Balancing Problem In Old Multi-Family

ktccapo

I’ve got a major problem trying to balance out a

single pipe system in an old multi-family dwelling. Here’s an overview of what

I’m dealing with:





Four-family residential built 1929 with one Peerless

oil-fired boiler installed 1994





Upstairs/Downstairs on each side





Five radiators per apartment





Vision Pro 8000 T-stat with a sensor in the upstairs

apartment on only one side of the building (there is also a sensor mounted in

the upstairs apartment on the opposite side, but when hooked up it always gives readings that

are three-four degrees less than the other side, which is unusual, as this is

the warmer side of the building (southern exposure). Independent thermometer

readings in the room verify that the sensor says it’s colder than it really is.

We’ve tried three different sensors, and they all give the same reading, so

perhaps it has something to do with the length of the bell wire run?)





Two main vents (Hofman #1’s, about two years old).

Took them out and was able to blow through them easily.





Radiator vents for size, not location (all brand

new, Maid ‘O Mist D’s and C’s for big/med radiators, Maid ‘O Mist #5’s for

small radiators)





Boiler recently flushed until water ran clear

(repeated process five times)





Pressuretrol set to .05 (was set to 2.5 before I

discovered heatinghelp.com)





All piping insulated in original asbestos

insulation; most in good shape, wrapped in plastic, some in bad shape and needs

to be replaced.





No hissing from vents or banging of any kind from

the risers; there is an intermittent banging in one for the pipes in the

basement that lasts for about two-three seconds, usually towards the mid-end of

a cycle.





So that’s my starting point. The following is a

typical pattern of what’s occurring on a daily basis: on a cold

morning, with the T-stat set to 68 degrees the system cycles on strong at 6:00

am. All of the radiators in the two apartments – same side, upstairs/downstairs

– with shorter runs to the boiler heat evenly after about 35-45 min. However,

the indoor temp in these two apartments is definitely on the “warm” side, as

the radiators are “cooking.” The sensor for the T-stat is located in the

upstairs apartment on this side.





On the other side of the building, the story is a

bit different. In the downstairs apartment, three of the radiators heat evenly.

One, the biggest, heats unevenly, about half way across. Another, the smallest,

does not heat at all, either with the air vent in or fully removed.





In the upstairs apartment, the radiators heat

unevenly, or not at all, sometimes just one section, sometimes just one or two

radiators and none of the others. When I pull the air vents out, they are full

of water, even though all of the radiators are shimmed and pitched,

level-verified. Strangely, if I remove the vent valves, then all of the

radiators heat evenly. I’ve tried three sets of brand new valves – Hoffman,

Varivalve, and now Maid ‘O Mists – and they all produce the same results.





If the T-stat is set any lower, say to 66, then the

results are a bit different still. The radiators in both apartments on the side

closest to the boiler heat evenly, and the indoor temp is more comfortable, as

the radiators don’t get as hot.  In the

apartments on the other side, only one of the radiators in the downstairs apartment

heats evenly, the rest barely or not at all. The story is the exactly same in

the upstairs apartment.





I'm stumped. Any and all advice that you can provide will be much

appreciated. Thanks to all, and best.

Jamie Hall

Couple of thoughts

just to get things going...



First, I like the old mercury Pressuretrol -- don't lose it!!!!!



Second, though: I'm a bit suspicious of the main venting.  Can you verify that steam gets to the ends of the mains all at about the same time?  And fairly quickly?  I use a rule of thumb for steam in insulated mains of about 15 feet per minute, but that's pretty general.  If you were to find that the cool one is much slower than the warmer one, you might want to put a bigger main vent on that one -- say a Gorton #2.



Also, double check the pitch of all the horizontals -- not just end to end, but check for sags.

Abracadabra

slow down the radiator venting

 Vent your radiators slower. Way slower.  Way way slower.  I've been battling a problem with a multi-unit building for about 4-5 weeks now. I was using Cs, a couple of Ds, and a lot of 6s and 5s. Close in radiators are literally stealing steam from the radiators that are furthest out.  I'd say use 4s for all small radiators and 5s for the larger rads.  Nothing bigger than a 5 for now.  Run it a few days like this and then you can determine if you need to bump up a vent a size.







Make 100% sure your mains are vented as fast as possible.

The Steam Whisperer (Formerly Boilerpro)

Undervented mains, overvented radiators..

sounds like your problem.  The Gorton #1 main vents have the same venting capacity as the Maid o Mist D.  The  steam is definitely not distributing through the system properly with this venting imbalance. The MoM D has the same capacity as 21 traditional radiator vents from the height of the steam era, so your radiators are way overvented. Even the MoM #4 is almost double the capacity of traditional vents.   Start by getting your mains vented better (probably need about 6 to 8 Gorton #2s to really do the job) and then go in with Ventrite adjustables if budget allows or use all MoM 4 or 5 on rads.

nicholas bonham-carter

main venting inadequacy

definitely, your main venting needs improvement. keep adding gorton #2's until your back-pressure on your good low-pressure gauge shows an ounce or so [what no l-p gauge?]. hoffman 40's are good for radiators, and last forever,[hope you saved the old ones!]. steam should arrive at each radiator on a floor simultaneously. if the top floor is a bit slow, then you can increase the venting on the top radiators only.

when you use a nighttime setback on the thermostat, i don't believe it saves any money, as the system has to burn fuel just to make up the daytime temperature, [a 2 week setback would be different]. if you really want to save money, get your gauge-verified pressure down to several ounces with lots of venting.

on my visionpro, i used the heaviest gauge thermostat wire to make the connection, as i think it could make a difference to the reading. there is an adjustment in the setup for changing the displayed temperature, so you can compensate.--nbc

ktccapo

Antler Set Up and Possible New Main Vent Location

Many Thanks to all for the replies. A pair of questions in response the to points on main venting that you brought up.



First, when adding more main venting capacity, should I utilize a typical "antler" setup with Gorton #2"s, as pictured here?



 http://www.heatinghelp.com/files/posts/5515/Menorah%20&%20Antler%20PDF.pdf



Secondly, based on the photos I posted before, would the two locations of the current Gorton #1 main vents be the correct locations for the new antlers (the main vents are currently placed on opposite sides of the back corner basement wall, where these two mains eventually "meet" below the water line).



Moreover, would it be a good idea to add an "antler" to this main (below, I've attached a few photos), which currently has no main venting capacity? If so, how would it be done, considering the pipe sizes are so dramatically different?



Again, many thanks for all of your advice, and best.

crash2009

Back to the drawing board

Yes, the 2 locations with the Gorton 1 would be the place to have the new antler.  Your most recent pic is a good location as well.  The problem is the height of the Gorton 2 (6 and 3/8") plus the union, nipple etc.  and your concrete ceiling.  All together you would need 12" from the top of the main to the top of the Gorton 2.  The antler would work pretty good where you have the height, but you need to do something else in the other 2 spots.  Maybe a weld-o-let and tap just after the drop?  I don't know what you can get away with there.  Wait for a pro's advice.

Abracadabra

MOM #4 vs. Hoffman 40

Dave,







Is't a MOM #4 half the venting capacity of a Hoffman 40? What do you mean by a "traditional" vent?  I need something between a MOM#4 and a MOM#5 on my other problem building.  I'm thinking of drilling the removeable orfices on the MOM vents with a drill a bit bigger than the MOM #4 hole.

crash2009

Ventrite or Dole

There is a few choices between MOM4 .060 and MOM5 .0200 

Ventrite #1 is probably the most flexible for your lower range (up to .158)

Dole #1 has some cfm in your upper ranges .186

Once tou find the correct setting you could disable the adjuster so the renters cant change it.

Abracadabra

vents

I kind of prefer the "non-adjustabillity" fixed vents for rentals.  I've already had some tenants unscrew the orfices out of the MOMs.  Once I get this one building balanced, the MOM orfices will be getting loctite.







I think Dole went of out business, no?

crash2009

Dam renters

Can't live with em and can't live without em.  I didn't know Dole is gone.

The Steam Whisperer (Formerly Boilerpro)

Traditional vents...

are vents that were used in the steam era like the Hofmann #1.....venting at a rate of .016 CFM.  A MoM #4 is at .028 CFM.

nicholas bonham-carter

vent location

[in the last pictures], why not whack the coupling on the horizontal, and replace it with a union. this will enable you to finally replace the vertical nipple under the elbow with a different configuration of shorter [or cut-down] nipples and a tee on which to mount the antler with the additional gortons, while keeping the location as high as possible, in case the returns are slow or reacting to high pressure.

if it were summertime, you could have the luxury of taking the pipe pieces to a good hardware store to have them re-threaded/shortened. as it is you will just have to measure twice and cut once.--nbc