too much pressure??

JohnG_3

Here is a schematic of my mains. The pipe diameter is 2". It is a one-pipe counterflow system. Counterflow systems are supposed to use one pipe size larger mains than non-counterflow systems; I don't know if that is the case for my system. Each main continues into a smaller-diameter horizontal runout and each of the two runouts feeds two radiators. My system works pretty well, but I have two minor complaints: 1) it takes a long time (30+ minutes?) to warm up all radiators from a cold start, and 2) the radiators fed by the runout on the bottom main take a long time to get hot.

xx_2

TOO MUCH PRESSURE???

I have a one pipe system.
When the system is running, the radiators get hot and then the vents start to hiss loudly and sometimes gurgle. I took one off and a big rush of air went out.
Any thoughts fellas? Thanks

xx_2

xxxx

Any thoughts??

Rich L.

Pressure

Your original subject line asks if you're running too much pressure, what pressures are you running?

Jamie Hall

Um...

just off hand, if you take a vent off and get air out... there's something amiss with the venting. They are supposed to let air out (with the rate on a one pipe system controlling how fast the radiator heats up); if they don't, it's a problem...

xx_2

Let me rephase that
I get a strong surge of steam coming out.
The vents close then open and stay open even when the steam is in the radiators. That is why I am wondering if the pressuretrol is working correctly.
Best way to check system pressure?
I currently have it set at .5/1.5 diff. No way is it running at that. If it was would I have a strong surge of steam when I removed the vent off the radiator?

Gary Segal

sounds like your vent is bad

If the vent continues venting adter steam reaches it, something is wrong with the vent.

The vents only let so much air through, so I am not totally surprised that there is some back pressure when you remove the vent., however, you may want to check your main venting. If too much air is trapped in the main, it will have no place to go, but the vents in the radiators.

Radiator vents are pretty cheap - look online @ pex supply.

xx_2

I have a 45 foot main with three gorton number one vents, and a 30 foot main with two. That should be enough?
I guesss the only way to tell if the pressuretrol is off would be to install a 1-5lb guage?

JohnG_3

Check the voltage

You can check the voltage across the pressuretrol contacts when the t-stat is calling for heat. If you get 0 volts the switch is closed. Something greater than 0 volts means the switch is open.

I just installed a 0-3 psi gauge (http://www.gaugestore.com/prodinfo.asp?number=33020) and I'm barely registering any pressure at all, and heating performance is fine. The gauge plus shipping will run you about $40 or so and it's probably a worthwhile investment if you want to find out what's going on with your system. I replaced my 0-30 psi gauge with the new gauge, but this might be a code violation.

xx_2

Thanks John.
Could I attach both the code guage and the low pressure on a T off a pigtail?

Phil_17

I think so. I think I saw some pictures here several weeks ago of a setup exactly like you describe. I may eventually do that too.

I monitored my gauge this morning near the end of the morning recovery, which is typically a long burn. The pressure fluctuated between about 3 and 5 oz. Actually, 0.2 psi and 0.3 psi based on the tick marks on the dial. My pressuretrol is set for a cut-in of just over 0.5 psi with a differential of about 3 psi, so I am operating way under the pressuretrol settings.

EDIT: I found the picture, it's here.

Phil_17

I checked the pressuretrol when the therm called for heat and I didn't get any voltage across it at all.The system shut off that way. Is that correct? The run time was short, only a couple of minutes.

Geno_17

I also have a one pipe steam system and the problem is too much pressure which causes the vent to shot out water over time. Is it because the size of the new pipe is 1" from 1 1/4 or could it be the presure needs to be adjusted. Already have a good pitch on the pipes. Any help on this would be great, Thanks Geno

JohnG_3

Your post appeared to be from me. Odd.

Anyway, no voltage across your pressuretrol when the t-stat is calling for heat means you haven't hit your cut-out pressure. When you say your system shut off that way, I assume you mean your t-stat became satisfied and shut off your boiler.

I have slowly come to the realization that my system, as best as I can tell, never cycles on pressure. That is, the pressuretrol never hits its cut-out pressure and is always a short-circuit. The voltage drop across the contacts would therefore always be zero, just as you found on your system.

My heating contractor told me that residential steam systems rarely cycle on pressure, bearing out what I am seeing on my system. I am now pondering the benefit of a system that cycles on pressure under normal operating circumstances. Is it the same comfort while consuming less fuel? Or is it higher comfort while consuming the same fuel? If I can increase my comfort-to-fuel-consumption ratio then I would consider investing in a vaporstat and fine-tuning my system. Otherwise I think I'll leave well enough alone.

Leah Frances

Many times when I go to post, the "Post Reply" box comes up with someone else's name and e-mail address. I go ahead and change it over to me.
I also have seen messages by "bruhl" and said to myself, "I didn't write that". But I guess I know how it happens. Fortunately, the post I remember was quite good, not some flame thing.

bruhl

Tom Hopkins

Not cycling on pressure

My residential system always cycles on pressure after recovery and occasionally in non-recovery situations. I do not believe the difference between the response of my system and yours is one pipe vs two pipe. I think it is a function of the boiler's capacity to produce steam versus the connected load. In my case, my boiler is a bit over capacity for the connected load.

For example, if your pipes are not insulated, you may be condensing a lot of stam in the pipes, limiting the amoung of pressure you can build. Althernatively, if your radiator vents (or main vents do not close with steam, you could also be losing pressure (and water) there.

If your pipes are well insulated and your vents are working properly, I agree, there is not much more you can do.

Good luck!

Gary

Tom Hopkins

too much pressure

Geno, Do your vents shoot water after the radiator is fully hot? If so, the vent could be bad. Do all your radiator vents behave the same way?

The radiator vent should only see water if it condenses in the vent ... there is no water at that level in the radiator.

What are your cut in and cut out pressures?

Gary

JohnG_3

Thanks for the info. I'm a newbie in terms of taking an interest in my steam system and just getting the feel for how it works.

I recently put Heat-Timer Varivalves on most of my radiators. They look like they're just about the fastest vents available, so offer little resistance until they close (if they close). I have no main vents. It's a small one-pipe counterflow system, with the net boiler I=B=R output almost exactly matched to the total radiator EDR, i.e. 320 sf for both. I insulated the mains with the wrong material, polyethylene, intended for hot water and not steam pipes, so there is some opportunity for improvement there.

What do you think the benefit is of your system cycling on pressure? Would you say it's increased comfort, lower fuel consumption, or a combination of both?

Gary Segal

Are there benefits of cycling on pressure?

John,

I am not sure there are benefits, per se, of cycling on pressure. The question is, what is the most efficient way to run your system? My point is that if your pipes are not well insulated, you are condensing more steam in the pipes and sending less steam to your living area for a given burn time.

Realistically, you can look at how long it takes to get steam to the end of your main(s) and also how long it takes to get your radiators fully hot. If the time is short, there is probably little to be gained by further improvements.

There are losses associated with cycling on pressure, because invariably, it equates to short burn times on subsequent cycles. However, I think preeusre cycles are more energy efficient than longer burns that dump heat in the basement with poorly insulated pipes.

In the end, it boils down to getting the shortest duty cycle that meets your comfort requirements (... my wife would probably argue that our comfort requirements have not been met!)

Just curious, how long and what diameter is your main?

Best of luck,

Gary

Gary Segal

Timing

John, I do not have the expertise to tell you how long it should take to get heat to all your radiators. Perhaps a fresh post might get you an answer from one of the experts.

What I can say is you can divide the operation of your system up into phases to better understand the functioning of your system and diagnose whether or not you could be heating faster.

Phase 1 - Boiler makes steam. You can measure this time by opening the high pressure vent from a cold start and timing until you feel steam (caution - if it is an old vent, it may not seal closed!) or by waiting to see your water line bouncing. On my boiler, I get steam at the pressure relief valve in about 7 minutes from a cold start. There is not much you can change regarding how fast the boiler steams ... it's firing rate dependent.

Phase 2 - Steam at the ends of the mains - measure by feel. Optimize by pulling a vent (or plug) at the end of the main and seeing how much faster you get steam. It takes 12 minuted for steam to get to the end of my main, but mine is 78 feet long (giant U). The time it takes to get steam to the ends of the mains is affected by the level of insulation (Less insulation = more condensation = longer heat up time) and the size of your vents.

Phase 3 - heating the radiators - obviously by feel. Rate of heating can be affected by venting on radiators.

On your slow heating radiators, you can see if they heat faster if you pull the radiator vent (Caution - when the steam comes out the vent hole, it will be hard to get the vent back in, so replace the vent when the radiator is partially hot. Of course, if the radiators heat faster without the vents, it may also mean that your main is insufficiently vented.

Good luck,

Gary

JohnG_3

Gary, Thanks for the info. I will do the tests you suggest. John G