Balancing Steam Systems Chart/Radiator Vent Capacity

Kjmass1

I purchased the e-book as I'm interested in trying to balance my 1 pipe steam system. I recently upgraded the main venting with some gorton #1s and #2s and both mains heat up at the same time in about 4 minutes. They could use a little more venting for maximum speed but for now I believe they are in good shape.

From reading on this site it seems that you don't want the radiators to heat all the way across except on the coldest day. I was wondering if someone could explain how that is efficient from a gas usage perspective. I would think you would want to fill the radiators completely in one shot and then turn off vs running more and heating less..but I defer to Dan and the pros that that is the best way to do it.

I've gone through measuring my radiators, run out lengths, etc and put together a spreadsheet to calculate venting capacity.

https://docs.google.com/spreadsheets/d/18LOry_veeZ9_ehIPtuRu2WSxGSoFqD9yA4HD6VRf_lg/edit?usp=sharing

Unless I have a numbers problem somewhere it seems like my venting needs exceed your typical 4/5/6/C/D vents? Wouldn't that make my radiators even hotter? I'm also confused on the 1/2/3 ounces of pressure. How do I determine what my system is running at? Attached is the gauge on my boiler. The cut in is at .5, and the boiler was recently serviced by someone off this board.

The system has been running well but it is heating the radiators all the way across during mild 50-60 degree weather. They all seem to get hot at about the same time and most are running Hoffman 40s with a couple larger C/Ds on big radiators. Does anyone have any advice for me?

Thanks,
Kevin

Mark N

If you heat all the rads all the way across on a 45 degree day it is going to be very hot in your house. The rads were sized to keep the house at like 70 when it is zero outside. Also, if your boiler is properly sized to the EDR of your attached radiation it should take nearly an hour of run time to heat all the way across. I've had steam heat for 25 years and even on the coldest days here in NJ my rads might heat 2/3 of the war across. What changes is how long the boiler stays off between cycles. The most efficient way to run is to be properly sized and properly vented. Are you using a thermostat that is properly set up to run a steam boiler?

Abracadabra

#1 - Each radiator is on it's own runout and riser? There aren't 2 radiators that share a riser?

#2 - I'm not sure, but does that gauge measure in PSI or oz/sq.in.?

"They all seem to get hot at about the same time"
Sounds like your system is balanced.

Kjmass1

My boiler is has a rated output of 153k BTUs. My radiator EDR was 144k + 33% run in would be closer to 183k. This doesn't include an attic radiator that we don't use, 2 ceiling mounted radiators in the basement that are turned off, as well as a radiator we removed in the kitchen during remodel...so I'm assuming it is undersized? I think it's from 1950.

While heat loss doesn't really apply to steam systems, the house had almost no insulation when we bought it. We've done blown in in the walls, foam sprayed the attic, as well as replaced all the windows with energy star ones.

I'm currently using a nest as it was a gift and I like being able to monitor the usage. It unfortunately doesn't have a CPH setting.

I do have a basic honeywell digital thermostat, but not sure if it has CPH either.

Kjmass1

Abracadabra said:

#1 - Each radiator is on it's own runout and riser? There aren't 2 radiators that share a riser?

#2 - I'm not sure, but does that gauge measure in PSI or oz/sq.in.?

"They all seem to get hot at about the same time"
Sounds like your system is balanced.

To the left of "0" shows "inches V.A.C", to the right of 0 shows lbs/pressure. The system wasn't running at the time of the picture.

I counted 10 risers/10 radiators.

I tested slowing down the radiator in the room with my thermostat, but that just caused the rest of the rooms to get too hot before the thermostat would turn off.

nicholas bonham-carter

The 1-2-3 ounce ratings are there because that is the optimum pressure for steam systems, attainable with a Vaporstat, or with a very correctly sized boiler.
I think your thermostat needs some adjusting, or maybe a complete changeout, so that it runs in the one cycle per hour range.--NBC

Abracadabra

That gauge measures PSI. What is the highest pressure you've seen it read? What is pressuretrol set at? Boiler of 153K and radiator EDR of 144K is fine. You don't need to add 33%.

Kjmass1

Abracadabra said:

That gauge measures PSI. What is the highest pressure you've seen it read? What is pressuretrol set at? Boiler of 153K and radiator EDR of 144K is fine. You don't need to add 33%.

The cut in is set at .5 oz I believe. I've never read the gauge before but the heat is about to turn on so I'll keep an eye on it.

Why don't you add 30%?

Mark N

The thermostat I use is a Honeywell FocusPro 5000 set to 1cph. I have knowledge of Nest thermostats. The boiler should be sized to the attached radiation. Add up the total sqft of EDR of all your radiators, even the ones that are turned off. Compare that number to the Net EDR on the boiler rating plate. If it is given in BTU's divide by 240 to get sq ft EDR. The pressure gage is so old I doubt it even works. How long does the boiler run on a call for heat? If it is running 20 minutes and truly heating the rads all the way across, by this I mean the all the sections of the rads are heated top to bottom not just hot across the top. I would think the boiler is oversized. In your spread sheet you show you have column rads and not tube rads. Are the top of the radiator sections connected together with push nipples? If they are they are tube rads and might be rated different.

Kjmass1

Mark N said:

The thermostat I use is a Honeywell FocusPro 5000 set to 1cph. I have knowledge of Nest thermostats. The boiler should be sized to the attached radiation. Add up the total sqft of EDR of all your radiators, even the ones that are turned off. Compare that number to the Net EDR on the boiler rating plate. If it is given in BTU's divide by 240 to get sq ft EDR. The pressure gage is so old I doubt it even works. How long does the boiler run on a call for heat? If it is running 20 minutes and truly heating the rads all the way across, by this I mean the all the sections of the rads are heated top to bottom not just hot across the top. I would think the boiler is oversized. In your spread sheet you show you have column rads and not tube rads. Are the top of the radiator sections connected together with push nipples? If they are they are tube rads and might be rated different.

Good catch! I mistakenly used the "column" number of .025 instead of the tube number of .013. That helps get my venting a little more in line? I will add up the remainder radiators shortly.

With the increased main venting, when the Nest calls for heat on a somewhat cold start, it will take 15 min total to go from 71 to 73 degrees to satisfy thermostat. 2.5 min to make steam, another 4-5 to travel mains, the rest heating. I have been monitoring the tops of the rads which get hot. I have not checked the bottom, will do. Thanks!

Kjmass1

The additional radiators brings it up to 192k give or take. We removed one radiator that was probably another 15k btus. The rating plate says:

192k input BTU
153k output BTU
1000 btu per cu ft
153 minimum relief valve lbs per hour

Net EDR of my radiators is 802.

Looks like my backup Thermostat is the Honeywell TH4110D which supports CPH. I may switch it out depending on how this winters goes and I can post some results of energy usage.

Mark N

Something is not adding up. A 192k btus worth of rads is 800 sq ft EDR. In your other thread you state your house is 2000 sqft. Having 800 sqft of rads in a 2000 soft home would be very excessive. That would be 96 btus per sq ft. Recheck the figures you came up with for the rads. You might be using the wrong number per section.

BobC

One good way to track efficiency is to measure fuel consumption and track it against degree days and sq ft being heated. This has to be done over a period time, maybe one month to be realistic

Fuel BTU's / Degree Days / Sq ft of house

That gives you a pretty accurate look at how the system is operating and it lets you see if something you have done has helped or hurt.

Bob

Kjmass1

Mark N said:

Something is not adding up. A 192k btus worth of rads is 800 sq ft EDR. In your other thread you state your house is 2000 sqft. Having 800 sqft of rads in a 2000 soft home would be very excessive. That would be 96 btus per sq ft. Recheck the figures you came up with for the rads. You might be using the wrong number per section.

The livable/finished area of my house (first and second floors) is 1800 sq ft. The basement is another 1000 with 2 radiators and the heated attic is another 250. I'll double check my numbers.

Kjmass1

How many columns/tubes are considered for the above picture? Which kind is it? Starting to get confused.

Kjmass1

How about EDR of 471, 113k BTUs? Does that make more sense? I think I had interchanged tubes/columns, and the PDF worksheet I was using was confusing. Thanks for your patience.

That should help out with the vent sizes as well.

Mark N

That number seems more reasonable. The rad in your picture above is a tube rad, with 5 tubes per section.

Kjmass1

BobC said:

One good way to track efficiency is to measure fuel consumption and track it against degree days and sq ft being heated. This has to be done over a period time, maybe one month to be realistic

Fuel BTU's / Degree Days / Sq ft of house

That gives you a pretty accurate look at how the system is operating and it lets you see if something you have done has helped or hurt.

Bob

Thanks Bob, I'll look in to this once it gets colder. As for today, it's rainy and 45, and the temp hasn't moved from 72 degrees for 7 hours and the heat hasn't kicked on, so at least the insulation is working!

Kjmass1

So by switching from #40 Hoffmans (which are like a 4.5 maid o mist) to 6/C/D, that would prevent the radiators from filling completely except on the coldest days? Think it is worth looking in to?

Mark N

I use #5 and #6's on my rads. C's and D's have very large venting capacities and would cause the rads to heat quicker not slower.

Bio

I have mostly all Hoffman 40s and I'm happy with them, heats evenly and pressure stays at 1oz, never heated across all the radiators except for last very cold winter, get your self a low pressure gauge to help you determine how Is your system/venting is behaving

Abracadabra

Kjmass1 said:

Abracadabra said:

That gauge measures PSI. What is the highest pressure you've seen it read? What is pressuretrol set at? Boiler of 153K and radiator EDR of 144K is fine. You don't need to add 33%.

The cut in is set at .5 oz I believe. I've never read the gauge before but the heat is about to turn on so I'll keep an eye on it.

Why don't you add 30%?

Any word on what pressure system is hitting?

You don't need to add 33% because the net ratings in BTU and EDR already include a 1.33 pickup factor

Kjmass1

So it doesn't look like that gauge works- it didn't move.

I'm not sure how to measure it ?

I did walk around when it was running for about 25 min and check how far each rad was heating. The smaller ones were filled 100%, the biggest ones varies from 30-80%. I added it to the spreadsheet.

I'm tempted to leave them as is until it starts to really get cold and to see how often it will run. As of now the house is comfortable without much cold spots...just trying to optimize the best I can.

I should have asked the technician a couple weeks ago, but I want to say it was 1oz.

Abracadabra

Kjmass1 said:

So it doesn't look like that gauge works- it didn't move.

Throw a gauge on there that will measure at least 16 oz./sq.in.

I doubt it's running at a max of 1 oz./sq.in.

Kjmass1

Can you point me to a gauge and where to test it from?

Kjmass1

Since I don't even have a gauge (and sounds like you should have at a min a 30psi gauge for regulation) can I just add one inline between the pressuretrol and pigtail siphon? Or should I use a tee?

Abracadabra

Needs to be after the pigtail to protect the gauge from steam.
I get my gauges from Grainger, but some on this forum have indicated that statesupply carries them as well.

Kjmass1

My boiler tech said he had it running at 1.5 lb with the cut in at .5. Are vaporstats preferred or should I stick with the pressuretrol?

BobC

If it's a single pipe system the payback would be pretty long unless the ptrol dies and you decide to replace it with a vstat rather than another ptrol. If it's a vapor system then a vaporstat would be worth it.

Bob

Kjmass1

It's a single pipe system so sounds like I should ride it out with the ptol for now. Thanks Bob.

nicholas bonham-carter

Whether you have a Pressuretrol, or a Vaporstat, you should have a low pressure gauge, to verify what is happenning in the system. It is not enough to think that the settings on the control are accurate, and you don't want your vents to become Christmas tree ornaments!--NBC

Abracadabra

I've found that pressuretrols don't work as accurately or as well as vaporstat at sub 1psi pressures. Can you take a picture of the pressuretrol showing the cut-in/cut-out setting?

Kjmass1

I picked up a 5 and 30 psi gauge with pigtail that I plan to install today. Anything I need to know? Any vales or anything that need to be turned off?

- cut power to boiler
- Disconnect pressuretrol wiring
- Install new piping and gauges
- Fill pigtails with water
- Power up

Kjmass1

Here are a couple pics. Will this work?

Bio

Looks good, it has to be connected above the pig tail to protect them from steam

Kjmass1

So I got the gauges hooked up. I let the system run for close to 45 minutes. It took a while for the gauge to move. After maybe 35 min all the vents were hissing pretty good. I expected them to close up but it never got that far. How long should it take for them to close once they start hissing? The gauge when I turned it off was at .5. The differential is set to 1.

I think the Hoffman 40s are too fast as those radiators fill up very quickly (they are also the smallest rads). At the same time the house is heating evenly. Would it make sense to step all the vents down one ? what is the goal, to fill the rads as slow as possibly?

Another thing- do you want to cycle on pressure? I can't imagine the system running this long in the winter. It heated the house +6 degrees in less than an hour. Would it be better to vent everything faster? 30 minutes seems like a long time to fill all the rads?

Thanks for everyone's help!

Bio

If vents are hissing is possible your water is dirty or the piping may be wrong, maybe you can post a pic, the fact that radiators are heating evenly @ 5oz and not tripping the pressuretrol is a very good thing, I will keep it like it is
Most radiators are oversize, so it may not be necessary to fully heat the whole radiator as long as the tstat is satisfy, a well matched system could take from cold start up to an hour to satisfy the tstat

Kjmass1

Bio said:

If vents are hissing is possible your water is dirty or the piping may be wrong, maybe you can post a pic, the fact that radiators are heating evenly @ 5oz and not tripping the pressuretrol is a very good thing, I will keep it like it is
Most radiators are oversize, so it may not be necessary to fully heat the whole radiator as long as the tstat is satisfy, a well matched system could take from cold start up to an hour to satisfy the tstat

I drained the automatic feed yesterday as it had been about 2 weeks and the glass was getting a little dirty. It's a tea color right now.

All the radiators seem pitched and there is rarely any banging. The hissing was coming from all the rads, which is a combination of Maid o Mists, Gorton's, and Hoffmans vents.

Using the spreadsheet to calculate my venting needs, if I add them all up I need to vent 2.004 CFM. If I add up all my vents using the "2 oz" scale method, I'm at 2.257.

I've never really heard the vents hissing before, so I was surprised that they were all hissing for what seemed like a long time and didn't close up quickly.

Highs in the 70s this week, so testing might have to wait...just finished insulating the mains as well.

Thanks

SWEI

You might consider adding an isolation valve ahead of the low pressure gauge. That will facilitate a pressurized blowdown should you ever need one.

DuggieFresh5

Abracadabra said:

Needs to be after the pigtail to protect the gauge from steam.
I get my gauges from Grainger, but some on this forum have indicated that statesupply carries them as well.

Could you give me an example of the gauges you get from Grainger? I was looking at the selection and wasn't sure what might be appropriate for steam.

Kjmass1

DuggieFresh5 said:

Abracadabra said:

Needs to be after the pigtail to protect the gauge from steam.
I get my gauges from Grainger, but some on this forum have indicated that statesupply carries them as well.

Could you give me an example of the gauges you get from Grainger? I was looking at the selection and wasn't sure what might be appropriate for steam.

This is the same one my local plumbing shop sold me:
http://www.supplyhouse.com/Winters-Instruments-PLP305-2-1-2-PLP-Steel-Low-Pressure-Gauge-1-4-Bottom-NPT-w-Brass-Internals-0-5-PSI

30 psi is also required per code but it doesn't look like supplyhouse has them. I'm sure amazon does though.