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ItsFixable

Hello, I am a homeowner and I had posted earlier this year about having a lot of air/sloshing going on in my hot water heating system after I had a new loop installed some 3 years ago. I have a gas fired Weil-Mclain boiler that is about 25 years old, that feeds my monoflow system. It worked well until I had this new loop installed and ever since then I have had this issue. It cycles regularly, I get heat, temp is about 160 and pressure goes from 15-18, supposedly all good according to those who have had a look. I have had numerous contractors to come out, charge me for their time, say I don't know what to tell you and walk away.

A few weeks ago I hired a contractor and they redid the work going to the new loop. Initially the first contractor, who had installed a baseboard, I have convector radiators elsewhere in the house, had installed a monoflow tee coming off the main pipe, going to the baseboard and then another monoflow tee rejoining the main pipe. This second contractor removed that and has the piping simply go to the baseboard and then rejoin the main piping without any tee's, see picture below. This second contractor also moved the expansion tank from the fill side to the pump away side, and added a spirovent.

This happened a few weeks ago and since then, the vent sounds like a tea kettle, 2-3 times per day and I also collect water by the pressure relief valve piping, which I never did before. When he first did the modification, there was about 3/4 cup of water and since then I get about a teaspoon each day. I was told the spirovent is functioning as should and not to worry about the water since that would involve draining the system again and it isn't worth it unless the amount of water gets to be a lot more.

If the system has been filled, and bled, then why do I keep having air coming out of the vent? All the radiators heat up, I only get air out of one of the radiators, and that is a large one right by the boiler. Also, the sloshing got worse again this past weekend. It was colder again and the system was working more frequently, I am not sure if that is why. According to what I have read, I should not be having this issue since it is a closed system.

Now I am beginning to wonder that maybe the work I had done initially did not cause the problem, it was just coincidence. Could I have a leak in the system? I started looking at the radiators as best I can and so far I do not see anything obvious. My basement is partially finished and I dread having to rip the ceiling apart, if I do not have to.

Also this morning, the temp shot up to 190 and the pressure was almost at 20. The weather is more mild but I would not think that would affect how high the temp would get.

I would greatly appreciate any input so I know what to look for and what to ask of contractors as I start calling them back and/or find new ones.

delta T

To clarify:
1. The expansion tank is now located on the return side of the black pump?
2. Is your monoflow loop only 3/4"? (Cant be sure but if the newest contractor removed the monoflow tees and piped directly to the baseboard loop makes it look like your monoflow loop is only 3/4, which seems very small)
3. Have you checked the pressure gauge on the boiler for accuracy? (attach another pressure gauge that you know is accurate or at least close, to a hose bib somewhere on the system)

Stand back and take a picture of all the piping near the boiler in one shot so we can see how it is piped please.

ItsFixable

Thank you for your questions.
1.The expansion tank is now on the side of the pump that goes away from the boiler.
2. I am not sure what size the loop is. I believe they matched the size of the existing piping. The last contractor definitely removed the tees, I am putting a picture below so that you can compare the before and after images.



3. I would not know how to do that. What is a hose bib?

Here is the complete system.

delta T

Okay.

The expansion tank is in the wrong place, I think the contractor does not understand the idea of 'pumping away'. The expansion tank should be on the inlet side of the pump. For a more detailed explanation of why that is, search 'pumping away' on this site.

If the rest of the monoflow loop that the new baseboard loop is connected to is 3/4, then careful consideration should be made as to how much baseboard that loop can support. How many feet of new baseboard was connected? How many feet were connected already?. When the monoflow loop is interrupted like that it adds a significant amount of restriction to the loop, and combined with the fact the pump is in the wrong place, should explain the air problems. Was the expansion tank replaced when the spirovent was added? If the expansion tank was not replaced, has it been verified to be set at the correct pressure? (This would involve removing it completely from the system). If the expansion tank is not functioning correctly, this would explain the relief valve dripping. A hose bib is anywhere with an easy hose pipe connection so you can attach a pressure gauge, you have one integrated into the shutoff valve above the black pump. If you check the pressure, be sure to check it when the system pumps are all off. This will give you the static pressure. The pressure in the expansion tank should be set to the system pressure when the system is cold. The system pressure should be set no lower than 12, and 6 psi for every 10 feet above the boiler. (12 works for up to two stories, 18 recommended for 3).

delta T

Now that I look more closely at the piping, are you sure you have a monoflow system? The black pump connects to a large diameter black pipe in the ceiling, where does the green pump connect to, does it too connect to a large diameter in the ceiling as well?

EBEBRATT-Ed

I'd like to comment but I can't see enough of the system. Can you post a sketch? There is probably a simple fix. Monoflow systems are fine. There only problem if there is one is that they can be finicky to get the air out. And your expansion tank is in the wrong location. To really fix it right the pumps need to be relocated to the supply pipes.

Check "find a contractor" on this site, where are you located? Someone may have a reccomendation

mattmia2

What is the pressure when both circulators are running and the boiler is hot? It would seem that would be the worst case. The way the system is piped the circulators are pushing water in to the expansion tank instead of through the system so if I'm thinking about it right, the worst case is when both circulators are running.

The test to see if there is a leak is to turn off the water to the pressure reducing valve and see if the system loses pressure, but I am hesitant to suggest that until we sort out which part of the knuckleheading is causing the relief valve to open.

The water is coming out of the lower open pipe from the relief valve in the boiler, not the higher open pipe from the backflow preventer before the pressure reducing valve, right?

ItsFixable

delta T,
Yes, I have been told by many that it is a monoflow system. That is the return pipe going to the black pump. I have two pictures showing coming back and going out to the boiler.






The green pump connects to a smaller pipe, which is on a separate second zone.