Newbie replacing the top of an air vent float on expansion tank

MRMATT

Hi, new here,and am in the process of learning about my (oil) hot water heater/boiler.
According to the Heater/boiler guy who was in working on my heater, he said my bill was getting rather high and offered to tell me what needs to be done next to the boiler, so instead of him doing it, I can save myself some $$.


I've done only pipe plumbing so boilers are new to me.
He stated I need to replace the top of the air vent associated with my expansion tank. He gave me a part number, and this is what I ordered.

https://www.amazon.com/gp/product/B008HQ58L0/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

which is this.




The Heating guy was telling me a a few things, so not sure if I caught all.
I know he said I can unscrew the top of my current air-vent, and screw the new one one with the associated replacement parts.

To do this switch-out, I am guessing I have to turn off the water - ( I don't remember him saying that but I would think so- likely so as the system is pressurized to the point of this air vent)...or is it not due to the expansion tank.. just want to be sure.

To depressurize the system, I turn off the water supply, turn off any zones, and trip the relief valve ... is this correct?

Would I have to turn off the boiler so as to let it cool down?

Thanks for helping me out.
Matt

STEVEusaPA

If you have a steel expansion tank (old style, not a bladder tank), you don't need an air vent, but I'm guessing a bladder type.

Show us some pictures first, close up and far enough back to see all the near boiler piping, shut off valves, etc. before proceeding-just so you get the best advice.

Yes, probably have to either isolate and drain, or drain the entire system.
Of if you're tricky, you can do it on the fly by pulling a slight vacuum.
If you trip the relief valve, better get another one of those too, as it may not seat properly.

I'm curious as to what else was discussed to determine the only thing wrong with your system is this air vent.

How did he determine it needs to be replaced? Leaking water?
You don't have to cool down the boiler, but you also don't want to add very cold water to a piping hot boiler.

You may want to also pull the bottom plug and clean that out too, but I'm guessing you have a bladder type expansion tank screwed into it?

MRMATT

Hi Steve,
Thank you for your patience, life gets me too busy,
Yes, I do have a bladder type expansion type.
In taking the pictures, I do see a shut off valve going to the expansion tank.
The whole issue we are having is bubbles in the piping of the baseboards. After a bubble purge of the system, the bubbles return rather quickly.

The heater guy found the expansion bladder had failed and replaced the tank. Afterwards I think he said he was not able to get any air out of the vent on the tank, and suggested we replace it...( I am not really sure the reason he stated, but thought it was that.)

We also had a leak at the relief valve, which was replaced.
Found also a leak at an elbow in the piping, I should be able to take of that.

There is also no venting at the top of the boiler, where a pipe comes out, and we ordered an air scoop for that (B157-7) and the proper reducer..( reducer not shown)

-





Here are some pictures of my system...




Leak at the elbow to the right of the blue lever





















shut off at pipe going to the expansion tank







Back of unit, new trip valve




I appreciate any help with this.

For the replacement at the top of the expansion tank, am I able just to shut it off there, and change the top of the vent as mentioned before?

I also want to put the air scoop on the pipe coming out of the boiler, so will need instruction on how to do that safely.

The heater guy feels with the leaks taking care of and the air vent valve replaced along with the air scoop, - should make a difference in the air in the baseboards by letting the air in the system finding its' way out.

I greatly appreciate any help.

Thanks
Matt

SuperTech

You have the circulator installed incorrectly, that likely contributed to the expansion tank failure. You need to be pumping away from the expansion tank and air separator for them to function properly.
Peerless does want an air vent on that tapping on top of the boiler. Rather than buying a reducer and an 1/8" vent I would get a coupling and a 1/2" air vent.

If you do these repairs and purge the boiler air won't be an issue again.

MRMATT

Thanks for your help,
Very surprised to hear the circulator is installed incorrectly, no one has caught that. Been looking for a good diagram of a boiler layout, this is only decent one I could find.



However, back to my original question, as things are set up the way they are now, to replace the vent on top of the boiler, ..





what do I need to do with respect to water shutoff, etc.. if anything.

MRMATT

And looks like some replumbing has to be done.... great.

SuperTech

That diagram you posted shows the proper location of the expansion tank and circulator.
To add a vent to the top of the boiler all you need to do is shut off the cold water supply to the boiler, shut off the valves on the supply and return lines if you have any. Then drain some water out of the boiler to take the pressure off it. Then install the air vent, refill the boiler and purge the zones.
If you are able to isolate the boiler from the zones by shutting off the valves on the supply and return you will only need to drain out a couple of gallons of water to to work on the boiler. If you don't have the valves then you will have to drain out the whole system. At that point it makes sense to install valves and correct the boiler component configuration.

MRMATT

"Then drain some water out of the boiler to take the pressure off it. "

Is this done by the relief valve?

Thank you

GroundUp

What was his reasoning for replacing the air separator guts?

SuperTech

> @MRMATT said:
> "Then drain some water out of the boiler to take the pressure off it. "
>
> Is this done by the relief valve?
>
> Thank you

No. Never. Always use the boiler drain at the bottom of the boiler. If you use the relief valve be prepared to replace it. Most of the time they leak after opening.

MRMATT

Hi Groundup..

Guess you missed my statement earlier: "The heater guy found the expansion bladder had failed and replaced the tank. Afterwards I think he said he was not able to get any air out of the vent on the tank, and suggested we replace it...( I am not really sure the reason he stated, but thought it was that.)" He said he did have a vent on his truck, suggested we replace it.



As for draining the boiler, I have been looking at youtubes, and manuals, but nothing really helped. A lot of boilers have spigots on a side of the burner, mine does not.
The only potential outlet I can see is this:



looks a screw for a ball valve or similar.guess if I undo the screw, everything will drain, including the vertical pipe feeding my baseboards...
Correct?



if so, thought shutting it off over time could cause leaks... rather have a spigot
Thanks again

STEVEusaPA

That's where you drain it, with a screwdriver. But you should rarely need to drain the boiler after repairs. If you find it leaking thru the valve when closed you can always get a hose bib cap.
Or you can replace it when you change the boiler.

SuperTech

Yeah that's your boiler drain that I was referring to. Use that to drain the boiler for service like Steve described.

delta T

Also be aware, that is likely a ball valve style drain, the screwdriver slot will only need to turn 1/4 turn to be fully open.

Intplm.

@MRMATT when replacing the vent on the top of the boiler. Use something called a spirotop made by spirovent or a equivalent product. This is much better then a hi-vent type venting practice that is used with little affectiveness.
And yes you can relieve vacuum by opening the relief valve to drain the boiler. But first look to isolating the system from the boiler as mentioned above.

MRMATT

Thank you all, so I need to drain the boiler to remove this cap and put on a vent.




Thank you intpim, very helpful

Intplm.

Yes that's the cap. Isolate and relieve the pressure.
That nipple that the cap is on. That should be ? a 3/4 inch. pipe.
You should need a 3/4 x 1/2 black malleable reducing coupling and a 1/2 x space black nipple if you are planning on installing a 1/2 inch spirovent spirotop.