good at heating and they did say that they evaluated the whole system and all radiators when reaching their conclusion.
We got a new honeywell digital thermometer while renovating. Oddly though, it seems to hit the exact temperature we set it at it and stay at that temperature, with very little use of the boiler. When I set it at 70, somehow it always seems to say the house is at 70 and that is on days when the heat barely goes on. It seems odd to me that it would not fluctuate more, if it is digital and precise to the degree. I will say, per a prior poster on this topic, it is pretty amazing how warm our house stays with no heat at all. I assume it is because the two houses on either side are heated and we have good windows.
Thanks to everyone who wrote so far – any more thoughts are welcome.
Col
henry@energysavingscience.com
you can contact henry at this link… he is a heating system expert and will answer any questions
I’m not a plumber but I’ve learned from experience.
If the plumbers you used before were not entirely competent, they may have replaced the valves on the radiators with the wrong ones.
In a steam system there are different valves needed for each level of radiator.
The stronger valves on the lower floors and the weaker valves on the upper floors, in order to balance the pressure.
The first radiator off of the main steam line even has it’s own valve.
If you go to the hardware store, they actually have a chart with a diagram of a typical home and the type of valve needed at that level of the home.
The valves are numbered 1,3,3 or A,B,C. These are imprinted on the side of the valve whether it’s circular or whistle shaped.
It may be something as simple as the possibility that they replaced the lower level valves with upper level valves and now the steam is escaping through the lower pressure valves and not reaching the upper levels.
If your pressure guage is reading zero when the furnace is on, there is obviously something not right, also look into the water gauge, it should have proper water levels to produce steam.
Did they measure the existing radiators in the building to accurately determine that 600’s is what you need? There could also be a problem with the pressure control on the boiler or maybe it was set incorrectly. Also, maybe a thermostat problem (which type is it? Old Mercury type or digital?) It is possible that if many of the radiators and or risers haven’t been operating for sometime and now that they are, they are collecting some extra steam, but this would have had to have been the case for a very long time (highly unlikely). Not that the local Plumber doesn’t know his business, but are they well versed in heating as well?
I mean “they’re” (not their).
I have a theory as to why no plumbers are online to answer the question. On this cold-ass day their probably all responding to service calls!