Venting risers?

ShachafL

Hello steam experts,
I have a new weil mclain eg-35 boiler and 6 radiators (4 in 1st floor and 2 in 2nd).
I want to increase the temperature of the 2 bedrooms on the second floor by 3-4 degrees as they measure 66 & 67 degrees (thermostat in 1st floor is set to 70). All the radiators seem to heat evenly (few ribs but not all), but I want the ones on the second floor to heat more.

I have tried faster venting by replacing the radiator vents from Hoffman 1A to a Maid-O-mist #C but it changed the temp by barely half a degree so I guess my problem is venting the mains or risers.
I have a Gorton #6 on the long main which I changed with a Maid-O-mist #C but again the change is minimal in the 2nd floor.
Do I need to vent the risers (10ft) going to second floor? and if yes, should I place the vent on the bottom of riser or the main just before it changes to a riser?

Any advise is welcome.

Many thanks

EBEBRATT-Ed

If you want to vent the risers it is best done at the top. But it involves a little work:

Remove the angle radiator valve
Install a tee with a riser vent & a straight radiator valve

But I wouldn't jump in and do that yet.

First optimize your main air venting in the basement & see if you can get by with that because you only need 3-4 degrees. Best bet would be to post some pictures of the boiler and piping around the boiler...stand back about 10'

Maybe redraw you sketch a little clearer and mark the rads that do not heat as well. Then we can size the main vents.

Also try this.

Start the boiler when it's not steaming and turn up the thermostat. Run the boiler until the pipe and the header just start to steam. Then see how much time it takes for steam to get to the end of both your mains.

Do you have (2) 1 1/4" mains??

cross_skier

I've added vents to the tops of my risers with good results, the second floor radiators start heating quickly.  My approach is pretty simple  I tapped a little street elbow into the very top of my risers near the ceilings on the first floor.  The straight radiator valves are screwed into the street elbow.  Happy to provide pic if interested.

ShachafL

Thank you EBEBRATT-Ed & cross_skier for the prompt reply.
I have attached below a picture of the boiler, where you can see the short main (1 1/4") goes to the right. The short main has a dry return and no vent.
The long main goes to the left and except for starting with 3' of 1 1/2" pipe (in picture) the rest is 1 1/4". The long main has 1 vent after 30' and just before the wet return and the fork to the 2 furthest radiators. (one in first floor and one in 2nd floor).


cross_skier - I would be happy to see your solution if you can share a picture.

EBEBRATT-Ed

Ok. And which main are the slow heating radiators on? I would install a vent on the short main that doesn't have one and increase the vent on the long main.

Test timing the venting as I mentioned above

ShachafL

Thank you EBEBRATT-Ed!
Where would you place the vent on the short main? (you can see my crude sketch in the first message).
As you recommend I will replace the vent on the long main to size D and test timing.

cross_skier

Hi, here are some pics.  I believe it is a 1/8" Gordon valve on top of a 1/8" street elbow.  It works well in my house and the Gordon valves sort of match my woodwork. 

We stumbled across a deal on a lot of the valves, I am pretty sure we used the largest ones and even drilled out some smaller ones.  I am pretty happy with them being trouble free through the years.

cross_skier

I am worried about the diameter of your mains, mine are 2", 2", and 1.5". 

The diameter of your main creates an upper limit on the number/size of radiators that can be fed. The pros can quickly tell you the EDR that can be supported by a 1.25'" main

EBEBRATT-Ed

@ShachafL Once you figure out what size vents you need you can drill and tap a hole in the steam main about 18" from the end of the main on top if possible is ideal.

delcrossv

cross_skier said:

I am worried about the diameter of your mains, mine are 2", 2", and 1.5". 

The diameter of your main creates an upper limit on the number/size of radiators that can be fed. The pros can quickly tell you the EDR that can be supported by a 1.25'" main

Thanks Peerless. Extrapolating down to 1-1/4 probably around 200 sqft.max



I'm thinking you'd have better luck splitting the mains and taking them back separately to the header (which should be at least 2-1/2) and adding that vent.

cross_skier

Another case where the "pro" didn't follow the instructions in the installation manual for the boiler.

delcrossv

cross_skier said:

Another case where the "pro" didn't follow the instructions in the installation manual for the boiler.

Yep. The copper header is the tell for that. 🙄

EBEBRATT-Ed

@cross_skier

Yeah its piped wrong but better than it was. Look at the plugged tee and where it used to go

Gordo

Does it actually say in the Weil-McLain instructions not to use copper for steam headers?
Really? Where?
Once not long ago a (former) customer called Weil-McLain directly and asked...
They told him his lovely new copper header was just fine.

BobC

A customer buys a new steam boiler once every 20+ years (if their lucky) while that installer installs many every year. They threw the customer under the bus so they wouldn't piss off the installer by making him repipe.

Bob

ShachafL

Thanks everyone for your feedback.
I have noticed that when starting from cold all the sections in all the radiators warm up, but during the heating cycles (once every 1 hour) only 2/3 of the sections get warm. I have a honeywell T4 pro which is set to steam heating but I don't see how to change the differential and if this will help.

@EBEBRATT-Ed just to clarify where to tap the short main (sketch below), Do you recommend putting it from the bottom (+18" up) of the riser to the 2nd floor ?


Another technical question about tapping (never done it), does an IRWIN 1/8" with 27 NPT, good for me?
Also, my local hardware store don't have a Q bit size, can I use 21/64 instead (slightly smaller)?

Hap_Hazzard

Yes, that's the right size tap.
Letter/number drills are usually sold in sets unless you have a really good hardware store. You can use 21/64 if you can get the tap to start. If you have a taper reamer you might want to take a couple turns with it. Since it might not work, you might want to practice on a junk fitting first, if you have one. You don't want to end up with a hole you can't plug.

cross_skier

Hi,
Yes the street elbow and the radiator vent will have npt threads.  There should be videos on tapping holes on YouTube.  

I think I drilled a tiny hole first, then the proper size hole for the tap.  I went pretty light on the tapping fluid.

Your header is the smallest I have ever seen but at least it is not missing.  Big headers and mains will carry more dry stream that can feed more radiation.  Yours may be ok if you have just a couple of small radiators.

ethicalpaul

I can't remember---did anyone ask you if the radiators were heating the spaces OK? There's no rule that radiators have to fully heat up during a call for heating.

ShachafL

@ethicalpaul the second floor 2 rooms (1 radiator on each room) are ~5F colder than the 1st floor (currently set to 70F), this is why I am trying to vent these radiators faster, but increasing the vent size from Hoffman 1A-setting 6 to a Maid-O-mist size C didn't change the number of sections heating up. This is why I thought to vent the riser on the long main and add a vent to the short main.

ethicalpaul

Ahh ok. Well I don't think it's the venting honestly. If a MoM C can't vent it fast enough, then it probably can't be vented fast enough. Especially just for a second floor radiator. When I re-ran one of my second floor risers to the interior of the room (rather than the interior of the wall), I installed a riser vent just for grins and I don't think it affects the timing very much. Third or 4th floor I could see.

How fast are your first floor vents? It might be better to slow them down.

cross_skier

I agree with @ethicalpaul.  MoM C has about 1/8" hole and that is big for a radiator.  Venting the risers certainly would not hurt but your resources might be better spent elsewhere

Hap_Hazzard

Cold upstairs, warm downstairs, hot basement can mean the heating cycles are too short. Check your thermostat's swing, differential, cycles per hour or heat anticipator setting. Cycles per hour should be as low as possible; swing, differential or heat anticipator should be as high as possible.

ShachafL

Thanks @Hap_Hazzard and @cross_skier . I think I found the issue (differential is set to 0F (see bold in the installer manual below). I will change the differential by increments of 1F and see if it helps.

ethicalpaul

I don't think Differential is what you're looking for. They say it's not deadband. What it is I think is when it switches from heating to cooling automatically.

Putting setting 370 as 1 CPH (steam) I think will get you the largest possible differential. As it says in the manual, they don't let you set the deadband (swing) explicitly.

ShachafL

Thanks @ethicalpaul for explaining. I couldn't change the differential settings anyway (it jumps over this), and setting 370 is already set to 1 (steam).

I forgot to mention that the basement is cold as most pipes are insulated (fiberglass), and the 3 radiators in the 1st floor are set to slowest venting (Gorton #4, Hoffman 40, Hoffman 1A-setting 1).

I think the location of the main vent is not ideal (before the wet return and between the split to the 1st floor radiator and the riser to second floor (see sketch in the topmost message).

cross_skier

I am a little worried about really big vents on radiators.  if you vent a radiator too fast, I suspect the vent closes before the radiator has had a chance to fill with steam in most of its sections.  You could check this out by careful observation.  I would actually be interested in what you find.

I have gotten best results by venting risers fast and radiators relatively slowly.

neilc

sometimes you don't vent the cold radiators faster,
sometimes you vent the hot ones slower

EBEBRATT-Ed

@ShachafL

Pick a spot where you can get the drill in for access. Ideally at the end of the 4.5' pipe before it rises up to the second floor

If that won't work move back towards the 90 where it turns onto the 2.5' pc

ethicalpaul

Is it all the upstairs ones that aren't getting hot enough? Or just some? On the ones that don't get hot, do you hear any gurgling or knocking from them?

If there is a sag in the pipe that's supplying the ones that don't heat up, it could be killing the steam going to them. In a long run from cold start that you described, that water eventually gets warmed up and either lets the steam pass, or becomes steam itself.

I had this problem myself on one radiator: https://forum.heatinghelp.com/discussion/167233/fixing-pitch-issues-in-old-house

But all my other upstairs radiators didn't have that problem and they heat up at basically the same time as the downstairs one despite being supplied by only 1" pipes.

ShachafL

Thanks @ethicalpaul, your old post was useful to discover that I have some water hammer from the short horizontal pipe they used to move the radiator away from the riser (see picture below). I am lifting the radiator slowly to see if this will solve it (currently has 3/4" blocks).


But I think my problem is that the radiators are not big enough for the rooms in the 2nd floor and the heat dissipation. Using some online calculator for BTU needed (below), and dividing the 9200 BTU by 240 (for steam) and by 4 EDR per section for my old column radiator, I see I need close to 10 sections instead of the 6 I have today.


What do people think about radiator sizing? I couldn't find a dedicated thread on that in the forum.

cross_skier

That looks like a 38", 3 column, 6 section radiator to me.  If I got the columns and height right from the single photo I believe the EDR is 30, not 24.

jhewings

Your sketch indicates that radiator is fed by a runout which is 16.5ft of 1" pipe. The chart above suggests the radiator is probably as big as the runout can handle. It seems unlikely a bigger radiator will help with the existing pipe.

Steamhead

@ShachafL , I've seen that piping pattern coming out of the boiler before. You're not in the Baltimore area, are you?

ShachafL

@cross_skier indeed it is 38" tall, but only 2 columns, so 4 EDR per section.
@jhewings - thanks for the reminder on the pipe size limit. Now I see I need a larger diameter pipe for the cold room in the 2nd floor.
@Steamhead you have a phenomenological memory! I am trying to do as much diagnostic and tweaking as possible by myself before calling the "big guns".

bburd

@op The 97.5% winter design temperature for the Baltimore airport is 13°F. In the city it is 17°F. This is from my 1989 ASHRAE Fundamentals handbook, so not current but probably very close to today’s number.

So unless you want your bedroom in the 50s on a very cold day, your desired temperature increase on the heating load calculation should be 53-57° depending on whether you are outside or inside the city, not 40°.

cross_skier

I do almost everything myself and even installed my own boiler.  But with your situation and current piping I think working with Steamhead would be money well spent.  You are lucky to have him in your area, I wish I did.

Chris_L

@ShachafL
I am not convinced that radiator is too small. The bedrooms in my house in the Boston area are comparable in size to yours. None have a radiator larger than 30 EDR (those in the corner of the house.)

The bedroom I am in now has and EDR 25 radiator, and it heats up fine. Though it did have problems before I fixed the radiator runout, which was collecting water, panting and gurgling, thus reducing the steam to the radiator.

See @ethicalpaul's post above again. When you've fixed the pitch issues, see how the radiator heats and if you can adjust the radiator venting to get that radiator to heat up the way you want.

(Also your heat load calculator seems to give a high result, though it is not clear what assumptions when into the calculation regarding insulation, windows, etc.)

ShachafL

@bburd thanks for the reference, as in the last 5 years winters in Baltimore were mild with an average temp of 32F for Jan-Feb.
@Chris_L, it is encouraging to hear that you can get descent heating with the same room and radiator size. I used some BTU calculator that Google gave me, so can't vouch for its accuracy, and so maybe my problem is not piping/radiators but lack of insulation (row house ~135 years old).

bburd

@op Heating systems are not sized for the average day, but for nearly the coldest conditions expected.  Either the 97.5% or 99% coldest temperature based on historical weather data is normally used.

If this method is followed, in extremely cold conditions—that other 2.5% or 1% of the heating season—the system may not maintain the thermostat setpoint. For this reason the industry has historically tended to oversize heating systems, resulting in higher first cost and lower seasonal efficiency, but fewer phone calls from cold customers.

There is also the question of the assumptions in the load calculation vs. the actual tightness and insulation level of the building.

ShachafL

UPDATE: I have shut-off a small radiator with a Gorton #4 vent (16 EDR) not far from the thermostat (after shutting off another a week ago). So the house now has 4 working radiators out of 6 (2 on each floor)
This increased the average temp on both bedrooms in the 2nd floor without changing temp on first floor (set to 70F on thermostat).
See below second bedroom on short main (no vent yet, and still a bit hammering I need to solve), radiator has a Hoffman 1A-#6:


See below main bedroom on long main (with MOM #C) and 28 EDR radiator with MOM #D:


This is a considerable improvement, but I still want to get an extra 1-2F for this bedroom.
I will try to time the mains and play around with the vents to see if this can solve it.