Boiler Short-Runs + Kettling

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Old 02-13-18, 06:06 PM
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Boiler Short-Runs + Kettling

Hey everyone,&amp;lt;br /&amp;gt;&lt;br /&gt;<br />
&amp;lt;br /&amp;gt;&lt;br /&gt;<br />
New homeowner here, not at all familiar with boilers and radiant heating. My house is 2 story, ~1,500 sq ft. I've had 3 different companies come out to try and fix the problem, none of them have acted like they've serviced a hot water boiler before. Next company can't make it until next week and my hopes aren't high. Each time they say to bleed the rads and the problem will go away, but it hasn't despite bleeding each rad until water comes out. Not only does it kettle, it has been short running, turns on and runs for a couple of minutes then shuts off. Tstat is old school mercury, anticipator set at .4 per the instructions on the boiler. Aquastat is set at 180 and pressure is around 12 PSI. I've noticed when the circulator turns on, the temperature drops from about 170 down to below 120 usually. It is my understanding this is not good for the boiler or pipes. I'm also not sure what the purpose of the 2 gate valves on what I believe to be the return pipes. The boiler is a Weil-Mclean CG-5-PIDN. Any thoughts of recommendations would be greatly appreciated.
 
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Last edited by Cubsfan2159; 02-13-18 at 06:35 PM.
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  #2  
Old 02-13-18, 07:23 PM
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C,
First, a couple of questions. In the 1st pic of the expansion tank. Is the valve to the tank open. It should be, if not open it.

Next, In the 2nd pic you have a red ball valve that's closed. What does that go to and why is it closed.

Your temp is fine , your stat is OK as far as the settings go. Being old is not a penalty.

My guess is you have 2 valves on your return lines because your system, although being just 1 zone might be separated by 2 feeds and returns for the different floors and those are isolation valves to shut off a floor if needed. Just a guess without seeing it.

As far as your large temp drop when the boiler first comes on is most likely because you have a large water content system connected to a low water content boiler and when the pump comes on it empties out the boiler of the hot water and sends back cold system water which is more than what you have in the boiler.

Judging by what the size of the pipes I can see, you had a large boiler at one time with most likely cast iron rads still be used. You could have used a bypass line to temper the return water temp coming back into the boiler but that is a quick fix if needed.

As far as short cycling goes you have a 5 section boiler, and although compared to what was there is smaller in size , it's still a good size boiler BTU wise and it may be shutting off on limit which means that the boiler is making hot water faster than it can be delivered.

You may have an oversize boiler for your system or you may need a little larger pump with a larger flow rate.

When the boiler was replaced it's possible a heat loss wasn't done to size it right.

Your pressure, although a little low for my taste is OK. I like 18-20 psi.

What are you calling kittling. If you are getting heat there is no sense to keep bleeding the rads.

Just my thoughts, hope this helps a little.
 
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Old 02-14-18, 05:04 AM
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All "Spotts" statements are correct and I can only add that If the old system had cast iron radiation, which most did, those old systems ran the circulating pump 24/7 any time the supply water temperature was above 110 degrees . This 110 degrees setting was arbitrary and could have been slightly higher to continually circulate the heating water in the system and would "even out " the temperature in the home. The boiler was controlled by a thermostat similar to yours and a reverse acting aquastat controlled the pump. Cast iron radiators are a great heating system since they heat by radiation and convection and baseboard finned tube only heat by convection. You are right when you stated that the high draw down of the temperature from near 170 degrees to about 120 degrees is hard on the boiler. That was another reason for running the pump 24/7 So let me ask; What problem or problems are you trying to correct, the boiler short cycling, uneven heating of the rooms, some other problem. Why did you have numerous contractors at your home? What were they trying to fix? Waiting for your reply with a little more information and what are you calling "KETTLING".
 
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Old 02-14-18, 09:16 PM
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Hey Spott,
Thanks for the response. I believe the valve to the expansion tank is fully open. That red ball joint is on the same line as the expansion tank. It sets right where this line splits, one line running in to the boiler, and the others going out to the rads. I'm calling the kettling the popping sound happening in the boiler that I can hear throughout the pipes and rads. Maybe this isn't the correct term.
 
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Old 02-14-18, 09:22 PM
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Hey Steamboy,<br />
<br />
The boilers seem to heat evenly. It's mainly the horrible popping sound that I've had them come out to look at. It's very loud, I can hear it clearly all through the house even though it seems to be originating in the boiler. I was also hoping someone would be able to explain the basic operations of the boiler, maintenance I should be doing, and if I could improve the efficiency and short-cycling. The most recent contractor couldn't even tell me how to add to water to the system. They weren't sure if it was an autofeed or manual feed (it's manual). This probably should have been my first red flag but he did bleed the rads some more and the popping sound decreased temporarily.
 
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Old 02-15-18, 03:49 AM
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You said that the boiler short cycles, does the pump stay running during these on/off cycles or does it cycle on/off with the boiler? Have you timed these on/off cycles? If you did, how long is the "on time" and the "off time"? Do you get the popping noise when the boiler water temperature falls to around 120 degrees or does it pop only after the boiler has been running and the water temperature is rising to near it's peak? When the burners come on, how long does it take for the water to rise from the low of 120 to 170/180 degrees? When the boiler is making the popping noise, use a rag or glove to protect your hand and hold the boilers discharge pipe. Does the popping noise coincide with a movement or vibration in the pipe? Does it feel as if the water is pulsating in the pipe? Is the popping just a noise or can you feel it in the pipe? When the boiler is making the popping noise, does the pressure gauge needle move with the popping noise? I am curious as to where in the US are you located?
 
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Old 02-15-18, 11:22 AM
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I am talking about the red handle valve on the black 1/2 or 3/4" pipe coming out of the boiler.

If that pipe goes to the expansion tank it should be open so the heated water has some place to go.

Can you post a wider angle shot of that line going into the tank and if it is you should open that valve.

Also do you have pics of your feed line going to the boiler.
 
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Old 02-15-18, 12:30 PM
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I live in Illinois. On colder days the cycle is usually run 3-4 minutes, then off for about 10. It also doesn't always get up to 170s even on the coldest days. For example it will be 170, circulator will turn on and cycle until temp drops around 120, then burners fire but only run for a coupe of minutes and the temperature only increases 10 degrees. It's warmer today so its only running about once an hour for a couple of minutes, boiler temp has been steady around 80 degrees. The popping starts shortly after the boiler starts running, regardless of temperature. And I can feel the popping noise when I hold the discharge pipe as you instructed, but there is no visable movement. The needle doesn't move with the popping.
 
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Old 02-15-18, 12:53 PM
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Hey Spott,<br />
<br />
Sorry for the misunderstanding, I see the valve you're talking about. It doesn't lead to anything and I'm not sure what it's for. I'm having a hard time getting a proper picture of the feed line. There's a gate valve on the other side of the wall and that line feeds into one of the return lines
 
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Old 02-15-18, 04:46 PM
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I can see it now, thanks. That tapping on a Weil McLain boiler is for an automatic air vent. If you wanted to feed your boiler with an auto feeder in stead of the way it is now you could do that as well.

If you wanted to replace that elbow above the valve with a tee and add a vent and your feeder station that's fine. You could shorten the pipe if you wanted but that would require you to drain the system. If you leave the pipe as is you wouldn't have to touch the system to add your pressure reducing valve.
 
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Old 02-17-18, 09:32 AM
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Awesome, that's good to know. I may do that this summer. I think one of the problems is the pressure is on the low side already, and when the system cools off it drops even further, allowing air in through the automatic bleeder valves on some of the upstairs rads. Thanks for all the advice spott & steamboy.
 
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