Main Vent location questions (MegaSteam Installation Questions)

steam_in_askam

I've recently had a new oil fired boiler installed in my 1400 sq ft 2-story home. The unit is a Burnham Megasteam and I have 7 radiators. The old unit was an American Standard from the 1970s. Before that I believe it was coal as the house was built in the 1920s. After reading an awful lot on this forum I've really looked over my system and found a few defects. I've got some sagging towards the end of the main which may explain some of the hammering. My main concern is the complete lack of main vents. At the very end of my main is an elbow and a junction (not sure of the term) which goes up to two radiators, one the first floor and one on the second floor. Can you add main vents in other places besides the end of the run? It also looks like the rear of the house is counter-flow back to the header where the front of the house has a long wet return coming off of the front rads. I will add some pictures here. A few of my radiator vents hiss or whistle either partially or through the entire heating cycle. They all get hot at about the same time and fairly evenly as far as I can tell by checking with an infrared thermometer.

JUGHNE

How about pictures from across the basement so we can see the main left to right?
Maybe 4 pictures to cover all the piping.
Also the nameplate of the boiler.

So the kitchen, bath and that bedroom main has no return drop?

steam_in_askam

There is no return drop on what I guess you would call the back side. It's all just pitched toward the boiler. When it drops into the header that appears pitched toward the return side. The boiler doesn't have a nameplate with any specs on it like the old one did. It's an MST396 and I attached the technical specs that came with it.

steam_in_askam

I also just noticed the oil filter has a slight leak and the IN and OUT are seemingly backwards.

EBEBRATT-Ed

and they left the old boiler in the basement

steam_in_askam

Yes they did. They'll be coming back for it though. I guess they have a scrap guy but we've had so much snow he couldn't make it at the time.

JUGHNE

Where does that pipe lying on the floor by the bike come from and go to?

steam_in_askam

@JUGHNE That is the wet return. It comes from the end of the main towards the front of the house.




I have a basic drawing of the system here. The joint is at the front of the house under the living room.

JUGHNE

Would add 2 or 3 supports to that main. It is parallel flow with the high end at the boiler and should drain to the far end into the wet return.
For insulated pipe like that I rip a 1' length of 4" PVC pipe, put a pipe half under the pipe and support the pipe without cutting the insulation.
On that end maybe tap a couple of 1/4" IPS spots in the drop pipe below the tee, space them so they are not above one another. 1/4" will vent all a Gorton #2 can do.
Use a 1/4" x 1/2 90 for each. Maybe one G2 and one G1 would do it.

The other main is a counterflow and not piped correctly at the boiler.
From seeing the old insulation intact, it never was correctly....just lucky..maybe.

Look in your install book and they may show you the method to drip a counter flow pipe.

For that main vent you could tap the top of the main just before the tee that supplies the last rad, not ideal but as close as practical.

Did you or the contractor size the boiler?
You show 206.18 connected EDR. The boiler you show checked is rated 396.....50% oversized.
The next smaller size is still too big at 288 EDR, the only difference may be the oil nozzle size.
Does the book show piping diagrams for this boiler, sometime 2 risers are required and often a larger header is required also.
If you haven't paid in full yet, this may be your last chance for corrections.

steam_in_askam

@JUGHNE Thanks for the replies. I did not size this myself. I've spent the last two weeks reading as much on here as I could and watching youtube videos in hopes that I could understand what needed to be fixed. Spent almost two weeks running space heaters waiting for this replacement to get here as my old boiler made the whole house stink of fumes. Originally the contractor brought in the next size up from the supply house but when it got here they couldn't fit it in. I expected them to know what they were doing. If I get the main pipe straightened out and add a few main vents and replace the hissing rad vents do you think this will manage to work out?

steam_in_askam

@JUGHNE also, in looking at the installation manual it shows two risers in all the piping but notes that for best results, two risers are strongly recommended. The piping diagrams only show the near boiler piping and don't mention anything about counter-flow drips, unfortunately.

HarryL

These two threads have diagrams and pictures that might help.
https://forum.heatinghelp.com/discussion/143789/one-pipe-counterflow-system
https://forum.heatinghelp.com/discussion/134802/near-boiler-piping-counter-flow-steam

Look for Rod's comments in both.

A Peerless manual recommends one size up on the main to accommodate the condensate and steam.

JUGHNE

So the next size up wouldn't fit thru the door?
If your EDR numbers are right you were lucky for a small doorway.

There are people here who know the Megasteam series very well and will hopefully comment.

Does the book show an increase in the horizontal header?
And can this be downfired to the next size smaller?

Can you post a picture of the old boiler label that states the BTUH ratings?

JUGHNE

If you edit your header at the top to include "Megasteam installation questions", you may get more input.

KC_Jones

The 396 and 288 are the same block with different firing rates. If your EDR calculations are correct (my opinion they are), then that boiler should be fired at the rate for the 288 and the burner retuned, and combustion analysis performed again.

They wanted to put in the next size up?! SMH

Noisy vents are, in part, a function of pressure. Pressure is a function of boiler size and venting rate. Over sized boiler (like yours) will build more pressure, lack of venting will amplify the problem.

steam_in_askam

@HarryL Thank you I'm going to take a look at those now.

@JUGHNE Here is the tag from the old boiler. Only slightly smaller than what is in now.

I am wondering if this is the location you suggest for main vents. This is the front wall furthest away from the boiler.


@KC_Jones I took the info from these locations to get the EDR. I could be wrong though.

https://heatinghelp.com/assets/documents/American-Radiators.pdf
https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

Only thing I could find in the Burnham literature about firing rate was a note that the MST288 utilizes a low fire baffle. Maybe more info would be available in the Beckett manual. I'll take a look when I get home.

Steamhead

Yup, they did not follow the boiler installation instructions. Don't give them their final payment until they do- and haul away the old boiler as well.

Burnham makes a piping kit for the MegaSteam which takes out all the guesswork for people who refuse to read installation manuals.

KC_Jones

steam_in_askam said:

@HarryL Thank you I'm going to take a look at those now.

@JUGHNE Here is the tag from the old boiler. Only slightly smaller than what is in now.

I am wondering if this is the location you suggest for main vents. This is the front wall furthest away from the boiler.


@KC_Jones I took the info from these locations to get the EDR. I could be wrong though.

https://heatinghelp.com/assets/documents/American-Radiators.pdf
https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

Only thing I could find in the Burnham literature about firing rate was a note that the MST288 utilizes a low fire baffle. Maybe more info would be available in the Beckett manual. I'll take a look when I get home.

I doubt your calculations are wrong. In order to need that much boiler, with 7 radiators, each radiator (if equally sized) would be quite large, roughly 54 EDR per rad. Personally I only have 1 in my whole house that size and it's heating ~350 sq ft, or 50% of my first floor, by itself. I read your chart, rads are obviously not that big.

Over sizing is common, for reasons that I can't figure out since the calculations are elementary.

IMHO they should fix this or you will be paying for it for the rest of the time you own the house. Especially since we aren't talking about a boiler change, just burner adjustments, tuning, and possibly a baffle installation.

If they don't believe your sizing, send them a link to this thread and we would be more than happy to educate them. It's really quite simple.

ethicalpaul

@KC_Jones speaks true. And I'll reiterate just for an additional opinion that the old boiler's rating plate is absolutely worthless as an indicator of the correct boiler size. They have been installing them too large for decades. My old boiler installed in the early nineties was about 30% oversized and it's far from unique in that aspect.

JUGHNE

They might have looked at your old boiler and thought we will go a size larger....just to be sure...ya' know.
You are fortunate to have small doorways, will the old one fit out of the house without breaking down?

For air venting I would drill and tap 1/4" holes in the side of the return pipe where you have the blue "return" label.
Do not go side by side nor straight above one another.
They must be well above the water level of the boiler.
1/4" nipple, 1/4" x 1/2" 90 ell with a 5-6" riser up to air vent.
Maybe a Gorton #2 on one of them and Gorton #1 on the other.
Those would be the best bang for the buck, IMO. You have 30' of 2" main

The other main might only need a G1 air vent, drill on the top of the nipple just before the last tee. (9' of main)