Main Line Air Vents in relation to the F&T

DIYSteam

Hello! I am the new recipient of an older 3 Story 1925 House. Just installed a brand new Natural Gas Steam Boiler. Its a 2 pipe system. It has one cross over upstream of the F&T. Directly downstream of the F&T there is a Hoffman 75 located 12" back from the 90 that goes down to the floor and into the boiler. There is a Hartford Loop. The system takes forever to heat up so I am sure that I need to add additional main line vents. My question are:

1. Is there supposed to be a F&T Installed?
2. Is a cross over necessary before the F&T?
3. If yes to the above should the main line vents be installed before or after the F&T? (right now the Hoffman 75 is installed after the F&T). My Contractor advised me to cap off the Hoffman and install a vent on the F&T 1 inch outlet opposite of the main line inlet. IS this a good idea?

thanks for any help you can give!!!

Jamie Hall

A bit more information would be helpful to determine how the system was originally set up to operate -- since it clearly has been "modified" along the way.

Particularly. What valves and traps are on the radiators? Does the crossover trap you mention go into a dry return, and if so, does it look as there may have been a main vent at the boiler? Are there other steam mains? Is there any sign of crossover traps at the ends of them into their respective dry returns?

JUGHNE

Do any rad returns connect to the dry return after the F&T?
Does the F&T install look original to the piping?
Do you have other returns, air vents or F&T's?

We assume you do not have a condensate or feeder pump.

Pictures would help.

DIYSteam

Thank you so much guys for answering back I will try to answer all questions below and also add pictures:

1. Valves are the old D&B pack less. 6 out of 14 were leaking so I changed those out with modern Mepco replacements
2. Traps are all J&B disc. Changed out 4 of those so far
3. The crossover goes from the 3”main to the return (see pic) no others present or signs of others
4. Only evidence of one main(Hoffman 75) until I added the Gorton #2 (see pic)
5. No rad returns after the F&T
6. F&T looks like it was added in the 80’s when coal was converted to natural gas. At that time a Dunkirk was installed but recently was replaced with a Williamson (see pic)
7. No other returns, vents, f&t’s or pumps are present

Thanks again!!

DIYSteam

Guys everything I am reading says that the Float & Hydrostatic Trap that I have, if working properly, should adequately vent the air from the system. I installed a Gorton #2 ahead of the F&T and believe me the system heats up faster but the boiler shuts down before all the radiators can get get fully warmed up and I also am getting a little water hammer. I installed the Gorton downstream of the F&T (like most diagrams show on a 2 pipe system) and water came pouring out of the Gorton. There is a check valve about 8’ down the line from the F&T and I believe the water/pressure was not able to pass through that check due to all the air and water passin g out through the Gorton. What are your thoughts? I am kind of leaning toward maybe installing a mainline vent after the F&T but maybe at Gorton number one instead of a two.

DIYSteam

Also This is how the system was piped when I purchased the house and we didn’t have a problem until we changed out the boiler. There was a Hoffmann 75 installed. After we installed the new boiler the F&T and Hoffman got completely packed with rust and other debris which I believe is why all my radiators were not heating up. The problem is that I did t catch any of this until after I purchased 2 Gorton #2’s and installed them.

JUGHNE

A check valve in the return line? Is it an old one?
You have a Hartford Loop, that does what the check valve was supposed to do years ago.

I hope some other more versed Wallies will review my next theory.

F&T will first pass air until steam reaches it,
---main steam line air vent will pass air until steam reaches it.

F&T will then pass water to the return without passing steam
----wet return alone, without F&T, will receive water and return it to the boiler, the water seal, if deep enough, will keep the steam contained.

Is the F&T necessary??

The check valve seems to be unnecessary and is probably plugged slowing down return.

Did the new boiler install raise the wet return?
What pressure do you run at?

clammy

f &t trap do all u say but they so don’t like to discharge into a pressurized returns I would ditch the f n t and install a vaporstat leave the crossover trap and vent the heck outta the dry return of course after the crossover trap connection. I would take a look at your end of the steam main drip and your dry return drip and make sure you have the appropriate water seal. It also looks like you need to insulate your near boiler and system piping. 1 inch wall Fiberglass last but not least was the boiler sized properly if so not many worries but if it’s short cycling on pressure then you should look to a 2 stage gas valve Peace and good luck clammy

clammy

Get rid of the check valve also and the as previous stated was the water lowered from the previous boiler if so do all I stated n either lower your wet returns to the floor or build a false water good luck clammy

DIYSteam

Excellent guys thanks so much for the advice and info!! With just the Hoffman and F&T we are running at 4 psi. With one Gorton added down to 1.5. The wet return is at the floor level. Absolutely need to insulate for sure. So I may just take the guts out of the F&T so I don’t have to re do any piping. I can also remove the flapper on the check! So the Gortons can go anywhere on the dry return up near the F&T correct?

EBEBRATT-Ed

The way the F & T is piped I would say it is probably not original. If the F & T outlet goes directly into a wet return and you have no condensate tank I don't think you need the F &T. Just vent it at the F & T location. You have unions their so putting the F & T back in would be easy if for some reason you find out otherwise. Boiler piping looks good.

Does the wet return piping look newish....not original? Maybe at one time it was up higher and they converted a dry return to a wet return

DIYSteam

Ed I think you are correct as it does look new! Thanks for your help.

KC_Jones

How was the new boiler sized? Being able to get up to 4 PSI is concerning to me. 2 pipe systems want to run at very low pressure, ounces.

JUGHNE

4 PSI is way out of line.
I would completely remove the F&T and just repipe with the unions as ED said. Leaving the body in the line could add more return issues. Then add the G-2 or Big Mouth.
Yes, then remove the guts of the check valve or the entire valve. IMO

DIYSteam

Thanks guys! Yeah the F&T was completely plugged. Took it OOO Now it’s running at 1 lb!!

JUGHNE

Your new low point sludge collector will be the wet return just below the Hartford Loop.
You have a nice drain port on that.
It would be good to check that often to prevent sludge from going into the boiler. IMO

mikeg2015

If the pressure rises before everything is heated up, then ultimately you are still venting too slow and/or boiler is oversized.

Step 1 is if the main is vented fast enough that all the radiators start to heat at about the same point, with exception of upstairs heating a little later as typical.

At that point the limit would be the venting rate of the traps on the radiator themselves, assuming the boiler is sized correctly and would not shut down if the radiators were fully heated.

DIYSteam

Mikeg you nailed it! KC you are right as well. When it got up to 4 lb I only had one hoffman75 and it was completely broke And not venting. Since my last post I now have installed 2 Gorton #2’s took the piece of crap 30lb gauge off ( that the contractor had on his truck and was trying to get rid of) with a precise 3lb gauge, changed out the rest of the faulty steam traps and set my pressuretrol at .5 and 1. Now the entire system is heating up in about 15 minutes if the house is cold and maybe eight minutes if the boiler had been on a couple hours before. I am seeing hot pipes at the end of my returns near the boiler in about eight minutes . All the radiators work pretty good now even the ones up on the third floor one of them only gets hot about halfway down the radiator and I think it might be plugged? I don’t see any pressure build up on the guage ever except a little fluctuations when the air vents start venting. I thought maybe my new gauge was bad so I plugged off the main air vents And the guage started climbing almost immediately so now I think my system is running on ounces way below even a half a pound!!!! I purchased the book the lost art of steam and think I might be able to fine-tune the system even more after reading the book I am learning a lot. I would like to replace my thermostat with a programmable one as sometimes I notice the boiler will short cycle. My thinking is I might be able set a time limit for when the boiler kicks back on??

Neild5

You need to add the 30 psi gauge back on, the insurance companies require a 30 pound gauge.

Jamie Hall

"I would like to replace my thermostat with a programmable one as sometimes I notice the boiler will short cycle. My thinking is I might be able set a time limit for when the boiler kicks back on?? "
Here we go again. If the boiler cycles on pressure towards the end of a long call for heat, before we start adding bells and whistles we need to think about why it is cycling.

It is cycling because it is capable of producing steam faster than the rest of the system can condense it.

The thermostat is still calling for heat -- you want the radiators to be hot. Therefore you want them to be condensing steam. OK.

So what is the logical thing to do? Turn the heat off in the boiler just long enough for the system to catch up, then turn it back on and give the system another shot of steam. Turn it back off until the system catches up. Turn it back on. Rinse and repeat until the thermostat is satisfied.

What is the best way to do that? With a pressure controller which senses when the system is full (not hard to set up with a low pressure gauge) and shuts the boiler off long enough for the system to catch up, then turns it back on.

You do not want the boiler to cool much below steaming if possible -- you will burn extra fuel to bring it back up to a boil. Therefore the off interval should be just long enough for the pressure to drop. In fact, most oil burners have a mandatory post purge pause pre purge timing cycle which isn't far off what you want.

Doesn't this waste fuel in comparison with turning the boiler off with a timer and then back on? No. Keep in mind that if you keep the off time short, the firebox is still hot, draught is still established, the water is still just below boiler, and no fuel is wasted establishing stable combustion and boiling, whereas with a longer off you do have a lower efficiency period while combustion is stabilized and the water brought back to a boil.

Doesn't this starting and stopping hurt the burner? Slightly greyer area. It won't hurt the motor, provided the motor has stopped actually spinning when it is restarted. If the control uses intermittent ignition, there will be slightly more wear on the electrodes. This should not be a problem over normal maintenance and replacement intervals.

So... relax. Set the pressure control (this often will require a vapourstat and a low pressure gauge to get right) so it shuts off when the system is at capacity with steam and with a differential long enough to allow the system to catch up (in practice, with oil burners, the post purge pause pre purge cycle om the burner itself will control) and enjoy.

Oh and for those who regard a pressure control as a safety only, my own opinion is that in a sense they are correct -- and indeed there should be at least one additional pressurestat on the system, set to turn the boiler off if, for some reason, it reaches a pressure high enough to start damaging things -- say around 2 psi. There is no reason, however, not to use an available control device as a control device...

ethicalpaul

Also @Jamie Hall couldn’t he hire a competent tech to see if there is any possibility of downfiring the burner within the spec of the boiler to get at least closer to an EDR match between boiler and radiation?

And to eliminate or at least reduce any setbacks in use?

DIYSteam

Neil, Jamie and Paul thanks guys for your input! I really appreciate it.

DIYSteam

Jamie is there a way I could contact you for specifics?

Jamie Hall

@DIYSteam -- you can PM me from this site -- click on my name in the header of this post and that will take you to a page where you can write a private message.