Water out selected radiators

Jamie Hall

Well, the old boiler was plenty big enough. The only number which counts is the steam square feet. The new one could be either around 470 or 560 square feet. Either one is much too big for your application. The -085 would have been amply big.

And that too is part of your problem. The much too big boiler produces much more steam -- at a much higher velocity. Which quite nicely explains why it didn't happen before and does now.

mattmia2

It was happening with the old boiler, just not as bad. That was why the auto feeder kept filling it during a cycle then you drained off that water, then it added more and you destroyed the old boiler with all that fresh, oxygenated water.

Jamie Hall

Even better! Perversely, I'm rather glad that it was happening with the old boiler -- just not as badly. Gives me some faith in my WAG...

mattmia2

It seems to have got to a point where it was a problem with the old system recently though, reading the original post.

transplant

But if the -085 steam square feet rating is 321, wouldn't it have been too small for my 336 required? And in sizing a system, isn't a certain percentage normally added to the EDR requirement to account for piping losses, etc?

So net: sounds like I paid a lot of money, for a too-big system, that was not plumbed in correctly and is over-straining my system to the point where I can't turn on the heat without flooding the house. Great.

Jamie Hall

The published EDR square feet rating of a boiler includes the percentage to be added for piping and what not -- called the pickup factor -- and is set at 30%. Which, if the piing is insulated is too much. In your situation, the -085 would have been perfect.

ethicalpaul

transplant said:

But if the -085 steam square feet rating is 321, wouldn't it have been too small for my 336 required? And in sizing a system, isn't a certain percentage normally added to the EDR requirement to account for piping losses, etc? So net: sounds like I paid a lot of money, for a too-big system, that was not plumbed in correctly and is over-straining my system to the point where I can't turn on the heat without flooding the house. Great.

I know it’s frustrating but it’s also very very common. Hopefully your installer will give the piping a third try to match the installation manual. I’d say your best shot is to get him gently to accept that there’s a reason for these designs—not just to connect a boiler to radiators.

then see if he or another professional is able to downfire your boiler in a safe way to get it closer to matching your EDR. That can be done when it’s colder and after you have some observations about if the system cycles on pressure.

Ironically when the header is correct it may deliver even more steam than now because there won’t be water in your mains interfering with your steam. 

If you have to get through this season with this piping, then get the water clean, keep it low, and see about that downfiring. Keeping the boiler water out of the mains will make your winter way more enjoyable. 

transplant

Thanks. By "downfiring" do you mean using a smaller nozzle size in the burner? I talked to my installer and we're going to go over things today, but he did tell me that he put in the same nozzle size that was being used in my old boiler, so would that be right? Also, should I close off those radiator vents a bit to slow down the amount of steam (and, therefore, water also) that is reaching them? Would that help avoid the water spouts I'm now getting?

mattmia2

I still wonder why the old boiler started having a noticeable problem (I suspect it is very likely it had a problem with wet steam ever since it was installed but got worse for some reason.). Did the water chemistry change or get contaminated with oil? Was the old water line surging? Did the pressuretrol get turned up when someone serviced it? Did someone increase the firing rate of the burner when they serviced it?

transplant

Mattmia2 - We had never had leakage out the radiator or main line vents with the old system, just the apparent over-filling of the boiler. Perhaps, as the guys we were working with at that time suggested, it really WAS the auto-feeder failing. We had made no changes to the system -- adding/deleting radiators, modifying lines, changing vents, etc. -- other than the replacement of one return line that had rotted and sprung a small leak in one spot. And if the service people did something like changing the pressuretrol or burner firing rate, they didn't tell me.

I'm hoping my installer will reconfigure the steam supply piping to the header in the manner described earlier. I'll also then ask him/someone else to correct those two main vents to a proper configuration. If you/others have additional recommendations, I'd be grateful to hear them.

transplant

If I'm going to improve the main vents, can anyone help me with the number and size needed for each main? Mains are 2". First one is 13' long from the header to the end where the return connects. Second one is 19' long. Third one is 26 and 1/2' long. All returns are 1".

transplant

Forgot to ask...All 3 returns from my 3 mains drop down a short bit initially, then go horizontal (with a slight tilt downward) for some distance before dropping to the floor and going back to the boiler. Those initial horizontal portions are all well over 28" above the boiler's water level. So would those portions be considered "dry returns" and, if so, would it be appropriate to locate the main vents in them? May be easier to locate new vents there than modifying the ends of my mains. Or will the reduction from the 2" main to the 1" return restrict the flow of air too much and hinder the venting we're trying to improve? Many thanks.

Jamie Hall

I'd probably use a Gorton #2 on both of those. Probably overkill, but not that much.

The pipes you are referring to as returns. If there are no traps between what you are calling mains and those pipes, and they are high -- as you say, more than 28 inches above the water line in the boiler -- some would call them dry returns. Some would call them steam main extensions. It doesn't matter what you call them; steam can -- and will -- reach them. There is some debate, also, as to whether one should vent them. However, in this instance they are a perfectly good location for main vents.

transplant

Thanks, Jamie.

Installer came back in today. Started by skimming the system again (3rd time) and also found some clogging in the pigtail. We ran the system and noticed the pressuretrol didn't seem to be holding at the .5-1 psi it was set for. Pressure gauge sometimes showed it rising to 2.5 psi, so that needs to be addressed.

We also noticed that as the boiler cycled, each time the water refilled just a little lower until during one off cycle the water remained below the LWCO (about 1/2" above the bottom of the sight glass) long enough for the auto feed to kick in. It raised the water level to about 75% of the glass. So we are next going to also look at the feeder set points for delay and amount to be added.

After that, we'll turn to the piping.

mattmia2

You need to add a low pressure gauge to accurately read the pressures a steam system should run at, you need a 0-3 or 0-5 psi gauge to be accurate at the pressuretrol range.

ethicalpaul

The piping is causing the level trouble so I wouldn’t waste any effort trying to address the auto feeder first. Just disable the water feeder until the pipes are fixed, it will only unnecessarily raise the water level.

transplant

Jamie, Mattmia2 and ethicalpaul - thanks for the additional info.

We did go ahead and turn off the valving to the autofeeder to set the water level control issue aside for now.

If we let the system run long enough, the pressure keeps getting up to 2.5psi (might have gone even higher if we didn't shut it off at that point) and we start to get some water dripping out of the main vent. The pressuretrol cut-in is set at .5 psi, cut-out at 1psi. And, again, the system was just skimmed for the third time and the pigtail cleaned. So either that controller is bad or the 2.5psi reading we're getting is wrong (per mattmia2's note, the current 0-30psi gauge is too coarse, so not sure that 2.5 is accurate).

Installer is coming back today to likely change that pressuretrol.
Once we get the pressure resolved, we'll turn back to that autofeeder again. A couple questions on that, though:

There is a plaque riveted to the front of the boiler just below the bottom fitting for the sight glass reading "Minimum water level." Yet, the LWCO (it's a probe-type) goes into the boiler at a level just under 50% up the sight glass (?). 1) Why would the probe be located well above the minimum water level? and 2) Why would the probe be located almost mid-way up the glass when that's about where the normal water level is? When the system starts making steam, it bounces a little, potentially down low enough to trip the LWCO? Should I simply put more water in to bring the standing level to, say, 75%?

Thanks for hanging in there and all the great info so far, guys...

ethicalpaul

Pressuretrols are notoriously inaccurate, always to the "heavy" side where they don't cut out as fast as we'd like. They can be calibrated, but it's a little tricky. Putting in the new one is good to try. After that, look on this site for the calibration procedure that @fred has helpfully posted many times.

Your questions:
1. The probe is always located above the minimum water level to provide additional safety. You don't want the probe at the very bottom of the boiler, only triggering LWCO when you are out of water.
2. You could take a straight-on photo of the controls side of your boiler and post it and then I can consult with the Peerless documentation to see how your boiler matches up with that. On my Peerless the normal water level is about 2/3 up the glass, and the LWCO probe is at about 1/3 up the glass. But your model may vary.

I wouldn't raise the water level of your boiler in particular, because you need to keep it on the low side due to your unfortunate near boiler piping. Otherwise gallons of water get carried into your mains (as we've been discussing)

mattmia2

if you're going to spend the money to replace it, put a vaporstat in series instead

transplant

Guys - Change of pressuretrol did nothing. System pressure still too high, cycling between 1.5 psi and 3 psi. Put a lower-pressure gauge on temporarily to verify.

So I gather the pressuretrols are really not appropriate at these low ranges, a vaporstat would be a good upgrade, but that neither should be used as on/off controllers anyway -- just as fail-safes. Ideally, a properly sized/designed system would run continuously at lowest pressure possible until thermostat temp is met.

But my boiler and, it seems from all the discussions I've read here, many/most others are not so perfectly tuned. Most people have at least some cycling, largely due to over-sized boilers like mine. The question is: how much is too much? Right now, we're having a fairly warm Fall and this boiler is running a cycle time of about 8 minutes (typically 6 on, 2 off). Is that way over the top?

This boiler is clearly oversized, but it's highly unlikely I'm going to get my installer or the Peerless dealer who told him this was the right fit to rip it out and replace it. Aside from addressing my obvious main venting and header plumbing issues, is there anything else I can do to get this close to a normally operating system?

Jamie Hall

First, the cycle timings are not way over the top -- we've seen much worse. It suggests that your boiler is only about 25 to 30 per cent oversized, which isn't bad at all. And certainly not worth ripping out and replacing -- although you might find out if it could be downfired.

You are quite right -- a perfectly tuned system will just sit there and hum along at a few ounces to half a pound. Right. Good luck with that in the real world. So in the real world, the pressure control device is more of a control device, to modulate the boiler output (on/off cycling, averaged over time, is a perfectly valid form of modulation -- whether it's a pressure control or a thermostat. Think about it.) than simply a fail safe control.

So... there would be some benefit to adding a vapourstat in series with the existing pressuretrol, however. Since you have a low pressure gauge, it is very easy to determine how it should be set. Observe the pressure gauge from a cold start. Once the boiler starts to steam, it should rise to some pressure -- usually no more than a few ounces, but it could be half a pound or so -- and then become pretty stable (if it continues to rise more than just slowly, you need more main venting) for some time. Then you will notice it start to rise again. That is the point at which the vapourstat should shut the boiler off (give it a margin of a couple of ounces), and the cutin then should be about half that fir some burners, the cutin timing will be controlled by a burner post purge and pre purge cycle instead -- don't worry about that).

transplant

Jamie - Many thanks. Adding the vaporstat seems like the way to go. Before I do, as you suggest, I want to improve the venting on two of my mains with those Groton #2s you mentioned earlier. I plan to tee into the short portion dry returns, an example of which is shown in the photo below, rather than try to somehow extend the ends of the mains themselves to give me room to put them there. Seems like a much simpler plumbing option and one that you/others said is ok to do and was echoed by a diagram in Dan's book.

One remaining question: when I install those vents, I know they need to be raised from the tee on a pipe nipple to get them well out of the way of the flow of water and any crud in the pipe. Is the normally recommended 6" still ok in this location?

Jamie Hall

That vent location should work just fine -- although photo didn't load, so I can't say for sure. And the 6 inches will be fine there, too.

dabrakeman

Similar location setup I did on my system.   Works great.  Saves me  nearly  2 minutes per cycle  as compared to having  the vents  at the other end of the dry return back by the boiler as they were previously.  Was easier for me I am sure because  there was a fitting  pre-existing on that dry return  with a plug in it  that used to be  the inlet for  a drip leg coming off  a  now non-existent  radiator.

transplant

Thanks to all for the help so far. But I think I'm back to square one.
I know I need to improve venting of the mains, re-plumb the connections to the header and a few other things. In the meantime, I've taken the advice given and kept the water level a bit low and set the dip switches on the auto feeder so it will only add a minimum of water and only after waiting the max of ten minutes.
This had been adequate for a few weeks, but the weather here in CT has been mild so it wasn't running much.
Then we had a sudden cold snap, the boiler was running more and low-and-behold the boiler over-filled again. The water was near the top of the sight glass. When it shut off and the condensate returned, it when out the top of the sight glass.
I shut it off and let it sit awhile to let all the condensate return. Then I closed off the water feed and drained it down. A full 3-4 gallons came out before I was back to a normal water level! Oddly, the auto feeder readout still showed 000.
So it looks like when the boiler runs a lot the condensate doesn't have a chance to get back, the LWCO trips and the auto feeder adds more water. This is where I was at the beginning of this saga.
Remember, I had checked the returns for clogs by pouring water down the vent holes at the end of the mains. My heating guy had also opened one return and verified it clear, along with the manifold at the back of the boiler where all the returns come together.
Any suggestions as to why all that water is apparently getting hung up in the system when the boiler runs alot?

ethicalpaul

We gave you suggestions on what causes that earlier in the thread I think.

Have you put a low pressure gauge on it yet to see what the pressure situation is like during your firing cycles?

If it were me, I would disable the autofeed while I worked on troubleshooting this.

neilc

I am suspicious of the pigtail,
I know you said it was checked, or cleaned,
but has anyone actually tried breathing thru It? including back into the boiler?
For 2 Ptrols to still fail to keep the boiler pressure down, which could be pushing water back into the returns system,
well I'm pigtail suspicious.