Fast return/slow return

delcrossv

As you can see, my mother in law's system has two dry returns. I replaced 2 Dole #5's where one was clogged and the other was incredibly slow with B&J big mouths. Now I have the "fast" loop that does the outer rooms of the apartments heating really fast (GREAT!) but the second loop that does the interior bedrooms and baths has a pretty long lag before it gets hot.

To try to even things out a little, I put a 3/4 x 1/8 bushing on the "Fast" return vent with a stub of brass nipple. It's "better" but not timed perfectly.

Questions: Was this done on purpose to get the more exposed rooms heat first?- so should I leave it like this with a little "drag" on the fast loop?

Or, should I keep tweaking to get all the rads to get hot simultaneously? Might require an even slower vent (Have any recommendations for the next step down from a Big Mouth?)

Any other ideas to even things up?

EBEBRATT-Ed

Looks like your on the right track.

I would put some thermometers sprinkled around and see how even the temps are not worrying about which rads are hot and how much of them is hot unless those areas prove to be cooler

Just keep tweaking and you will get there.

Air and steam will take the path of least resistance. Venting the large main with a big mouth is giving that main less resistance. It could also be something in the way the steam mains are taken off the boiler that favors the larger main.

Try to increase the venting on the smaller main rather than choking the bigger main....but you may have to choke the large one a little.

Also check the mains for any water hammer? Is the system quiet? Check the piping pitch, a little water in the smaller main could kill the steam. Check to see if the vent on the smaller main is panting

delcrossv

The bedrooms are noticeably cooler- until the steam gets there.

System is dead quiet no noise/ water hammer/gurgle anywhere.

What do you mean by "panting" for the smaller main? Like breathing in & out panting? (???)

The air from the fast main comes out quickly, the slow main I can barely feel it's working- keep checking to see the disc is open. I'll check pitch next time I'm there, but the slow loop rads do get hot- eventually.

EBEBRATT-Ed

If you had water (condensate) lying in a steam main due to a sagging pipe the water will cause some steam to condense and the air vents will breath in and out "panting"

If your system is quiet then that's probably not the issue.

So on a normal call for heat does the slow main heat before the burner shuts down? Or does it only heat when you crank the stat way up?

delcrossv

Can't tell yet, system only goes on if the stat is at 80+ due to the weather.
Now that it's getting cooler, I can put the setpoint a degree or two above ambient and see what happens.
Running full out, there's a lag

gfrbrookline

Some people would love to have this problem as they prefer the bedrooms to be cooler than the capital rooms. If it is a problem you can increase the size of the vents on the radiators on the cold/slow loop.

delcrossv

gfrbrookline said:

Some people would love to have this problem as they prefer the bedrooms to be cooler than the capital rooms. If it is a problem you can increase the size of the vents on the radiators on the cold/slow loop.

True, if only the bathrooms weren't on the slow main (Brrr)

EBEBRATT-Ed

@delcrossv

Your problem is better than most. Usually all we here about is banging, leaking and crappy piping

neilc

why not post a picture of the 2 mains as they come off the header,

delcrossv

neilc said:

why not post a picture of the 2 mains as they come off the header,

Will do, tomorrow. Goes up to the ceiling, out about 6' and splits as a T. Can't tell sizes as everything is lagged (and I'm not messing with the lagging if I can avoid it).

delcrossv

Now that I look at it, it's pretty obvious which main is favored.


So, a little more throttling on the big (fast) main vent?
I might fire it with no vent (open pipe) on the slow one to see if that helps. 

Cheapo Chinese  water feed valve is leaking , so I have to attend to that first.

More to come. 

gfrbrookline

Maybe not throttling the mains as much as adjusting the vents on the bathroom radiators. What do you currently have for vents on these radiators and what type of radiators do you have? Pics help. You might benefit from a faster vent in the bathroom and keeping the bedrooms cooler for sleeping purposes.

gfrbrookline

I think the last pic may have been you hinting at this but you will likely even things out greatly if you insulate your mains, which the first pic shows the boiler piping lacks. You are loosing a tremendous amount of your output into your basement instead of your living space and wasting fuel.

delcrossv

gfrbrookline said:

I think the last pic may have been you hinting at this but you will likely even things out greatly if you insulate your mains, which the first pic shows the boiler piping lacks. You are loosing a tremendous amount of your output into your basement instead of your living space and wasting fuel.

??? The mains are all lagged. The condensate returns next to the boiler aren't.  

delcrossv

gfrbrookline said:

Maybe not throttling the mains as much as adjusting the vents on the bathroom radiators. What do you currently have for vents on these radiators and what type of radiators do you have? Pics help. You might benefit from a faster vent in the bathroom and keeping the bedrooms cooler for sleeping purposes.

If anything they're probably over vented. Hoffman 40s on 3 section column rads in the bathrooms. 

It's not that the slow loop rads don't get hot, it's that they heat after the fast loop ones.

delcrossv

@gfrbrookline
Walked the line and there is a long bare section- in the basement on the other side of the building. It was a basement apartment at one time and that was the only source of heat there. As the thermostat for the building is there, I can insulate some of the line, but not all of it. Am I right that I should start closest to the boiler and work my way around?

@EBEBRATT-Ed
I ran an open pipe (no vent) test, and things were much improved. I put a cross and a couple of nipples since, if I figure correctly, 3 big mouths should be pretty close to an open 3/4 pipe. I'm gonna pull the choke off the fast line as it's just trapping stuff against the disc. That plus a little more lagging and I think it'll be as good as I can get it and still heat the basement (some).

Thanks guys for the advice!

EBEBRATT-Ed

@delcrossv

Sounds like you have it under control...a little tweaking. Does the boiler build any gauge pressure? You might add a 0-5psi gauge in addition to the 0-30.

And yes the steam will be less likely to go through the branch of the tee than the run.

delcrossv

@EBEBRATT-Ed

If I really get it going, runs at 1 psig per the 0-30 . Matches the pressuretrol (also set at 1psi).

If I don't set the thermostat for a big jump in temperature for a long burn, maybe a couple of ounces then the t-stat reaches temp and shuts off. The steam was coming out of the open pipe at low pressure then the stat ended the cycle (setpoint 3 degrees above ambient)

A 0-5 sounds like a good idea.

EBEBRATT-Ed

Sounds like you have enough venting

gfrbrookline

@delcrossv Walked the line and there is a long bare section- in the basement on the other side of the building. It was a basement apartment at one time and that was the only source of heat there. As the thermostat for the building is there, I can insulate some of the line, but not all of it. Am I right that I should start closest to the boiler and work my way around?

I would recommend insulating all of your mains as much as possible with 1" fiberglass, this will give you even steam distribution. If you have uninsulated pipes the steam will condense and turn back to water until the pipe heats up and the radiators will take much longer to see steam. This is likely your problem.

Your thermostat should also be in a section of the house that is were the heat is evenly distributed. If it is on the side that is heating slowly now, as you have stated, you will likely have to make adjustments once you insulate the pipes.

After you insulate you can look at the rad vents.

With the current vents/insulation do the rads on the slow side get hot across the top and eventually heat through or are they just slow to get steam? If they heat across the top an eventually fill they are over vented, if they are just slow to heat and fill from section to section that is usually an insulation issue. The hoffman 40, .067cfm, is a very slow vent, the only slower fixed vent is the Gorton no. 4, .040cfm, so I don't think you are over venting the radiator.

delcrossv

@gfrbrookline They are just slow to heat section to section. Rear bedroom being the worst (end of the line). E.G. Front bedroom hot 6 sections, bathroom 2 1/2 sections, rear bedroom maybe 1section off whatever is in the line after the boiler stops firing. There's a wide open 1A on the rear bedroom rad. The branches to the various risers are also bare in the basement apartment, so I'll get those too.
Out of town next week, so I'll update when I get the insulation in and retest.

gfrbrookline

www.buyinsulationproductstore.com is where many of us get out insulation. Much better than the box stores and has the 1" you need for steam.

delcrossv

Thanks for the buyinsulationproducts tip. They were very helpful. Insulated about 20' of main and an equal amount of branches, leaving about 12' of main exposed. I have not, as yet insulated the fittings.

Ran it with the setpoint about 3 degrees above ambient and it's "better" but the burner switches off before the steam gets to the end of the slow line. About 5 minutes later, the slow main catches up and it's hot.

The slow main is pushing 19 rads (7 are 6 footers) and the fast one is pushing 11 - and the 11 are smaller. So probably half the load or less than the slow one.

Nest step is to completely cover the main and get some insulating cement for the fittings. Worth it?

Then I'm left with choking the fast main (either a Gorton #2 (50% slower than what's on there now) or a Hoffman 75 (50% of a #2). So crank it down with the Hoffman or half as fast with #2?

The thermostat is is a bad place, just under the returns (insulated in that section) in the basement apartment. I'm thinking moving it 5-6 feet further away and off the common wall from the boiler room, might get me a longer cycle time. Any thoughts on that? I can't move it upstairs, so that's off the table.

gfrbrookline

People on the forum have had bad luck with Nest's on steam systems. You are better off with something like a Honeywell Vision Pro 8500 which lets you have several wireless sensors.

I would start by adding the Big mouth from the fast main to the slow using a close nipple and a 90 and replace it with a Gorton No 2 so the steam doesn't favor the fast main as much.

Also since the slow main is feeding a lot of radiators with large capacities the radiator vents could be part of the problem on both sides. You may need to slow down the radiators closer to the boiler and smaller radiators on both sides so the steam has a chance to reach the end rads on the slow side. If the radiator vents on the fast side are too aggressive they will rob steam from the slow side as steam takes the path of least resistance. Use the link below to find the proper vents for your radiators and include the runouts in your calculations as indicated in the opening paragraphs. I recommend gorton's or ventrite No. 1's, some like maid o mist, Hoffman 1A's are hard to adjust correctly. Just don't buy the junk from the big box stores.

https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf.



As for the fitting I would use fiberglass with PVC covers from the same place you ordered the insulation. They are very easy to install with tacks.

delcrossv

@gfrbrookline
Thanks, good advice. Here's where I'm at on the main venting. 3 bigmouths on the slow one and a Hoffman 75 on the fast one

With both mains warm from the previous cycle they're pretty much in sync now. Once it gets colder,so I can tell what's going on with the system running regularly,  I'm gonna throttle back the radiator vents in the hot apartment that's closest to the boiler. If that puts the mains out of sync, I can swap vents around.

I put a Gorton #6 on the cold bedroom rad and it's heating better.

The guy at the insulation store recommended the resin bonded glass blanket and the tape used on the pipe butts so Im going with that. Should have it all in Saturday. Got some mastic to make it pretty. 

@EBEBRATT-Ed
Here's the gauge mid cycle set 3 degrees above ambient. I think I need an oz gauge, but they're $$$.



Regarding controls, I saw that Tekmar 279, that would be pretty sweet- one sensor in the hot apt, one in the coolest one and average them. Just got to talk the MIL into it for next year. If it pays for itself in fuel costs over a couple of seasons, it sounds like a good deal. Any thoughts on those?

It's presently running off a simple   White-Rodgers probably from the 90's.

gfrbrookline

I prefer the Honeywell VisionPro 8500 with wireless remote sensors. Much less complicated and works just as well.

On the antler you may want to move the big mouth closest to the drop to the wall side so it goes 123 and the 90 to the main. This will let it drain better.

delcrossv

@gfrbrookline Good idea, easy enough to swap around.

Temp'd the thermostat up to the empty apartment with a spool of wire. Lots of heat now! What was interesting was the radiator in the cold bedroom was venting like crazy. ( much more than you'd need to empty that size radiator)

The slow main goes from 2 1/2 to 1 1/4 at the end. Wonder if the main vents which are at the very end aren't emptying the pipe efficiently. Are there ever main vents put along the line? Like after the last takeoff?

gfrbrookline

Right after the last take off is ideal if you have access, most of us don't and the boiler room makes them easy to service and monitor.

delcrossv

gfrbrookline said:

Right after the last take off is ideal if you have access, most of us don't and the boiler room makes them easy to service and monitor.

@gfrbrookline
I can get to it, but will have to drill the pipe and weld on a fitting or use a saddle.

Saddle fitting okay? (less time to install)

So, have one vent after the last takeoff and another at the end of the line at the boiler?

gfrbrookline

I don't like saddles, I would leave them were they are. What you would gain is not worth the effort.

delcrossv

Me neither, son's a welder so a welded fitting is doable. Anvil makes them pre-beveled. So having one after the last takeoff and another at the end is okay?

gfrbrookline

You aren't going to gain anything noticeable from all of the effort. Maybe the main might vent 30 seconds faster if they are vented correctly in your current set up which sounds like they are. Not worth it.

delcrossv

Gotcha. I'll work with what I have then.

delcrossv

gfrbrookline said:

I prefer the Honeywell VisionPro 8500 with wireless remote sensors. Much less complicated and works just as well.

Looks slick, but:
Needs internet and a router (neither of which is available). A wired, stand-alone, solution is what I need.

For this season, I'm thinking of just running the present t-stat to where one of the sensors will go and putting a lockbox on it. If I do the far 2nd floor apt, I already have the sensor wire run to the hardest location.

gfrbrookline

It only needs internet and a router if you are going to control it via your phone. The main unit can be installed in the boiler room, in a lock box if needed and the wireless sensors feed into it without an internet connection. I added the router so I can use it with my phone.

delcrossv

That's more like it. Sensors will make it though a couple of floors and a brick wall? I saw "router" and said Oh #$&%! That's not gonna happen.

Does it average between sensors? How long do the sensor batteries last?

gfrbrookline

I have a three story brick building, the furthest sensor is about 80 feet from the control unit and has no issues connecting.

It averages the sensors and I replace the batteries once a year with no issues.

It is a great unit for steam heat. You can turn the connection to each sensor off in Programming mode to check your units temps and make sure you are balanced throughout your building.

delcrossv

so just the stat and the sensors? Seems too simple. Hope it comes with the programming guide.

gfrbrookline

It is pretty easy to set up, the interface is very user friendly.

delcrossv

Update: Every last fitting, flange and pipe on the slow main is now insulated. The end of the line radiator is "better" but I think part of the problem is the two risers for that rad and the one on the floor above it come off the main screwy: There's a vertical tee off the main and the two risers come off as horizontal branches one above the other, off that tee, rather than individually like elsewhere. Since I'm not redoing the main this year -LOL: , I'm stuck.

I do notice that the old rockwool/asbestos insulation is not nearly as effective as the new fiberglass insulation. The old sections are warm to the touch and the basement apt is still pretty toasty warm. It's in the 40's now so we'll see when winter really hits.

Moving the t-stat this weekend to its final resting place in my MIL's apt on the second floor, warm side of the building - far from any emitters- (I have it temped in on the first floor apt cool side) so we'll see what happens with that.

Here's where we're at:

gfrbrookline

Your OP looks good.

You are also probably correct about the fiberglass being a better insulator than the old asbestos which has probably turned to dust at this point, you may want to look at replacing it. The cost of asbestos abatement is much less than it used to be and the benefits of evenly heating your mains with fiberglass will recoup the cost in a year or two. You will also have a healthier environment in your basement, I had a friend that died from asbestos lung disease, it's not a pleasant way to go.