Balancing steam heat system

bucium

Hi everyone,

We just purchased a house with steam heating. We are new to it and slowly trying to balance the system by ourselves. We are still having trouble with the even heating of the house. Half of the house (the front ) gets heated while the back of the house is cooler. The thermostat is located at the front of the house and the boiler the same. We noticed that on colder days the house gets better heated than when it is not as cold outside. We cannot figure out yet why this is the case even though we have one theory.

Besides the heat unevenness we also have one weird situation. Regardless of how long the boiler runs one of the radiators will never heat up (the one in the kitchen). The moment the radiator in the playroom is closed the one in the kitchen warms up. I checked the pipe feeding the kitchen radiator in the basement and it seems that the pipe warms up to a point and after that is totally cold. We checked to see if there we any obstructions on the pipe and there are none. Besides if there was something there, why would the radiator warm up once the one in playroom was off?

We did the following in an attempt to balance the system and get the two radiators to warm up at the same time:

1. Put in new vents on the mainline – gorton #1 at the front of the house and 2- gorton#2 at the back of the house. We admit that it is overkill at the back of the house ( we calculated the cubic feet of air we need to vent versus capacity of the vent and we need only 1 gorton #2)

2. Put in new vents at all the radiators ( adjustable vents)

3. Checked the pitch of the radiators

4. Regularly cleaned the boiler

5. Cleaned the pipe where the 2 – gorton #2 vents were installed

6. Lowered the boiler cut in pressure to ½ psi

7. Insulated all the pipes in the basement

One thing I should mention is that there are no vents on the raisers at the back of the house. We did not install any as all the pipes are cast iron and we are nervous to drill in any openings.

There is one thing left on the list. I need to calculate the boiler capacity and determine if somehow it is undersized. How can one tell if the boiler is undersized besides running numbers?

Please let us know your thoughts and suggestions on how we can balance the system. Thank you.

Snowmelt

Have to take the dimensions of the rads, where are you located? If local to one of us tech guys on here let us do it all for you. Did you try putting the smaller bleeder valves on the close rads and the one with the bigger bleeders on the furthest, have you tried shutting the closer ones and letting the steám go to the furthest rads? Let's see a picture of the near boiler piping first.

KC_Jones

If you want to calculate the size of the system you need to measure and add up all radiation and get the sq ft and compare that to the sq ft rating of the boiler. Here is a link to a thread listing some sources for radiator sizing. Next to last post in thread.
http://forum.heatinghelp.com/discussion/153477/filling-up-my-boiler-almost-every-day#latest
How long and what size and length are your mains? The mains should be vented to fill at about the same time. General rule is a Gorton#2 for every 20' of 2" pipe. How fast are you venting the rads near the Tstat? You want a slower vent near the Tstat to make sure the house gets plenty of heat. Too fast and it cuts off before the house is warm, this could be part of the issue with the unevenness. The kitchen rad sounds like a venting issue. Open up the kitchen vent some and close down the playroom a bit. Steam goes to path of least resistance and many times one rad basically steals from another because of venting speed. Balancing steam can be delicate. Agreed on some pics of the near boiler piping.

Fizz

Great advice given to you already. I too am a homeowner with 2 pipe steam system. Is yours one or 2 pipe system? If 2 pipe maybe you can turn down valve in room which has tstat. My cycle times on cold(single digit or colder) is between 24-27 min every 2 hours with a setting of 72 degrees on honeywell round analog type. Like you, when radiators cool down, comfort seems lessened, but temp is 70. Our bodies feed us false info based on radiant heat available(like when sun goes behind clouds).

bucium

Thank you for all the above. I believe the 2 gorton #2 are sized correctly as we have about 45 ft for the boiler to the vents. One thing I noticed is that the vent at the front of the house gets hot while the vents at the back of the house are not even warm. I would expect to have them a little warm as the steam reaches them. We checked for obstructions but there are none.
The radiator in the room where the thermostat is installed is turned off.
Both he pipes that feed the playroom and kitchen have their takeoffs for the main. Both pipes have the same diameter ( 1 3/4 in outside diameter so I expect inside would be roughly 1 1/2 in). The length of the runout from the main to the kitchen is about 10 ft and yes it is horizontal pipe. the pipe leading to the playroom is vertical only.
Thanks again for your help!

nicholas bonham-carter

How will the system operate with the thermostat in an unheated room?--NBC

bucium

Heat from the adjacent rooms warm up the whole area. It is more like a open floor plan.

vaporvac

Is this a two or one-pipe system? If two-pipe, you may be missing the guts in the valves that allow you to meter the steam so it just take the path of least resistance. If so you could try orifices. That long horizintal run i s problematic.

Jamie Hall

Does the steam main to the vents at the back of the house get warm at all? If not, and the vents are open, you have a blockage in there somewhere... trace back to where the main does get warm, and then figure out why it stops at that point.

bucium

It is a one pipe system and yes the main to the back of the house gets warm. In fact today the radiator in the kitchen was warm all day and the one in playroom was cold all day. Cannot figure out why this is happening.

ChrisJ

bucium said:

It is a one pipe system and yes the main to the back of the house gets warm. In fact today the radiator in the kitchen was warm all day and the one in playroom was cold all day. Cannot figure out why this is happening.

My system did that when I had several large radiators acting as hogs.

Once I slowed them up a little things fell right into balance.

You said you used adjustable vents, which ones?

What size is your boiler and do you know how much radiation you have in EDR?

Fred

Did you check the pitch of the horizontal steam suppy lines (in the basement) that feed the radiators? If they don't have some pitch, back towards the Main, they are likely to cause the steam to condense where the water is pooling.
You do need to figure out where to put some Main venting on that back Main. With no vents on that, steam will always take the path of least resistence and that is the main with the vents. Even if you have to put the vents further down on the return, that is better than no venting at all.
Do total up the EDR of your radiators and see how that compares to the Sq. Ft. steam output of your boiler. It could be undersized but the fact you say the house is warmer on colder days suggests to me it is a venting issue. When it's colder outside, the boiler has an opportunity to run longer and it continues to push air out of the system (through those small radiator vents).
Also check the radiator vent on the radiator where the supply pipe gets warm/hot to a point and then cold from there to the radiator. Even though the vents are new, one could be defective or sticking closed from time to time. Also make sure that vent isn't waterlogged. Shake it out and put it back on if it seems to otherwise be ok.

bucium

Swe are using varivalve for the radiators.

ChrisJ

I would bet that's your problem. Buy a set of vent rite 1 s and replace all of the varivalves. I personally like Gorton vents but they are not adjustable

Charlie from wmass

I agree quite with Chris.

Dave in QCA

Yes, I too am in complete agreement that your problem is caused by the varivalves. They vent much too fast, even at their slowest setting. I helped friend with a situation very similar, one radiator that happened to be in the room with the thermostat would not heat at all. The rest of the huge old house would be heating like crazy and this one radiator would not get a bit of steam. The problem had been going on since a contractor had replaced all the radiator vents on the first floor, removing the Hoffman #40s and putting in Hoffman 1As. I reset the 1A vents to about 25%, which is not easy to do given the crappy design of the adjustment cap. The next time the boiler fired, the whole house heated evenly and the radiator that had been stone cold heated just fine.

Dave Bunnell, a very good steam man in Chicago emphasized the mantra, "Vent you mains fast and your radiators slow". He wrote a nice article several years ago on the subject. As I recall he analyzed the venting that the dead men used, that is, very slow vents like the Hoffman #40. From my own experience and from a few others on this forum, it is amazing how a system with various sizes of radiators will usually be in perfect balance when using the good old Hoffman #40. Now granted, the big advantage is that there is no adjustable parts to fiddle with and many of us go crazy when we are deprived of that. But... you can usually find these vents cheap on Ebay, or supplyhouse.com

Dave in QCA

It took me awhile, but here is a link to the Steam Whisperer's article. Read it completely and it will make a LOT of sense.
https://heatinghelp.com/systems-help-center/taking-another-look-at-steam-boiler-sizing-methods/

ChrisJ

Hatterasguy said:

Dave makes perfect sense on the design day. If you downfire the boiler and restrict the venting to effectively downsize the radiation, you might get to the point where the boiler runs 100% on the design day.

In my own situation, the boiler runs 58% on the design day and sits idle for 42%.

However, on every day but the design day, the smaller and highly restricted system that Dave has suggested now ALSO must cycle. And cycling his system is now made much more difficult because it is very slow and lazy due to the design. As he stated............it takes 20 minutes to get steam to fill all the radiators.

So, I conclude that, at the end of the day, a more powerful system that may sit idle for a bit more time will be far easier to control on every day but the design day.

Whether one or the other has a significant fuel benefit is really unknown. I cannot imagine that it is very efficient to burn fuel for 20 minutes waiting for the steam to arrive................when I currently do it 4 minutes.

There is an optimal point somewhere between his approach and the general accepted practice of a boiler rated at 133% of the EDR. I'm just not sure where it is, but I suspect that it's probably near the 100% point judging by some of Chris' results.

Now, if he uses his approach on a vacuum system................where he can dramatically shorten the preheat time................the entire analysis may produce a different conclusion.

Read Dave Brunell's article that Dave in QCA just posted.
Mr Brunell has been saying to stop oversizing boilers since 2009. In fact, it looks like he is saying to size it for heatloss + piping losses which may be far smaller than the total radiation. It would be in my case, I'd need a DOE output of around 65,000-70,000 btu.

https://heatinghelp.com/systems-help-center/taking-another-look-at-steam-boiler-sizing-methods/

SWEI

I hate to sound repetitive, but two stage firing would really help a lot...

ChrisJ

SWEI said:

I hate to sound repetitive, but two stage firing would really help a lot...

Two stage? That's so old.
Modulating burner. Can be setup to run continuously or close to it on almost any day.

SWEI

ChrisJ said:

SWEI said:

I hate to sound repetitive, but two stage firing would really help a lot...

Two stage? That's so old.
Modulating burner. Can be setup to run continuously or close to it on almost any day.

Completely agreed. LMK when you find one for an atmospheric boiler, and how you set it up.

Meanwhile, two stages is 100% better than one...

ChrisJ

SWEI said:

ChrisJ said:

SWEI said:

I hate to sound repetitive, but two stage firing would really help a lot...

Two stage? That's so old.
Modulating burner. Can be setup to run continuously or close to it on almost any day.

Completely agreed. LMK when you find one for an atmospheric boiler, and how you set it up.

Meanwhile, two stages is 100% better than one...

Well,
I figured since right now we're dreaming that we would obviously use our modulating burner in a 3 pass wet based boiler.

Spare no expense when dreaming!

Jamie Hall

And while you are at it, throw in a controllable vacuum pump on the system, not only to speed up time to fill radiators, but to control the radiator temperatures (higher vacuum, lower temp) and run that off an outdoor temperature sensor -- maybe with a windspeed sensor?

KC_Jones

ChrisJ said:

SWEI said:

ChrisJ said:

SWEI said:

I hate to sound repetitive, but two stage firing would really help a lot...

Two stage? That's so old.
Modulating burner. Can be setup to run continuously or close to it on almost any day.

Completely agreed. LMK when you find one for an atmospheric boiler, and how you set it up.

Meanwhile, two stages is 100% better than one...

Well,
I figured since right now we're dreaming that we would obviously use our modulating burner in a 3 pass wet based boiler.

Spare no expense when dreaming!

You can't do that....they won't approve it for gas. Are they listening?