Pressuretrol setting and tapping air vents

Ralph Blaine

I've been reading chapter 8 in Dan's "Lost Art..." - I'm finding out stuff I should have known about this house of mine 25 years ago. I have a couple (for now anyway) questions. First off I should note that I have a one-pipe steam system that originally ran on coal (house built in 1883) then switched to oil and now natural gas. The house was split into a duplex and a few rads moved around a bit. There are no vents on the mains except a little Gorton (like you see on a rad) on a riser in the basement that goes up to the third floor. This riser (and the whole system) is very quiet and well behaved at the start of the season but when the weather gets real cold I start to hear banging. I suspect the pressure is set too high because I have had problems with rads working well at the beginning of the season but then steam just will not get to them(the vents became water logged) later on although this problem is less severe now that I have replaced Hoffman valves (1A's) with Gortons.

1. All but one of my rads have air vents on the opposite side from steam inlet but they are up on the highest point - like a hot water rad. Sure enough they don't get very hot in the botton sections away from the inlet side. I'm going to tap some holes to put the vents down lower. Here's the problem. One of the rads has the vent hole smack up against the wall - can't get a drill in there. I could only get a Gorton vent on this rad by putting a small male elbow into the tapped hole, coming up with some 1/8" pipe and then another elbow for the vent. So the vent is quite a bit higher than the rad. If I can't drill into the far end of the rad could I drill into the last "vane" on the side away from the wall? It might be an angled surface and it might look funny but...

Also when I got the tap the specs said to use a drill bit labelled "R". The hardware store didn't have letter bits - they said 21/64 would do the job. Will this be OK?

2. In Dan's book he talks about the Pressuretrol. I have a Weil McLain gas furnace with two Honeywell PA404A Pressuretrol's. One of these is hooked up to a coiled copper pipe coming out of the furnace -the CutIn setting is at 2 PSI. This Pressuretol is on a T joint leading to a standard needle pressure guage and this needle guage is also on a T which leads to the second Pressuretrol which is also set at 2 PSI. This second Pressuretrol is wired into the low water cut off valve and also into the first Pressuretrol. The first one is wired into the furnace. Why do I need two?

I'm wondering if my Hoffman valves have a lower "Drop-Away" pressure than the Gortons's and that's why I'm getting better performance once I replaced the HOffmans or is there still a problem with the 2PSI setting? Would it hurt to lower the setting?

Finally, if I install proper main vents I need to know where to put them. I'm hoping I find the answer to this question in Dan's book so I'll hold this one for now.

Finally thanks for all the good stuff in this forum. I only found it last year and it has made a big difference in my understanding of my steam system.

Steamhead

First, crank that Pressuretrol down

as far as it will go. If the system is large, your local code may require redundant controls.

Second, move the radiator vents to the lower holes. I'm not sure of the exact drill size but it should be no larger than the end of the tap at its narrowest point. For the one rad that needs the pipe extension, use 1/8" brass pipe and fittings so they will not rust up. Drilling into the last section where it's more accessible is another option.

Third, you NEED to add main vents. Measure the length and diameter of each main and we'll tell you what's needed. They go near the ends of the mains between the last radiator takeoff and the drop pipe to the return.

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Ralph Blaine

Thanks for the advice. I did lower the pressuretol setting and and tapped the holes lower on the rad (the 21/64th drill worked fine if anyone out there needs to do such a job) everything is working fine - the real test will be come January. I know I need to add vents to the mains but ... These mains have corrugated asbestos around then and at the ends (90 degree joints) there is some kind of asbestos plaster that has been mudded on and then wrapped with cheesecloth or something like that. I know this is not nice stuff and probably best left alone but any advice you could give me about this would be greatly appreciated - especially since at a few locations the covering on the asbestos is degrading and the asbestos itself will flake off if touched. I have to confess that I tend to push this problem to the back of my mind because I don't know what to do and am afraid of what I might find out.