I have a 1-pipe steam system with a new Burnham IN-4 boiler. The boiler was installed in September, replacing an old converted coal-fired unit that was probably 80 years old. The gas conversion, at least, was done in 1963.
One of the changes to the system has been that the new boiler can now make steam pressure, where the old boiler could fire all day and never raise the pressure above 1/2 psi or so. So I need a recommendation on a bullet-proof air vent. The air vents from Home Depot seem to work OK, but tend to fail often. When they fail, they will burble steam and water, hissing and spitting all the time. I also tried some Vent-Rite vents that I got from a plumbing supply house. These seem to work better, but still have failed in some cases. (The HD vents were adjustable, the Vent Rites were fixed rate).
One fix that sort of solved the vent problem was to set the pressuretrol really low, so that it cuts out around 2 psi. But this then means that the boiler short-cycles. It will satisfy the pressuretrol, cut out, and then restart again in a matter of a few minutes. Recently with the really cold weather, I turned the pressure back up to around 5 psi to see if I could get more heat out of the system. (I had some windows open at night because of some polyurethane work being done downstairs) This worked, but now the air vents are leaking again and I need to add water to the boiler too frequently.
I suspect that part of the problem is that the boiler is oversized relative to the piping and radiator load. The benefit is that everything comes up to temperature quickly, but I’d also like to have the system run more steady state without cycling. Also, I think the overzealous steam production might cause too high a steam velocity in the system, causing the air vents to clog.
Is there a way to adjust the firing rate of the boiler? I have two methods in mind – adjusting the pressure regulator, and resizing the jets in the burner manifold. However, I have not tried either of these – the regulator does not seem to have an easy adjustment and I need a new source of pipe plugs to play around with the jetting.
So here are the questions:
1)What’s the best air vent? Can I use a high volume vent to reduce clogging?
2)What’s the right pressuretrol cut out and differential setting?
3)How do I adjust the firing rate of the boiler?
Thanks for reading this long-winded post, I appreciate any help and suggestions.
Alec S
Replies
You may get the answer you seek here, but you should also try your question here:
http://forums.invision.net/index.cfm?CFApp=2
The Heating Help site of Dan Holohan.
carpenter in transition
I had one of these with roughly the same problem a long time ago.
I ended up reducing the flame size in the unit somehow. Trouble is, I don't recall how it was done. But it helped quite a bit.
Maybe whoever put the boiler in would be the one to contact...
You can always spot a well informed man - his views are the same as yours [Ilka Chase]
Go to http://www.heatinghelp.com and go to the FAQ section. There are excellent books you can buy. You do not wantyour pressure above 2 psi. It should be running at 1/2 psi.
The problem may be your boiler size. Was it sized based on the radiators and pipe runs in the house, accounting for room wall/roof/window exposures, or was it replaced in kind? The original coal boiler was sized for having the window open on the coldest day, which you probably will not be doing. An oversized boiler will short cycle.
The spraying from the vents is probably from dirty water. Was the oil bled from the new boiler? Have you been flushing it regularly?
...that's not a mistake, it's rustic
Jeff,
Thanks for the info. The boiler was sized by the contractor based on the radiators and piping. I think it was the case that the next smaller boiler (IN3) would be cutting it close, so they went with the IN4. I have been flushing the water, which was extremely dirty at first, both from the disruption to the piping system that occurred and from the new boiler. The water is cleaner now when I drain it, but I have reduced the frequency that I am draining the water.
Setting the pressuretrol at 1/2 psi will be difficult, partly because the lowest indication on the pressuretrol gage is 2 psi, going up to about 15 psi.
I agree that it's probably oversized, that's why I wanted to adjust the firing rate.
I posted the question @ heating help. Thanks for the tip.
Alec