Steam Heat Radiators Not Heating

HelpMeImCold

Hi,

I have a two-story home with single pipe steam heat. Lately it seems the first floor radiators are only half heated, while the upstairs radiators rarely work at all. I’ve tried bleeding all of the air valves, and they all whistle and sound like they are running normally, only no heat comes after. I’ve checked each air valve and they are not clogged. All the supply valves are open.

I even changed the pitch of the radiators to lean toward the supply valve, which seemed to fix them temporarily, but not long after they went back to not heating.

A plumber was over a year ago and serviced the boiler, so I don’t think that is the issue.

Is there anything I’m overlooking or missing? Thanks in advance!

KC_Jones

Is this house new to you? I only ask to verify if you have a history of it working and now it's not. If it's new to you then let's start with basics.

You describe a classic balancing issue. That is usually venting related. So, what type of main vents do you have on the main piping in the basement? These will either be located at the end of main in the area of the last radiator connection, or sometimes where the return piping drops straight down to the wet return. The mains need adequate venting to get all those pipes filled first, prior to getting steam to the radiators.

What type of vents are on the radiators. Once the mains are vented the radiators need the appropriate size of vent to get the steam to that radiator, and fill that radiator appropriately.

HelpMeImCold

Thank you for the reply. This will be my third winter in this house. I’ve had this issue before but a simple bleeding of the air valves seemed to do the trick.

the only vent I see so far is the one pictured below. I’m not sure if this is at the end of the main in the area of the last radiator connection. It’s on the opposite side of the basement from the boiler. I don’t believe I see a valve by the wet return

Jamie Hall

There is no need to "bleed" a steam radiator. If the vent is working at all, the air will escape every time the boiler comes on. If the vent isn't working properly, the radiator won't heat.

It is a venting issue, as @KC_Jones said, but I have a feeling that at least some of the vents may simply not be working at all.

So -- first question. What is the pressure control on the boiler set at? If it's too high, the vents may get stuck shut. If it's been too high for some time, that stuck shut may be permanent...

HelpMeImCold

Currently it is at 0, unless I am reading the wrong gauge

HelpMeImCold

either that or around 2, according to this gauge

delcrossv

Might just be time for a radiator vent replacement. None of them work?

Can we have some pictures of the radiator vents?

Next test is does a radiator get hot with the vent removed?

Close radiator valve
Remove vent
open valve

Steam should come out of the vent hole

HelpMeImCold

The vents are a mix of one of these two. Interesting enough the older ones are the ones that seem to be working (they are on the first floor)

All the vents whistle and have air coming out of them when the boiler fires, and I’ve taken them all out and blown through them myself to make sure they are not clogged.

I will try to remove the air vent next to see if it gets hot with it removed

Jamie Hall

Boiler pressure is set a bit high -- the pressure controller should be set to 0.7, not 2 -- and that may be why the vents whistle. Assuming, of course, that the pressure controller is actually working... does the boiler ever turn off on pressure?

How long does the boiler run at a time? That is, how long after the thermostat calls for heat does it run before the thermostat turns it off?

HelpMeImCold

@Jamie Hall I’m not sure I understand your first question.

My best estimate is that the boiler runs for about a minute or so each time. I am listening for it right now and will respond back if it is something different.

delcrossv

HelpMeImCold said:

@Jamie Hall I’m not sure I understand your first question.

My best estimate is that the boiler runs for about a minute or so each time. I am listening for it right now and will respond back if it is something different.

It should be running a lot longer than 1 minute.

This is your pressure controller:



The screw on the top should be turned so the indicator goes down to about half what is is presently.

HelpMeImCold

Thank you @delcrossv. I am able to lower the pressure simply by turning that screw? I figured I’d have to release some of the water or something

Jamie Hall

If the boiler is only running for a minute at a whack -- or even as little as five or ten minutes -- something is very much amiss with whatever is controlling it.

Which is why I asked the question.

There are probably only three controls: the thermostat, the pressuretrol, and a low water level control.

So -- next test for you. Turn the thermostat up as high as it will go and see if the boiler keeps running long enough to get the radiators hot. It should run continuously until the radiators are nice and warm, at least.

And report back.

HelpMeImCold

Very good, I will do that and let you know!

Hap_Hazzard

One more thing you should check. If your thermostat has a heat anticipator setting (see the manual), you need to turn it all the way up. If it has something like a cycles per hour setting instead, turn it all the way down. Running a lot of short cycles will make your basement hot, first floor warm, and second floor cold because the boiler is only running long enough to get the pipes hot and maybe some of the first floor radiators.

If you can't find the manual for your thermostat, let us know what you have and we can probably look it up for you.

HelpMeImCold

Thank you @Hap_Hazzard. The thermostat is a Honeywell. I don’t see a model anywhere, and u fortunately I don’t have the manual, it came with the house. A picture of it is below.

Usually the boiler goes off for a minute or two at a time, maybe twice an hour. That makes sense that it’s not enough time to reach the second floor, you described it perfectly. I just turned the heat up all the way, will report back.

 

Jamie Hall

That Honeywell does have a cycles per hour setting. Here's the manual: https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-1532.pdf

The settings you want to check are found under Step 8, customize your thermostat. You want Feature Number 4, system type, set to 1

HelpMeImCold

Thank you @Jamie Hall! I will certainly take a look at that.

Update: I turned the heat all the way up, and the boiler has been running for a solid 20 minutes. We’ve got heat upstairs! How long should I let this go for, and is it just a matter of adjusting the settings on my thermostat?

Hap_Hazzard

Ah, @Jamie Hall , you beat me to it. I used the part number at the bottom of the door (32207501-002 REV. B ) to look it up, but I ended up with a different model. There's a whole family of programmable thermostats that use that part.

Both of the manuals we found say "Wake, Leave, Return, Sleep" on the Set Program buttons, and his says "Morning, Daytime, Evening, Night," so I'm not sure either one's exactly right.

Jamie Hall

All of that series uses the System Type setting, I think, @Hap_Hazzard . Big help... buried in the documentation.

For, @HelpMeImCold -- hooray! I think we've found most of the problem. Thank you! Now do check the system type which @Hap_Hazzard and I have given you and get that set right, then try running the system normally. I'm going to bet that that takes care of most of the troubles.

If not, we'll try some more.

Hap_Hazzard

This is where your experience comes in, @Jamie Hall . Those programmable thermostats confuse me. I ditched mine for one of the old, round ones with the mercury switch, and I still don't really understand what the anticipator is all about, but I can make it do what I want.

HelpMeImCold

@Hap_Hazzard and @Jamie Hall so the thermostat was still on the preset, which was gas or oil forced air. I switched it to the steam system setting. That would certainly explain a lot haha. It’s gotta cool down in here a little, but I will monitor and listen to make sure the boiler stays on longer. I will report back by tonight, or tomorrow morning to give it enough time.

I appreciate everybody taking the time to help me through this. Fingers crossed this does the trick!

KC_Jones

Based on the pictures you posted I'd say you will still need to work on that venting to get the system to run as efficiently and evenly as possible.

Hap_Hazzard

Believe it or not, @HelpMeImCold , we enjoy doing this.

Be sure and print out a copy of one of those manuals and keep it with your other heating manuals. (I hope you have other heating manuals.) It will come in handy when you need to change the batteries. (I suggest you use lithium batteries.)

HelpMeImCold

@Hap_Hazzard I will certainly do that!

@KC_Jones I took a look at the vent I found in the basement and wasn’t quite sure what to do with it, it didn’t move at all. Should I also work on lowering the pressure as well?

KC_Jones

In reality, truly lowering the pressure can be done with proper venting. The pressuretrol simply cuts things off when a pressure is reached. With proper venting (and a properly sized boiler) you may never get to the cut out pressure.

The venting also balances the system. You would be surprised how much control you can have with venting. The coolest room in my house is the bedroom on the second floor, we like it cool at night so I keep it cooler with a small vent. The warmest room in the house is the walk in closet off that same bedroom. Small rad with a huge vent. It's also next to the bathroom, so we like those areas warmer. Nothing like a piping hot steam radiator when you get out of the shower.

For the vent in the basement you would need a couple of wrenches to unscrew it, but make sure you have the new venting plan in place and all supplies on hand before doing anything.

HelpMeImCold

@KC_Jones I see, so ideally I could grab a couple of larger air vents for rooms that I want warmer, and in turn those could actually help alleviate some of the pressure, if I am understanding correctly 

Hap_Hazzard

Make sure your mains have adequate venting first, or balancing can be very tricky. Say you put a D vent on a radiator on a long runout near the end of the main. Now you're venting that main through that radiator, but if a radiator before it has a shorter runout, it may get steam first, and if it's close to the thermostat, it might end the cycle before the radiator you want to get hot really gets warm. You want to make sure the mains fill up with steam as fast as possible, so the steam starts flowing out to all the radiators at once. Then you add venting to the radiators in proportion to their size, the size & length of the runouts and how hot you want them to get (or how fast you want them to get hot).

Also, if you have a room you don't use, like a guest bedroom, you can turn the radiator valve off in that room, but never turn a radiator valve down part of the way. They need to be all or nothing.

HelpMeImCold

What is the best way to confirm the main vent in the basement is working correctly? I took a look and while it looks like the air vent on a radiator it was stationary, not moving at all

KC_Jones

The moving parts are internal you won’t see anything.  Even if it is working, that vent is quite inadequate for a main vent.  If you measure the length of the mains we could recommend how much moan venting you would need.

Also if you have a second main that main should be vented as well.

HelpMeImCold

So I’ve actually found another hidden main vent, pictured below. I’d say the pipe that the original main vent is on is about 15 feet. Then that pipe goes into another one that’s connected to the boiler 

Hap_Hazzard

That seems like an odd place for a main vent. It's also too small to be a main vent—see how they added a reducing bushing to mount a ⅛" vent in a ¼" tapping? There might even be a ½" x ¼" bushing under that. It has probably been destroyed by water hammer since it's not mounted on an extension.

For comparison, these are my main vents. They're mounted on the dry returns, just beyond the ends of the mains.

HelpMeImCold

Hmm, I’ll take another look, but I don’t remember seeing any vents that looked like that. I’ll look again now that I have a better frame of reference 

Hap_Hazzard

Don't be surprised if you can't find them. When I bought my house it didn't have any main vents. When they built an addition back in the 60's, they added some radiators and removed all traces of the main vents.

People aren't used to thinking about how steam behaves in enclosed spaces, so they don't realize that steam can't move into a pipe unless the air gets out of the way, and they don't understand what those vents are for.

HelpMeImCold

so I did a pretty thorough search this morning, and those two vents were the only things I could find that resembled a vent. I couldn’t find anything else.

Good news is that the heat has been working consistently since I switched the thermostat settings. Of course efficiency is key so if you guys have any suggestions on what I should do with my main valves, I’m all ears.

Jamie Hall

Not surprised that you couldn't find any other vents.

And I'm very happy that the thermostat change seems to have helped out!

Now in adding vents and the like -- a couple of observations. The primary one is this: does the house heat reasonably uniformly, or at least as uniformly as you would like, and does it do it reasonably quickly, without the boiler shutting itself off on pressure? If it does -- don't worry about vents. Yes, it might be fractionally better in some other way. But not to worry about it. The secondary one is this: there are preferred ways and places to mount vents. They aren't the only ways, just the preferred ways. Sometimes one just has to get creative.

HelpMeImCold

So far, the house is pretty evenly heated. I’m just happy to not be freezing upstairs at the moment. All rooms seem to be getting the same amount of heat, maybe give or take a tiny bit. But overall I am happy with it

Jamie Hall

Good! That's what we like! Now don't go and "fix" it...!