Changing pitch and high pressure

malex

I am just starting to use the steam system that came with my 1939 cape colonial. I'm trying to tune up the system to work as well as possible and I will insulate the mains, change out vents (radiator and main stem) but I have a few remaining questions:



One of the two main stems goes along the length of the basement with a upward pitch until it gets to the end of the basement where it makes a 90 and starts pitching down a couple of feet in until it gets to the return line at the end of this stretch. There are a few elbows out to radiators where it is pitching down and they do work as far as giving off heat. I'm wondering if this is a sag or by design, which would mean that the condensate from the radiators on the first stretch of the main stem flows back in the main stem while the condensate from the radiators on the last stretch flows the other way into the return. If by design, is it good design and if not, what are the alternatives? The return line runs a few feet up along the wall and will complicate the the basment refinish I am considering so re-piping parts of the system is not out of the question, especially if the performance would also increase.



My other questions is about pressure. I have only been running the system for a few days and the pressure hovers around 10psi while cycling, which I understand is high. The preassuretrol cut in was set to 0.5 and i decreased the differential to 1 from the 4 it was set to, but with no change in pressure. Even before adjusting the differential it seems the pressure should not go as high as 10psi. Could a clog cause this (maybe in the pig tail) or could the old main vents be the culprit? (I found a hanging label on one of the vents that said it had been replaced in 1964 so they definitely need replacing). Or is there anything else that would cause the system to run at 10psi. Its a fairly compact house and the boiler seems well proportioned but I can get the details if that will help.

Steamhead

Fix the pressure situation first

there is no way you need to run 10 PSI. I suspect the pigtail under the pressuretrol is plugged, or maybe the pressuretrol itself is.



It would be best to have the system looked at by a pro, since you're new to it. Where are you located? Have you tried the Find a Contractor page of this site?

Hap_Hazzard

It has to be the control

Whatever the vents are doing to the pressure, that should only cause the pressuretrol to shut off the burners sooner. If the pressure rises above the setting, the control is not working. A clogged pigtail (steam trap, siphon, etc.) is the most likely culprit, and it's the easiest thing to test and replace. 10 psi is way too high. Five more and your safety valve will open, and you'll have a big puddle on your basement floor and a furnace heating a rapidly diminishing volume of water. Then the fun really starts.



Regarding the pitch of the mains, that depends on whether you have a concurrent or countercurrent system, and you can tell that from where the drip connections are.



In a concurrent or parallel flow system, the mains slope steadily downward from the riser, so that condensate and steam both flow away from the boiler, to the drip connection, which drop vertically to the wet return--or, there may be a dry return that runs back towards the boiler and drops shortly before reaching the boiler. In either case, the main vents should be located just before the drip connections.



In a countercurrent system, the mains pitch upwards as they go away from the boiler so the condensate runs back towards the boiler, where drip connections allow it to run back to the return rather than re-entering the risers.



If your mains are pitched upwards initially, and there are no drip connections between the high points of the mains and the risers, that sounds like a mistake. You never want water running back down your riser when you're trying to send steam up it. If there are no branches in those upwardly-pitched sections, the only condensate would be what is formed in the mains themselves, and you can minimize this by insulating them thoroughly, but you can't eliminate it without correcting the piping--but don't get started on that now.

BobC

gauge?

What does the pressure gauge read when the boiler is cool? it's possible that gauge just isn't working anymore.



Does the system act or sound any different since you moved that wheel from 4 to 1? If it all seems to be the same i agree that the pigtail tube maybe blocked with sludge, it should be removed and checked and the pressuretrol should be checked for blockage as well.



If your not comfortable doing this yourself, call in a knowledgeable steam pro.



Bob

malex

Copper return from header

Thanks folks, I will be bringing in a pro for the preassure situation as needs to be addresses correctly the first time (no trial and error here).

For the pitch question, I noticed that the header is pitched awayfrom the riser and at the low end there is a 1 1/2 inch copper pipe that is connected to the boiler return but it doesnt have a hartford loop like the other return coming from the end of the basement has.

is this a common design that some radiators condensate flows back to the header and the furthest radiator's condensate go the other way to the far end return. It seems like this is a mix of counterflow and paralell design.

I will try to get some pics up tonight as that will likely explain things better.

malex

Guage working

Bob,

The guage seem to be working and is at 0 when cold and slowly goes down from 10 in the off cycle. must be the pressuretrol then that is either not working or the pig tail is clogged. I have read about pros preferring vaporstats. What is the main advantage and should I ask to have one installed if the pressuretrol is shot?

BobC

saves fuel

If the pressuretrol is shot a vaporstat will allow the system to run at lower pressure and will save fuel in the long run. It may take a few of years to pay you back but it will even though it costs almost twice what a pressuretrol does..



Bob