expansion tank part 2 critique my system

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Mar 10, 2009
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WV
I started a new thread on this because my previous picture was fairly innaccurate. I have included a drawing that is exactly what I have The propane boiler was already at the house and setup this way. I just piped in the wood boiler.
You guys please tell me what you would do different. I dont want to get complex just keep a basic system. This sytem worked great this winter with the exception of air getting trapped inthe propane boiler daily. I would raise the popoff valve and get air for about 1-2 seconds.

My thinking is to swap locations with the pressure tank and the air vent stem? Whats your thoughts
 

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Usually the vent and the pressure tank are in the same location. 1 common way is with a "air scoop" with vent on top and tank hanging off bottom. 2nd would be a Spirovent which is like a really efficient scoop with tank on the bottom.
Are you adding a lot of make up water ? Try shutting off you make up water supply and see what happens to your system pressure.
Rob
 
Thanks for the reply. From the previous post folks were saying to put the air vent at teh highest point and highest temp and to put the expansion tank right before the pump on the suction side. I was also under the impression that the pressure tank would also help purge the system of air so putting the vent and tank together would probably not help much. Like I said earlier I am getting air caught in the propane boiler. So if I switch the air vent location and pressure tank location I'm thinking it will fix my problem and from earlier posts those will be in the right place
 
You haven't mentioned where your air scoop or spirovent is located. The ideal is to have the scoop/ vent /tank on the return side (cold) just before the circulator that is pushing into the boiler. This positioning has to do with when the air is most available for extraction ( low pressure / cold water ). The catch is when plumbing to a WB that has a tempering or mixing valve that is no longer an ideal spot because of the reduced water flow. So. you would move the assembly to the supply side ( hot / out ). But the way you have it drawn you aren't showing a mixing valve so it seem the best place would be to locate scoop/ vent/ tank at your current vent position.
If you look through the stickies at the top of our forum you will see the proper positing in a couple different applications. There were also of threads on this topic too.....
Rob.
 
I dont have either one of the vents you are referring too. The vent in the drawing is like a taco 400 hyvent. Small canister with valve like a car tire on top. I have these vents on all the baseboards in the house as well.

So what I am understanding is this. I should relocate the expansion tank to right before the pump on the cool suction side. Now where and what kind of air vent should I install. Keep in mind that the only air that i get in my system is in the propane boiler and it is a daily occurrence. Not a big deal to pull the popoff for a second and even if I dont it still seems to heat fine and move water good.
I'm still thinking some type of vent on the hot line between the wood and propane. This is the hottest and highest point besides the second floor baseboards which all have vents
 
Search under "location spirovent"
This is a thread that I asked the same question a while back and a good, reliable response.
https://www.hearth.com/econtent/index.php/forums/viewthread/40804/
another response about the same issue from same individual
https://www.hearth.com/econtent/index.php/forums/viewthread/40760/ go about half way down page.
The suggestion of putting the tank where the vent is now and the scoop or spirovent between the WB and propane unit might be the correct answer for your situation. The spirovent style is a more expensive unit but it is more efficient at removing small air and they have a vent built into the top.
One problem with poping off the air in your propane boiler is you may develop a leak if you get some debris caught in the seal.
I have looked into this stuff myself so I jumped in but I'm not a hydronics pro.
Rob
 
thanks, yeah the popoff has actually leaked a little from time to time and I figured it was from me fooling with it. Thanks for your time and the thread locations
 
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