My daughter's 1927-built house has a Weil-Mclain boiler, model # cg-5, series #9. Max 50psi wp. One upstairs radiator does not get hot(2nd floor), while all others do. We have bleed the radiator several times to no avail.
Could we have an expansion tank problem? Other problems?
What is recommended way to bleed the expansion tank?
Also, where can I get a schematic drawing/explanation of how this system should work?
Thanks in advance for any help you may provide.
dadthehelper

 

What's the pressure?

If your pressure is 15-20#... next thing I'd check is path obstructions. Is that rad part of a zone or a whole house zone where everything else is getting heat? If so, check for closed valves or once again for air.

The expansion tank should only be drained if the pressure is going into the higher 20# range once the water is heated up. If its not, draining the expansion tank will add more new water to the system and new water contains entrained air bubbles that will be dropped off wherever...

If you can, think about replacing the conventional tank with a diaphram tank. The diaphram tanks won't last nearly as long but even at $50 every 10 years it is worth it not to have to do annual or twice annual bleedings. Been there, done that - what a difference a small tank and an autovent made.

 

Who,s got it all there. Psi 18for 2 story but do you get water or air out of the RAD???

 

Is it only 1 whos not working, but others on the same height works?
All valves has been deemd to be open?
When bleeding it comes water, or moastly water?
The radiator is cold on top and bottom?

If yes on oll theese, it may be blocked by rust in one valve.
(It use to be one for adjusting in the other end of the radiator, covered by a nut.) Dont try to open it if you not are able to deal with a major leak.

An other possibility is a valve like this: http://www.marinelektro.no/shop/index.html?loadfile=item07051.html
it may be stuck in closed position, and you belive you have opened it.

dsk

 

Thanks for your replies. Here are the answers to your q's:
Pressure is below 10#'s when system is on. Not in the 15-20 range at all.
Rad is one of 4 on 2nd floor. 1 is very hot; 2 are lukewarm; 1 is cold.
When bleeding, we get air, no water. Pressure issue?
Outbound pipe from boiler is very hot and 1st floor rads are working, although not super hot.
thanks. dadthehelper

 

When bleeding, we get air, no water. Pressure issue?
Yes you have to get water out of it . If just 10 psi you dont have the pressure to get up to it. Bleed it till you get water.
Most boilers are on at 160o and off at 180o

 

The pressure shall be at least equal to the difference in hight (water) (1psi=2.3 foot of water ) + at least 6 feet. An open expansion makes this self-adjusting, you just fill to its full, and refill when you get problems with air in the worst located radiator. (you know witch). If you hav a closed expansion tank, without membrane, it shold be 2/3 full of air when system is cold and pressure as stated here. If you have a membrane tank it is a little bit tricky. The air pressure shold be measured when no waterpress is there, (usually not possible) At this lo pressure you have discribed I wold guess on a pressure of approx 10 PSI. Then fill up with water until the system reaches 15 PSI (34-35 feet). Bleed the problem radiator until water comes out stop bleeding.
You may refill water, during prosess.
When it starts working, bleed other radiators if not hot on top, or sound of bubbeling.
Fresh water contains air (and oxygen) wich cause rust. You have to bleed regulary until system is stable, and refill wit more water to keep pressure.

If pressure keeps falling, you have a leak, this costs, but the worst is you have to refill with oxygen-rich water, and get rust. The pressure may wary with the watertemp, but shold never be under eg 15 psi (if that equals the hight of the system + approx 6 ft.) Higer pressure may reduse air problem, but stresses the pining, and increases the risk of leaks.

The system may have additives in the water, theese may be harmful. Black water is water containing iron-oxide, and is not an bad sign. (redish is iron-di-oxide or rust, this is a bad sign.)

You may get automatic bleeding systems, but thay have tendecy to stop working, and start leaking when you just left for peridode. Such system shold be plased on a location where spill is no problem.

since the system has worke without this in many years it may be unnecessary, but:
I may sugest Spirovent as maybe the most reliable solution on the market,
http://www.spirotherm.com/air/
But probably to expensive.
Not that expensive, but probably OK:
http://www.armatec.se/produkter/start/!/mgid/39259/sgid/39412/pid/46212/
You may get simular products at your local supplier.


dsk

 

I plan to go to the house tomorrow.
I think the expansion tank is very old, so probably does not have a bladder. Right?
So, how do I add more water?
To the expansion tank? Thru the drain valve?
To the boiler?
The boiler is a Weil-Mclain Model CG-5. Series #9. I could not find any info. on it. Do you know where I can get a schematic or manual to read?
Thanks, again.
Dadthehelper

 

There should be a automatic water feed(its brass and about the size of a softball, butt not round) that will add water, well, automaticly as the name states The only time it won't do it on its own if it gets a lot of junk build up and it blocks the strainer. You can try lifting the manual feed to see what happens, its the lever on top of the water feed. The water feed will come from the house cold water line and *should* feed somewhere in the return side, but its not a guarentee. Bring it up between 12 - 15psi. The PSI will rise when the furnace gets hot, which is part of the expansions tank job.

The difference between your furnace and another oil fired furnace is slim. Most of them use the same parts(except for the fancier burners). Try to find a manual from Weil-Mclain that looks like yours and it should do the trick. Everything on a oil fired system(plumbing and the furnace) is pretty much standard on every furnace.

 

Hey dad...

All systems are pretty well unique.

If the tank is a horizontal and up between the joists, it's conventional. If it has a water connection on one end and valve like a tire on teh other end then it is a diaphram style tank.

If the pressure is low and you need to add water, check all the domestic tap water piping around the boiler and see if there is a feed from the domestic system to the boiler system. If there is, it is either on and adding when needed or isolated by a valve. Typically systems are best when isolated to control any leaks. These systems should have some form of protection from low water situations so that the boiler can't dry fire.

If there is no feed that you can find, hook a garden hose up to a boiler drain and connect the other end to a hose bib somewhere in the house. Once the hose is connected, open up the house bib to pressurize the hose. Then at the boiler drain, slowly open the drain until the boiler has sufficient pressure. 15# or so...

A schematic may or may not help you. You can go to W-M's web site and look up the OIM pdf file and read the recommended way to install it. That may or may not be the way this boiler was installed.

What you should take is a digital camera... if you get stuck, show us pix.

----- ----- ----- ----- -----

0. Cut the power to the boiler and pump(s)...

1. Pressurize - final cold state should be around 15# unless it's 3 storeys or more...

2. Bleed everything until you get water -- while doing this you will be losing pressure so if you have to manually add water through a hose, bump it to 25# if it's just you filling and then running around and bleeding everything. You can let a bit off pressure off at the drain at the end of bleeding if it's still over 20#.

3. If once, everything is bled and you fire up the boiler and you find the pressure going into the high 20s and you have a conventional tank, then you'll need to drain it.

3a Shut it all down
3b Close the valve on the pipe between the tank and the boiler piping
3c Open the expansion tank drain and drain it completely - 100% empty
3d Close the drain, then crack the isolation valve to the system a wee bit
3e You'll need to add more water through the feed or hose to get pressure

 

A belated thanks to each of you for all the information. Turns out she had a water feed valve that was closed, causing low pressure. Once I opened it, we got pressure, turned the furnace on, bleeded each rad and maintained pressure. I "overfilled" the system and the relief valve kicked in. I re-bleeded the rads and the system is working!! Heat in all rads, including 2nd floor. You guys are great!! Again, thanks.
Dadthehelper